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package sun.jvm.hotspot.code;

import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.utilities.*;

A port of the VM's StubQueue. Note that the VM implicitly knows the type of the objects contained in each StubQueue because it passes in an instance of a StubInterface to the StubQueue's constructor; the goal in the VM was to save space in the generated code. In the SA APIs the pattern has been to use the VirtualConstructor mechanism to instantiate wrapper objects of the appropriate type for objects down in the VM; see, for example, the CodeCache, which identifies NMethods, RuntimeStubs, etc.

In this port we eliminate the StubInterface in favor of passing in the class corresponding to the type of Stub which this StubQueue contains.

/** <P> A port of the VM's StubQueue. Note that the VM implicitly knows the type of the objects contained in each StubQueue because it passes in an instance of a StubInterface to the StubQueue's constructor; the goal in the VM was to save space in the generated code. In the SA APIs the pattern has been to use the VirtualConstructor mechanism to instantiate wrapper objects of the appropriate type for objects down in the VM; see, for example, the CodeCache, which identifies NMethods, RuntimeStubs, etc. </P> <P> In this port we eliminate the StubInterface in favor of passing in the class corresponding to the type of Stub which this StubQueue contains. </P> */
public class StubQueue extends VMObject { // FIXME: add the rest of the fields private static AddressField stubBufferField; private static CIntegerField bufferLimitField; private static CIntegerField queueBeginField; private static CIntegerField queueEndField; private static CIntegerField numberOfStubsField; // The type of the contained stubs (i.e., InterpreterCodelet, // ICStub). Must be a subclass of type Stub. private Class stubType; static { VM.registerVMInitializedObserver(new Observer() { public void update(Observable o, Object data) { initialize(VM.getVM().getTypeDataBase()); } }); } private static synchronized void initialize(TypeDataBase db) { Type type = db.lookupType("StubQueue"); stubBufferField = type.getAddressField("_stub_buffer"); bufferLimitField = type.getCIntegerField("_buffer_limit"); queueBeginField = type.getCIntegerField("_queue_begin"); queueEndField = type.getCIntegerField("_queue_end"); numberOfStubsField = type.getCIntegerField("_number_of_stubs"); } public StubQueue(Address addr, Class stubType) { super(addr); this.stubType = stubType; } public boolean contains(Address pc) { if (pc == null) return false; long offset = pc.minus(getStubBuffer()); return ((0 <= offset) && (offset < getBufferLimit())); } public Stub getStubContaining(Address pc) { if (contains(pc)) { int i = 0; for (Stub s = getFirst(); s != null; s = getNext(s)) { if (stubContains(s, pc)) { return s; } } } return null; } public boolean stubContains(Stub s, Address pc) { return (s.codeBegin().lessThanOrEqual(pc) && s.codeEnd().greaterThan(pc)); } public int getNumberOfStubs() { return (int) numberOfStubsField.getValue(addr); } public Stub getFirst() { return ((getNumberOfStubs() > 0) ? getStubAt(getQueueBegin()) : null); } public Stub getNext(Stub s) { long i = getIndexOf(s) + getStubSize(s); if (i == getBufferLimit()) { i = 0; } return ((i == getQueueEnd()) ? null : getStubAt(i)); } public Stub getPrev(Stub s) { if (getIndexOf(s) == getQueueBegin()) { return null; } Stub temp = getFirst(); Stub prev = null; while (temp != null && getIndexOf(temp) != getIndexOf(s)) { prev = temp; temp = getNext(temp); } return prev; } //-------------------------------------------------------------------------------- // Internals only below this point // private long getQueueBegin() { return queueBeginField.getValue(addr); } private long getQueueEnd() { return queueEndField.getValue(addr); } private long getBufferLimit() { return bufferLimitField.getValue(addr); } private Address getStubBuffer() { return stubBufferField.getValue(addr); } private Stub getStubAt(long offset) { checkIndex(offset); return (Stub) VMObjectFactory.newObject(stubType, getStubBuffer().addOffsetTo(offset)); } private long getIndexOf(Stub s) { long i = s.getAddress().minus(getStubBuffer()); checkIndex(i); return i; } private long getStubSize(Stub s) { return s.getSize(); } private void checkIndex(long i) { if (Assert.ASSERTS_ENABLED) { Assert.that(0 <= i && i < getBufferLimit() && (i % VM.getVM().getAddressSize() == 0), "illegal index"); } } }