/*
* Copyright 2002-2014 the original author or authors.
*
* 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 org.springframework.web.context.request.async;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.task.AsyncTaskExecutor;
import org.springframework.core.task.SimpleAsyncTaskExecutor;
import org.springframework.util.Assert;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.async.DeferredResult.DeferredResultHandler;
import org.springframework.web.util.UrlPathHelper;
/**
* The central class for managing asynchronous request processing, mainly intended
* as an SPI and not typically used directly by application classes.
*
* <p>An async scenario starts with request processing as usual in a thread (T1).
* Concurrent request handling can be initiated by calling
* {@link #startCallableProcessing(Callable, Object...) startCallableProcessing} or
* {@link #startDeferredResultProcessing(DeferredResult, Object...) startDeferredResultProcessing},
* both of which produce a result in a separate thread (T2). The result is saved
* and the request dispatched to the container, to resume processing with the saved
* result in a third thread (T3). Within the dispatched thread (T3), the saved
* result can be accessed via {@link #getConcurrentResult()} or its presence
* detected via {@link #hasConcurrentResult()}.
*
* @author Rossen Stoyanchev
* @since 3.2
* @see org.springframework.web.context.request.AsyncWebRequestInterceptor
* @see org.springframework.web.servlet.AsyncHandlerInterceptor
* @see org.springframework.web.filter.OncePerRequestFilter#shouldNotFilterAsyncDispatch
* @see org.springframework.web.filter.OncePerRequestFilter#isAsyncDispatch
*/
public final class WebAsyncManager {
private static final Object RESULT_NONE = new Object();
private static final Log logger = LogFactory.getLog(WebAsyncManager.class);
private static final UrlPathHelper urlPathHelper = new UrlPathHelper();
private static final CallableProcessingInterceptor timeoutCallableInterceptor =
new TimeoutCallableProcessingInterceptor();
private static final DeferredResultProcessingInterceptor timeoutDeferredResultInterceptor =
new TimeoutDeferredResultProcessingInterceptor();
private AsyncWebRequest asyncWebRequest;
private AsyncTaskExecutor taskExecutor = new SimpleAsyncTaskExecutor(this.getClass().getSimpleName());
private Object concurrentResult = RESULT_NONE;
private Object[] concurrentResultContext;
private final Map<Object, CallableProcessingInterceptor> callableInterceptors =
new LinkedHashMap<Object, CallableProcessingInterceptor>();
private final Map<Object, DeferredResultProcessingInterceptor> deferredResultInterceptors =
new LinkedHashMap<Object, DeferredResultProcessingInterceptor>();
/**
* Package-private constructor.
* @see WebAsyncUtils#getAsyncManager(javax.servlet.ServletRequest)
* @see WebAsyncUtils#getAsyncManager(org.springframework.web.context.request.WebRequest)
*/
WebAsyncManager() {
}
/**
* Configure the {@link AsyncWebRequest} to use. This property may be set
* more than once during a single request to accurately reflect the current
* state of the request (e.g. following a forward, request/response
* wrapping, etc). However, it should not be set while concurrent handling
* is in progress, i.e. while {@link #isConcurrentHandlingStarted()} is
* {@code true}.
* @param asyncWebRequest the web request to use
*/
public void setAsyncWebRequest(final AsyncWebRequest asyncWebRequest) {
Assert.notNull(asyncWebRequest, "AsyncWebRequest must not be null");
Assert.state(!isConcurrentHandlingStarted(), "Can't set AsyncWebRequest with concurrent handling in progress");
this.asyncWebRequest = asyncWebRequest;
this.asyncWebRequest.addCompletionHandler(new Runnable() {
@Override
public void run() {
asyncWebRequest.removeAttribute(WebAsyncUtils.WEB_ASYNC_MANAGER_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
}
});
}
/**
* Configure an AsyncTaskExecutor for use with concurrent processing via
* {@link #startCallableProcessing(Callable, Object...)}.
* <p>By default a {@link SimpleAsyncTaskExecutor} instance is used.
*/
public void setTaskExecutor(AsyncTaskExecutor taskExecutor) {
this.taskExecutor = taskExecutor;
}
/**
* Whether the selected handler for the current request chose to handle the
* request asynchronously. A return value of "true" indicates concurrent
* handling is under way and the response will remain open. A return value
* of "false" means concurrent handling was either not started or possibly
* that it has completed and the request was dispatched for further
* processing of the concurrent result.
*/
public boolean isConcurrentHandlingStarted() {
return ((this.asyncWebRequest != null) && this.asyncWebRequest.isAsyncStarted());
}
/**
* Whether a result value exists as a result of concurrent handling.
*/
public boolean hasConcurrentResult() {
return (this.concurrentResult != RESULT_NONE);
}
/**
* Provides access to the result from concurrent handling.
* @return an Object, possibly an {@code Exception} or {@code Throwable} if
* concurrent handling raised one.
* @see #clearConcurrentResult()
*/
public Object getConcurrentResult() {
return this.concurrentResult;
}
/**
* Provides access to additional processing context saved at the start of
* concurrent handling.
* @see #clearConcurrentResult()
*/
public Object[] getConcurrentResultContext() {
return this.concurrentResultContext;
}
/**
* Get the {@link CallableProcessingInterceptor} registered under the given key.
* @param key the key
* @return the interceptor registered under that key or {@code null}
*/
public CallableProcessingInterceptor getCallableInterceptor(Object key) {
return this.callableInterceptors.get(key);
}
/**
* Get the {@link DeferredResultProcessingInterceptor} registered under the given key.
* @param key the key
* @return the interceptor registered under that key or {@code null}
*/
public DeferredResultProcessingInterceptor getDeferredResultInterceptor(Object key) {
return this.deferredResultInterceptors.get(key);
}
/**
* Register a {@link CallableProcessingInterceptor} under the given key.
* @param key the key
* @param interceptor the interceptor to register
*/
public void registerCallableInterceptor(Object key, CallableProcessingInterceptor interceptor) {
Assert.notNull(key, "Key is required");
Assert.notNull(interceptor, "CallableProcessingInterceptor is required");
this.callableInterceptors.put(key, interceptor);
}
/**
* Register a {@link CallableProcessingInterceptor} without a key.
* The key is derived from the class name and hashcode.
* @param interceptors one or more interceptors to register
*/
public void registerCallableInterceptors(CallableProcessingInterceptor... interceptors) {
Assert.notNull(interceptors, "A CallableProcessingInterceptor is required");
for (CallableProcessingInterceptor interceptor : interceptors) {
String key = interceptor.getClass().getName() + ":" + interceptor.hashCode();
this.callableInterceptors.put(key, interceptor);
}
}
/**
* Register a {@link DeferredResultProcessingInterceptor} under the given key.
* @param key the key
* @param interceptor the interceptor to register
*/
public void registerDeferredResultInterceptor(Object key, DeferredResultProcessingInterceptor interceptor) {
Assert.notNull(key, "Key is required");
Assert.notNull(interceptor, "DeferredResultProcessingInterceptor is required");
this.deferredResultInterceptors.put(key, interceptor);
}
/**
* Register one or more {@link DeferredResultProcessingInterceptor}s without a specified key.
* The default key is derived from the interceptor class name and hash code.
* @param interceptors one or more interceptors to register
*/
public void registerDeferredResultInterceptors(DeferredResultProcessingInterceptor... interceptors) {
Assert.notNull(interceptors, "A DeferredResultProcessingInterceptor is required");
for (DeferredResultProcessingInterceptor interceptor : interceptors) {
String key = interceptor.getClass().getName() + ":" + interceptor.hashCode();
this.deferredResultInterceptors.put(key, interceptor);
}
}
/**
* Clear {@linkplain #getConcurrentResult() concurrentResult} and
* {@linkplain #getConcurrentResultContext() concurrentResultContext}.
*/
public void clearConcurrentResult() {
this.concurrentResult = RESULT_NONE;
this.concurrentResultContext = null;
}
/**
* Start concurrent request processing and execute the given task with an
* {@link #setTaskExecutor(AsyncTaskExecutor) AsyncTaskExecutor}. The result
* from the task execution is saved and the request dispatched in order to
* resume processing of that result. If the task raises an Exception then
* the saved result will be the raised Exception.
* @param callable a unit of work to be executed asynchronously
* @param processingContext additional context to save that can be accessed
* via {@link #getConcurrentResultContext()}
* @throws Exception if concurrent processing failed to start
* @see #getConcurrentResult()
* @see #getConcurrentResultContext()
*/
@SuppressWarnings({"unchecked", "rawtypes"})
public void startCallableProcessing(Callable<?> callable, Object... processingContext) throws Exception {
Assert.notNull(callable, "Callable must not be null");
startCallableProcessing(new WebAsyncTask(callable), processingContext);
}
/**
* Use the given {@link WebAsyncTask} to configure the task executor as well as
* the timeout value of the {@code AsyncWebRequest} before delegating to
* {@link #startCallableProcessing(Callable, Object...)}.
* @param webAsyncTask a WebAsyncTask containing the target {@code Callable}
* @param processingContext additional context to save that can be accessed
* via {@link #getConcurrentResultContext()}
* @throws Exception if concurrent processing failed to start
*/
public void startCallableProcessing(final WebAsyncTask<?> webAsyncTask, Object... processingContext) throws Exception {
Assert.notNull(webAsyncTask, "WebAsyncTask must not be null");
Assert.state(this.asyncWebRequest != null, "AsyncWebRequest must not be null");
Long timeout = webAsyncTask.getTimeout();
if (timeout != null) {
this.asyncWebRequest.setTimeout(timeout);
}
AsyncTaskExecutor executor = webAsyncTask.getExecutor();
if (executor != null) {
this.taskExecutor = executor;
}
List<CallableProcessingInterceptor> interceptors = new ArrayList<CallableProcessingInterceptor>();
interceptors.add(webAsyncTask.getInterceptor());
interceptors.addAll(this.callableInterceptors.values());
interceptors.add(timeoutCallableInterceptor);
final Callable<?> callable = webAsyncTask.getCallable();
final CallableInterceptorChain interceptorChain = new CallableInterceptorChain(interceptors);
this.asyncWebRequest.addTimeoutHandler(new Runnable() {
@Override
public void run() {
logger.debug("Processing timeout");
Object result = interceptorChain.triggerAfterTimeout(asyncWebRequest, callable);
if (result != CallableProcessingInterceptor.RESULT_NONE) {
setConcurrentResultAndDispatch(result);
}
}
});
this.asyncWebRequest.addCompletionHandler(new Runnable() {
@Override
public void run() {
interceptorChain.triggerAfterCompletion(asyncWebRequest, callable);
}
});
interceptorChain.applyBeforeConcurrentHandling(this.asyncWebRequest, callable);
startAsyncProcessing(processingContext);
this.taskExecutor.submit(new Runnable() {
@Override
public void run() {
Object result = null;
try {
interceptorChain.applyPreProcess(asyncWebRequest, callable);
result = callable.call();
}
catch (Throwable ex) {
result = ex;
}
finally {
result = interceptorChain.applyPostProcess(asyncWebRequest, callable, result);
}
setConcurrentResultAndDispatch(result);
}
});
}
private void setConcurrentResultAndDispatch(Object result) {
synchronized (WebAsyncManager.this) {
if (hasConcurrentResult()) {
return;
}
this.concurrentResult = result;
}
if (this.asyncWebRequest.isAsyncComplete()) {
logger.error("Could not complete async processing due to timeout or network error");
return;
}
if (logger.isDebugEnabled()) {
logger.debug("Concurrent result value [" + this.concurrentResult +
"] - dispatching request to resume processing");
}
this.asyncWebRequest.dispatch();
}
/**
* Start concurrent request processing and initialize the given
* {@link DeferredResult} with a {@link DeferredResultHandler} that saves
* the result and dispatches the request to resume processing of that
* result. The {@code AsyncWebRequest} is also updated with a completion
* handler that expires the {@code DeferredResult} and a timeout handler
* assuming the {@code DeferredResult} has a default timeout result.
* @param deferredResult the DeferredResult instance to initialize
* @param processingContext additional context to save that can be accessed
* via {@link #getConcurrentResultContext()}
* @throws Exception if concurrent processing failed to start
* @see #getConcurrentResult()
* @see #getConcurrentResultContext()
*/
public void startDeferredResultProcessing(
final DeferredResult<?> deferredResult, Object... processingContext) throws Exception {
Assert.notNull(deferredResult, "DeferredResult must not be null");
Assert.state(this.asyncWebRequest != null, "AsyncWebRequest must not be null");
Long timeout = deferredResult.getTimeoutValue();
if (timeout != null) {
this.asyncWebRequest.setTimeout(timeout);
}
List<DeferredResultProcessingInterceptor> interceptors = new ArrayList<DeferredResultProcessingInterceptor>();
interceptors.add(deferredResult.getInterceptor());
interceptors.addAll(this.deferredResultInterceptors.values());
interceptors.add(timeoutDeferredResultInterceptor);
final DeferredResultInterceptorChain interceptorChain = new DeferredResultInterceptorChain(interceptors);
this.asyncWebRequest.addTimeoutHandler(new Runnable() {
@Override
public void run() {
try {
interceptorChain.triggerAfterTimeout(asyncWebRequest, deferredResult);
}
catch (Throwable ex) {
setConcurrentResultAndDispatch(ex);
}
}
});
this.asyncWebRequest.addCompletionHandler(new Runnable() {
@Override
public void run() {
interceptorChain.triggerAfterCompletion(asyncWebRequest, deferredResult);
}
});
interceptorChain.applyBeforeConcurrentHandling(this.asyncWebRequest, deferredResult);
startAsyncProcessing(processingContext);
try {
interceptorChain.applyPreProcess(this.asyncWebRequest, deferredResult);
deferredResult.setResultHandler(new DeferredResultHandler() {
@Override
public void handleResult(Object result) {
result = interceptorChain.applyPostProcess(asyncWebRequest, deferredResult, result);
setConcurrentResultAndDispatch(result);
}
});
}
catch (Throwable ex) {
setConcurrentResultAndDispatch(ex);
}
}
private void startAsyncProcessing(Object[] processingContext) {
clearConcurrentResult();
this.concurrentResultContext = processingContext;
this.asyncWebRequest.startAsync();
if (logger.isDebugEnabled()) {
HttpServletRequest request = this.asyncWebRequest.getNativeRequest(HttpServletRequest.class);
String requestUri = urlPathHelper.getRequestUri(request);
logger.debug("Concurrent handling starting for " + request.getMethod() + " [" + requestUri + "]");
}
}
}