org.jikesrvm.mm.mminterface
Class Handshake

java.lang.Object
  org.jikesrvm.mm.mminterface.Handshake

public class Handshake
extends Object

Handshake handles mutator requests to initiate a collection, and wait for a collection to complete. It implements the process of suspending all mutator threads executing in Java and starting all the GC threads (CollectorThreads) for the processors that will be participating in a collection. This may not be all processors, if we exclude those executing in native code. Because the threading strategy within RVM is currently under revision, the logic here is also changing and somewhat "messy".

See Also:

CollectorThread

verbose

public static final int verbose

Class variables

See Also:

Constant Field Values

lock

private Monitor lock

Instance variables

requestFlag

protected boolean requestFlag

gcTrigger

public int gcTrigger

collectorThreadsParked

private int collectorThreadsParked

Handshake

public Handshake()

boot

public void boot()

waitForGCToFinish

public void waitForGCToFinish()

Call this if you know that a GC request has already been made and you'd like to wait on that GC to finish - presumably because you're trying to allocate and cannot reasonably do so before GC is done. Note, there CANNOT be a GC safe point between when you realize that there is already a GC request and when you call this method!

requestAndAwaitCompletion

public void requestAndAwaitCompletion(int why)

Called by mutators to request a garbage collection and wait for it to complete. Waiting is actually just yielding the processor to schedule the collector thread, which will disable further thread switching on the processor until it has completed the collection.

requestAndContinue

public void requestAndContinue(int why)

Called by mutators to request an asynchronous garbage collection. After initiating a GC (if one is not already initiated), the caller continues until it yields to the GC. It may thus make this call at an otherwise unsafe point.

reset

public void reset()

parkCollectorThread

void parkCollectorThread()

request

private boolean request(int why)

Called by mutators to request a garbage collection.

Returns:

true if the completion flag is not already set.