BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
The contents of this file are subject to the Eclipse Public
License Version 2.0 (the "License"); you may not use this file
except in compliance with the License. You may obtain a copy of
the License at http://www.eclipse.org/legal/epl-v20.html
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
Copyright (C) 2004 Charles O Nutter 
Copyright (C) 2004 Jan Arne Petersen 
Copyright (C) 2004 Stefan Matthias Aust 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
END LICENSE BLOCK /***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * License Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2004 Charles O Nutter <headius@headius.com>
 * Copyright (C) 2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
 * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby;

import java.util.Collections;
import java.util.Set;
import org.jruby.anno.JRubyMethod;
import org.jruby.anno.JRubyClass;

import org.jruby.runtime.Block;
import org.jruby.runtime.ClassIndex;
import org.jruby.runtime.ObjectAllocator;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.util.collections.WeakHashSet;

Implementation of Ruby's ThreadGroup class. This is currently
just a stub.

Author:
Charles O Nutter (headius@headius.com)/**
 * Implementation of Ruby's <code>ThreadGroup</code> class. This is currently
 * just a stub.
 * <p>
 *
 * @author Charles O Nutter (headius@headius.com)
 */
@JRubyClass(name="ThreadGroup")
public class RubyThreadGroup extends RubyObject {
    private final Set<RubyThread> rubyThreadList = Collections.synchronizedSet(new WeakHashSet<RubyThread>());
    private boolean enclosed = false;

    public static RubyClass createThreadGroupClass(Ruby runtime) {
        RubyClass threadGroupClass = runtime.defineClass("ThreadGroup", runtime.getObject(), THREADGROUP_ALLOCATOR);
        runtime.setThreadGroup(threadGroupClass);

        threadGroupClass.setClassIndex(ClassIndex.THREADGROUP);
        
        threadGroupClass.defineAnnotatedMethods(RubyThreadGroup.class);
        
        // create the default thread group
        RubyThreadGroup defaultThreadGroup = new RubyThreadGroup(runtime, threadGroupClass);
        runtime.setDefaultThreadGroup(defaultThreadGroup);
        threadGroupClass.defineConstant("Default", defaultThreadGroup);

        return threadGroupClass;
    }

    private static final ObjectAllocator THREADGROUP_ALLOCATOR = new ObjectAllocator() {
        public IRubyObject allocate(Ruby runtime, RubyClass klazz) {
            return new RubyThreadGroup(runtime, klazz);
        }
    };

    @JRubyMethod(name = "add", required = 1)
    public IRubyObject add(IRubyObject rubyThread, Block block) {
        if (!(rubyThread instanceof RubyThread)) throw getRuntime().newTypeError(rubyThread, getRuntime().getThread());
        
        // synchronize on the RubyThread for threadgroup updates
        if (isFrozen()) {
            throw getRuntime().newTypeError("can't add to the frozen thread group");
        }

        if (enclosed) {
            throw getRuntime().newTypeError("can't move to the enclosed thread group");
        }
        
        RubyThread thread = (RubyThread)rubyThread;

        RubyThreadGroup threadGroup = thread.getThreadGroup();

        // edit by headius: ThreadGroup may be null, perhaps if this is an adopted thread etc
        if(threadGroup != null) {
            if (threadGroup.isFrozen()) {
                throw getRuntime().newTypeError("can't move from the frozen thread group");
            }

            if (threadGroup.enclosed_p(block).isTrue()) {
                throw getRuntime().newTypeError("can't move from the enclosed thread group");
            }
        }

        // we only add live threads
        if (thread.alive_p().isTrue()) {
            addDirectly(thread);
        }
        
        return this;
    }
    
    void addDirectly(RubyThread rubyThread) {
        synchronized (rubyThread) {
            IRubyObject oldGroup = rubyThread.group();
            if (!oldGroup.isNil()) {
                RubyThreadGroup threadGroup = (RubyThreadGroup) oldGroup;
                threadGroup.rubyThreadList.remove(rubyThread);
            }

            rubyThread.setThreadGroup(this);
            rubyThreadList.add(rubyThread);
        }
    }
    
    public void remove(RubyThread rubyThread) {
        synchronized (rubyThread) {
            rubyThread.setThreadGroup(null);
            rubyThreadList.remove(rubyThread);
        }
    }
    
    @JRubyMethod
    public IRubyObject enclose(Block block) {
        enclosed = true;

        return this;
    }
    
    @JRubyMethod(name = "enclosed?")
    public IRubyObject enclosed_p(Block block) {
        return getRuntime().newBoolean(enclosed);
    }

    @JRubyMethod
    public IRubyObject list(Block block) {
        RubyArray ary = RubyArray.newArray(getRuntime());
        synchronized (rubyThreadList) {
            for (RubyThread thread : rubyThreadList) {
                if (thread != null) {
                    ary.append(thread);
                }
            }
        }
        return ary;
    }

    
Number of threads in this thread group. Note that threads that have
recently died may still be counted here.
Returns:
number of threads in this thread group/**
     * Number of threads in this thread group. Note that threads that have
     * recently died may still be counted here.
     *
     * @return number of threads in this thread group
     */
    public int size() {
        return rubyThreadList.size();
    }

    private RubyThreadGroup(Ruby runtime, RubyClass type) {
        super(runtime, type);
    }

}