Android Open Source - android Fault Recovering Output Stream






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License

The source code is released under:

GNU General Public License

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Java Source Code

/*
 * Copyright (C) 2013 Square, Inc.//from  w ww . jav a 2s . co m
 *
 * 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.squareup.okhttp.internal;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import static com.squareup.okhttp.internal.Util.checkOffsetAndCount;

/**
 * An output stream wrapper that recovers from failures in the underlying stream
 * by replacing it with another stream. This class buffers a fixed amount of
 * data under the assumption that failures occur early in a stream's life.
 * If a failure occurs after the buffer has been exhausted, no recovery is
 * attempted.
 *
 * <p>Subclasses must override {@link #replacementStream} which will request a
 * replacement stream each time an {@link IOException} is encountered on the
 * current stream.
 */
public abstract class FaultRecoveringOutputStream extends AbstractOutputStream {
  private final int maxReplayBufferLength;

  /** Bytes to transmit on the replacement stream, or null if no recovery is possible. */
  private ByteArrayOutputStream replayBuffer;
  private OutputStream out;

  /**
   * @param maxReplayBufferLength the maximum number of successfully written
   *     bytes to buffer so they can be replayed in the event of an error.
   *     Failure recoveries are not possible once this limit has been exceeded.
   */
  public FaultRecoveringOutputStream(int maxReplayBufferLength, OutputStream out) {
    if (maxReplayBufferLength < 0) throw new IllegalArgumentException();
    this.maxReplayBufferLength = maxReplayBufferLength;
    this.replayBuffer = new ByteArrayOutputStream(maxReplayBufferLength);
    this.out = out;
  }

  @Override public final void write(byte[] buffer, int offset, int count) throws IOException {
    if (closed) throw new IOException("stream closed");
    checkOffsetAndCount(buffer.length, offset, count);

    while (true) {
      try {
        out.write(buffer, offset, count);

        if (replayBuffer != null) {
          if (count + replayBuffer.size() > maxReplayBufferLength) {
            // Failure recovery is no longer possible once we overflow the replay buffer.
            replayBuffer = null;
          } else {
            // Remember the written bytes to the replay buffer.
            replayBuffer.write(buffer, offset, count);
          }
        }
        return;
      } catch (IOException e) {
        if (!recover(e)) throw e;
      }
    }
  }

  @Override public final void flush() throws IOException {
    if (closed) {
      return; // don't throw; this stream might have been closed on the caller's behalf
    }
    while (true) {
      try {
        out.flush();
        return;
      } catch (IOException e) {
        if (!recover(e)) throw e;
      }
    }
  }

  @Override public final void close() throws IOException {
    if (closed) {
      return;
    }
    while (true) {
      try {
        out.close();
        closed = true;
        return;
      } catch (IOException e) {
        if (!recover(e)) throw e;
      }
    }
  }

  /**
   * Attempt to replace {@code out} with another equivalent stream. Returns true
   * if a suitable replacement stream was found.
   */
  private boolean recover(IOException e) {
    if (replayBuffer == null) {
      return false; // Can't recover because we've dropped data that we would need to replay.
    }

    while (true) {
      OutputStream replacementStream = null;
      try {
        replacementStream = replacementStream(e);
        if (replacementStream == null) {
          return false;
        }
        replaceStream(replacementStream);
        return true;
      } catch (IOException replacementStreamFailure) {
        // The replacement was also broken. Loop to ask for another replacement.
        Util.closeQuietly(replacementStream);
        e = replacementStreamFailure;
      }
    }
  }

  /**
   * Returns true if errors in the underlying stream can currently be recovered.
   */
  public boolean isRecoverable() {
    return replayBuffer != null;
  }

  /**
   * Replaces the current output stream with {@code replacementStream}, writing
   * any replay bytes to it if they exist. The current output stream is closed.
   */
  public final void replaceStream(OutputStream replacementStream) throws IOException {
    if (!isRecoverable()) {
      throw new IllegalStateException();
    }
    if (this.out == replacementStream) {
      return; // Don't replace a stream with itself.
    }
    replayBuffer.writeTo(replacementStream);
    Util.closeQuietly(out);
    out = replacementStream;
  }

  /**
   * Returns a replacement output stream to recover from {@code e} thrown by the
   * previous stream. Returns a new OutputStream if recovery was successful, in
   * which case all previously-written data will be replayed. Returns null if
   * the failure cannot be recovered.
   */
  protected abstract OutputStream replacementStream(IOException e) throws IOException;
}




Java Source Code List

com.phonegap.helloworld.BuildConfig.java
com.phonegap.helloworld.HelloWorld.java
com.squareup.okhttp.Address.java
com.squareup.okhttp.ConnectionPool.java
com.squareup.okhttp.Connection.java
com.squareup.okhttp.Dispatcher.java
com.squareup.okhttp.Failure.java
com.squareup.okhttp.HttpResponseCache.java
com.squareup.okhttp.Job.java
com.squareup.okhttp.MediaType.java
com.squareup.okhttp.OkAuthenticator.java
com.squareup.okhttp.OkHttpClient.java
com.squareup.okhttp.OkResponseCache.java
com.squareup.okhttp.Request.java
com.squareup.okhttp.ResponseSource.java
com.squareup.okhttp.Response.java
com.squareup.okhttp.RouteDatabase.java
com.squareup.okhttp.Route.java
com.squareup.okhttp.TunnelRequest.java
com.squareup.okhttp.internal.AbstractOutputStream.java
com.squareup.okhttp.internal.Base64.java
com.squareup.okhttp.internal.DiskLruCache.java
com.squareup.okhttp.internal.Dns.java
com.squareup.okhttp.internal.FaultRecoveringOutputStream.java
com.squareup.okhttp.internal.NamedRunnable.java
com.squareup.okhttp.internal.Platform.java
com.squareup.okhttp.internal.StrictLineReader.java
com.squareup.okhttp.internal.Util.java
com.squareup.okhttp.internal.http.AbstractHttpInputStream.java
com.squareup.okhttp.internal.http.HeaderParser.java
com.squareup.okhttp.internal.http.HttpAuthenticator.java
com.squareup.okhttp.internal.http.HttpDate.java
com.squareup.okhttp.internal.http.HttpEngine.java
com.squareup.okhttp.internal.http.HttpTransport.java
com.squareup.okhttp.internal.http.HttpURLConnectionImpl.java
com.squareup.okhttp.internal.http.HttpsEngine.java
com.squareup.okhttp.internal.http.HttpsURLConnectionImpl.java
com.squareup.okhttp.internal.http.OkResponseCacheAdapter.java
com.squareup.okhttp.internal.http.Policy.java
com.squareup.okhttp.internal.http.RawHeaders.java
com.squareup.okhttp.internal.http.RequestHeaders.java
com.squareup.okhttp.internal.http.ResponseHeaders.java
com.squareup.okhttp.internal.http.RetryableOutputStream.java
com.squareup.okhttp.internal.http.RouteSelector.java
com.squareup.okhttp.internal.http.SpdyTransport.java
com.squareup.okhttp.internal.http.Transport.java
com.squareup.okhttp.internal.http.UnknownLengthHttpInputStream.java
com.squareup.okhttp.internal.spdy.ErrorCode.java
com.squareup.okhttp.internal.spdy.FrameReader.java
com.squareup.okhttp.internal.spdy.FrameWriter.java
com.squareup.okhttp.internal.spdy.HeadersMode.java
com.squareup.okhttp.internal.spdy.Hpack.java
com.squareup.okhttp.internal.spdy.Http20Draft06.java
com.squareup.okhttp.internal.spdy.IncomingStreamHandler.java
com.squareup.okhttp.internal.spdy.NameValueBlockReader.java
com.squareup.okhttp.internal.spdy.Ping.java
com.squareup.okhttp.internal.spdy.Settings.java
com.squareup.okhttp.internal.spdy.Spdy3.java
com.squareup.okhttp.internal.spdy.SpdyConnection.java
com.squareup.okhttp.internal.spdy.SpdyStream.java
com.squareup.okhttp.internal.spdy.Variant.java
com.squareup.okhttp.internal.tls.DistinguishedNameParser.java
com.squareup.okhttp.internal.tls.OkHostnameVerifier.java
org.apache.cordova.App.java
org.apache.cordova.AuthenticationToken.java
org.apache.cordova.BuildConfig.java
org.apache.cordova.CallbackContext.java
org.apache.cordova.Config.java
org.apache.cordova.CordovaActivity.java
org.apache.cordova.CordovaArgs.java
org.apache.cordova.CordovaChromeClient.java
org.apache.cordova.CordovaInterface.java
org.apache.cordova.CordovaPlugin.java
org.apache.cordova.CordovaResourceApi.java
org.apache.cordova.CordovaUriHelper.java
org.apache.cordova.CordovaWebViewClient.java
org.apache.cordova.CordovaWebView.java
org.apache.cordova.DirectoryManager.java
org.apache.cordova.DroidGap.java
org.apache.cordova.ExifHelper.java
org.apache.cordova.ExposedJsApi.java
org.apache.cordova.FileHelper.java
org.apache.cordova.IceCreamCordovaWebViewClient.java
org.apache.cordova.JSONUtils.java
org.apache.cordova.LOG.java
org.apache.cordova.LinearLayoutSoftKeyboardDetect.java
org.apache.cordova.NativeToJsMessageQueue.java
org.apache.cordova.PluginEntry.java
org.apache.cordova.PluginManager.java
org.apache.cordova.PluginResult.java
org.apache.cordova.ScrollEvent.java
org.apache.cordova.Whitelist.java