protected <E extends Throwable> 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());
}
}
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;
}
/**
* 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);
}
}
/**
* 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 <T> 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> T handleRetryExhausted(
RecoveryCallback<T> 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());
}
@Override
public Object doWithRetry(RetryContext context) throws Exception {
context.setAttribute(RetryContext.NAME, label);
try {
return this.invocation.proceed();
} catch (Exception e) {
throw e;
} catch (Error e) {
throw e;
} catch (Throwable e) {
throw new IllegalStateException(e);
}
}
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;
}
/**
* 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());
}
/**
* 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 <T> the type of the return value
* @param <E> 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, E extends Throwable> T doExecute(
RetryCallback<T, E> retryCallback, RecoveryCallback<T> 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.<E>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.<E>wrapIfNecessary(e);
} finally {
close(retryPolicy, context, state, lastException == null || exhausted);
doCloseInterceptors(retryCallback, context, lastException);
RetrySynchronizationManager.clear();
}
}
public Object recover(RetryContext context) {
if (recoverer != null) {
return recoverer.recover(args, context.getLastThrowable());
}
throw new ExhaustedRetryException("Retry was exhausted but there was no recovery path.");
}
@Override
public Object recover(RetryContext context) {
return this.recoverer.recover(this.args, context.getLastThrowable());
}