io.bitsensor.plugins.shaded.org.springframework.retry.support.RetryTemplate Maven / Gradle / Ivy
/*
* Copyright 2006-2014 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 io.bitsensor.plugins.shaded.org.springframework.retry.support;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import io.bitsensor.plugins.shaded.org.apache.commons.logging.Log;
import io.bitsensor.plugins.shaded.org.apache.commons.logging.LogFactory;
import io.bitsensor.plugins.shaded.org.springframework.retry.ExhaustedRetryException;
import io.bitsensor.plugins.shaded.org.springframework.retry.RecoveryCallback;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryCallback;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryContext;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryException;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryListener;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryOperations;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryPolicy;
import io.bitsensor.plugins.shaded.org.springframework.retry.RetryState;
import io.bitsensor.plugins.shaded.org.springframework.retry.TerminatedRetryException;
import io.bitsensor.plugins.shaded.org.springframework.retry.backoff.BackOffContext;
import io.bitsensor.plugins.shaded.org.springframework.retry.backoff.BackOffInterruptedException;
import io.bitsensor.plugins.shaded.org.springframework.retry.backoff.BackOffPolicy;
import io.bitsensor.plugins.shaded.org.springframework.retry.backoff.NoBackOffPolicy;
import io.bitsensor.plugins.shaded.org.springframework.retry.policy.MapRetryContextCache;
import io.bitsensor.plugins.shaded.org.springframework.retry.policy.RetryContextCache;
import io.bitsensor.plugins.shaded.org.springframework.retry.policy.SimpleRetryPolicy;
/**
* Template class that simplifies the execution of operations with retry semantics.
*
* Retryable operations are encapsulated in implementations of the {@link RetryCallback}
* interface and are executed using one of the supplied execute methods.
*
* By default, an operation is retried if is throws any {@link Exception} or subclass of
* {@link Exception}. This behaviour can be changed by using the
* {@link #setRetryPolicy(RetryPolicy)} method.
*
* Also by default, each operation is retried for a maximum of three attempts with no back
* off in between. This behaviour can be configured using the
* {@link #setRetryPolicy(RetryPolicy)} and {@link #setBackOffPolicy(BackOffPolicy)}
* properties. The {@link io.bitsensor.plugins.shaded.org.springframework.retry.backoff.BackOffPolicy} controls how
* long the pause is between each individual retry attempt.
*
* This class is thread-safe and suitable for concurrent access when executing operations
* and when performing configuration changes. As such, it is possible to change the number
* of retries on the fly, as well as the {@link BackOffPolicy} used and no in progress
* retryable operations will be affected.
*
* @author Rob Harrop
* @author Dave Syer
* @author Gary Russell
* @author Artem Bilan
* @author Josh Long
*/
public class RetryTemplate implements RetryOperations {
/**
* Retry context attribute name that indicates the context should be considered global
* state (never closed). TODO: convert this to a flag in the RetryState.
*/
private static final String GLOBAL_STATE = "state.global";
protected final Log logger = LogFactory.getLog(getClass());
private volatile BackOffPolicy backOffPolicy = new NoBackOffPolicy();
private volatile RetryPolicy retryPolicy = new SimpleRetryPolicy(3);
private volatile RetryListener[] listeners = new RetryListener[0];
private RetryContextCache retryContextCache = new MapRetryContextCache();
private boolean throwLastExceptionOnExhausted;
/**
* @param throwLastExceptionOnExhausted the throwLastExceptionOnExhausted to set
*/
public void setThrowLastExceptionOnExhausted(boolean throwLastExceptionOnExhausted) {
this.throwLastExceptionOnExhausted = throwLastExceptionOnExhausted;
}
/**
* Public setter for the {@link RetryContextCache}.
*
* @param retryContextCache the {@link RetryContextCache} to set.
*/
public void setRetryContextCache(RetryContextCache retryContextCache) {
this.retryContextCache = retryContextCache;
}
/**
* Setter for listeners. The listeners are executed before and after a retry block
* (i.e. before and after all the attempts), and on an error (every attempt).
*
* @param listeners the {@link RetryListener}s
* @see RetryListener
*/
public void setListeners(RetryListener[] listeners) {
this.listeners = Arrays.asList(listeners)
.toArray(new RetryListener[listeners.length]);
}
/**
* Register an additional listener.
*
* @param listener the {@link RetryListener}
* @see #setListeners(RetryListener[])
*/
public void registerListener(RetryListener listener) {
List list = new ArrayList(
Arrays.asList(this.listeners));
list.add(listener);
this.listeners = list.toArray(new RetryListener[list.size()]);
}
/**
* Setter for {@link BackOffPolicy}.
*
* @param backOffPolicy the {@link BackOffPolicy}
*/
public void setBackOffPolicy(BackOffPolicy backOffPolicy) {
this.backOffPolicy = backOffPolicy;
}
/**
* Setter for {@link RetryPolicy}.
*
* @param retryPolicy the {@link RetryPolicy}
*/
public void setRetryPolicy(RetryPolicy retryPolicy) {
this.retryPolicy = retryPolicy;
}
/**
* Keep executing the callback until it either succeeds or the policy dictates that we
* stop, in which case the most recent exception thrown by the callback will be
* rethrown.
*
* @see RetryOperations#execute(RetryCallback)
* @param retryCallback the {@link RetryCallback}
*
* @throws TerminatedRetryException if the retry has been manually terminated by a
* listener.
*/
@Override
public final T execute(RetryCallback retryCallback)
throws E {
return doExecute(retryCallback, null, null);
}
/**
* Keep executing the callback until it either succeeds or the policy dictates that we
* stop, in which case the recovery callback will be executed.
*
* @see RetryOperations#execute(RetryCallback, RecoveryCallback)
* @param retryCallback the {@link RetryCallback}
* @param recoveryCallback the {@link RecoveryCallback}
* @throws TerminatedRetryException if the retry has been manually terminated by a
* listener.
*/
@Override
public final T execute(RetryCallback retryCallback,
RecoveryCallback recoveryCallback) throws E {
return doExecute(retryCallback, recoveryCallback, null);
}
/**
* Execute the callback once if the policy dictates that we can, re-throwing any
* exception encountered so that clients can re-present the same task later.
*
* @see RetryOperations#execute(RetryCallback, RetryState)
* @param retryCallback the {@link RetryCallback}
* @param retryState the {@link RetryState}
* @throws ExhaustedRetryException if the retry has been exhausted.
*/
@Override
public final T execute(RetryCallback retryCallback,
RetryState retryState) throws E, ExhaustedRetryException {
return doExecute(retryCallback, null, retryState);
}
/**
* Execute the callback once if the policy dictates that we can, re-throwing any
* exception encountered so that clients can re-present the same task later.
*
* @see RetryOperations#execute(RetryCallback, RetryState)
* @param retryCallback the {@link RetryCallback}
* @param recoveryCallback the {@link RecoveryCallback}
* @param retryState the {@link RetryState}
*/
@Override
public final T execute(RetryCallback retryCallback,
RecoveryCallback recoveryCallback, RetryState retryState)
throws E, ExhaustedRetryException {
return doExecute(retryCallback, recoveryCallback, retryState);
}
/**
* Execute the callback once if the policy dictates that we can, otherwise execute the
* recovery callback.
* @param recoveryCallback the {@link RecoveryCallback}
* @param retryCallback the {@link RetryCallback}
* @param state the {@link RetryState}
* @param the type of the return value
* @param the exception type to throw
* @see RetryOperations#execute(RetryCallback, RecoveryCallback, RetryState)
* @throws ExhaustedRetryException if the retry has been exhausted.
* @throws E an exception if the retry operation fails
* @return T the retried value
*/
protected T doExecute(RetryCallback retryCallback,
RecoveryCallback recoveryCallback, RetryState state)
throws E, ExhaustedRetryException {
RetryPolicy retryPolicy = this.retryPolicy;
BackOffPolicy backOffPolicy = this.backOffPolicy;
// Allow the retry policy to initialise itself...
RetryContext context = open(retryPolicy, state);
if (this.logger.isTraceEnabled()) {
this.logger.trace("RetryContext retrieved: " + context);
}
// Make sure the context is available globally for clients who need
// it...
RetrySynchronizationManager.register(context);
Throwable lastException = null;
boolean exhausted = false;
try {
// Give clients a chance to enhance the context...
boolean running = doOpenInterceptors(retryCallback, context);
if (!running) {
throw new TerminatedRetryException(
"Retry terminated abnormally by interceptor before first attempt");
}
// Get or Start the backoff context...
BackOffContext backOffContext = null;
Object resource = context.getAttribute("backOffContext");
if (resource instanceof BackOffContext) {
backOffContext = (BackOffContext) resource;
}
if (backOffContext == null) {
backOffContext = backOffPolicy.start(context);
if (backOffContext != null) {
context.setAttribute("backOffContext", backOffContext);
}
}
/*
* We allow the whole loop to be skipped if the policy or context already
* forbid the first try. This is used in the case of external retry to allow a
* recovery in handleRetryExhausted without the callback processing (which
* would throw an exception).
*/
while (canRetry(retryPolicy, context) && !context.isExhaustedOnly()) {
try {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Retry: count=" + context.getRetryCount());
}
// Reset the last exception, so if we are successful
// the close interceptors will not think we failed...
lastException = null;
return retryCallback.doWithRetry(context);
}
catch (Throwable e) {
lastException = e;
try {
registerThrowable(retryPolicy, state, context, e);
}
catch (Exception ex) {
throw new TerminatedRetryException("Could not register throwable",
ex);
}
finally {
doOnErrorInterceptors(retryCallback, context, e);
}
if (canRetry(retryPolicy, context) && !context.isExhaustedOnly()) {
try {
backOffPolicy.backOff(backOffContext);
}
catch (BackOffInterruptedException ex) {
lastException = e;
// back off was prevented by another thread - fail the retry
if (this.logger.isDebugEnabled()) {
this.logger
.debug("Abort retry because interrupted: count="
+ context.getRetryCount());
}
throw ex;
}
}
if (this.logger.isDebugEnabled()) {
this.logger.debug(
"Checking for rethrow: count=" + context.getRetryCount());
}
if (shouldRethrow(retryPolicy, context, state)) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Rethrow in retry for policy: count="
+ context.getRetryCount());
}
throw RetryTemplate.wrapIfNecessary(e);
}
}
/*
* A stateful attempt that can retry may rethrow the exception before now,
* but if we get this far in a stateful retry there's a reason for it,
* like a circuit breaker or a rollback classifier.
*/
if (state != null && context.hasAttribute(GLOBAL_STATE)) {
break;
}
}
if (state == null && this.logger.isDebugEnabled()) {
this.logger.debug(
"Retry failed last attempt: count=" + context.getRetryCount());
}
exhausted = true;
return handleRetryExhausted(recoveryCallback, context, state);
}
catch (Throwable e) {
throw RetryTemplate.wrapIfNecessary(e);
}
finally {
close(retryPolicy, context, state, lastException == null || exhausted);
doCloseInterceptors(retryCallback, context, lastException);
RetrySynchronizationManager.clear();
}
}
/**
* Decide whether to proceed with the ongoing retry attempt. This method is called
* before the {@link RetryCallback} is executed, but after the backoff and open
* interceptors.
*
* @param retryPolicy the policy to apply
* @param context the current retry context
* @return true if we can continue with the attempt
*/
protected boolean canRetry(RetryPolicy retryPolicy, RetryContext context) {
return retryPolicy.canRetry(context);
}
/**
* Clean up the cache if necessary and close the context provided (if the flag
* indicates that processing was successful).
*
* @param retryPolicy the {@link RetryPolicy}
* @param context the {@link RetryContext}
* @param state the {@link RetryState}
* @param succeeded whether the close succeeded
*/
protected void close(RetryPolicy retryPolicy, RetryContext context, RetryState state,
boolean succeeded) {
if (state != null) {
if (succeeded) {
if (!context.hasAttribute(GLOBAL_STATE)) {
this.retryContextCache.remove(state.getKey());
}
retryPolicy.close(context);
context.setAttribute(RetryContext.CLOSED, true);
}
}
else {
retryPolicy.close(context);
context.setAttribute(RetryContext.CLOSED, true);
}
}
protected void registerThrowable(RetryPolicy retryPolicy, RetryState state,
RetryContext context, Throwable e) {
retryPolicy.registerThrowable(context, e);
registerContext(context, state);
}
private void registerContext(RetryContext context, RetryState state) {
if (state != null) {
Object key = state.getKey();
if (key != null) {
if (context.getRetryCount() > 1
&& !this.retryContextCache.containsKey(key)) {
throw new RetryException(
"Inconsistent state for failed item key: cache key has changed. "
+ "Consider whether equals() or hashCode() for the key might be inconsistent, "
+ "or if you need to supply a better key");
}
this.retryContextCache.put(key, context);
}
}
}
/**
* Delegate to the {@link RetryPolicy} having checked in the cache for an existing
* value if the state is not null.
*
* @param state a {@link RetryState}
* @param retryPolicy a {@link RetryPolicy} to delegate the context creation
*
* @return a retry context, either a new one or the one used last time the same state
* was encountered
*/
protected RetryContext open(RetryPolicy retryPolicy, RetryState state) {
if (state == null) {
return doOpenInternal(retryPolicy);
}
Object key = state.getKey();
if (state.isForceRefresh()) {
return doOpenInternal(retryPolicy, state);
}
// If there is no cache hit we can avoid the possible expense of the
// cache re-hydration.
if (!this.retryContextCache.containsKey(key)) {
// The cache is only used if there is a failure.
return doOpenInternal(retryPolicy, state);
}
RetryContext context = this.retryContextCache.get(key);
if (context == null) {
if (this.retryContextCache.containsKey(key)) {
throw new RetryException(
"Inconsistent state for failed item: no history found. "
+ "Consider whether equals() or hashCode() for the item might be inconsistent, "
+ "or if you need to supply a better ItemKeyGenerator");
}
// The cache could have been expired in between calls to
// containsKey(), so we have to live with this:
return doOpenInternal(retryPolicy, state);
}
// Start with a clean slate for state that others may be inspecting
context.removeAttribute(RetryContext.CLOSED);
context.removeAttribute(RetryContext.EXHAUSTED);
context.removeAttribute(RetryContext.RECOVERED);
return context;
}
private RetryContext doOpenInternal(RetryPolicy retryPolicy, RetryState state) {
RetryContext context = retryPolicy.open(RetrySynchronizationManager.getContext());
if (state != null) {
context.setAttribute(RetryContext.STATE_KEY, state.getKey());
}
if (context.hasAttribute(GLOBAL_STATE)) {
registerContext(context, state);
}
return context;
}
private RetryContext doOpenInternal(RetryPolicy retryPolicy) {
return doOpenInternal(retryPolicy, null);
}
/**
* Actions to take after final attempt has failed. If there is state clean up the
* cache. If there is a recovery callback, execute that and return its result.
* Otherwise throw an exception.
*
* @param recoveryCallback the callback for recovery (might be null)
* @param context the current retry context
* @param state the {@link RetryState}
* @param the type to classify
* @throws Exception if the callback does, and if there is no callback and the state
* is null then the last exception from the context
* @throws ExhaustedRetryException if the state is not null and there is no recovery
* callback
* @return T the payload to return
*/
protected T handleRetryExhausted(RecoveryCallback recoveryCallback,
RetryContext context, RetryState state) throws Throwable {
context.setAttribute(RetryContext.EXHAUSTED, true);
if (state != null && !context.hasAttribute(GLOBAL_STATE)) {
this.retryContextCache.remove(state.getKey());
}
if (recoveryCallback != null) {
context.setAttribute(RetryContext.RECOVERED, true);
return recoveryCallback.recover(context);
}
if (state != null) {
this.logger
.debug("Retry exhausted after last attempt with no recovery path.");
rethrow(context, "Retry exhausted after last attempt with no recovery path");
}
throw wrapIfNecessary(context.getLastThrowable());
}
protected void rethrow(RetryContext context, String message)
throws E {
if (this.throwLastExceptionOnExhausted) {
@SuppressWarnings("unchecked")
E rethrow = (E) context.getLastThrowable();
throw rethrow;
}
else {
throw new ExhaustedRetryException(message, context.getLastThrowable());
}
}
/**
* Extension point for subclasses to decide on behaviour after catching an exception
* in a {@link RetryCallback}. Normal stateless behaviour is not to rethrow, and if
* there is state we rethrow.
*
* @param retryPolicy the retry policy
* @param context the current context
* @param state the current retryState
* @return true if the state is not null but subclasses might choose otherwise
*/
protected boolean shouldRethrow(RetryPolicy retryPolicy, RetryContext context,
RetryState state) {
return state != null && state.rollbackFor(context.getLastThrowable());
}
private boolean doOpenInterceptors(
RetryCallback callback, RetryContext context) {
boolean result = true;
for (RetryListener listener : this.listeners) {
result = result && listener.open(context, callback);
}
return result;
}
private void doCloseInterceptors(
RetryCallback callback, RetryContext context, Throwable lastException) {
for (int i = this.listeners.length; i-- > 0;) {
this.listeners[i].close(context, callback, lastException);
}
}
private void doOnErrorInterceptors(
RetryCallback callback, RetryContext context, Throwable throwable) {
for (int i = this.listeners.length; i-- > 0;) {
this.listeners[i].onError(context, callback, throwable);
}
}
/**
* Re-throws the original throwable if it is an Exception, and wraps non-exceptions
* into {@link RetryException}.
*/
private static E wrapIfNecessary(Throwable throwable)
throws RetryException {
if (throwable instanceof Error) {
throw (Error) throwable;
}
else if (throwable instanceof Exception) {
@SuppressWarnings("unchecked")
E rethrow = (E) throwable;
return rethrow;
}
else {
throw new RetryException("Exception in retry", throwable);
}
}
}