Copyright (c) 2012, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2012, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.osgi.container;

import java.io.Closeable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.eclipse.osgi.container.Module.StartOptions;
import org.eclipse.osgi.container.Module.State;
import org.eclipse.osgi.container.Module.StopOptions;
import org.eclipse.osgi.container.ModuleContainer.ResolutionLock.Permits;
import org.eclipse.osgi.container.ModuleContainerAdaptor.ContainerEvent;
import org.eclipse.osgi.container.ModuleContainerAdaptor.ModuleEvent;
import org.eclipse.osgi.container.ModuleDatabase.Sort;
import org.eclipse.osgi.container.ModuleRequirement.DynamicModuleRequirement;
import org.eclipse.osgi.framework.eventmgr.CopyOnWriteIdentityMap;
import org.eclipse.osgi.framework.eventmgr.EventDispatcher;
import org.eclipse.osgi.framework.eventmgr.EventManager;
import org.eclipse.osgi.framework.eventmgr.ListenerQueue;
import org.eclipse.osgi.framework.util.SecureAction;
import org.eclipse.osgi.framework.util.ThreadInfoReport;
import org.eclipse.osgi.internal.container.InternalUtils;
import org.eclipse.osgi.internal.container.LockSet;
import org.eclipse.osgi.internal.debug.Debug;
import org.eclipse.osgi.internal.framework.EquinoxConfiguration;
import org.eclipse.osgi.internal.messages.Msg;
import org.eclipse.osgi.report.resolution.ResolutionReport;
import org.eclipse.osgi.report.resolution.ResolutionReport.Entry;
import org.eclipse.osgi.service.debug.DebugOptions;
import org.eclipse.osgi.service.debug.DebugOptionsListener;
import org.eclipse.osgi.util.NLS;
import org.osgi.framework.AdminPermission;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleException;
import org.osgi.framework.Constants;
import org.osgi.framework.FrameworkListener;
import org.osgi.framework.Version;
import org.osgi.framework.namespace.HostNamespace;
import org.osgi.framework.namespace.IdentityNamespace;
import org.osgi.framework.namespace.PackageNamespace;
import org.osgi.framework.startlevel.FrameworkStartLevel;
import org.osgi.framework.wiring.BundleCapability;
import org.osgi.framework.wiring.BundleRevision;
import org.osgi.framework.wiring.FrameworkWiring;
import org.osgi.resource.Namespace;
import org.osgi.resource.Requirement;
import org.osgi.resource.Resource;
import org.osgi.resource.Wire;
import org.osgi.service.resolver.ResolutionException;

A container for installing, updating, uninstalling and resolve modules.
Since:
3.10/**
 * A container for installing, updating, uninstalling and resolve modules.
 * @since 3.10
 */
public final class ModuleContainer implements DebugOptionsListener {
	private final static SecureAction secureAction = AccessController.doPrivileged(SecureAction.createSecureAction());

	
Used by install operations to establish a write lock on an install location
/**
	 * Used by install operations to establish a write lock on an install location
	 */
	private final LockSet<String> locationLocks = new LockSet<>();

	
Used by install and update operations to establish a write lock for a name
/**
	 * Used by install and update operations to establish a write lock for a name
	 */
	private final LockSet<String> nameLocks = new LockSet<>();

	
An implementation of FrameworkWiring for this container
/**
	 * An implementation of FrameworkWiring for this container
	 */
	private final ContainerWiring frameworkWiring;

	
An implementation of FrameworkStartLevel for this container
/**
	 * An implementation of FrameworkStartLevel for this container
	 */
	private final ContainerStartLevel frameworkStartLevel;

	
The module database for this container.
/**
	 * The module database for this container.
	 */
	final ModuleDatabase moduleDatabase;

	
The module adaptor for this container.
/**
	 * The module adaptor for this container.
	 */
	final ModuleContainerAdaptor adaptor;

	
The module resolver which implements the ResolverContext and handles calling the 
resolver service.
/**
	 * The module resolver which implements the ResolverContext and handles calling the 
	 * resolver service.
	 */
	private final ModuleResolver moduleResolver;

	
Holds the system module while it is being refreshed
/**
	 * Holds the system module while it is being refreshed
	 */
	private final AtomicReference<SystemModule> refreshingSystemModule = new AtomicReference<>();

	private final long moduleLockTimeout;

	private final boolean autoStartOnResolve;

	final boolean restrictParallelStart;

	boolean DEBUG_MONITOR_LAZY = false;
	boolean DEBUG_BUNDLE_START_TIME = false;

	
Constructs a new container with the specified adaptor, module database.
Params:
adaptor – the adaptor for the container
moduledataBase – the module database/**
	 * Constructs a new container with the specified adaptor, module database.
	 * @param adaptor the adaptor for the container
	 * @param moduledataBase the module database
	 */
	public ModuleContainer(ModuleContainerAdaptor adaptor, ModuleDatabase moduledataBase) {
		this.adaptor = adaptor;
		this.moduleResolver = new ModuleResolver(adaptor);
		this.moduleDatabase = moduledataBase;
		this.frameworkWiring = new ContainerWiring();
		this.frameworkStartLevel = new ContainerStartLevel();
		long tempModuleLockTimeout = 30;
		String moduleLockTimeoutProp = adaptor.getProperty(EquinoxConfiguration.PROP_MODULE_LOCK_TIMEOUT);
		if (moduleLockTimeoutProp != null) {
			try {
				tempModuleLockTimeout = Long.parseLong(moduleLockTimeoutProp);
				// don't do anything less than one second
				if (tempModuleLockTimeout < 1) {
					tempModuleLockTimeout = 1;
				}
			} catch (NumberFormatException e) {
				// will default to 30
			}
		}
		this.moduleLockTimeout = tempModuleLockTimeout;
		DebugOptions debugOptions = adaptor.getDebugOptions();
		if (debugOptions != null) {
			this.DEBUG_MONITOR_LAZY = debugOptions.getBooleanOption(Debug.OPTION_MONITOR_LAZY, false);
		}

		String autoStartOnResolveProp = adaptor.getProperty(EquinoxConfiguration.PROP_MODULE_AUTO_START_ON_RESOLVE);
		if (autoStartOnResolveProp == null) {
			autoStartOnResolveProp = Boolean.toString(true);
		}
		this.autoStartOnResolve = Boolean.parseBoolean(autoStartOnResolveProp);
		this.restrictParallelStart = Boolean.parseBoolean(adaptor.getProperty(EquinoxConfiguration.PROP_EQUINOX_START_LEVEL_RESTRICT_PARALLEL));
	}

	
Returns the adaptor for this container
Returns:
the adaptor for this container/**
	 * Returns the adaptor for this container
	 * @return the adaptor for this container
	 */
	public ModuleContainerAdaptor getAdaptor() {
		return adaptor;
	}

	
Returns the list of currently installed modules sorted by module id.
Returns:
the list of currently installed modules sorted by module id./**
	 * Returns the list of currently installed modules sorted by module id.
	 * @return the list of currently installed modules sorted by module id.
	 */
	public List<Module> getModules() {
		return moduleDatabase.getModules();
	}

	
Returns the module installed with the specified id, or null if no 
such module is installed.
Params:
id – the id of the module
Returns:
the module with the specified id, or null of no such module is installed./**
	 * Returns the module installed with the specified id, or null if no 
	 * such module is installed.
	 * @param id the id of the module
	 * @return the module with the specified id, or null of no such module is installed.
	 */
	public Module getModule(long id) {
		return moduleDatabase.getModule(id);
	}

	
Returns the module installed with the specified location, or null if no 
such module is installed.
Params:
location – the location of the module
Returns:
the module with the specified location, or null of no such module is installed./**
	 * Returns the module installed with the specified location, or null if no 
	 * such module is installed.
	 * @param location the location of the module
	 * @return the module with the specified location, or null of no such module is installed.
	 */
	public Module getModule(String location) {
		return moduleDatabase.getModule(location);
	}

	
Creates a synthetic requirement that is not associated with any module revision. This is useful for calling FrameworkWiring.findProviders(Requirement). 
Params:
namespace – the requirement namespace
directives – the requirement directives
attributes – the requirement attributes
Returns:
a synthetic requirement/**
	 * Creates a synthetic requirement that is not associated with any module revision.
	 * This is useful for calling {@link FrameworkWiring#findProviders(Requirement)}.
	 * @param namespace the requirement namespace
	 * @param directives the requirement directives
	 * @param attributes the requirement attributes
	 * @return a synthetic requirement
	 */
	public static Requirement createRequirement(String namespace, Map<String, String> directives, Map<String, ?> attributes) {
		return new ModuleRequirement(namespace, directives, attributes, null);
	}

	
Installs a new module using the specified location. The specified builder is used to create a new revision which will become the current revision of the new module. 

If a module already exists with the specified location then the 
existing module is returned and the builder is not used.
Params:
origin – the module performing the install, may be null.
location – The location identifier of the module to install.
builder – the builder used to create the revision to install.
revisionInfo – the revision info for the new revision, may be null.
Throws:
BundleException – if some error occurs installing the module
Returns:
a new module or a existing module if one exists at the 
    specified location./**
	 * Installs a new module using the specified location.  The specified
	 * builder is used to create a new {@link ModuleRevision revision} 
	 * which will become the {@link Module#getCurrentRevision() current}
	 * revision of the new module.
	 * <p>
	 * If a module already exists with the specified location then the 
	 * existing module is returned and the builder is not used.
	 * @param origin the module performing the install, may be {@code null}.
	 * @param location The location identifier of the module to install. 
	 * @param builder the builder used to create the revision to install.
	 * @param revisionInfo the revision info for the new revision, may be {@code null}.
	 * @return a new module or a existing module if one exists at the 
	 *     specified location.
	 * @throws BundleException if some error occurs installing the module
	 */
	public Module install(Module origin, String location, ModuleRevisionBuilder builder, Object revisionInfo) throws BundleException {
		long id = builder.getId();
		ModuleRevisionBuilder adaptBuilder = getAdaptor().adaptModuleRevisionBuilder(ModuleEvent.INSTALLED, origin, builder, revisionInfo);
		if (adaptBuilder != null) {
			// be sure to restore the id from the original builder
			adaptBuilder.setInternalId(id);
			builder = adaptBuilder;
		}
		String name = builder.getSymbolicName();
		boolean locationLocked = false;
		boolean nameLocked = false;
		try {
			// Attempt to lock the location and name
			try {
				locationLocked = locationLocks.tryLock(location, 5, TimeUnit.SECONDS);
				nameLocked = name != null && nameLocks.tryLock(name, 5, TimeUnit.SECONDS);
				if (!locationLocked) {
					throw new BundleException("Failed to obtain location lock for installation: " + location, BundleException.STATECHANGE_ERROR, new ThreadInfoReport(locationLocks.getLockInfo(location))); //$NON-NLS-1$
				}
				if (name != null && !nameLocked) {
					throw new BundleException("Failed to obtain symbolic name lock for installation: " + name, BundleException.STATECHANGE_ERROR, new ThreadInfoReport(nameLocks.getLockInfo(name))); //$NON-NLS-1$
				}
			} catch (InterruptedException e) {
				Thread.currentThread().interrupt();
				throw new BundleException("Failed to obtain id locks for installation.", BundleException.STATECHANGE_ERROR, e); //$NON-NLS-1$
			}

			Module existingLocation = null;
			Collection<Module> collisionCandidates = Collections.emptyList();
			moduleDatabase.readLock();
			try {
				existingLocation = moduleDatabase.getModule(location);
				if (existingLocation == null) {
					// Collect existing current revisions with the same name and version as the revision we want to install
					// This is to perform the collision check below
					List<ModuleCapability> sameIdentity = moduleDatabase.findCapabilities(getIdentityRequirement(name, builder.getVersion()));
					if (!sameIdentity.isEmpty()) {
						collisionCandidates = new ArrayList<>(1);
						for (ModuleCapability identity : sameIdentity) {
							ModuleRevision equinoxRevision = identity.getRevision();
							if (!equinoxRevision.isCurrent())
								continue; // only pay attention to current revisions
							// need to prevent duplicates here; this is in case a revisions object contains multiple revision objects.
							if (!collisionCandidates.contains(equinoxRevision.getRevisions().getModule()))
								collisionCandidates.add(equinoxRevision.getRevisions().getModule());
						}
					}
				}
			} finally {
				moduleDatabase.readUnlock();
			}
			// Check that the existing location is visible from the origin module
			if (existingLocation != null) {
				if (origin != null) {
					Bundle bundle = origin.getBundle();
					BundleContext context = bundle == null ? null : bundle.getBundleContext();
					if (context != null && context.getBundle(existingLocation.getId()) == null) {
						Bundle b = existingLocation.getBundle();
						throw new BundleException(NLS.bind(Msg.ModuleContainer_NameCollisionWithLocation, new Object[] {b.getSymbolicName(), b.getVersion(), location}), BundleException.REJECTED_BY_HOOK);
					}
				}
				return existingLocation;
			}
			// Check that the bundle does not collide with other bundles with the same name and version
			// This is from the perspective of the origin bundle
			if (origin != null && !collisionCandidates.isEmpty()) {
				adaptor.getModuleCollisionHook().filterCollisions(ModuleCollisionHook.INSTALLING, origin, collisionCandidates);
			}
			if (!collisionCandidates.isEmpty()) {
				throw new BundleException(NLS.bind(Msg.ModuleContainer_NameCollision, name, builder.getVersion()), BundleException.DUPLICATE_BUNDLE_ERROR);
			}

			Module result = moduleDatabase.install(location, builder, revisionInfo);

			adaptor.publishModuleEvent(ModuleEvent.INSTALLED, result, origin);

			return result;
		} finally {
			if (locationLocked)
				locationLocks.unlock(location);
			if (nameLocked)
				nameLocks.unlock(name);
		}
	}

	
Updates the specified module with a new revision. The specified builder is used to create a new revision which will become the current revision of the new module. 
Params:
module – the module to update
builder – the builder used to create the revision for the update.
revisionInfo – the revision info for the new revision, may be null.
Throws:
BundleException – if some error occurs updating the module/**
	 * Updates the specified module with a new revision.  The specified
	 * builder is used to create a new {@link ModuleRevision revision} 
	 * which will become the {@link Module#getCurrentRevision() current}
	 * revision of the new module.
	 * @param module the module to update
	 * @param builder the builder used to create the revision for the update.
	 * @param revisionInfo the revision info for the new revision, may be {@code null}.
	 * @throws BundleException if some error occurs updating the module
	 */
	public void update(Module module, ModuleRevisionBuilder builder, Object revisionInfo) throws BundleException {
		long id = builder.getId();
		ModuleRevisionBuilder adaptBuilder = getAdaptor().adaptModuleRevisionBuilder(ModuleEvent.UPDATED, module, builder, revisionInfo);
		if (adaptBuilder != null) {
			// be sure to restore the id from the original builder
			adaptBuilder.setInternalId(id);
			builder = adaptBuilder;
		}
		checkAdminPermission(module.getBundle(), AdminPermission.LIFECYCLE);
		String name = builder.getSymbolicName();
		boolean nameLocked = false;
		try {
			// Attempt to lock the name
			try {
				if (name != null && !(nameLocked = nameLocks.tryLock(name, 5, TimeUnit.SECONDS))) {
					throw new BundleException("Failed to obtain id locks for installation.", BundleException.STATECHANGE_ERROR, new ThreadInfoReport(nameLocks.getLockInfo(name))); //$NON-NLS-1$
				}
			} catch (InterruptedException e) {
				Thread.currentThread().interrupt();
				throw new BundleException("Failed to obtain id locks for installation.", BundleException.STATECHANGE_ERROR, e); //$NON-NLS-1$
			}

			Collection<Module> collisionCandidates = Collections.emptyList();
			moduleDatabase.readLock();
			try {
				// Collect existing bundles with the same name and version as the bundle we want to install
				// This is to perform the collision check below
				List<ModuleCapability> sameIdentity = moduleDatabase.findCapabilities(getIdentityRequirement(name, builder.getVersion()));
				if (!sameIdentity.isEmpty()) {
					collisionCandidates = new ArrayList<>(1);
					for (ModuleCapability identity : sameIdentity) {
						ModuleRevision equinoxRevision = identity.getRevision();
						if (!equinoxRevision.isCurrent())
							continue;
						Module m = equinoxRevision.getRevisions().getModule();
						if (m.equals(module))
							continue; // don't worry about the updating modules revisions
						// need to prevent duplicates here; this is in case a revisions object contains multiple revision objects.
						if (!collisionCandidates.contains(m))
							collisionCandidates.add(m);
					}
				}

			} finally {
				moduleDatabase.readUnlock();
			}

			// Check that the module does not collide with other modules with the same name and version
			// This is from the perspective of the module being updated
			if (module != null && !collisionCandidates.isEmpty()) {
				adaptor.getModuleCollisionHook().filterCollisions(ModuleCollisionHook.UPDATING, module, collisionCandidates);
			}

			if (!collisionCandidates.isEmpty()) {
				throw new BundleException(NLS.bind(Msg.ModuleContainer_NameCollision, name, builder.getVersion()), BundleException.DUPLICATE_BUNDLE_ERROR);
			}

			module.lockStateChange(ModuleEvent.UPDATED);
			State previousState;
			try {
				module.checkValid();
				previousState = module.getState();
				if (Module.ACTIVE_SET.contains(previousState)) {
					// throwing an exception from stop terminates update
					module.stop(StopOptions.TRANSIENT);
				}
				if (Module.RESOLVED_SET.contains(previousState)) {
					// set the state to installed and publish unresolved event
					module.setState(State.INSTALLED);
					adaptor.publishModuleEvent(ModuleEvent.UNRESOLVED, module, module);
				}
				moduleDatabase.update(module, builder, revisionInfo);
			} finally {
				module.unlockStateChange(ModuleEvent.UPDATED);
			}
			// only publish updated event on success
			adaptor.publishModuleEvent(ModuleEvent.UPDATED, module, module);

			if (Module.ACTIVE_SET.contains(previousState)) {
				try {
					// restart the module if necessary
					module.start(StartOptions.TRANSIENT_RESUME);
				} catch (BundleException e) {
					getAdaptor().publishContainerEvent(ContainerEvent.ERROR, module, e);
				}
			}
		} finally {
			if (nameLocked)
				nameLocks.unlock(name);
		}
	}

	
Uninstalls the specified module.
Params:
module – the module to uninstall
Throws:
BundleException – if some error occurs uninstalling the module/**
	 * Uninstalls the specified module.
	 * @param module the module to uninstall
	 * @throws BundleException if some error occurs uninstalling the module
	 */
	public void uninstall(Module module) throws BundleException {
		checkAdminPermission(module.getBundle(), AdminPermission.LIFECYCLE);
		module.lockStateChange(ModuleEvent.UNINSTALLED);
		State previousState;
		try {
			module.checkValid();
			previousState = module.getState();
			if (Module.ACTIVE_SET.contains(module.getState())) {
				try {
					module.stop(StopOptions.TRANSIENT);
				} catch (BundleException e) {
					adaptor.publishContainerEvent(ContainerEvent.ERROR, module, e);
				}
			}
			if (Module.RESOLVED_SET.contains(previousState)) {
				// set the state to installed and publish unresolved event
				module.setState(State.INSTALLED);
				adaptor.publishModuleEvent(ModuleEvent.UNRESOLVED, module, module);
			}
			moduleDatabase.uninstall(module);
			module.setState(State.UNINSTALLED);
		} finally {
			module.unlockStateChange(ModuleEvent.UNINSTALLED);
		}
		adaptor.publishModuleEvent(ModuleEvent.UNINSTALLED, module, module);
	}

	ModuleWiring getWiring(ModuleRevision revision) {
		return moduleDatabase.getWiring(revision);
	}

	
Returns the FrameworkWiring for this container 
Returns:
the framework wiring for this container./**
	 * Returns the {@link FrameworkWiring} for this container
	 * @return the framework wiring for this container.
	 */
	public FrameworkWiring getFrameworkWiring() {
		return frameworkWiring;
	}

	
Returns the FrameworkStartLevel for this container 
Returns:
the framework start level for this container/**
	 * Returns the {@link FrameworkStartLevel} for this container
	 * @return the framework start level for this container
	 */
	public FrameworkStartLevel getFrameworkStartLevel() {
		return frameworkStartLevel;
	}

	
Attempts to resolve the current revisions of the specified modules.
Params:
triggers – the modules to resolve or null to resolve all unresolved current revisions.
triggersMandatory – true if the triggers must be resolved. This will result in a ResolutionException if set to true and one of the triggers could not be resolved.
See Also:
FrameworkWiring.resolveBundles(Collection<Bundle>)
Returns:
A resolution report for the resolve operation/**
	 * Attempts to resolve the current revisions of the specified modules.
	 * @param triggers the modules to resolve or {@code null} to resolve all unresolved
	 *    current revisions.
	 * @param triggersMandatory true if the triggers must be resolved.  This will result in 
	 *   a {@link ResolutionException} if set to true and one of the triggers could not be resolved.
	 * @see FrameworkWiring#resolveBundles(Collection)
	 * @return A resolution report for the resolve operation
	 */
	public ResolutionReport resolve(Collection<Module> triggers, boolean triggersMandatory) {
		return resolve(triggers, triggersMandatory, false);
	}

	private ResolutionReport resolve(Collection<Module> triggers, boolean triggersMandatory, boolean restartTriggers) {
		if (isRefreshingSystemModule()) {
			return new ModuleResolutionReport(null, Collections.<Resource, List<Entry>> emptyMap(), new ResolutionException("Unable to resolve while shutting down the framework.")); //$NON-NLS-1$
		}
		ResolutionReport report = null;
		try (ResolutionLock.Permits resolutionPermits = _resolutionLock.acquire(1)) {
			do {
				try {
					report = resolveAndApply(triggers, triggersMandatory, restartTriggers, resolutionPermits);
				} catch (RuntimeException e) {
					if (e.getCause() instanceof BundleException) {
						BundleException be = (BundleException) e.getCause();
						if (be.getType() == BundleException.REJECTED_BY_HOOK || be.getType() == BundleException.STATECHANGE_ERROR) {
							return new ModuleResolutionReport(null, Collections.<Resource, List<Entry>> emptyMap(), new ResolutionException(be));
						}
					}
					throw e;
				}
			} while (report == null);
		} catch (ResolutionLockException e) {
			return new ModuleResolutionReport(null, Collections.<Resource, List<Entry>> emptyMap(), new ResolutionException("Timeout acquiring lock for resolution", e, Collections.<Requirement> emptyList())); //$NON-NLS-1$
		}
		return report;
	}

	private ResolutionReport resolveAndApply(Collection<Module> triggers, boolean triggersMandatory, boolean restartTriggers, ResolutionLock.Permits resolutionPermits) {
		if (triggers == null)
			triggers = new ArrayList<>(0);
		Collection<ModuleRevision> triggerRevisions = new ArrayList<>(triggers.size());
		Collection<ModuleRevision> unresolved = new ArrayList<>();
		Map<ModuleRevision, ModuleWiring> wiringClone;
		long timestamp;
		moduleDatabase.readLock();
		try {
			timestamp = moduleDatabase.getRevisionsTimestamp();
			wiringClone = moduleDatabase.getWiringsClone();
			for (Module module : triggers) {
				if (!State.UNINSTALLED.equals(module.getState())) {
					ModuleRevision current = module.getCurrentRevision();
					if (current != null)
						triggerRevisions.add(current);
				}
			}
			Collection<Module> allModules = moduleDatabase.getModules();
			for (Module module : allModules) {
				ModuleRevision revision = module.getCurrentRevision();
				if (revision != null && !wiringClone.containsKey(revision))
					unresolved.add(revision);
			}
		} finally {
			moduleDatabase.readUnlock();
		}

		ModuleResolutionReport report = moduleResolver.resolveDelta(triggerRevisions, triggersMandatory, unresolved, wiringClone, moduleDatabase);
		Map<Resource, List<Wire>> resolutionResult = report.getResolutionResult();
		Map<ModuleRevision, ModuleWiring> deltaWiring = resolutionResult == null ? Collections.<ModuleRevision, ModuleWiring> emptyMap() : moduleResolver.generateDelta(resolutionResult, wiringClone);
		if (deltaWiring.isEmpty())
			return report; // nothing to do

		Collection<Module> modulesResolved = new ArrayList<>();
		for (ModuleRevision deltaRevision : deltaWiring.keySet()) {
			if (!wiringClone.containsKey(deltaRevision))
				modulesResolved.add(deltaRevision.getRevisions().getModule());
		}

		return applyDelta(deltaWiring, modulesResolved, triggers, timestamp, restartTriggers, resolutionPermits) ? report : null;
	}

	
Attempts to resolve the specified dynamic package name request for the specified revision.
Params:
dynamicPkgName – the package name to attempt a dynamic resolution for
revision – the module revision the dynamic resolution request is for
Returns:
the new resolution wire establishing a dynamic package resolution or null if 
a dynamic wire could not be established./**
	 * Attempts to resolve the specified dynamic package name request for the specified revision.
	 * @param dynamicPkgName the package name to attempt a dynamic resolution for
	 * @param revision the module revision the dynamic resolution request is for
	 * @return the new resolution wire establishing a dynamic package resolution or null if 
	 * a dynamic wire could not be established.
	 */
	public ModuleWire resolveDynamic(String dynamicPkgName, ModuleRevision revision) {
		ModuleWire result;
		Map<ModuleRevision, ModuleWiring> deltaWiring;
		Collection<Module> modulesResolved;
		long timestamp;
		try (Permits resolutionPermits = _resolutionLock.acquire(ResolutionLock.MAX_RESOLUTION_PERMITS)) {
			do {
				result = null;
				Map<ModuleRevision, ModuleWiring> wiringClone = null;
				List<DynamicModuleRequirement> dynamicReqs = null;
				Collection<ModuleRevision> unresolved = new ArrayList<>();
				moduleDatabase.readLock();
				try {
					ModuleWiring wiring = revision.getWiring();
					if (wiring == null) {
						// not resolved!!
						return null;
					}
					if (wiring.isDynamicPackageMiss(dynamicPkgName)) {
						// cached a miss for this package
						return null;
					}
					// need to check that another thread has not done the work already
					result = findExistingDynamicWire(revision.getWiring(), dynamicPkgName);
					if (result != null) {
						return result;
					}
					dynamicReqs = getDynamicRequirements(dynamicPkgName, revision);
					if (dynamicReqs.isEmpty()) {
						// save the miss for the package name
						wiring.addDynamicPackageMiss(dynamicPkgName);
						return null;
					}
					timestamp = moduleDatabase.getRevisionsTimestamp();
					wiringClone = moduleDatabase.getWiringsClone();
					Collection<Module> allModules = moduleDatabase.getModules();
					for (Module module : allModules) {
						ModuleRevision current = module.getCurrentRevision();
						if (current != null && !wiringClone.containsKey(current))
							unresolved.add(current);
					}
				} finally {
					moduleDatabase.readUnlock();
				}

				deltaWiring = null;
				boolean foundCandidates = false;
				for (DynamicModuleRequirement dynamicReq : dynamicReqs) {
					ModuleResolutionReport report = moduleResolver.resolveDynamicDelta(dynamicReq, unresolved, wiringClone, moduleDatabase);
					Map<Resource, List<Wire>> resolutionResult = report.getResolutionResult();
					deltaWiring = resolutionResult == null ? Collections.<ModuleRevision, ModuleWiring> emptyMap() : moduleResolver.generateDelta(resolutionResult, wiringClone);
					if (deltaWiring.get(revision) != null) {
						break;
					}
					// Did not establish a valid wire.
					// Check to see if any candidates were available.
					// this is used for caching purposes below
					List<Entry> revisionEntries = report.getEntries().get(revision);
					if (revisionEntries == null || revisionEntries.isEmpty()) {
						foundCandidates = true;
					} else {
						// must make sure there is no MISSING_CAPABILITY type entry
						boolean isMissingCapability = false;
						for (Entry entry : revisionEntries) {
							isMissingCapability |= Entry.Type.MISSING_CAPABILITY.equals(entry.getType());
						}
						foundCandidates |= !isMissingCapability;
					}
				}
				if (deltaWiring == null || deltaWiring.get(revision) == null) {
					if (!foundCandidates) {
						ModuleWiring wiring = revision.getWiring();
						if (wiring != null) {
							// save the miss for the package name
							wiring.addDynamicPackageMiss(dynamicPkgName);
						}
					}
					return null; // nothing to do
				}

				modulesResolved = new ArrayList<>();
				for (ModuleRevision deltaRevision : deltaWiring.keySet()) {
					if (!wiringClone.containsKey(deltaRevision))
						modulesResolved.add(deltaRevision.getRevisions().getModule());
				}

				// Save the result
				ModuleWiring wiring = deltaWiring.get(revision);
				result = findExistingDynamicWire(wiring, dynamicPkgName);
			} while (!applyDelta(deltaWiring, modulesResolved, Collections.<Module> emptyList(), timestamp, false, resolutionPermits));
		} catch (ResolutionLockException e) {
			return null;
		}

		return result;
	}

	private ModuleWire findExistingDynamicWire(ModuleWiring wiring, String dynamicPkgName) {
		if (wiring == null) {
			return null;
		}
		List<ModuleWire> wires = wiring.getRequiredModuleWires(PackageNamespace.PACKAGE_NAMESPACE);
		// No null check; we are holding the database lock here.
		// Work backwards to find the first wire with the dynamic requirement that matches package name
		for (int i = wires.size() - 1; i >= 0; i--) {
			ModuleWire wire = wires.get(i);
			if (dynamicPkgName.equals(wire.getCapability().getAttributes().get(PackageNamespace.PACKAGE_NAMESPACE))) {
				return wire;
			}
			if (!PackageNamespace.RESOLUTION_DYNAMIC.equals(wire.getRequirement().getDirectives().get(Namespace.REQUIREMENT_RESOLUTION_DIRECTIVE))) {
				return null;
			}
		}
		return null;
	}

	// The resolution algorithm uses optimistic locking approach;
	// This involves taking a snapshot of the state and performing an
	// operation on the snapshot while holding no locks and then
	// obtaining the write lock to apply the results.  If we
	// detect the state has changed since the snapshot taken then
	// the process is started over.  If we allow too many threads
	// to try to do this at the same time it causes thrashing
	// between taking the snapshot and successfully applying the
	// results.  Instead of resorting to single threaded operations
	// we choose to limit the number of concurrent resolves
	final ResolutionLock _resolutionLock = new ResolutionLock();
	final ReentrantLock _bundleStateLock = new ReentrantLock();

	static class ResolutionLockException extends Exception {
		private static final long serialVersionUID = 1L;

		public ResolutionLockException() {
			super();
		}

		public ResolutionLockException(Throwable cause) {
			super(cause);
		}
	}

	
A resolution hook allows for a max of 10 threads to do resolution operations
at the same time.  The implementation uses a semaphore to grant the max number
of permits (threads) but a reentrant read lock is also used to detect reentry.
If a thread reenters then no extra permits are required by the thread.
This lock returns a Permits object that implements closeable for use in
try->with.  If permits is closed multiple times then the additional close
operations are a no-op.
/**
	 * A resolution hook allows for a max of 10 threads to do resolution operations
	 * at the same time.  The implementation uses a semaphore to grant the max number
	 * of permits (threads) but a reentrant read lock is also used to detect reentry.
	 * If a thread reenters then no extra permits are required by the thread.
	 * This lock returns a Permits object that implements closeable for use in
	 * try->with.  If permits is closed multiple times then the additional close
	 * operations are a no-op.
	 */
	static class ResolutionLock {
		final static int MAX_RESOLUTION_PERMITS = 10;
		final Semaphore permitPool = new Semaphore(MAX_RESOLUTION_PERMITS);
		final ReentrantReadWriteLock reenterLock = new ReentrantReadWriteLock();

		class Permits implements Closeable {
			private final int aquiredPermits;
			private final AtomicBoolean closed = new AtomicBoolean();

			Permits(int requestedPermits) throws ResolutionLockException {
				if (reenterLock.getReadHoldCount() > 0) {
					// thread is already holding permits; don't request more
					requestedPermits = 0;
				}
				this.aquiredPermits = requestedPermits;
				boolean previousInterruption = Thread.interrupted();
				try {
					if (!permitPool.tryAcquire(requestedPermits, 30, TimeUnit.SECONDS)) {
						throw new ResolutionLockException();
					}
				} catch (InterruptedException e) {
					throw new ResolutionLockException(e);
				} finally {
					if (previousInterruption) {
						Thread.currentThread().interrupt();
					}
				}
				// mark this thread as holding permits
				reenterLock.readLock().lock();
			}

			@Override
			public void close() {
				if (closed.compareAndSet(false, true)) {
					permitPool.release(aquiredPermits);
					reenterLock.readLock().unlock();
				}
			}
		}

		Permits acquire(int requestedPermits) throws ResolutionLockException {
			return new Permits(requestedPermits);
		}
	}

	private boolean applyDelta(Map<ModuleRevision, ModuleWiring> deltaWiring, Collection<Module> modulesResolved, Collection<Module> triggers, long timestamp, boolean restartTriggers, ResolutionLock.Permits resolutionPermits) {
		List<Module> modulesLocked = new ArrayList<>(modulesResolved.size());
		// now attempt to apply the delta
		try {
			// Acquire the necessary RESOLVED state change lock.
			// Note this is done while holding a global lock to avoid multiple threads trying to compete over
			// locking multiple modules; otherwise out of order locks between modules can happen
			// NOTE this MUST be done outside of holding the moduleDatabase lock also to avoid
			// introducing out of order locks between the bundle state change lock and the moduleDatabase
			// lock.
			_bundleStateLock.lock();
			try {
				for (Module module : modulesResolved) {
					try {
						// avoid grabbing the lock if the timestamp has changed
						if (timestamp != moduleDatabase.getRevisionsTimestamp()) {
							return false; // need to try again
						}
						module.lockStateChange(ModuleEvent.RESOLVED);
						modulesLocked.add(module);
					} catch (BundleException e) {
						// before throwing an exception here, see if the timestamp has changed
						if (timestamp != moduleDatabase.getRevisionsTimestamp()) {
							return false; // need to try again
						}
						// TODO throw some appropriate exception
						throw new IllegalStateException(Msg.ModuleContainer_StateLockError, e);
					}
				}
			} finally {
				_bundleStateLock.unlock();
			}

			Map<ModuleWiring, Collection<ModuleRevision>> hostsWithDynamicFrags = new HashMap<>(0);
			moduleDatabase.writeLock();
			try {
				if (timestamp != moduleDatabase.getRevisionsTimestamp())
					return false; // need to try again

				Map<ModuleRevision, ModuleWiring> wiringCopy = moduleDatabase.getWiringsCopy();
				for (Map.Entry<ModuleRevision, ModuleWiring> deltaEntry : deltaWiring.entrySet()) {
					ModuleWiring current = wiringCopy.get(deltaEntry.getKey());
					if (current != null) {
						// need to update the provided capabilities, provided and required wires for currently resolved
						current.setCapabilities(deltaEntry.getValue().getModuleCapabilities(null));
						current.setProvidedWires(deltaEntry.getValue().getProvidedModuleWires(null));
						current.setRequiredWires(deltaEntry.getValue().getRequiredModuleWires(null));
						deltaEntry.setValue(current); // set the real wiring into the delta
					} else {
						ModuleRevision revision = deltaEntry.getValue().getRevision();
						modulesResolved.add(revision.getRevisions().getModule());
						if ((revision.getTypes() & BundleRevision.TYPE_FRAGMENT) != 0) {
							for (ModuleWire hostWire : deltaEntry.getValue().getRequiredModuleWires(HostNamespace.HOST_NAMESPACE)) {
								// check to see if the host revision has a wiring
								ModuleWiring hostWiring = hostWire.getProvider().getWiring();
								if (hostWiring != null) {
									Collection<ModuleRevision> dynamicFragments = hostsWithDynamicFrags.get(hostWiring);
									if (dynamicFragments == null) {
										dynamicFragments = new ArrayList<>();
										hostsWithDynamicFrags.put(hostWiring, dynamicFragments);
									}
									dynamicFragments.add(hostWire.getRequirer());
								}
							}
						}
					}
				}
				moduleDatabase.mergeWiring(deltaWiring);
				moduleDatabase.sortModules(modulesLocked, Sort.BY_DEPENDENCY, Sort.BY_START_LEVEL);
			} finally {
				moduleDatabase.writeUnlock();
			}
			// set the modules state to resolved
			for (Module module : modulesLocked) {
				module.setState(State.RESOLVED);
			}
			// attach fragments to already resolved hosts that have
			// dynamically attached fragments
			for (Map.Entry<ModuleWiring, Collection<ModuleRevision>> dynamicFragments : hostsWithDynamicFrags.entrySet()) {
				dynamicFragments.getKey().loadFragments(dynamicFragments.getValue());
			}
		} finally {
			for (Module module : modulesLocked) {
				module.unlockStateChange(ModuleEvent.RESOLVED);
			}
		}

		// release resolution permits before firing events
		resolutionPermits.close();

		for (Module module : modulesLocked) {
			adaptor.publishModuleEvent(ModuleEvent.RESOLVED, module, module);
		}

		// If there are any triggers re-start them now if requested
		Set<Module> triggerSet = restartTriggers ? new HashSet<>(triggers) : Collections.<Module> emptySet();
		if (restartTriggers) {
			for (Module module : triggers) {
				if (module.getId() != 0 && Module.RESOLVED_SET.contains(module.getState())) {
					start(module, StartOptions.TRANSIENT_RESUME);
				}
			}
		}
		if (autoStartOnResolve) {
			// This is questionable behavior according to the spec but this was the way equinox previously behaved
			// Need to auto-start any persistently started bundles that got resolved
			for (Module module : modulesLocked) {
				// Note that we check inStart here.  There is still a timing issue that is impossible to avoid.
				// Another thread could attempt to start the module but we could check inStart() before that thread
				// increments inStart.  One thread will win the race to grab the module STARTED lock.  That thread
				// will end up actually starting the module and the other thread will block.  If a timeout occurs
				// the blocking thread will get an exception.
				if (!module.inStart() && module.getId() != 0 && !triggerSet.contains(module)) {
					start(module, StartOptions.TRANSIENT_IF_AUTO_START, StartOptions.TRANSIENT_RESUME);
				}
			}
		}
		return true;
	}

	private void start(Module module, StartOptions... options) {
		try {
			secureAction.start(module, options);
		} catch (BundleException e) {
			if (e.getType() == BundleException.STATECHANGE_ERROR) {
				if (Module.ACTIVE_SET.contains(module.getState())) {
					// There is still a timing issue here;
					// but at least try to detect that another thread is starting the module
					return;
				}
			}
			adaptor.publishContainerEvent(ContainerEvent.ERROR, module, e);
		} catch (IllegalStateException e) {
			// been uninstalled
			return;
		}
	}

	private List<DynamicModuleRequirement> getDynamicRequirements(String dynamicPkgName, ModuleRevision revision) {
		// TODO Will likely need to optimize this
		if ((revision.getTypes() & BundleRevision.TYPE_FRAGMENT) != 0) {
			// only do this for hosts
			return Collections.emptyList();
		}
		ModuleWiring wiring = revision.getWiring();
		if (wiring == null) {
			// not resolved!
			return Collections.emptyList();
		}
		List<DynamicModuleRequirement> result = new ArrayList<>(1);
		// check the dynamic import packages
		DynamicModuleRequirement dynamicRequirement;
		for (ModuleRequirement requirement : wiring.getModuleRequirements(PackageNamespace.PACKAGE_NAMESPACE)) {
			dynamicRequirement = requirement.getDynamicPackageRequirement(revision, dynamicPkgName);
			if (dynamicRequirement != null) {
				result.add(dynamicRequirement);
			}
		}

		if (!result.isEmpty()) {
			// must check that the wiring does not export the package
			for (ModuleCapability capability : wiring.getModuleCapabilities(PackageNamespace.PACKAGE_NAMESPACE)) {
				if (dynamicPkgName.equals(capability.getAttributes().get(PackageNamespace.PACKAGE_NAMESPACE))) {
					// the package is exported, must not allow dynamic import
					return Collections.emptyList();
				}
			}
		}
		return result;
	}

	private Collection<Module> unresolve(Collection<Module> initial) {
		Collection<Module> refreshTriggers = null;
		while (refreshTriggers == null) {
			refreshTriggers = unresolve0(initial);
		}
		return refreshTriggers;
	}

	private Collection<Module> unresolve0(Collection<Module> initial) {
		Map<ModuleRevision, ModuleWiring> wiringCopy;
		List<Module> refreshTriggers;
		Collection<ModuleRevision> toRemoveRevisions;
		Collection<ModuleWiring> toRemoveWirings;
		Map<ModuleWiring, Collection<ModuleWire>> toRemoveWireLists;
		long timestamp;
		moduleDatabase.readLock();
		try {
			checkSystemExtensionRefresh(initial);
			timestamp = moduleDatabase.getRevisionsTimestamp();
			wiringCopy = moduleDatabase.getWiringsCopy();
			refreshTriggers = new ArrayList<>(getRefreshClosure(initial, wiringCopy));
			toRemoveRevisions = new ArrayList<>();
			toRemoveWirings = new ArrayList<>();
			toRemoveWireLists = new HashMap<>();
			for (Iterator<Module> iTriggers = refreshTriggers.iterator(); iTriggers.hasNext();) {
				Module module = iTriggers.next();
				boolean first = true;
				for (ModuleRevision revision : module.getRevisions().getModuleRevisions()) {
					ModuleWiring removedWiring = wiringCopy.remove(revision);
					if (removedWiring != null) {
						toRemoveWirings.add(removedWiring);
						List<ModuleWire> removedWires = removedWiring.getRequiredModuleWires(null);
						for (ModuleWire wire : removedWires) {
							Collection<ModuleWire> providerWires = toRemoveWireLists.get(wire.getProviderWiring());
							if (providerWires == null) {
								providerWires = new ArrayList<>();
								toRemoveWireLists.put(wire.getProviderWiring(), providerWires);
							}
							providerWires.add(wire);
						}
					}
					if (!first || revision.getRevisions().isUninstalled()) {
						toRemoveRevisions.add(revision);
					}
					first = false;
				}
				if (module.getState().equals(State.UNINSTALLED)) {
					iTriggers.remove();
				}
			}
			moduleDatabase.sortModules(refreshTriggers, Sort.BY_START_LEVEL, Sort.BY_DEPENDENCY);
		} finally {
			moduleDatabase.readUnlock();
		}

		Module systemModule = moduleDatabase.getModule(0);
		if (refreshTriggers.contains(systemModule) && Module.ACTIVE_SET.contains(systemModule.getState())) {
			refreshSystemModule();
			return Collections.emptyList();
		}
		Collection<Module> modulesLocked = new ArrayList<>(refreshTriggers.size());
		Collection<Module> modulesUnresolved = new ArrayList<>();
		try {
			// Acquire the module state change locks.
			// Note this is done while holding a global lock to avoid multiple threads trying to compete over
			// locking multiple modules; otherwise out of order locks between modules can happen
			// NOTE this MUST be done outside of holding the moduleDatabase lock also to avoid
			// introducing out of order locks between the bundle state change lock and the moduleDatabase
			// lock.
			_bundleStateLock.lock();
			try {
				// go in reverse order
				for (ListIterator<Module> iTriggers = refreshTriggers.listIterator(refreshTriggers.size()); iTriggers.hasPrevious();) {
					Module refreshModule = iTriggers.previous();
					refreshModule.lockStateChange(ModuleEvent.UNRESOLVED);
					modulesLocked.add(refreshModule);
				}
			} catch (BundleException e) {
				// TODO throw some appropriate exception
				throw new IllegalStateException(Msg.ModuleContainer_StateLockError, e);
			} finally {
				_bundleStateLock.unlock();
			}
			// Must not hold the module database lock while stopping bundles
			// Stop any active bundles and remove non-active modules from the refreshTriggers
			for (ListIterator<Module> iTriggers = refreshTriggers.listIterator(refreshTriggers.size()); iTriggers.hasPrevious();) {
				Module refreshModule = iTriggers.previous();
				State previousState = refreshModule.getState();
				if (Module.ACTIVE_SET.contains(previousState)) {
					try {
						refreshModule.stop(StopOptions.TRANSIENT);
					} catch (BundleException e) {
						adaptor.publishContainerEvent(ContainerEvent.ERROR, refreshModule, e);
					}
				} else {
					iTriggers.remove();
				}
			}

			// do a sanity check on states of the modules, they must be INSTALLED, RESOLVED or UNINSTALLED
			for (Module module : modulesLocked) {
				if (Module.ACTIVE_SET.contains(module.getState())) {
					throw new IllegalStateException("Module is in the wrong state: " + module + ": " + module.getState()); //$NON-NLS-1$ //$NON-NLS-2$
				}
			}

			// finally apply the unresolve to the database
			moduleDatabase.writeLock();
			try {
				if (timestamp != moduleDatabase.getRevisionsTimestamp())
					return null; // need to try again
				// remove any wires from unresolved wirings that got removed
				for (Map.Entry<ModuleWiring, Collection<ModuleWire>> entry : toRemoveWireLists.entrySet()) {
					List<ModuleWire> provided = entry.getKey().getProvidedModuleWires(null);
					provided.removeAll(entry.getValue());
					entry.getKey().setProvidedWires(provided);
					for (ModuleWire removedWire : entry.getValue()) {
						// invalidate the wire
						removedWire.invalidate();
					}

				}
				// remove any revisions that got removed as part of the refresh
				for (ModuleRevision removed : toRemoveRevisions) {
					removed.getRevisions().removeRevision(removed);
					moduleDatabase.removeCapabilities(removed);
				}
				// invalidate any removed wiring objects
				for (ModuleWiring moduleWiring : toRemoveWirings) {
					moduleWiring.invalidate();
				}
				moduleDatabase.setWiring(wiringCopy);
				// check for any removal pendings
				moduleDatabase.cleanupRemovalPending();
			} finally {
				moduleDatabase.writeUnlock();
			}
			// set the state of modules to unresolved
			for (Module module : modulesLocked) {
				if (State.RESOLVED.equals(module.getState())) {
					module.setState(State.INSTALLED);
					modulesUnresolved.add(module);
				}
			}
		} finally {
			for (Module module : modulesLocked) {
				module.unlockStateChange(ModuleEvent.UNRESOLVED);
			}
		}
		// publish unresolved events after giving up all locks
		for (Module module : modulesUnresolved) {
			adaptor.publishModuleEvent(ModuleEvent.UNRESOLVED, module, module);
		}
		return refreshTriggers;
	}

	private void checkSystemExtensionRefresh(Collection<Module> initial) {
		if (initial == null) {
			return;
		}
		Long zero = new Long(0);
		for (Iterator<Module> iModules = initial.iterator(); iModules.hasNext();) {
			Module m = iModules.next();
			if (m.getId().equals(zero)) {
				// never allow system bundle to be unresolved directly if the system module is active
				if (Module.ACTIVE_SET.contains(m.getState())) {
					iModules.remove();
				}
			} else {
				if (Module.RESOLVED_SET.contains(m.getState())) {
					// check if current revision is an extension of the system module
					ModuleRevision current = m.getCurrentRevision();
					if ((current.getTypes() & BundleRevision.TYPE_FRAGMENT) != 0) {
						ModuleWiring wiring = current.getWiring();
						if (wiring != null) {
							List<ModuleWire> hostWires = wiring.getRequiredModuleWires(HostNamespace.HOST_NAMESPACE);
							for (ModuleWire hostWire : hostWires) {
								if (hostWire.getProvider().getRevisions().getModule().getId().equals(zero)) {
									// The current revision is the extension to allow it to refresh
									// this would just shutdown the framework for no reason
									iModules.remove();
								}
							}
						}
					}
				}
			}
		}
	}

	
Refreshes the specified collection of modules.
Params:
initial – the modules to refresh or null to refresh the removal pending.
See Also:
FrameworkWiring.refreshBundles(Collection<Bundle>, FrameworkListener...)
Returns:
a resolution report for the resolve operation that may have
occurred during the refresh operation./**
	 * Refreshes the specified collection of modules.
	 * @param initial the modules to refresh or {@code null} to refresh the
	 *     removal pending.
	 * @return a resolution report for the resolve operation that may have
	 * occurred during the refresh operation.
	 * @see FrameworkWiring#refreshBundles(Collection, FrameworkListener...)
	 */
	public ResolutionReport refresh(Collection<Module> initial) {
		initial = initial == null ? null : new ArrayList<>(initial);
		Collection<Module> refreshTriggers = unresolve(initial);
		if (!isRefreshingSystemModule()) {
			return resolve(refreshTriggers, false, true);
		}
		return new ModuleResolutionReport(null, null, null);
	}

	
Returns the dependency closure of for the specified modules.
Params:
initial – The initial modules for which to generate the dependency closure
Returns:
A collection containing a snapshot of the dependency closure of the specified 
   modules, or an empty collection if there were no specified modules./**
	 * Returns the dependency closure of for the specified modules.
	 * @param initial The initial modules for which to generate the dependency closure
	 * @return A collection containing a snapshot of the dependency closure of the specified 
	 *    modules, or an empty collection if there were no specified modules. 
	 */
	public Collection<Module> getDependencyClosure(Collection<Module> initial) {
		moduleDatabase.readLock();
		try {
			return getRefreshClosure(initial, moduleDatabase.getWiringsCopy());
		} finally {
			moduleDatabase.readUnlock();
		}
	}

	
Returns the revisions that have non-current, in use module wirings. 
Returns:
A collection containing a snapshot of the revisions which have non-current, in use ModuleWirings,
or an empty collection if there are no such revisions./**
	 * Returns the revisions that have {@link ModuleWiring#isCurrent() non-current}, {@link ModuleWiring#isInUse() in use} module wirings.
	 * @return A collection containing a snapshot of the revisions which have non-current, in use ModuleWirings,
	 * or an empty collection if there are no such revisions.
	 */
	public Collection<ModuleRevision> getRemovalPending() {
		return moduleDatabase.getRemovalPending();
	}

	
Return the active start level value of this container.
If the container is in the process of changing the start level this
method must return the active start level if this differs from the
requested start level.
Returns:
The active start level value of the Framework./**
	 * Return the active start level value of this container.
	 * 
	 * If the container is in the process of changing the start level this
	 * method must return the active start level if this differs from the
	 * requested start level.
	 * 
	 * @return The active start level value of the Framework.
	 */
	public int getStartLevel() {
		return frameworkStartLevel.getStartLevel();
	}

	void setStartLevel(Module module, int startlevel) {
		frameworkStartLevel.setStartLevel(module, startlevel);
	}

	long getModuleLockTimeout() {
		return this.moduleLockTimeout;
	}

	void open() {
		loadModules();
		frameworkStartLevel.open();
		frameworkWiring.open();
		refreshingSystemModule.set(null);
	}

	void close() {
		frameworkStartLevel.close();
		frameworkWiring.close();
		unloadModules();
	}

	private void loadModules() {
		List<Module> modules = null;
		moduleDatabase.readLock();
		try {
			modules = getModules();
			for (Module module : modules) {
				try {
					module.lockStateChange(ModuleEvent.RESOLVED);
					ModuleWiring wiring = moduleDatabase.getWiring(module.getCurrentRevision());
					if (wiring != null) {
						module.setState(State.RESOLVED);
					} else {
						module.setState(State.INSTALLED);
					}
				} catch (BundleException e) {
					throw new IllegalStateException("Unable to lock module state.", e); //$NON-NLS-1$
				}
			}
			Map<ModuleRevision, ModuleWiring> wirings = moduleDatabase.getWiringsCopy();
			for (ModuleWiring wiring : wirings.values()) {
				wiring.validate();
			}
		} finally {
			if (modules != null) {
				for (Module module : modules) {
					try {
						module.unlockStateChange(ModuleEvent.RESOLVED);
					} catch (IllegalMonitorStateException e) {
						// ignore
					}
				}
			}
			moduleDatabase.readUnlock();
		}
	}

	private void unloadModules() {
		List<Module> modules = null;
		moduleDatabase.readLock();
		try {
			modules = getModules();
			for (Module module : modules) {
				if (module.getId() != 0) {
					try {
						module.lockStateChange(ModuleEvent.UNINSTALLED);
					} catch (BundleException e) {
						throw new IllegalStateException("Unable to lock module state.", e); //$NON-NLS-1$
					}
					module.setState(State.UNINSTALLED);
				}
			}
			Map<ModuleRevision, ModuleWiring> wirings = moduleDatabase.getWiringsCopy();
			for (ModuleWiring wiring : wirings.values()) {
				wiring.unload();
			}
		} finally {
			if (modules != null) {
				for (Module module : modules) {
					if (module.getId() != 0) {
						try {
							module.unlockStateChange(ModuleEvent.UNINSTALLED);
						} catch (IllegalMonitorStateException e) {
							// ignore
						}
					}
				}
			}
			moduleDatabase.readUnlock();
		}
	}

	
Sets all the module states uninstalled except for the system module.
Throws:
BundleException – /**
	 * Sets all the module states uninstalled except for the system module.
	 * @throws BundleException
	 */
	public void setInitialModuleStates() throws BundleException {
		moduleDatabase.readLock();
		try {
			List<Module> modules = getModules();
			for (Module module : modules) {
				if (module.getId() == 0) {
					module.lockStateChange(ModuleEvent.UNINSTALLED);
					try {
						module.setState(State.INSTALLED);
					} finally {
						module.unlockStateChange(ModuleEvent.UNINSTALLED);
					}
				} else {
					module.lockStateChange(ModuleEvent.UNINSTALLED);
					try {
						module.setState(State.UNINSTALLED);
					} finally {
						module.unlockStateChange(ModuleEvent.UNINSTALLED);
					}
				}
			}
			Map<ModuleRevision, ModuleWiring> wirings = moduleDatabase.getWiringsCopy();
			for (ModuleWiring wiring : wirings.values()) {
				wiring.unload();
			}
		} finally {
			moduleDatabase.readUnlock();
		}
	}

	Set<Module> getRefreshClosure(Collection<Module> initial, Map<ModuleRevision, ModuleWiring> wiringCopy) {
		Set<Module> refreshClosure = new HashSet<>();
		if (initial == null) {
			initial = new HashSet<>();
			Collection<ModuleRevision> removalPending = moduleDatabase.getRemovalPending();
			for (ModuleRevision revision : removalPending) {
				initial.add(revision.getRevisions().getModule());
			}
		}
		for (Module module : initial)
			addDependents(module, wiringCopy, refreshClosure);
		return refreshClosure;
	}

	private static void addDependents(Module module, Map<ModuleRevision, ModuleWiring> wiringCopy, Set<Module> refreshClosure) {
		if (refreshClosure.contains(module))
			return;
		refreshClosure.add(module);
		List<ModuleRevision> revisions = module.getRevisions().getModuleRevisions();
		for (ModuleRevision revision : revisions) {
			ModuleWiring wiring = wiringCopy.get(revision);
			if (wiring == null)
				continue;
			List<ModuleWire> provided = wiring.getProvidedModuleWires(null);
			// No null checks; we are holding the read lock here.
			// Add all requirers of the provided wires
			for (ModuleWire providedWire : provided) {
				addDependents(providedWire.getRequirer().getRevisions().getModule(), wiringCopy, refreshClosure);
			}
			// add all hosts of a fragment
			if (revision.getTypes() == BundleRevision.TYPE_FRAGMENT) {
				List<ModuleWire> hosts = wiring.getRequiredModuleWires(HostNamespace.HOST_NAMESPACE);
				for (ModuleWire hostWire : hosts) {
					addDependents(hostWire.getProvider().getRevisions().getModule(), wiringCopy, refreshClosure);
				}
			}
		}
	}

	static Collection<ModuleRevision> getDependencyClosure(ModuleRevision initial, Map<ModuleRevision, ModuleWiring> wiringCopy) {
		Set<ModuleRevision> dependencyClosure = new HashSet<>();
		addDependents(initial, wiringCopy, dependencyClosure);
		return dependencyClosure;
	}

	private static void addDependents(ModuleRevision revision, Map<ModuleRevision, ModuleWiring> wiringCopy, Set<ModuleRevision> dependencyClosure) {
		if (dependencyClosure.contains(revision))
			return;
		dependencyClosure.add(revision);
		ModuleWiring wiring = wiringCopy.get(revision);
		if (wiring == null)
			return;
		List<ModuleWire> provided = wiring.getProvidedModuleWires(null);
		// No null checks; we are holding the read lock here.
		// Add all requirers of the provided wires
		for (ModuleWire providedWire : provided) {
			addDependents(providedWire.getRequirer(), wiringCopy, dependencyClosure);
		}
		// add all hosts of a fragment
		if (revision.getTypes() == BundleRevision.TYPE_FRAGMENT) {
			List<ModuleWire> hosts = wiring.getRequiredModuleWires(HostNamespace.HOST_NAMESPACE);
			for (ModuleWire hostWire : hosts) {
				addDependents(hostWire.getProvider(), wiringCopy, dependencyClosure);
			}
		}
	}

	Bundle getSystemBundle() {
		Module systemModule = moduleDatabase.getModule(0);
		return systemModule == null ? null : systemModule.getBundle();
	}

	void checkAdminPermission(Bundle bundle, String action) {
		if (bundle == null)
			return;
		SecurityManager sm = System.getSecurityManager();
		if (sm != null)
			sm.checkPermission(new AdminPermission(bundle, action));
	}

	void refreshSystemModule() {
		final SystemModule systemModule = (SystemModule) moduleDatabase.getModule(0);
		if (systemModule == refreshingSystemModule.getAndSet(systemModule)) {
			return;
		}
		getAdaptor().refreshedSystemModule();
		Thread t = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					systemModule.lockStateChange(ModuleEvent.UNRESOLVED);
					try {
						systemModule.stop();
					} finally {
						systemModule.unlockStateChange(ModuleEvent.UNRESOLVED);
					}
				} catch (BundleException e) {
					e.printStackTrace();
				}
			}
		});
		t.start();
	}

	boolean isRefreshingSystemModule() {
		return refreshingSystemModule.get() != null;
	}

	static Requirement getIdentityRequirement(String name, Version version) {
		version = version == null ? Version.emptyVersion : version;
		String filter = "(&(" + IdentityNamespace.IDENTITY_NAMESPACE + "=" + name + ")(" + IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE + "=" + version.toString() + "))"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$//$NON-NLS-4$//$NON-NLS-5$
		Map<String, String> directives = Collections.<String, String> singletonMap(Namespace.REQUIREMENT_FILTER_DIRECTIVE, filter);
		return new ModuleRequirement(IdentityNamespace.IDENTITY_NAMESPACE, directives, Collections.<String, Object> emptyMap(), null);
	}

	class ContainerWiring implements FrameworkWiring, EventDispatcher<ContainerWiring, FrameworkListener[], Collection<Module>> {
		private final Object monitor = new Object();
		private EventManager refreshThread = null;

		@Override
		public Bundle getBundle() {
			return getSystemBundle();
		}

		@Override
		public void refreshBundles(Collection<Bundle> bundles, FrameworkListener... listeners) {
			checkAdminPermission(getBundle(), AdminPermission.RESOLVE);
			Collection<Module> modules = getModules(bundles);

			// queue to refresh in the background
			// notice that we only do one refresh operation at a time
			CopyOnWriteIdentityMap<ContainerWiring, FrameworkListener[]> dispatchListeners = new CopyOnWriteIdentityMap<>();
			dispatchListeners.put(this, listeners);
			ListenerQueue<ContainerWiring, FrameworkListener[], Collection<Module>> queue = new ListenerQueue<>(getManager());
			queue.queueListeners(dispatchListeners.entrySet(), this);

			// dispatch the refresh job
			queue.dispatchEventAsynchronous(0, modules);
		}

		@Override
		public boolean resolveBundles(Collection<Bundle> bundles) {
			checkAdminPermission(getBundle(), AdminPermission.RESOLVE);
			Collection<Module> modules = getModules(bundles);
			resolve(modules, false);

			if (modules == null) {
				modules = ModuleContainer.this.getModules();
			}
			for (Module module : modules) {
				if (getWiring(module.getCurrentRevision()) == null)
					return false;
			}
			return true;
		}

		@Override
		public Collection<Bundle> getRemovalPendingBundles() {
			moduleDatabase.readLock();
			try {
				Collection<Bundle> removalPendingBundles = new HashSet<>();
				Collection<ModuleRevision> removalPending = moduleDatabase.getRemovalPending();
				for (ModuleRevision moduleRevision : removalPending) {
					removalPendingBundles.add(moduleRevision.getBundle());
				}
				return removalPendingBundles;
			} finally {
				moduleDatabase.readUnlock();
			}
		}

		@Override
		public Collection<Bundle> getDependencyClosure(Collection<Bundle> bundles) {
			Collection<Module> modules = getModules(bundles);
			moduleDatabase.readLock();
			try {
				Collection<Module> closure = getRefreshClosure(modules, moduleDatabase.getWiringsCopy());
				Collection<Bundle> result = new ArrayList<>(closure.size());
				for (Module module : closure) {
					result.add(module.getBundle());
				}
				return result;
			} finally {
				moduleDatabase.readUnlock();
			}
		}

		@Override
		public Collection<BundleCapability> findProviders(Requirement requirement) {
			return InternalUtils.asListBundleCapability(moduleDatabase.findCapabilities(requirement));
		}

		private Collection<Module> getModules(final Collection<Bundle> bundles) {
			if (bundles == null)
				return null;
			return AccessController.doPrivileged(new PrivilegedAction<Collection<Module>>() {
				@Override
				public Collection<Module> run() {
					Collection<Module> result = new ArrayList<>(bundles.size());
					for (Bundle bundle : bundles) {
						Module module = bundle.adapt(Module.class);
						if (module == null)
							throw new IllegalStateException("Could not adapt a bundle to a module."); //$NON-NLS-1$
						result.add(module);
					}
					return result;
				}
			});
		}

		@Override
		public void dispatchEvent(ContainerWiring eventListener, FrameworkListener[] frameworkListeners, int eventAction, Collection<Module> eventObject) {
			try {
				refresh(eventObject);
			} finally {
				adaptor.publishContainerEvent(ContainerEvent.REFRESH, moduleDatabase.getModule(0), null, frameworkListeners);
			}
		}

		private EventManager getManager() {
			synchronized (monitor) {
				if (refreshThread == null) {
					refreshThread = new EventManager("Refresh Thread: " + adaptor.toString()); //$NON-NLS-1$
				}
				return refreshThread;
			}
		}

		// because of bug 378491 we have to synchronize access to the manager
		// so we can close and re-open ourselves
		void close() {
			synchronized (monitor) {
				// force a manager to be created if it did not exist
				EventManager manager = getManager();
				// this prevents any operations until open is called
				manager.close();
			}
		}

		void open() {
			synchronized (monitor) {
				if (refreshThread != null) {
					// Make sure it is closed just incase
					refreshThread.close();
					// a new one will be constructed on demand
					refreshThread = null;
				}
			}
		}
	}

	@Override
	public void optionsChanged(DebugOptions options) {
		moduleResolver.setDebugOptions();
		frameworkStartLevel.setDebugOptions();
		if (options != null) {
			this.DEBUG_MONITOR_LAZY = options.getBooleanOption(Debug.OPTION_MONITOR_LAZY, false);
			this.DEBUG_BUNDLE_START_TIME = options.getBooleanOption(Debug.OPTION_DEBUG_BUNDLE_START_TIME, false);
		}
	}

	class ContainerStartLevel implements FrameworkStartLevel, EventDispatcher<Module, FrameworkListener[], Integer> {
		static final int USE_BEGINNING_START_LEVEL = Integer.MIN_VALUE;
		private static final int FRAMEWORK_STARTLEVEL = 1;
		private static final int MODULE_STARTLEVEL = 2;
		private final AtomicInteger activeStartLevel = new AtomicInteger(0);
		private final Object eventManagerLock = new Object();
		private EventManager startLevelThread = null;
		private final Object frameworkStartLevelLock = new Object();
		boolean debugStartLevel = false;
		{
			setDebugOptions();
		}

		void setDebugOptions() {
			DebugOptions options = getAdaptor().getDebugOptions();
			debugStartLevel = options == null ? false : options.getBooleanOption(Debug.OPTION_DEBUG_STARTLEVEL, false);
		}

		@Override
		public Bundle getBundle() {
			return getSystemBundle();
		}

		@Override
		public int getStartLevel() {
			return activeStartLevel.get();
		}

		void setStartLevel(Module module, int startlevel) {
			checkAdminPermission(module.getBundle(), AdminPermission.EXECUTE);
			if (module.getId() == 0) {
				throw new IllegalArgumentException(Msg.ModuleContainer_SystemStartLevelError);
			}
			if (startlevel < 1) {
				throw new IllegalArgumentException(Msg.ModuleContainer_NegativeStartLevelError + startlevel);
			}
			int currentLevel = module.getStartLevel();
			if (currentLevel == startlevel) {
				return; // do nothing
			}
			moduleDatabase.setStartLevel(module, startlevel);
			// only queue the start level if
			// 1) the current level is less than the new startlevel, may need to stop or
			// 2) the module is marked for persistent activation, may need to start
			if (currentLevel < startlevel || module.isPersistentlyStarted()) {
				// queue start level operation in the background
				// notice that we only do one start level operation at a time
				CopyOnWriteIdentityMap<Module, FrameworkListener[]> dispatchListeners = new CopyOnWriteIdentityMap<>();
				dispatchListeners.put(module, new FrameworkListener[0]);
				ListenerQueue<Module, FrameworkListener[], Integer> queue = new ListenerQueue<>(getManager());
				queue.queueListeners(dispatchListeners.entrySet(), this);

				// dispatch the start level job
				queue.dispatchEventAsynchronous(MODULE_STARTLEVEL, startlevel);
			}
		}

		@Override
		public void setStartLevel(int startlevel, FrameworkListener... listeners) {
			checkAdminPermission(getBundle(), AdminPermission.STARTLEVEL);
			if (startlevel < 1) {
				throw new IllegalArgumentException(Msg.ModuleContainer_NegativeStartLevelError + startlevel);
			}

			if (activeStartLevel.get() == 0) {
				throw new IllegalStateException(Msg.ModuleContainer_SystemNotActiveError);
			}
			if (debugStartLevel) {
				Debug.println("StartLevel: setStartLevel: " + startlevel); //$NON-NLS-1$
			}
			// queue start level operation in the background
			// notice that we only do one start level operation at a time
			CopyOnWriteIdentityMap<Module, FrameworkListener[]> dispatchListeners = new CopyOnWriteIdentityMap<>();
			dispatchListeners.put(moduleDatabase.getModule(0), listeners);
			ListenerQueue<Module, FrameworkListener[], Integer> queue = new ListenerQueue<>(getManager());
			queue.queueListeners(dispatchListeners.entrySet(), this);

			// dispatch the start level job
			queue.dispatchEventAsynchronous(FRAMEWORK_STARTLEVEL, startlevel);
		}

		@Override
		public int getInitialBundleStartLevel() {
			return moduleDatabase.getInitialModuleStartLevel();
		}

		@Override
		public void setInitialBundleStartLevel(int startlevel) {
			checkAdminPermission(getBundle(), AdminPermission.STARTLEVEL);
			if (startlevel < 1) {
				throw new IllegalArgumentException(Msg.ModuleContainer_NegativeStartLevelError + startlevel);
			}
			moduleDatabase.setInitialModuleStartLevel(startlevel);
		}

		@Override
		public void dispatchEvent(Module module, FrameworkListener[] listeners, int eventAction, Integer startlevel) {
			switch (eventAction) {
				case FRAMEWORK_STARTLEVEL :
					doContainerStartLevel(module, startlevel, listeners);
					break;
				case MODULE_STARTLEVEL :
					if (debugStartLevel) {
						Debug.println("StartLevel: changing bundle startlevel; " + toString(module) + "; newSL=" + startlevel + "; activeSL=" + getStartLevel()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
					}
					try {
						if (getStartLevel() < startlevel) {
							if (Module.ACTIVE_SET.contains(module.getState())) {
								if (debugStartLevel) {
									Debug.println("StartLevel: stopping bundle; " + toString(module) + "; with startLevel=" + startlevel); //$NON-NLS-1$ //$NON-NLS-2$
								}
								// Note that we don't need to hold the state change lock
								// here when checking the active status because no other
								// thread will successfully be able to start this bundle
								// since the start-level is no longer met.
								module.stop(StopOptions.TRANSIENT);
							}
						} else {
							if (debugStartLevel) {
								Debug.println("StartLevel: resuming bundle; " + toString(module) + "; with startLevel=" + startlevel); //$NON-NLS-1$ //$NON-NLS-2$
							}
							module.start(StartOptions.TRANSIENT_IF_AUTO_START, StartOptions.TRANSIENT_RESUME);
						}
					} catch (BundleException e) {
						adaptor.publishContainerEvent(ContainerEvent.ERROR, module, e);
					}
					break;
				default :
					break;
			}
		}

		void doContainerStartLevel(Module module, int newStartLevel, FrameworkListener... listeners) {
			synchronized (frameworkStartLevelLock) {
				if (newStartLevel == USE_BEGINNING_START_LEVEL) {
					String beginningSL = adaptor.getProperty(Constants.FRAMEWORK_BEGINNING_STARTLEVEL);
					newStartLevel = beginningSL == null ? 1 : Integer.parseInt(beginningSL);
				}
				try {
					int currentSL = getStartLevel();
					if (currentSL == 0) {
						// check for an active framework; this is only valid when the system bundle is starting
						Module systemModule = moduleDatabase.getModule(0);
						if (systemModule != null && !State.STARTING.equals(systemModule.getState())) {
							return;
						}
					}
					// Note that we must get a new list of modules each time;
					// this is because additional modules could have been installed from the previous start-level
					// but only do this if the module database has changed!!
					List<Module> sorted = null;
					long currentTimestamp = Long.MIN_VALUE;
					if (newStartLevel > currentSL) {
						List<Module> lazyStart = null;
						List<Module> lazyStartParallel = null;
						List<Module> eagerStart = null;
						List<Module> eagerStartParallel = null;
						for (int i = currentSL; i < newStartLevel; i++) {
							int toStartLevel = i + 1;
							activeStartLevel.set(toStartLevel);
							if (debugStartLevel) {
								Debug.println("StartLevel: incremented active start level to; " + toStartLevel); //$NON-NLS-1$
							}
							if (sorted == null || currentTimestamp != moduleDatabase.getTimestamp()) {
								moduleDatabase.readLock();
								try {
									sorted = moduleDatabase.getSortedModules(Sort.BY_START_LEVEL);
									lazyStart = new ArrayList<>(sorted.size());
									lazyStartParallel = new ArrayList<>(sorted.size());
									eagerStart = new ArrayList<>(sorted.size());
									eagerStartParallel = new ArrayList<>(sorted.size());
									separateModulesByActivationPolicy(sorted, lazyStart, lazyStartParallel, eagerStart, eagerStartParallel);
									currentTimestamp = moduleDatabase.getTimestamp();
								} finally {
									moduleDatabase.readUnlock();
								}
							}
							incStartLevel(toStartLevel, lazyStart, lazyStartParallel, eagerStart, eagerStartParallel);
						}
					} else {
						for (int i = currentSL; i > newStartLevel; i--) {
							int toStartLevel = i - 1;
							activeStartLevel.set(toStartLevel);
							if (debugStartLevel) {
								Debug.println("StartLevel: decremented active start level to " + toStartLevel); //$NON-NLS-1$
							}
							if (sorted == null || currentTimestamp != moduleDatabase.getTimestamp()) {
								moduleDatabase.readLock();
								try {
									sorted = moduleDatabase.getSortedModules(Sort.BY_START_LEVEL, Sort.BY_DEPENDENCY);
									currentTimestamp = moduleDatabase.getTimestamp();
								} finally {
									moduleDatabase.readUnlock();
								}
							}
							decStartLevel(toStartLevel, sorted);
						}
					}
					if (currentSL > 0 && newStartLevel > 0) {
						// Only fire the start level event if we are not in the middle
						// of launching or shutting down the framework
						adaptor.publishContainerEvent(ContainerEvent.START_LEVEL, module, null, listeners);
					}
				} catch (Error | RuntimeException e) {
					adaptor.publishContainerEvent(ContainerEvent.ERROR, module, e, listeners);
					throw e;
				}
			}
		}

		private void incStartLevel(int toStartLevel, List<Module> lazyStart, List<Module> lazyStartParallel, List<Module> eagerStart, List<Module> eagerStartParallel) {
			// start lazy activated first
			// start parallel bundles first
			incStartLevel(toStartLevel, lazyStartParallel, true);
			incStartLevel(toStartLevel, lazyStart, false);
			incStartLevel(toStartLevel, eagerStartParallel, true);
			incStartLevel(toStartLevel, eagerStart, false);
		}

		private void separateModulesByActivationPolicy(List<Module> sortedModules, List<Module> lazyStart, List<Module> lazyStartParallel, List<Module> eagerStart, List<Module> eagerStartParallel) {
			for (Module module : sortedModules) {
				if (!restrictParallelStart || module.isParallelActivated()) {
					if (module.isLazyActivate()) {
						lazyStartParallel.add(module);
					} else {
						eagerStartParallel.add(module);
					}
				} else {
					if (module.isLazyActivate()) {
						lazyStart.add(module);
					} else {
						eagerStart.add(module);
					}
				}
			}
		}

		private void incStartLevel(final int toStartLevel, List<Module> candidatesToStart, boolean inParallel) {
			if (candidatesToStart.isEmpty()) {
				return;
			}
			final List<Module> toStart = new ArrayList<>();
			for (final Module module : candidatesToStart) {
				if (isRefreshingSystemModule()) {
					return;
				}
				try {
					int moduleStartLevel = module.getStartLevel();
					if (moduleStartLevel < toStartLevel) {
						// skip modules who should have already been started
						continue;
					} else if (moduleStartLevel == toStartLevel) {
						toStart.add(module);
					} else {
						break;
					}
				} catch (IllegalStateException e) {
					// been uninstalled
					continue;
				}
			}
			if (toStart.isEmpty()) {
				return;
			}
			final Executor executor = inParallel ? adaptor.getStartLevelExecutor() : new Executor() {
				@Override
				public void execute(Runnable command) {
					command.run();
				}
			};
			final CountDownLatch done = new CountDownLatch(toStart.size());
			for (final Module module : toStart) {
				executor.execute(new Runnable() {
					@Override
					public void run() {
						try {
							if (debugStartLevel) {
								Debug.println("StartLevel: resuming bundle; " + ContainerStartLevel.this.toString(module) + "; with startLevel=" + toStartLevel); //$NON-NLS-1$ //$NON-NLS-2$
							}
							module.start(StartOptions.TRANSIENT_IF_AUTO_START, StartOptions.TRANSIENT_RESUME);
						} catch (BundleException e) {
							adaptor.publishContainerEvent(ContainerEvent.ERROR, module, e);
						} catch (IllegalStateException e) {
							// been uninstalled
						} finally {
							done.countDown();
						}
					}
				});

			}
			try {
				done.await();
			} catch (InterruptedException e) {
				adaptor.publishContainerEvent(ContainerEvent.ERROR, moduleDatabase.getModule(0), e);
			}
		}

		private void decStartLevel(int toStartLevel, List<Module> sortedModules) {
			ListIterator<Module> iModules = sortedModules.listIterator(sortedModules.size());
			while (iModules.hasPrevious()) {
				Module module = iModules.previous();
				try {
					int moduleStartLevel = module.getStartLevel();
					if (moduleStartLevel > toStartLevel + 1) {
						// skip modules who should have already been stopped
						continue;
					} else if (moduleStartLevel <= toStartLevel) {
						// stopped all modules we are going to for this start level
						break;
					}
					try {
						if (Module.ACTIVE_SET.contains(module.getState())) {
							if (debugStartLevel) {
								Debug.println("StartLevel: stopping bundle; " + toString(module) + "; with startLevel=" + moduleStartLevel); //$NON-NLS-1$ //$NON-NLS-2$
							}
							// Note that we don't need to hold the state change lock
							// here when checking the active status because no other
							// thread will successfully be able to start this bundle
							// since the start-level is no longer met.
							module.stop(StopOptions.TRANSIENT);
						}
					} catch (BundleException e) {
						adaptor.publishContainerEvent(ContainerEvent.ERROR, module, e);
					}
				} catch (IllegalStateException e) {
					// been uninstalled
					continue;
				}
			}
		}

		private EventManager getManager() {
			synchronized (eventManagerLock) {
				if (startLevelThread == null) {
					startLevelThread = new EventManager("Start Level: " + adaptor.toString()); //$NON-NLS-1$
				}
				return startLevelThread;
			}
		}

		// because of bug 378491 we have to synchronize access to the manager
		// so we can close and re-open ourselves
		void close() {
			synchronized (eventManagerLock) {
				// force a manager to be created if it did not exist
				EventManager manager = getManager();
				// this prevents any operations until open is called
				manager.close();
			}
		}

		void open() {
			synchronized (eventManagerLock) {
				if (startLevelThread != null) {
					// Make sure it is closed just incase
					startLevelThread.close();
					// a new one will be constructed on demand
					startLevelThread = null;
				}
			}
		}

		String toString(Module m) {
			Bundle b = m.getBundle();
			return b != null ? b.toString() : m.toString();
		}
	}
}