/*
* Copyright 2010-2011 Amazon.com, Inc. or its affiliates. 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.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. 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.http;
import java.io.IOException;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpEntityEnclosingRequest;
import org.apache.http.HttpStatus;
import org.apache.http.NoHttpResponseException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
import org.apache.http.client.methods.HttpRequestBase;
import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.AmazonWebServiceRequest;
import com.amazonaws.AmazonWebServiceResponse;
import com.amazonaws.ClientConfiguration;
import com.amazonaws.Request;
import com.amazonaws.ResponseMetadata;
import com.amazonaws.handlers.RequestHandler;
import com.amazonaws.util.CountingInputStream;
import com.amazonaws.util.ResponseMetadataCache;
import com.amazonaws.util.TimingInfo;
public class AmazonHttpClient {
/**
* Logger providing detailed information on requests/responses. Users can
* enable this logger to get access to AWS request IDs for responses,
* individual requests and parameters sent to AWS, etc.
*/
private static final Log requestLog = LogFactory.getLog("com.amazonaws.request");
/**
* Logger for more detailed debugging information, that might not be as
* useful for end users (ex: HTTP client configuration, etc).
*/
static final Log log = LogFactory.getLog(AmazonHttpClient.class);
/** Internal client for sending HTTP requests */
private HttpClient httpClient;
private static final String BYTES_PROCESSED_COUNTER = "bytes-processed";
private static final String RESPONSE_PROCESSING_SUBMEASUREMENT = "response-processing";
/** Maximum exponential back-off time before retrying a request */
private static final int MAX_BACKOFF_IN_MILLISECONDS = 20 * 1000;
/** Client configuration options, such as proxy settings, max retries, etc. */
private final ClientConfiguration config;
/** Cache of metadata for recently executed requests for diagnostic purposes */
private ResponseMetadataCache responseMetadataCache = new ResponseMetadataCache(50);
private static final Random random = new Random();
private static HttpRequestFactory httpRequestFactory = new HttpRequestFactory();
private static HttpClientFactory httpClientFactory = new HttpClientFactory();
/** Internal system property to enable advanced timing info collection. */
public static final String PROFILING_SYSTEM_PROPERTY = "com.amazonaws.sdk.enableRuntimeProfiling";
static {
// Customers have reported XML parsing issues with the following
// JVM versions, which don't occur with more recent versions, so
// if we detect any of these, give customers a heads up.
List<String> problematicJvmVersions = Arrays.asList(new String[] {
"1.6.0_06", "1.6.0_13", "1.6.0_17", });
String jvmVersion = System.getProperty("java.version");
if (problematicJvmVersions.contains(jvmVersion)) {
log.warn("Detected a possible problem with the current JVM version (" + jvmVersion + "). " +
"If you experience XML parsing problems using the SDK, try upgrading to a more recent JVM update.");
}
}
/**
* Constructs a new AWS client using the specified client configuration
* options (ex: max retry attempts, proxy settings, etc).
*
* @param clientConfiguration
* Configuration options specifying how this client will
* communicate with AWS (ex: proxy settings, retry count, etc.).
*/
public AmazonHttpClient(ClientConfiguration clientConfiguration) {
this.config = clientConfiguration;
this.httpClient = httpClientFactory.createHttpClient(config);
}
/**
* Returns additional response metadata for an executed request. Response
* metadata isn't considered part of the standard results returned by an
* operation, so it's accessed instead through this diagnostic interface.
* Response metadata is typically used for troubleshooting issues with AWS
* support staff when services aren't acting as expected.
*
* @param request
* A previously executed AmazonWebServiceRequest object, whose
* response metadata is desired.
*
* @return The response metadata for the specified request, otherwise null
* if there is no response metadata available for the request.
*/
public ResponseMetadata getResponseMetadataForRequest(AmazonWebServiceRequest request) {
return responseMetadataCache.get(request);
}
/**
* Executes the request and returns the result.
*
* @param request
* The AmazonWebServices request to send to the remote server
* @param responseHandler
* A response handler to accept a successful response from the
* remote server
* @param errorResponseHandler
* A response handler to accept an unsuccessful response from the
* remote server
* @param executionContext
* Additional information about the context of this web service
* call
*/
public <T> T execute(Request<?> request,
HttpResponseHandler<AmazonWebServiceResponse<T>> responseHandler,
HttpResponseHandler<AmazonServiceException> errorResponseHandler,
ExecutionContext executionContext) throws AmazonClientException, AmazonServiceException {
long startTime = System.currentTimeMillis();
/*
* TODO: Ideally, we'd run the "beforeRequest" on any request handlers here, but
* we have to run that code *before* signing the request, since it could change
* request parameters.
*/
if (executionContext == null) throw new AmazonClientException("Internal SDK Error: No execution context parameter specified.");
List<RequestHandler> requestHandlers = executionContext.getRequestHandlers();
if (requestHandlers == null) requestHandlers = new ArrayList<RequestHandler>();
try {
TimingInfo timingInfo = new TimingInfo(startTime);
executionContext.setTimingInfo(timingInfo);
T t = executeHelper(request, responseHandler, errorResponseHandler, executionContext);
timingInfo.setEndTime(System.currentTimeMillis());
for (RequestHandler handler : requestHandlers) {
try {
handler.afterResponse(request, t, timingInfo);
} catch (ClassCastException cce) {}
}
return t;
} catch (AmazonClientException e) {
for (RequestHandler handler : requestHandlers) {
handler.afterError(request, e);
}
throw e;
}
}
/**
* Internal method to execute the HTTP method given.
*
* @see AmazonHttpClient#execute(Request, HttpResponseHandler, HttpResponseHandler)
* @see AmazonHttpClient#execute(Request, HttpResponseHandler, HttpResponseHandler, ExecutionContext)
*/
private <T extends Object> T executeHelper(Request<?> request,
HttpResponseHandler<AmazonWebServiceResponse<T>> responseHandler,
HttpResponseHandler<AmazonServiceException> errorResponseHandler,
ExecutionContext executionContext)
throws AmazonClientException, AmazonServiceException {
/*
* Depending on which response handler we end up choosing to handle the
* HTTP response, it might require us to leave the underlying HTTP
* connection open, depending on whether or not it reads the complete
* HTTP response stream from the HTTP connection, or if delays reading
* any of the content until after a response is returned to the caller.
*/
boolean leaveHttpConnectionOpen = false;
// When we release connections, the connection manager leaves them
// open so they can be reused. We want to close out any idle
// connections so that they don't sit around in CLOSE_WAIT.
httpClient.getConnectionManager().closeIdleConnections(30, TimeUnit.SECONDS);
requestLog.info("Sending Request: " + request.toString());
// Apply whatever request options we know how to handle, such as user-agent.
applyRequestData(request);
int retries = 0;
URI redirectedURI = null;
HttpEntity entity = null;
AmazonServiceException exception = null;
while (true) {
// Sign the request if a signer was provided
if (executionContext.getSigner() != null && executionContext.getCredentials() != null) {
executionContext.getSigner().sign(request, executionContext.getCredentials());
}
HttpRequestBase httpRequest = httpRequestFactory.createHttpRequest(request, config, entity, executionContext);
if (httpRequest instanceof HttpEntityEnclosingRequest) {
entity = ((HttpEntityEnclosingRequest)httpRequest).getEntity();
}
if (redirectedURI != null) {
httpRequest.setURI(redirectedURI);
}
org.apache.http.HttpResponse response = null;
try {
if (retries > 0) pauseExponentially(retries, exception);
exception = null;
retries++;
response = httpClient.execute(httpRequest);
if (isRequestSuccessful(response)) {
/*
* If we get back any 2xx status code, then we know we should
* treat the service call as successful.
*/
leaveHttpConnectionOpen = responseHandler.needsConnectionLeftOpen();
return handleResponse(request, responseHandler, httpRequest, response, executionContext);
} else if (isTemporaryRedirect(response)) {
/*
* S3 sends 307 Temporary Redirects if you try to delete an
* EU bucket from the US endpoint. If we get a 307, we'll
* point the HTTP method to the redirected location, and let
* the next retry deliver the request to the right location.
*/
Header[] locationHeaders = response.getHeaders("location");
String redirectedLocation = locationHeaders[0].getValue();
log.debug("Redirecting to: " + redirectedLocation);
redirectedURI = URI.create(redirectedLocation);
httpRequest.setURI(redirectedURI);
} else {
leaveHttpConnectionOpen = errorResponseHandler.needsConnectionLeftOpen();
exception = handleErrorResponse(request, errorResponseHandler, httpRequest, response);
if (!shouldRetry(httpRequest, exception, retries)) {
throw exception;
}
}
} catch (IOException ioe) {
log.warn("Unable to execute HTTP request: " + ioe.getMessage());
if (!shouldRetry(httpRequest, ioe, retries)) {
throw new AmazonClientException("Unable to execute HTTP request: " + ioe.getMessage(), ioe);
}
} finally {
/*
* Some response handlers need to manually manage the HTTP
* connection and will take care of releasing the connection on
* their own, but if this response handler doesn't need the
* connection left open, we go ahead and release the it to free
* up resources.
*/
if (!leaveHttpConnectionOpen) {
try {response.getEntity().getContent().close();} catch (Throwable t) {}
}
}
}
}
/**
* Applies any additional options set in the request.
*/
private void applyRequestData(Request<?> request) {
if ( request.getOriginalRequest() != null && request.getOriginalRequest().getRequestClientOptions() != null
&& request.getOriginalRequest().getRequestClientOptions().getClientMarker() != null ) {
request.addHeader(
"User-Agent",
createUserAgentString(config.getUserAgent(), request.getOriginalRequest().getRequestClientOptions()
.getClientMarker()));
}
}
/**
* Appends the given user-agent string to the existing one and returns it.
*/
private static String createUserAgentString(String existingUserAgentString, String userAgent) {
if (existingUserAgentString.contains(userAgent)) {
return existingUserAgentString;
} else {
return existingUserAgentString + " " + userAgent;
}
}
/**
* Shuts down this HTTP client object, releasing any resources that might be
* held open. This is an optional method, and callers are not expected to
* call it, but can if they want to explicitly release any open resources.
* Once a client has been shutdown, it cannot be used to make more requests.
*/
public void shutdown() {
httpClient.getConnectionManager().shutdown();
}
/**
* Returns true if a failed request should be retried.
*
* @param method
* The current HTTP method being executed.
* @param exception
* The exception from the failed request.
* @param retries
* The number of times the current request has been attempted.
*
* @return True if the failed request should be retried.
*/
private boolean shouldRetry(HttpRequestBase method, Exception exception, int retries) {
if (retries > config.getMaxErrorRetry()) return false;
if (exception instanceof NoHttpResponseException
|| exception instanceof SocketException
|| exception instanceof SocketTimeoutException) {
log.debug("Retrying on " + exception.getClass().getName()
+ ": " + exception.getMessage());
return true;
}
if (exception instanceof AmazonServiceException) {
AmazonServiceException ase = (AmazonServiceException)exception;
/*
* For 500 internal server errors and 503 service
* unavailable errors, we want to retry, but we need to use
* an exponential back-off strategy so that we don't overload
* a server with a flood of retries. If we've surpassed our
* retry limit we handle the error response as a non-retryable
* error and go ahead and throw it back to the user as an exception.
*/
if (ase.getStatusCode() == HttpStatus.SC_INTERNAL_SERVER_ERROR
|| ase.getStatusCode() == HttpStatus.SC_SERVICE_UNAVAILABLE) {
return true;
}
/*
* Throttling is reported as a 400 error from newer services. To try
* and smooth out an occasional throttling error, we'll pause and
* retry, hoping that the pause is long enough for the request to
* get through the next time.
*/
if (isThrottlingException(ase)) return true;
}
return false;
}
private boolean isTemporaryRedirect(org.apache.http.HttpResponse response) {
int status = response.getStatusLine().getStatusCode();
return status == HttpStatus.SC_TEMPORARY_REDIRECT &&
response.getHeaders("Location") != null &&
response.getHeaders("Location").length > 0;
}
private boolean isRequestSuccessful(org.apache.http.HttpResponse response) {
int status = response.getStatusLine().getStatusCode();
return status / 100 == HttpStatus.SC_OK / 100;
}
/**
* Handles a successful response from a service call by unmarshalling the
* results using the specified response handler.
*
* @param <T>
* The type of object expected in the response.
*
* @param request
* The original request that generated the response being
* handled.
* @param responseHandler
* The response unmarshaller used to interpret the contents of
* the response.
* @param method
* The HTTP method that was invoked, and contains the contents of
* the response.
* @param executionContext
* Extra state information about the request currently being
* executed.
* @return The contents of the response, unmarshalled using the specified
* response handler.
*
* @throws IOException
* If any problems were encountered reading the response
* contents from the HTTP method object.
*/
private <T> T handleResponse(Request<?> request,
HttpResponseHandler<AmazonWebServiceResponse<T>> responseHandler, HttpRequestBase method, org.apache.http.HttpResponse apacheHttpResponse, ExecutionContext executionContext)
throws IOException {
HttpResponse httpResponse = createResponse(method, request, apacheHttpResponse);
if (responseHandler.needsConnectionLeftOpen() && method instanceof HttpEntityEnclosingRequest) {
HttpEntityEnclosingRequest httpEntityEnclosingRequest = (HttpEntityEnclosingRequest)method;
httpResponse.setContent(new HttpMethodReleaseInputStream(httpEntityEnclosingRequest));
}
try {
CountingInputStream countingInputStream = null;
if (System.getProperty(PROFILING_SYSTEM_PROPERTY) != null) {
countingInputStream = new CountingInputStream(httpResponse.getContent());
httpResponse.setContent(countingInputStream);
}
long startTime = System.currentTimeMillis();
AmazonWebServiceResponse<? extends T> awsResponse = responseHandler.handle(httpResponse);
long endTime = System.currentTimeMillis();
if (System.getProperty(PROFILING_SYSTEM_PROPERTY) != null) {
if (executionContext.getTimingInfo() != null) {
TimingInfo timingInfo = executionContext.getTimingInfo();
TimingInfo responseProcessingTiming = new TimingInfo(startTime, endTime);
timingInfo.addSubMeasurement(RESPONSE_PROCESSING_SUBMEASUREMENT, responseProcessingTiming);
if (countingInputStream != null) {
responseProcessingTiming.addCounter(BYTES_PROCESSED_COUNTER, countingInputStream.getByteCount());
}
}
}
if (awsResponse == null)
throw new RuntimeException("Unable to unmarshall response metadata");
responseMetadataCache.add(request.getOriginalRequest(), awsResponse.getResponseMetadata());
requestLog.info("Received successful response: " + apacheHttpResponse.getStatusLine().getStatusCode()
+ ", AWS Request ID: " + awsResponse.getRequestId());
return awsResponse.getResult();
} catch (Exception e) {
String errorMessage = "Unable to unmarshall response (" + e.getMessage() + ")";
log.error(errorMessage, e);
throw new AmazonClientException(errorMessage, e);
}
}
/**
* Responsible for handling an error response, including unmarshalling the
* error response into the most specific exception type possible, and
* throwing the exception.
*
* @param request
* The request that generated the error response being handled.
* @param errorResponseHandler
* The response handler responsible for unmarshalling the error
* response.
* @param method
* The HTTP method containing the actual response content.
*
* @throws IOException
* If any problems are encountering reading the error response.
*/
private AmazonServiceException handleErrorResponse(Request<?> request,
HttpResponseHandler<AmazonServiceException> errorResponseHandler,
HttpRequestBase method, org.apache.http.HttpResponse apacheHttpResponse) throws IOException {
int status = apacheHttpResponse.getStatusLine().getStatusCode();
HttpResponse response = createResponse(method, request, apacheHttpResponse);
if (errorResponseHandler.needsConnectionLeftOpen() && method instanceof HttpEntityEnclosingRequestBase) {
HttpEntityEnclosingRequestBase entityEnclosingRequest = (HttpEntityEnclosingRequestBase)method;
response.setContent(new HttpMethodReleaseInputStream(entityEnclosingRequest));
}
AmazonServiceException exception = null;
try {
exception = errorResponseHandler.handle(response);
requestLog.info("Received error response: " + exception.toString());
} catch (Exception e) {
String errorMessage = "Unable to unmarshall error response (" + e.getMessage() + ")";
log.error(errorMessage, e);
throw new AmazonClientException(errorMessage, e);
}
exception.setStatusCode(status);
exception.setServiceName(request.getServiceName());
exception.fillInStackTrace();
return exception;
}
/**
* Creates and initializes an HttpResponse object suitable to be passed to
* an HTTP response handler object.
*
* @param method
* The HTTP method that was invoked to get the response.
* @param request
* The HTTP request associated with the response.
*
* @return The new, initialized HttpResponse object ready to be passed to an
* HTTP response handler object.
*
* @throws IOException
* If there were any problems getting any response information
* from the HttpClient method object.
*/
private HttpResponse createResponse(HttpRequestBase method, Request<?> request, org.apache.http.HttpResponse apacheHttpResponse) throws IOException {
HttpResponse httpResponse = new HttpResponse(request);
if (apacheHttpResponse.getEntity() != null) {
httpResponse.setContent(apacheHttpResponse.getEntity().getContent());
}
httpResponse.setStatusCode(apacheHttpResponse.getStatusLine().getStatusCode());
httpResponse.setStatusText(apacheHttpResponse.getStatusLine().getReasonPhrase());
for (Header header : apacheHttpResponse.getAllHeaders()) {
httpResponse.addHeader(header.getName(), header.getValue());
}
return httpResponse;
}
/**
* Exponential sleep on failed request to avoid flooding a service with
* retries.
*
* @param retries
* Current retry count.
* @param previousException
* Exception information for the previous attempt, if any.
*/
private void pauseExponentially(int retries, AmazonServiceException previousException) {
long scaleFactor = 300;
if ( isThrottlingException(previousException) ) {
scaleFactor = 500 + random.nextInt(100);
}
long delay = (long) (Math.pow(2, retries) * scaleFactor);
delay = Math.min(delay, MAX_BACKOFF_IN_MILLISECONDS);
log.debug("Retriable error detected, will retry in " + delay + "ms, attempt number: " + retries);
try {
Thread.sleep(delay);
} catch (InterruptedException e) {
throw new AmazonClientException(e.getMessage(), e);
}
}
/**
* Returns true if the specified exception is a throttling error.
*
* @param ase
* The exception to test.
*
* @return True if the exception resulted from a throttling error message
* from a service, otherwise false.
*/
private boolean isThrottlingException(AmazonServiceException ase) {
if (ase == null) return false;
return "Throttling".equals(ase.getErrorCode());
}
@Override
protected void finalize() throws Throwable {
this.shutdown();
super.finalize();
}
}