Split page cache tracer into page cache tracer and page cursor tracer…

…. Cleanup interfaces. Tests are in best case compilable.

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

@@ -27,9 +27,9 @@
 import org.neo4j.io.pagecache.CursorException;
 import org.neo4j.io.pagecache.PageCursor;
 import org.neo4j.io.pagecache.PageSwapper;
-import org.neo4j.io.pagecache.tracing.PageCacheTracer;
 import org.neo4j.io.pagecache.tracing.PageFaultEvent;
 import org.neo4j.io.pagecache.tracing.PinEvent;
+import org.neo4j.io.pagecache.tracing.cursor.DefaultPageCursorTracer;
 import org.neo4j.unsafe.impl.internal.dragons.UnsafeUtil;
 
 import static org.neo4j.io.pagecache.PagedFile.PF_SHARED_WRITE_LOCK;
@@ -54,7 +54,6 @@ abstract class MuninnPageCursor extends PageCursor
     private final long victimPage;
     protected MuninnPagedFile pagedFile;
     protected PageSwapper swapper;
-    protected PageCacheTracer tracer;
     protected MuninnPage page;
     protected PinEvent pinEvent;
     protected long pageId;
@@ -72,6 +71,8 @@ abstract class MuninnPageCursor extends PageCursor
     // offending code.
     private Object cursorException;
 
+    private DefaultPageCursorTracer pageCursorTracer = new DefaultPageCursorTracer();
+
     MuninnPageCursor( long victimPage )
     {
         this.victimPage = victimPage;
@@ -81,7 +82,7 @@ abstract class MuninnPageCursor extends PageCursor
     final void initialiseFile( MuninnPagedFile pagedFile )
     {
         this.swapper = pagedFile.swapper;
-        this.tracer = pagedFile.tracer;
+        this.pageCursorTracer.init( pagedFile.tracer );
     }
 
     final void initialiseFlags( MuninnPagedFile pagedFile, long pageId, int pf_flags )
@@ -131,6 +132,7 @@ public final void close()
             if ( cursor.pagedFile != null )
             {
                 cursor.unpinCurrentPage();
+                cursor.pageCursorTracer.reportEvents();
                 cursor.releaseCursor();
                 // We null out the pagedFile field to allow it and its (potentially big) translation table to be garbage
                 // collected when the file is unmapped, since the cursors can stick around in thread local caches, etc.
@@ -209,7 +211,7 @@ public final File getCurrentFile()
      */
     protected void pin( long filePageId, boolean writeLock ) throws IOException
     {
-        pinEvent = tracer.beginPin( writeLock, filePageId, swapper );
+        pinEvent = pageCursorTracer.beginPin( writeLock, filePageId, swapper );
         int chunkId = MuninnPagedFile.computeChunkId( filePageId );
         // The chunkOffset is the addressing offset into the chunk array object for the relevant array slot. Using
         // this, we can access the array slot with Unsafe.

community/io/src/main/java/org/neo4j/io/pagecache/tracing/AutoCloseablePageCacheTracerEvent.java

@@ -27,5 +27,5 @@
 public interface AutoCloseablePageCacheTracerEvent extends AutoCloseable
 {
     @Override
-    public void close();
+    void close();
 }

community/io/src/main/java/org/neo4j/io/pagecache/tracing/DefaultPageCacheTracer.java

@@ -36,52 +36,6 @@
  */
 public class DefaultPageCacheTracer implements PageCacheTracer
 {
-    private static final MethodHandle beginPinMH;
-    private static final SwitchPoint beginPinSwitchPoint;
-    static
-    {
-        try
-        {
-            // A hidden setting to have pin/unpin monitoring enabled from the start by default.
-            // NOTE: This flag is documented in jmx.asciidoc
-            boolean alwaysEnabled = packageFlag( DefaultPageCacheTracer.class, "tracePinUnpin", false );
-
-            MethodType type = MethodType.methodType( PinEvent.class );
-            MethodHandles.Lookup lookup = MethodHandles.lookup();
-            MethodHandle monitoredPinMH = lookup.findVirtual( DefaultPageCacheTracer.class, "beginTracingPin", type );
-            if ( alwaysEnabled )
-            {
-                beginPinMH = monitoredPinMH;
-                beginPinSwitchPoint = null;
-            }
-            else
-            {
-                MethodHandle nullPinMH = lookup.findVirtual( DefaultPageCacheTracer.class, "beginNullPin", type );
-                beginPinSwitchPoint = new SwitchPoint();
-                beginPinMH = beginPinSwitchPoint.guardWithTest( nullPinMH, monitoredPinMH );
-            }
-        }
-        catch ( Exception e )
-        {
-            throw new AssertionError( "Unexpected MethodHandle initiation error", e );
-        }
-    }
-
-    /**
-     * Enable monitoring of page pins and unpins, which is disabled by default for
-     * performance reasons.
-     *
-     * This is a one-way operation; once monitoring of pinning and unpinning has been
-     * enabled, it cannot be disabled again without restarting the JVM.
-     */
-    public static void enablePinUnpinTracing()
-    {
-        if ( beginPinSwitchPoint != null && !beginPinSwitchPoint.hasBeenInvalidated() )
-        {
-            SwitchPoint.invalidateAll( new SwitchPoint[]{ beginPinSwitchPoint } );
-        }
-    }
-
     protected final AtomicLong faults = new AtomicLong();
     protected final AtomicLong evictions = new AtomicLong();
     protected final AtomicLong pins = new AtomicLong();
@@ -178,77 +132,6 @@ public void close()
         }
     };
 
-    private final PageFaultEvent pageFaultEvent = new PageFaultEvent()
-    {
-        @Override
-        public void addBytesRead( long bytes )
-        {
-            bytesRead.getAndAdd( bytes );
-        }
-
-        @Override
-        public void done()
-        {
-            faults.getAndIncrement();
-        }
-
-        @Override
-        public void done( Throwable throwable )
-        {
-            done();
-        }
-
-        @Override
-        public EvictionEvent beginEviction()
-        {
-            return evictionEvent;
-        }
-
-        @Override
-        public void setCachePageId( int cachePageId )
-        {
-        }
-    };
-
-    private final PinEvent pinTracingEvent = new PinEvent()
-    {
-        @Override
-        public void setCachePageId( int cachePageId )
-        {
-        }
-
-        @Override
-        public PageFaultEvent beginPageFault()
-        {
-            return pageFaultEvent;
-        }
-
-        @Override
-        public void done()
-        {
-            unpins.getAndIncrement();
-        }
-    };
-
-    private final PinEvent nullPinEvent = new PinEvent()
-    {
-        @Override
-        public void setCachePageId( int cachePageId )
-        {
-        }
-
-        @Override
-        public PageFaultEvent beginPageFault()
-        {
-            return pageFaultEvent;
-        }
-
-        @Override
-        public void done()
-        {
-        }
-    };
-
     private final MajorFlushEvent majorFlushEvent = new MajorFlushEvent()
     {
         @Override
@@ -281,38 +164,6 @@ public EvictionRunEvent beginPageEvictions( int pageCountToEvict )
         return evictionRunEvent;
     }
 
-    @Override
-    public PinEvent beginPin( boolean writeLock, long filePageId, PageSwapper swapper )
-    {
-        try
-        {
-            return (PinEvent) beginPinMH.invokeExact( this );
-        }
-        catch ( Throwable throwable )
-        {
-            throw new AssertionError( "Unexpected MethodHandle error", throwable );
-        }
-    }
-
-    /**
-     * Invoked through beginPinMH.
-     */
-    @SuppressWarnings( "UnusedDeclaration" )
-    private PinEvent beginNullPin()
-    {
-        return nullPinEvent;
-    }
-
-    /**
-     * Invoked through beginPinMH.
-     */
-    @SuppressWarnings( "UnusedDeclaration" )
-    private PinEvent beginTracingPin()
-    {
-        pins.getAndIncrement();
-        return pinTracingEvent;
-    }
-
     @Override
     public MajorFlushEvent beginFileFlush( PageSwapper swapper )
     {
@@ -384,4 +235,28 @@ public long evictionExceptions()
     {
         return evictionExceptions.get();
     }
+
+    @Override
+    public void pins( long pins )
+    {
+        this.pins.getAndAdd( pins );
+    }
+
+    @Override
+    public void unpins( long unpins )
+    {
+        this.unpins.getAndAdd( unpins );
+    }
+
+    @Override
+    public void faults( long faults )
+    {
+        this.faults.getAndAdd( faults );
+    }
+
+    @Override
+    public void bytesRead( long bytesRead )
+    {
+        this.bytesRead.getAndAdd( bytesRead );
+    }
 }

community/io/src/main/java/org/neo4j/io/pagecache/tracing/EvictionEvent.java

@@ -68,26 +68,26 @@ public void close()
     /**
      * The file page id the evicted page was bound to.
      */
-    public void setFilePageId( long filePageId );
+    void setFilePageId( long filePageId );
 
     /**
      * The swapper the evicted page was bound to.
      */
-    public void setSwapper( PageSwapper swapper );
+    void setSwapper( PageSwapper swapper );
 
     /**
      * Eviction implies an opportunity to flush.
      */
-    public FlushEventOpportunity flushEventOpportunity();
+    FlushEventOpportunity flushEventOpportunity();
 
     /**
      * Indicates that the eviction caused an exception to be thrown.
      * This can happen if some kind of IO error occurs.
      */
-    public void threwException( IOException exception );
+    void threwException( IOException exception );
 
     /**
      * The cache page id of the evicted page.
      */
-    public void setCachePageId( int cachePageId );
+    void setCachePageId( int cachePageId );
 }

community/io/src/main/java/org/neo4j/io/pagecache/tracing/EvictionRunEvent.java

@@ -47,5 +47,5 @@ public void close()
     /**
      * An eviction is started as part of this eviction run.
      */
-    public EvictionEvent beginEviction();
+    EvictionEvent beginEviction();
 }

community/io/src/main/java/org/neo4j/io/pagecache/tracing/FlushEventOpportunity.java

@@ -31,17 +31,10 @@ public interface FlushEventOpportunity
     /**
      * A FlushEventOpportunity that only returns the FlushEvent.NULL.
      */
-    FlushEventOpportunity NULL = new FlushEventOpportunity()
-    {
-        @Override
-        public FlushEvent beginFlush( long filePageId, int cachePageId, PageSwapper swapper )
-        {
-            return FlushEvent.NULL;
-        }
-    };
+    FlushEventOpportunity NULL = ( filePageId, cachePageId, swapper ) -> FlushEvent.NULL;
 
     /**
      * Begin flushing the given page.
      */
-    public FlushEvent beginFlush( long filePageId, int cachePageId, PageSwapper swapper );
+    FlushEvent beginFlush( long filePageId, int cachePageId, PageSwapper swapper );
 }

community/io/src/main/java/org/neo4j/io/pagecache/tracing/MajorFlushEvent.java

@@ -44,5 +44,5 @@ public void close()
     /**
      * Mass-flushing obviously imply flushing opportunities.
      */
-    public FlushEventOpportunity flushEventOpportunity();
+    FlushEventOpportunity flushEventOpportunity();
 }

community/io/src/main/java/org/neo4j/io/pagecache/tracing/PageCacheTracer.java

@@ -52,12 +52,6 @@ public EvictionRunEvent beginPageEvictions( int pageCountToEvict )
             return EvictionRunEvent.NULL;
         }
 
-        @Override
-        public PinEvent beginPin( boolean writeLock, long filePageId, PageSwapper swapper )
-        {
-            return PinEvent.NULL;
-        }
-
         @Override
         public MajorFlushEvent beginFileFlush( PageSwapper swapper )
         {
@@ -130,6 +124,26 @@ public long evictionExceptions()
             return 0;
         }
 
+        @Override
+        public void pins( long pins )
+        {
+        }
+
+        @Override
+        public void unpins( long unpins )
+        {
+        }
+
+        @Override
+        public void faults( long faults )
+        {
+        }
+
+        @Override
+        public void bytesRead( long bytesRead )
+        {
+        }
+
         @Override
         public String toString()
         {
@@ -156,11 +170,6 @@ public String toString()
      **/
     EvictionRunEvent beginPageEvictions( int pageCountToEvict );
 
-    /**
-     * A page is to be pinned.
-     */
-    PinEvent beginPin( boolean writeLock, long filePageId, PageSwapper swapper );
-
     /**
      * A PagedFile wants to flush all its bound pages.
      */
@@ -170,4 +179,12 @@ public String toString()
      * The PageCache wants to flush all its bound pages.
      */
     MajorFlushEvent beginCacheFlush();
+
+    void pins( long pins );
+
+    void unpins( long unpins );
+
+    void faults( long faults );
+
+    void bytesRead( long bytesRead );
 }