/*
* Copyright 2012-2014 Amazon Technologies, Inc.
*
* 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://aws.amazon.com/apache2.0
*
* This file 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.amazonaws.services.s3.model;
import java.io.IOException;
import java.io.InputStream;
import java.net.SocketException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.conn.EofSensorInputStream;
import com.amazonaws.internal.MetricAware;
import com.amazonaws.internal.SdkFilterInputStream;
import com.amazonaws.metrics.AwsSdkMetrics;
import com.amazonaws.metrics.MetricFilterInputStream;
import com.amazonaws.services.s3.metrics.S3ServiceMetric;
/**
* Input stream representing the content of an {@link S3Object}. In addition to
* the methods supplied by the {@link InputStream} class,
* {@link S3ObjectInputStream} supplies the abort() method, which will terminate
* an HTTP connection to the S3 object.
*/
public class S3ObjectInputStream extends SdkFilterInputStream {
private final HttpRequestBase httpRequest;
public S3ObjectInputStream(InputStream in, HttpRequestBase httpRequest) {
this(in, httpRequest, wrapWithByteCounting(in));
}
public S3ObjectInputStream(
InputStream in,
HttpRequestBase httpRequest,
boolean collectMetrics) {
super(collectMetrics
? new MetricFilterInputStream(S3ServiceMetric.S3DownloadThroughput, in)
: in);
this.httpRequest = httpRequest;
}
/**
* Returns true if we should wrap the given input stream with a byte
* counting wrapper; false otherwise.
*/
private static boolean wrapWithByteCounting(InputStream in) {
if (!AwsSdkMetrics.isMetricsEnabled())
return false; // metrics is disabled
if (in instanceof MetricAware) {
MetricAware aware = (MetricAware)in;
// wrap only if not already wrapped in one of it's inner chain of input stream
return !aware.isMetricActivated();
}
return true; // this is a raw input stream so metric wrapping is necessary
}
/**
* Aborts the underlying http request without reading any more data and
* closes the stream.
* <p>
* By default Apache {@link HttpClient} tries to reuse http connections by
* reading to the end of an attached input stream on
* {@link InputStream#close()}. This is efficient from a socket pool
* management perspective, but for objects with large payloads can incur
* significant overhead while bytes are read from s3 and discarded. It's up
* to clients to decide when to take the performance hit implicit in not
* reusing an http connection in order to not read unnecessary information
* from S3.
*
* @see EofSensorInputStream
*/
public void abort() throws IOException {
getHttpRequest().abort();
try {
close();
} catch (SocketException e) {
// expected from some implementations because the stream is closed
}
}
/**
* Returns the http request from which this input stream is derived.
*/
public HttpRequestBase getHttpRequest() {
return httpRequest;
}
}