Try to show lock owner in MONITOR thread dump.

A thread in the MONITOR state is blocked waiting on a monitor.  This
raises two interesting questions: (1) what lock is it waiting on, and
(2) who holds that lock?  The answer to (1) can be determined easily by
looking at the source code, but (2) is a bit harder.

This change extracts the target object from the instruction stream and
prints some information about it, e.g.:

- waiting to lock <0x40028c68> (a java.lang.Object) held by threadid=1 (main)

Change-Id: Iad18fc6f2df4142368bdf1063b8cc71de2d66156
Also: fiddled with "must [not] be locked" on a recently-added function.

1 files changed, 9 insertions, 1 deletions

diff --git a/vm/Thread.h b/vm/Thread.h
index 44004bfd9..e2af2531d 100644
--- a/vm/Thread.h
+++ b/vm/Thread.h
@@ -441,13 +441,21 @@ Thread* dvmGetThreadFromThreadObject(Object* vmThreadObj);
 
 /*
  * Given a pthread handle, return the associated Thread*.
- * Caller must NOT hold the thread list lock.
+ * Caller must hold the thread list lock.
  *
  * Returns NULL if the thread was not found.
  */
 Thread* dvmGetThreadByHandle(pthread_t handle);
 
 /*
+ * Given a thread ID, return the associated Thread*.
+ * Caller must hold the thread list lock.
+ *
+ * Returns NULL if the thread was not found.
+ */
+Thread* dvmGetThreadByThreadId(u4 threadId);
+
+/*
  * Sleep in a thread.  Returns when the sleep timer returns or the thread
  * is interrupted.
  */