Merge lp:~pbeaman/akiban-persistit/add-lock2 into lp:akiban-persistit

[Peter Beaman]

Make the status fields (e.g., _commitCompleted) volatile. Use of a Transaction instance is almost entirely thread-private, but the CLEANUP_MANAGER thread looks at the transaction state of Transaction instances that formerly belonged to now-ended threads. I believe a failure we are seeing in WriteSkewIT is caused by an intermittent failure to read that state coherently. Specifically, it is trying to run rollback on a Transaction that actually has already been rolled back (by its own thread), and that attempt is throwing an IllegalMonitorStateException for that reason.

[Nathan Williams (nwilliams)]

Sounds plausible.

review: Approve

=== modified file 'src/main/java/com/persistit/Transaction.java'
--- src/main/java/com/persistit/Transaction.java	2012-11-30 20:33:30 +0000
+++ src/main/java/com/persistit/Transaction.java	2013-01-31 20:56:24 +0000
@@ -412,14 +412,15 @@
     private final Persistit _persistit;
     private final SessionId _sessionId;
     private final long _id;
-    private int _nestedDepth;
-    private boolean _rollbackPending;
-    private boolean _rollbackCompleted;
-    private boolean _commitCompleted;
+    
+    private volatile int _nestedDepth;
+    private volatile boolean _rollbackPending;
+    private volatile boolean _rollbackCompleted;
+    private volatile boolean _commitCompleted;
 
-    private long _rollbackCount = 0;
-    private long _commitCount = 0;
-    private int _rollbacksSinceLastCommit = 0;
+    private volatile long _rollbackCount = 0;
+    private volatile long _commitCount = 0;
+    private volatile int _rollbacksSinceLastCommit = 0;
 
     private volatile TransactionStatus _transactionStatus;
     private volatile long _startTimestamp;