Import atomix/{storage,utils}

[controller.git] / third-party / atomix / utils / src / main / java / io / atomix / utils / memory / MappedMemoryAllocator.java

diff --git a/third-party/atomix/utils/src/main/java/io/atomix/utils/memory/MappedMemoryAllocator.java b/third-party/atomix/utils/src/main/java/io/atomix/utils/memory/MappedMemoryAllocator.java
new file mode 100644 (file)
index 0000000..7a3a270
--- /dev/null
+++ b/third-party/atomix/utils/src/main/java/io/atomix/utils/memory/MappedMemoryAllocator.java
@@ -0,0 +1,131 @@
+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.atomix.utils.memory;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.channels.FileChannel;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Mapped memory allocator.
+ * <p>
+ * The mapped memory allocator provides direct memory access to memory mapped from a file on disk. The mapped allocator
+ * supports allocating memory in any {@link FileChannel.MapMode}. Once the file is mapped and the
+ * memory has been allocated, the mapped allocator provides the memory address of the underlying
+ * {@link java.nio.MappedByteBuffer} for access via {@link sun.misc.Unsafe}.
+ *
+ * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
+ */
+public class MappedMemoryAllocator implements MemoryAllocator<MappedMemory> {
+  public static final FileChannel.MapMode DEFAULT_MAP_MODE = FileChannel.MapMode.READ_WRITE;
+
+  private final AtomicInteger referenceCount = new AtomicInteger();
+  private final RandomAccessFile file;
+  private final FileChannel channel;
+  private final FileChannel.MapMode mode;
+  private final long offset;
+
+  public MappedMemoryAllocator(File file) {
+    this(file, DEFAULT_MAP_MODE, 0);
+  }
+
+  public MappedMemoryAllocator(File file, FileChannel.MapMode mode) {
+    this(file, mode, 0);
+  }
+
+  public MappedMemoryAllocator(File file, FileChannel.MapMode mode, long offset) {
+    this(createFile(file, mode), mode, offset);
+  }
+
+  public MappedMemoryAllocator(RandomAccessFile file, FileChannel.MapMode mode, long offset) {
+    if (file == null) {
+      throw new NullPointerException("file cannot be null");
+    }
+    if (mode == null) {
+      throw new NullPointerException("mode cannot be null");
+    }
+    if (offset < 0) {
+      throw new IllegalArgumentException("offset cannot be negative");
+    }
+    this.file = file;
+    this.channel = this.file.getChannel();
+    this.mode = mode;
+    this.offset = offset;
+  }
+
+  private static RandomAccessFile createFile(File file, FileChannel.MapMode mode) {
+    if (file == null) {
+      throw new NullPointerException("file cannot be null");
+    }
+    if (mode == null) {
+      mode = DEFAULT_MAP_MODE;
+    }
+    try {
+      return new RandomAccessFile(file, parseMode(mode));
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private static String parseMode(FileChannel.MapMode mode) {
+    if (mode == FileChannel.MapMode.READ_ONLY) {
+      return "r";
+    } else if (mode == FileChannel.MapMode.READ_WRITE) {
+      return "rw";
+    }
+    throw new IllegalArgumentException("unsupported map mode");
+  }
+
+  @Override
+  public MappedMemory allocate(int size) {
+    try {
+      if (file.length() < size) {
+        file.setLength(size);
+      }
+      referenceCount.incrementAndGet();
+      return new MappedMemory(channel.map(mode, offset, size), this);
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  @Override
+  public MappedMemory reallocate(MappedMemory memory, int size) {
+    MappedMemory newMemory = allocate(size);
+    memory.free();
+    return newMemory;
+  }
+
+  public void close() {
+    try {
+      file.close();
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  /**
+   * Releases a reference from the allocator.
+   */
+  void release() {
+    if (referenceCount.decrementAndGet() == 0) {
+      close();
+    }
+  }
+
+}