extract reader/writer impl, increase their default buffer and minimize footprint when possible.

src/main/java/com/google/gcloud/examples/StorageExample.java

@@ -16,6 +16,7 @@
 
 package com.google.gcloud.examples;
 
+import com.google.gcloud.RetryParams;
 import com.google.gcloud.spi.StorageRpc.Tuple;
 import com.google.gcloud.storage.BatchRequest;
 import com.google.gcloud.storage.BatchResponse;
@@ -498,7 +499,8 @@ public static void main(String... args) throws Exception {
       printUsage();
       return;
     }
-    StorageServiceOptions.Builder optionsBuilder = StorageServiceOptions.builder();
+    StorageServiceOptions.Builder optionsBuilder =
+        StorageServiceOptions.builder().retryParams(RetryParams.getDefaultInstance());
     StorageAction action;
     if (args.length >= 2 && !ACTIONS.containsKey(args[0])) {
       optionsBuilder.projectId(args[0]);

src/main/java/com/google/gcloud/storage/BlobReadChannelImpl.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright 2015 Google Inc. All Rights Reserved.
+ *
+ * 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 com.google.gcloud.storage;
+
+import static com.google.gcloud.RetryHelper.runWithRetries;
+
+import com.google.api.services.storage.model.StorageObject;
+import com.google.gcloud.spi.StorageRpc;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.nio.ByteBuffer;
+import java.util.Map;
+import java.util.concurrent.Callable;
+
+/**
+ * Default implementation for BlobReadChannel.
+ */
+class BlobReadChannelImpl implements BlobReadChannel {
+
+  private static final int MIN_BUFFER_SIZE = 2 * 1024 * 1024;
+  private static final long serialVersionUID = 4821762590742862669L;
+
+  private final StorageServiceOptions serviceOptions;
+  private final Blob blob;
+  private final Map<StorageRpc.Option, ?> requestOptions;
+  private int position;
+  private boolean isOpen;
+  private boolean endOfStream;
+
+  private transient StorageRpc storageRpc;
+  private transient StorageObject storageObject;
+  private transient int bufferPos;
+  private transient byte[] buffer;
+
+  BlobReadChannelImpl(StorageServiceOptions serviceOptions, Blob blob,
+      Map<StorageRpc.Option, ?> requestOptions) {
+    this.serviceOptions = serviceOptions;
+    this.blob = blob;
+    this.requestOptions = requestOptions;
+    isOpen = true;
+    initTransients();
+  }
+
+  private void writeObject(ObjectOutputStream out) throws IOException {
+    if (buffer != null) {
+      position += bufferPos;
+      buffer = null;
+      bufferPos = 0;
+      endOfStream = false;
+    }
+    out.defaultWriteObject();
+  }
+
+  private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+    in.defaultReadObject();
+    initTransients();
+  }
+
+  private void initTransients() {
+    storageRpc = serviceOptions.storageRpc();
+    storageObject = blob.toPb();
+  }
+
+  @Override
+  public boolean isOpen() {
+    return isOpen;
+  }
+
+  @Override
+  public void close() {
+    if (isOpen) {
+      buffer = null;
+      isOpen = false;
+    }
+  }
+
+  private void validateOpen() throws IOException {
+    if (!isOpen) {
+      throw new IOException("stream is closed");
+    }
+  }
+
+  @Override
+  public void seek(int position) throws IOException {
+    validateOpen();
+    this.position = position;
+    buffer = null;
+    bufferPos = 0;
+    endOfStream = false;
+  }
+
+  @Override
+  public int read(ByteBuffer byteBuffer) throws IOException {
+    validateOpen();
+    if (buffer == null) {
+      if (endOfStream) {
+        return -1;
+      }
+      final int toRead = Math.max(byteBuffer.remaining(), MIN_BUFFER_SIZE);
+      buffer = runWithRetries(new Callable<byte[]>() {
+        @Override
+        public byte[] call() {
+          return storageRpc.read(storageObject, requestOptions, position, toRead);
+        }
+      }, serviceOptions.retryParams(), StorageServiceImpl.EXCEPTION_HANDLER);
+      if (toRead > buffer.length) {
+        endOfStream = true;
+        if (buffer.length == 0) {
+          buffer = null;
+          return -1;
+        }
+      }
+    }
+    int toWrite = Math.min(buffer.length - bufferPos, byteBuffer.remaining());
+    byteBuffer.put(buffer, bufferPos, toWrite);
+    bufferPos += toWrite;
+    if (bufferPos >= buffer.length) {
+      position += buffer.length;
+      buffer = null;
+      bufferPos = 0;
+    }
+    return toWrite;
+  }
+}

src/main/java/com/google/gcloud/storage/BlobWriterChannelImpl.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2015 Google Inc. All Rights Reserved.
+ *
+ * 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 com.google.gcloud.storage;
+
+import static com.google.gcloud.RetryHelper.runWithRetries;
+import static java.util.concurrent.Executors.callable;
+
+import com.google.api.services.storage.model.StorageObject;
+import com.google.gcloud.spi.StorageRpc;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.Map;
+
+/**
+ * Default implementation for BlobWriteChannel.
+ */
+class BlobWriterChannelImpl implements BlobWriteChannel {
+
+  private static final long serialVersionUID = 8675286882724938737L;
+  private static final int CHUNK_SIZE = 256 * 1024;
+  private static final int MIN_BUFFER_SIZE = 8 * CHUNK_SIZE;
+
+  private final StorageServiceOptions options;
+  private final Blob blob;
+  private final String uploadId;
+  private int position;
+  private byte[] buffer = new byte[0];
+  private int limit;
+  private boolean isOpen = true;
+
+  private transient StorageRpc storageRpc;
+  private transient StorageObject storageObject;
+
+  public BlobWriterChannelImpl(StorageServiceOptions options, Blob blob,
+      Map<StorageRpc.Option, ?> optionsMap) {
+    this.options = options;
+    this.blob = blob;
+    initTransients();
+    uploadId = options.storageRpc().open(storageObject, optionsMap);
+  }
+
+  private void writeObject(ObjectOutputStream out) throws IOException {
+    if (isOpen) {
+      flush(true);
+    }
+    out.defaultWriteObject();
+  }
+
+  private void flush(boolean compact) {
+    if (limit >= MIN_BUFFER_SIZE || compact && limit >= CHUNK_SIZE) {
+      final int length = limit - limit % CHUNK_SIZE;
+      runWithRetries(callable(new Runnable() {
+        @Override
+        public void run() {
+          storageRpc.write(uploadId, buffer, 0, storageObject, position, length, false);
+        }
+      }), options.retryParams(), StorageServiceImpl.EXCEPTION_HANDLER);
+      position += length;
+      limit -= length;
+      byte[] temp = new byte[compact ? limit : MIN_BUFFER_SIZE];
+      System.arraycopy(buffer, length, temp, 0, limit);
+      buffer = temp;
+    }
+  }
+
+  private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+    in.defaultReadObject();
+    if (isOpen) {
+      initTransients();
+    }
+  }
+
+  private void initTransients() {
+    storageRpc = options.storageRpc();
+    storageObject = blob.toPb();
+  }
+
+  private void validateOpen() throws IOException {
+    if (!isOpen) {
+      throw new IOException("stream is closed");
+    }
+  }
+
+  @Override
+  public int write(ByteBuffer byteBuffer) throws IOException {
+    validateOpen();
+    int toWrite = byteBuffer.remaining();
+    int spaceInBuffer = buffer.length - limit;
+    if (spaceInBuffer >= toWrite) {
+      byteBuffer.get(buffer, limit, toWrite);
+    } else {
+      buffer = Arrays.copyOf(buffer,
+          Math.max(MIN_BUFFER_SIZE, buffer.length + toWrite - spaceInBuffer));
+      byteBuffer.get(buffer, limit, toWrite);
+    }
+    limit += toWrite;
+    flush(false);
+    return toWrite;
+  }
+
+  @Override
+  public boolean isOpen() {
+    return isOpen;
+  }
+
+  @Override
+  public void close() throws IOException {
+    if (isOpen) {
+      runWithRetries(callable(new Runnable() {
+        @Override
+        public void run() {
+          storageRpc.write(uploadId, buffer, 0, storageObject, position, limit, true);
+        }
+      }), options.retryParams(), StorageServiceImpl.EXCEPTION_HANDLER);
+      position += buffer.length;
+      isOpen = false;
+      buffer = null;
+    }
+  }
+}