Make MuninnPage extend OptiLock and make things *compile*

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/DaemonThreadFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2015 "Neo Technology,"
+ * Copyright (c) 2002-2016 "Neo Technology,"
  * Network Engine for Objects in Lund AB [http://neotechnology.com]
  *
  * This file is part of Neo4j.

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnPage.java

@@ -21,7 +21,6 @@
 
 import java.io.IOException;
 
-import org.neo4j.concurrent.jsr166e.StampedLock;
 import org.neo4j.io.pagecache.Page;
 import org.neo4j.io.pagecache.PageCursor;
 import org.neo4j.io.pagecache.PageSwapper;
@@ -34,7 +33,7 @@
 
 import static java.lang.String.format;
 
-final class MuninnPage extends StampedLock implements Page
+final class MuninnPage extends OptiLock implements Page
 {
     private static final long usageStampOffset = UnsafeUtil.getFieldOffset( MuninnPage.class, "usageStamp" );
 
@@ -144,7 +143,6 @@ private void doFlush(
             long filePageId,
             FlushEventOpportunity flushOpportunity ) throws IOException
     {
-        assert isReadLocked() || isWriteLocked() : "doFlush requires lock";
         FlushEvent event = flushOpportunity.beginFlush( filePageId, getCachePageId(), swapper );
         try
         {
@@ -168,7 +166,6 @@ public void fault(
             long filePageId,
             PageFaultEvent faultEvent ) throws IOException
     {
-        assert isWriteLocked(): "Cannot fault page without write-lock";
         if ( this.swapper != null || this.filePageId != PageCursor.UNBOUND_PAGE_ID )
         {
             String msg = format(
@@ -198,7 +195,6 @@ public void fault(
      */
     public void evict( EvictionEvent evictionEvent ) throws IOException
     {
-        assert isWriteLocked(): "Cannot evict page without write-lock";
         long filePageId = this.filePageId;
         evictionEvent.setCachePageId( getCachePageId() );
         evictionEvent.setFilePageId( filePageId );
@@ -232,7 +228,6 @@ public boolean isBoundTo( PageSwapper swapper, long filePageId )
      */
     public void initBuffer()
     {
-        assert isWriteLocked(): "Cannot initBuffer without write-lock";
         if ( pointer == 0 )
         {
             pointer = memoryManager.allocateAligned( size() );
@@ -249,6 +244,6 @@ public String toString()
     {
         return format( "MuninnPage@%x[%s -> %x, filePageId = %s%s, swapper = %s]%s",
                 hashCode(), getCachePageId(), pointer, filePageId, (isDirty() ? ", dirty" : ""),
-                swapper, getLockStateString() );
+                swapper, super.toString() );
     }
 }

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnPageCache.java

@@ -663,8 +663,7 @@ private MuninnPage cooperativelyEvict( PageFaultEvent faultEvent ) throws IOExce
 
             if ( page.isLoaded() && page.decrementUsage() )
             {
-                long stamp = page.tryWriteLock();
-                if ( stamp != 0 )
+                if ( page.tryExclusiveLock() )
                 {
                     // We got the write lock. Time to evict the page!
                     try ( EvictionEvent evictionEvent = faultEvent.beginEviction() )
@@ -673,7 +672,7 @@ private MuninnPage cooperativelyEvict( PageFaultEvent faultEvent ) throws IOExce
                     }
                     finally
                     {
-                        page.unlockWrite( stamp );
+                        page.unlockExclusive();
                     }
                 }
             }
@@ -790,8 +789,7 @@ int evictPages( int pageCountToEvict, int clockArm, EvictionRunEvent evictionRun
 
             if ( page.isLoaded() && page.decrementUsage() )
             {
-                long stamp = page.tryWriteLock();
-                if ( stamp != 0 )
+                if ( page.tryExclusiveLock() )
                 {
                     // We got the lock.
                     // Assume that the eviction is going to succeed, so that we
@@ -812,7 +810,7 @@ int evictPages( int pageCountToEvict, int clockArm, EvictionRunEvent evictionRun
                     }
                     finally
                     {
-                        page.unlockWrite( stamp );
+                        page.unlockExclusive();
                     }
 
                     if ( pageEvicted )
@@ -951,14 +949,13 @@ private long flushAtIORatio( double ratio )
 
                 // Skip the page if it is already write locked, or not dirty, or too popular.
                 boolean thisPageIsDirty = false;
-                if ( page.isWriteLocked() || !(thisPageIsDirty = page.isDirty()) || !page.decrementUsage() )
+                if ( !(thisPageIsDirty = page.isDirty()) || !page.decrementUsage() )
                 {
                     seenDirtyPages |= thisPageIsDirty;
                     continue; // Continue looping to the next page.
                 }
 
-                long stamp = page.tryReadLock();
-                if ( stamp != 0 )
+                if ( page.tryExclusiveLock() ) // TODO somehow avoid taking these exclusive locks, that we currently need to avoid racing with other flushes
                 {
                     try
                     {
@@ -984,7 +981,7 @@ private long flushAtIORatio( double ratio )
                     }
                     finally
                     {
-                        page.unlockRead( stamp );
+                        page.unlockExclusive();
                     }
                 }
 

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnPageCursor.java

@@ -47,7 +47,6 @@ abstract class MuninnPageCursor implements PageCursor
     protected int pf_flags;
     protected long currentPageId;
     protected long nextPageId;
-    protected long lockStamp;
     private long pointer;
     private int size;
 
@@ -115,7 +114,6 @@ public final void close()
     protected void clearPageState()
     {
         size = 0; // make all future bound checks fail
-        lockStamp = 0; // make sure not to accidentally keep a lock state around
         page = null; // make all future page navigation fail
     }
 
@@ -236,7 +234,6 @@ private MuninnPage pageFault(
         // we must make sure to release that write lock as well.
         PageFaultEvent faultEvent = pinEvent.beginPageFault();
         MuninnPage page;
-        long stamp;
         try
         {
             // The grabFreePage method might throw.
@@ -247,7 +244,10 @@ private MuninnPage pageFault(
             // their translation tables might race with eviction) and try to pin it.
             // However, they will all fail because when they try to pin, the page will either be 1) free, 2) bound to
             // our file, or 3) the page is write locked.
-            stamp = page.writeLock();
+            if ( !page.tryExclusiveLock() )
+            {
+                throw new AssertionError( "Unable to take exclusive lock on free page" );
+            }
         }
         catch ( Throwable throwable )
         {
@@ -273,15 +273,15 @@ private MuninnPage pageFault(
         catch ( Throwable throwable )
         {
             // Make sure to unlock the page, so the eviction thread can pick up our trash.
-            page.unlockWrite( stamp );
+            page.unlockExclusive();
             // Make sure to unstuck the page fault latch.
             UnsafeUtil.putObjectVolatile( chunk, chunkOffset, null );
             latch.release();
             faultEvent.done( throwable );
             pinEvent.done();
             throw throwable;
         }
-        convertPageFaultLock( page, stamp );
+        convertPageFaultLock( page );
         UnsafeUtil.putObjectVolatile( chunk, chunkOffset, page );
         latch.release();
         faultEvent.done();
@@ -295,7 +295,7 @@ protected long assertPagedFileStillMappedAndGetIdOfLastPage()
 
     protected abstract void unpinCurrentPage();
 
-    protected abstract void convertPageFaultLock( MuninnPage page, long stamp );
+    protected abstract void convertPageFaultLock( MuninnPage page );
 
     protected abstract void pinCursorToPage( MuninnPage page, long filePageId, PageSwapper swapper );
 

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnPagedFile.java

@@ -193,7 +193,6 @@ public void flushAndForce() throws IOException
     void flushAndForceInternal( FlushEventOpportunity flushOpportunity ) throws IOException
     {
         pageCache.pauseBackgroundFlushTask();
-        long[] stamps = new long[translationTableChunkSize];
         MuninnPage[] pages = new MuninnPage[translationTableChunkSize];
         long filePageId = -1; // Start at -1 because we increment at the *start* of the chunk-loop iteration.
         try
@@ -210,7 +209,7 @@ void flushAndForceInternal( FlushEventOpportunity flushOpportunity ) throws IOEx
                     if ( element instanceof MuninnPage )
                     {
                         MuninnPage page = (MuninnPage) element;
-                        stamps[pagesGrabbed] = page.readLock();
+                        page.writeLock();
                         if ( page.isBoundTo( swapper, filePageId ) && page.isDirty() )
                         {
                             // The page is still bound to the expected file and file page id after we locked it,
@@ -222,17 +221,17 @@ void flushAndForceInternal( FlushEventOpportunity flushOpportunity ) throws IOEx
                         }
                         else
                         {
-                            page.unlockRead( stamps[pagesGrabbed] );
+                            page.unlockWrite();
                         }
                     }
                     if ( pagesGrabbed > 0 )
                     {
-                        pagesGrabbed = vectoredFlush( stamps, pages, pagesGrabbed, flushOpportunity );
+                        pagesGrabbed = vectoredFlush( pages, pagesGrabbed, flushOpportunity );
                     }
                 }
                 if ( pagesGrabbed > 0 )
                 {
-                    vectoredFlush( stamps, pages, pagesGrabbed, flushOpportunity );
+                    vectoredFlush( pages, pagesGrabbed, flushOpportunity );
                 }
             }
 
@@ -244,8 +243,7 @@ void flushAndForceInternal( FlushEventOpportunity flushOpportunity ) throws IOEx
         }
     }
 
-    private int vectoredFlush(
-            long[] stamps, MuninnPage[] pages, int pagesGrabbed, FlushEventOpportunity flushOpportunity )
+    private int vectoredFlush( MuninnPage[] pages, int pagesGrabbed, FlushEventOpportunity flushOpportunity )
             throws IOException
     {
         FlushEvent flush = null;
@@ -284,7 +282,7 @@ private int vectoredFlush(
             // Always unlock all the pages in the vector
             for ( int j = 0; j < pagesGrabbed; j++ )
             {
-                pages[j].unlockRead( stamps[j] );
+                pages[j].unlockWrite();
             }
         }
     }

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnReadPageCursor.java

@@ -25,7 +25,7 @@
 
 final class MuninnReadPageCursor extends MuninnPageCursor
 {
-    private boolean optimisticLock;
+    protected long lockStamp;
 
     @Override
     protected void unpinCurrentPage()
@@ -35,14 +35,8 @@ protected void unpinCurrentPage()
         if ( p != null )
         {
             pinEvent.done();
-            assert optimisticLock || p.isReadLocked() :
-                    "pinned page wasn't really locked; not even optimistically: " + p;
-
-            if ( !optimisticLock )
-            {
-                p.unlockRead( lockStamp );
-            }
         }
+        lockStamp = 0; // make sure not to accidentally keep a lock state around
         clearPageState();
     }
 
@@ -64,8 +58,7 @@ public boolean next() throws IOException
     @Override
     protected void lockPage( MuninnPage page )
     {
-        lockStamp = page.tryOptimisticRead();
-        optimisticLock = true;
+        lockStamp = page.tryOptimisticReadLock();
     }
 
     @Override
@@ -81,43 +74,37 @@ protected void pinCursorToPage( MuninnPage page, long filePageId, PageSwapper sw
     }
 
     @Override
-    protected void convertPageFaultLock( MuninnPage page, long stamp )
+    protected void convertPageFaultLock( MuninnPage page )
     {
-        stamp = page.tryConvertToReadLock( stamp );
-        assert stamp != 0: "Converting a write lock to a read lock should always succeed";
-        lockStamp = stamp;
-        optimisticLock = false; // We're using a pessimistic read lock
+        lockStamp = page.unlockExclusive();
     }
 
     @Override
     public boolean shouldRetry() throws IOException
     {
-        boolean needsRetry = optimisticLock && !page.validate( lockStamp );
+        boolean needsRetry = !page.validateReadLock( lockStamp );
         if ( needsRetry )
         {
             setOffset( 0 );
-            optimisticLock = false;
-            lockStamp = page.readLock();
-            // We have a pessimistic read lock on the page now. This prevents
-            // writes to the page, and it prevents the page from being evicted.
-            // However, it might have been evicted while we held the optimistic
+            lockStamp = page.tryOptimisticReadLock();
+            // The page might have been evicted while we held the optimistic
             // read lock, so we need to check with page.pin that this is still
             // the page we're actually interested in:
             if ( !page.isBoundTo( pagedFile.swapper, currentPageId ) )
             {
                 // This is no longer the page we're interested in, so we have
-                // to release our lock and redo the pinning.
+                // to redo the pinning.
                 // This might in turn lead to a new optimistic lock on a
                 // different page if someone else has taken the page fault for
                 // us. If nobody has done that, we'll take the page fault
-                // ourselves, and in that case we'll end up with first a write
-                // lock during the faulting, and then a read lock once the
+                // ourselves, and in that case we'll end up with first an exclusive
+                // lock during the faulting, and then an optimistic read lock once the
                 // fault itself is over.
-                page.unlockRead( lockStamp );
-                // Forget about this page in case pin() throws and the cursor
+                // First, forget about this page in case pin() throws and the cursor
                 // is closed; we don't want unpinCurrentPage() to try unlocking
                 // this page.
                 page = null;
+                // Then try pin again.
                 pin( currentPageId, false );
             }
         }

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnWritePageCursor.java

@@ -32,7 +32,6 @@ protected void unpinCurrentPage()
         if ( page != null )
         {
             pinEvent.done();
-            assert page.isWriteLocked(): "page pinned for writing was not write locked: " + page;
             unlockPage( page );
         }
         clearPageState();
@@ -63,13 +62,13 @@ public boolean next() throws IOException
     @Override
     protected void lockPage( MuninnPage page )
     {
-        lockStamp = page.writeLock();
+        page.writeLock();
     }
 
     @Override
     protected void unlockPage( MuninnPage page )
     {
-        page.unlockWrite( lockStamp );
+        page.unlockWrite();
     }
 
     @Override
@@ -87,9 +86,10 @@ protected void pinCursorToPage( MuninnPage page, long filePageId, PageSwapper sw
     }
 
     @Override
-    protected void convertPageFaultLock( MuninnPage page, long stamp )
+    protected void convertPageFaultLock( MuninnPage page )
     {
-        lockStamp = stamp;
+        page.unlockExclusive(); // TODO page.unlockExclusiveAndTakeWriteLock
+        page.writeLock();
     }
 
     @Override

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/OptiLock.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2015 "Neo Technology,"
+ * Copyright (c) 2002-2016 "Neo Technology,"
  * Network Engine for Objects in Lund AB [http://neotechnology.com]
  *
  * This file is part of Neo4j.
@@ -222,6 +222,11 @@ public long unlockExclusive()
         return n;
     }
 
+    public void unlockExclusiveAndTakeWriteLock()
+    {
+        // TODO
+    }
+
     private void throwUnmatchedUnlockExclusive( long s )
     {
         throw new IllegalMonitorStateException( "Unmatched unlockExclusive: " + describeState( s ) );

community/io/src/test/java/org/neo4j/io/pagecache/impl/muninn/OptiLockStressTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2015 "Neo Technology,"
+ * Copyright (c) 2002-2016 "Neo Technology,"
  * Network Engine for Objects in Lund AB [http://neotechnology.com]
  *
  * This file is part of Neo4j.