ctf: Provide a utility for "safe" mapping of a ByteBuffer

This works around a bug on Windows which prevents deleting a file after it
was mapped. See http://bugs.java.com/view_bug.do?bug_id=4715154

Running TraceSeekBenchmark, I noticed a 10% decreased in performance (3.8s vs 3.4s) on Windows. On Linux, the difference is negligible (2.41s vs 2.40).

Change-Id: Ie590709df4149708a37257ee3bc3d3d017f31c21
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/32448
Tested-by: Hudson CI

4 files changed, 69 insertions, 7 deletions

diff --git a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInput.java b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInput.java
index 157b1049c0..db8c6371c6 100644
--- a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInput.java
+++ b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInput.java
@@ -14,7 +14,7 @@ package org.eclipse.linuxtools.ctf.core.trace;
 
 import java.io.File;
 import java.io.IOException;
-import java.nio.MappedByteBuffer;
+import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileChannel.MapMode;
 import java.nio.file.StandardOpenOption;
@@ -32,6 +32,7 @@ import org.eclipse.linuxtools.ctf.core.event.types.IntegerDefinition;
 import org.eclipse.linuxtools.ctf.core.event.types.StringDefinition;
 import org.eclipse.linuxtools.ctf.core.event.types.StructDeclaration;
 import org.eclipse.linuxtools.ctf.core.event.types.StructDefinition;
+import org.eclipse.linuxtools.internal.ctf.core.SafeMappedByteBuffer;
 import org.eclipse.linuxtools.internal.ctf.core.event.types.ArrayDefinition;
 import org.eclipse.linuxtools.internal.ctf.core.trace.StreamInputPacketIndex;
 import org.eclipse.linuxtools.internal.ctf.core.trace.StreamInputPacketIndexEntry;
@@ -289,7 +290,7 @@ public class CTFStreamInput implements IDefinitionScope, AutoCloseable {
          * Map the packet.
          */
         try (FileChannel fc = FileChannel.open(fFile.toPath(), StandardOpenOption.READ)) {
-            MappedByteBuffer map = fc.map(MapMode.READ_ONLY, packetOffsetBytes, mapSize);
+            ByteBuffer map = SafeMappedByteBuffer.map(fc, MapMode.READ_ONLY, packetOffsetBytes, mapSize);
             if (map == null) {
                 throw new CTFReaderException("Failed to allocate mapped byte buffer"); //$NON-NLS-1$
             }
diff --git a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInputPacketReader.java b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInputPacketReader.java
index 9509a9929d..29ef23f9ff 100644
--- a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInputPacketReader.java
+++ b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFStreamInputPacketReader.java
@@ -13,7 +13,6 @@ package org.eclipse.linuxtools.ctf.core.trace;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
-import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel.MapMode;
 
 import org.eclipse.jdt.annotation.NonNull;
@@ -35,6 +34,7 @@ import org.eclipse.linuxtools.ctf.core.event.types.SimpleDatatypeDefinition;
 import org.eclipse.linuxtools.ctf.core.event.types.StructDeclaration;
 import org.eclipse.linuxtools.ctf.core.event.types.StructDefinition;
 import org.eclipse.linuxtools.ctf.core.event.types.VariantDefinition;
+import org.eclipse.linuxtools.internal.ctf.core.SafeMappedByteBuffer;
 import org.eclipse.linuxtools.internal.ctf.core.event.EventDeclaration;
 import org.eclipse.linuxtools.internal.ctf.core.event.types.composite.EventHeaderDefinition;
 import org.eclipse.linuxtools.internal.ctf.core.trace.StreamInputPacketIndexEntry;
@@ -221,7 +221,7 @@ public class CTFStreamInputPacketReader implements IDefinitionScope, AutoCloseab
 
     @NonNull
     private ByteBuffer getByteBufferAt(long position, long size) throws CTFReaderException, IOException {
-        MappedByteBuffer map = fStreamInputReader.getFc().map(MapMode.READ_ONLY, position, size);
+        ByteBuffer map = SafeMappedByteBuffer.map(fStreamInputReader.getFc(), MapMode.READ_ONLY, position, size);
         if (map == null) {
             throw new CTFReaderException("Failed to allocate mapped byte buffer"); //$NON-NLS-1$
         }
diff --git a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFTrace.java b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFTrace.java
index 0c2ee5a5cb..3414110a2c 100644
--- a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFTrace.java
+++ b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/ctf/core/trace/CTFTrace.java
@@ -19,8 +19,8 @@ import java.io.FileFilter;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.Serializable;
+import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
-import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileChannel.MapMode;
 import java.util.Arrays;
@@ -44,6 +44,7 @@ import org.eclipse.linuxtools.ctf.core.event.types.IDefinition;
 import org.eclipse.linuxtools.ctf.core.event.types.IntegerDefinition;
 import org.eclipse.linuxtools.ctf.core.event.types.StructDeclaration;
 import org.eclipse.linuxtools.ctf.core.event.types.StructDefinition;
+import org.eclipse.linuxtools.internal.ctf.core.SafeMappedByteBuffer;
 import org.eclipse.linuxtools.internal.ctf.core.event.CTFCallsiteComparator;
 import org.eclipse.linuxtools.internal.ctf.core.event.metadata.exceptions.ParseException;
 import org.eclipse.linuxtools.internal.ctf.core.event.types.ArrayDefinition;
@@ -507,7 +508,7 @@ public class CTFTrace implements IDefinitionScope, AutoCloseable {
      *             if there is a file error
      */
     private CTFStream openStreamInput(File streamFile) throws CTFReaderException {
-        MappedByteBuffer byteBuffer;
+        ByteBuffer byteBuffer;
         BitBuffer streamBitBuffer;
         CTFStream stream;
 
@@ -519,7 +520,7 @@ public class CTFTrace implements IDefinitionScope, AutoCloseable {
         try (FileInputStream fis = new FileInputStream(streamFile);
                 FileChannel fc = fis.getChannel()) {
             /* Map one memory page of 4 kiB */
-            byteBuffer = fc.map(MapMode.READ_ONLY, 0, (int) Math.min(fc.size(), 4096L));
+            byteBuffer = SafeMappedByteBuffer.map(fc, MapMode.READ_ONLY, 0, (int) Math.min(fc.size(), 4096L));
             if (byteBuffer == null) {
                 throw new IllegalStateException("Failed to allocate memory"); //$NON-NLS-1$
             }
diff --git a/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/internal/ctf/core/SafeMappedByteBuffer.java b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/internal/ctf/core/SafeMappedByteBuffer.java
new file mode 100644
index 0000000000..8b06b2733b
--- /dev/null
+++ b/lttng/org.eclipse.linuxtools.ctf.core/src/org/eclipse/linuxtools/internal/ctf/core/SafeMappedByteBuffer.java
@@ -0,0 +1,60 @@
+/*******************************************************************************
+ * Copyright (c) 2014 Ericsson
+ *
+ * All rights reserved. This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License v1.0 which
+ * accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Marc-Andre Laperle - Initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.linuxtools.internal.ctf.core;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+
+import org.eclipse.core.runtime.Platform;
+
+/**
+ * A common utility for mapping a ByteBuffer safely to work around a bug on
+ * Windows which prevents deleting a file after it was mapped. On Windows, the
+ * ByteBuffer will be allocated and the file will be read instead of being
+ * mapped.
+ *
+ * http://bugs.java.com/view_bug.do?bug_id=4715154
+ */
+public class SafeMappedByteBuffer {
+
+    private static final boolean IS_WIN32 = Platform.OS_WIN32.equals(Platform.getOS());
+
+    /**
+     * Maps a region of this channel's file directly into memory. On Windows,
+     * this will allocate a new ByteBuffer and read the file.
+     *
+     * @param fc
+     *            the file channel
+     * @param mode
+     *            the mapping mode
+     * @param position
+     *            the position within the file
+     * @param size
+     *            the size of the region to be mapped (or read)
+     * @return the mapped ByteBuffer
+     * @throws IOException
+     *             on FileChannel operations failures
+     */
+    public static ByteBuffer map(FileChannel fc, FileChannel.MapMode mode, long position, long size) throws IOException {
+        ByteBuffer byteBuffer;
+        if (IS_WIN32) {
+            byteBuffer = ByteBuffer.allocate((int) size);
+            fc.read(byteBuffer, position);
+        } else {
+            byteBuffer = fc.map(mode, position, size);
+        }
+
+        return byteBuffer;
+    }
+}