org.esbtools.eventhandler.lightblue.client.BulkLightblueRequester Maven / Gradle / Ivy
/*
* Copyright 2016 esbtools Contributors and/or its affiliates.
*
* This file is part of esbtools.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see This class may be used across multiple threads safely, however the returned {@code Future}s
* are not threadsafe. That is, a given future instance should not be shared among multiple threads,
* which should not be a relevant limitation (if it is, however, it would not be hard to make them
* thread safe). Requests are queued up atomically, and performed and cleared atomically as well.
* That is, when one future is resolved, the current batch of requests is frozen, copied, cleared,
* and performed. A thread queueing a request while another thread resolves a future will
* not result in a loss of requests. It will either make it in for the batch, or be queued
* for the next.
*
*
While this class is thread safe, the logical "scope" of returned {@code Future}s is
* significant to consider. If you know you are going to batch up a bunch of requests, you don't
* want some other thread interrupting your batch performing your requests before you've finished
* queueing all of them up. So, you should create a new {@code BulkLightblueRequester} instance per
* logical "batch," and generally should avoid sharing an instance among multiple threads.
*/
public class BulkLightblueRequester implements LightblueRequester {
private final LightblueClient lightblue;
private final List queuedRequests =
Collections.synchronizedList(new ArrayList<>());
public BulkLightblueRequester(LightblueClient lightblue) {
this.lightblue = lightblue;
}
@Override
public TransformableFuture request(AbstractLightblueDataRequest... requests) {
LazyRequestTransformableFuture responseFuture = new LazyRequestTransformableFuture(requests);
queuedRequests.add(responseFuture);
return responseFuture;
}
@Override
public TransformableFuture request(
Collection requests) {
return request(requests.toArray(new AbstractLightblueDataRequest[requests.size()]));
}
private void doQueuedRequestsAndCompleteFutures() {
List batch;
synchronized (queuedRequests) {
batch = new ArrayList<>(queuedRequests);
queuedRequests.clear();
}
DataBulkRequest bulkRequest = new DataBulkRequest();
for (LazyRequestTransformableFuture batchedFuture : batch) {
for (AbstractLightblueDataRequest requestInBatch : batchedFuture.requests) {
// TODO: Determine if any requests are equivalent / duplicated and filter out
bulkRequest.add(requestInBatch);
}
}
try {
LightblueBulkDataResponse bulkResponse = tryBulkRequest(bulkRequest);
for (LazyRequestTransformableFuture batchedFuture : batch) {
AbstractLightblueDataRequest[] requests = batchedFuture.requests;
Map responseMap =
new HashMap<>(requests.length);
List errors = new ArrayList<>();
for (AbstractLightblueDataRequest request : requests) {
LightblueDataResponse response = bulkResponse.getResponse(request);
if (response instanceof LightblueErrorResponse) {
LightblueErrorResponse errorResponse = (LightblueErrorResponse) response;
DataError[] dataErrors = errorResponse.getDataErrors();
Error[] lightblueErrors = errorResponse.getLightblueErrors();
if (dataErrors != null) {
for (DataError dataError : dataErrors) {
errors.addAll(dataError.getErrors());
}
}
if (lightblueErrors != null) {
Collections.addAll(errors, lightblueErrors);
}
}
responseMap.put(request, response);
}
if (errors.isEmpty()) {
batchedFuture.complete(new BulkResponses(responseMap));
} else {
batchedFuture.completeExceptionally(new BulkLightblueResponseException(errors));
}
}
} catch (LightblueException e) {
for (LazyRequestTransformableFuture batchedFuture : batch) {
batchedFuture.completeExceptionally(e);
}
}
}
/**
* Swallows exceptions related to errors in individual requests on purpose. The returned
* bulk response object may have failed responses.
*
* @throws LightblueException if something else went wrong, in which case there is no usable
* response at all.
*/
private LightblueBulkDataResponse tryBulkRequest(DataBulkRequest bulkRequest)
throws LightblueException {
try {
return lightblue.bulkData(bulkRequest);
} catch (LightblueBulkResponseException e) {
return e.getBulkResponse();
}
}
static class BulkResponses implements LightblueResponses {
private final Map responseMap;
BulkResponses(Map responseMap) {
this.responseMap = responseMap;
}
@Override
public LightblueDataResponse forRequest(AbstractLightblueDataRequest request) {
if (responseMap.containsKey(request)) {
return responseMap.get(request);
}
throw new NoSuchElementException("No response for request: " + request);
}
}
/**
* A core future implementation which accepts its result externally, triggering this result
* lazily on the first call to {@link #get()}.
*
* This future is used to back more specific cases in {@link LazyRequestTransformableFuture}
* and {@link LazyTransformingFuture}.
*
*
{@link Future}s typically work asynchronously in another thread. This implementation
* intentionally does not. To reap the performance benefits of batching requests, we need a
* future design which puts off doing any work as long as possible: until something
* calls {@code .get()}. Spinning of work in another thread is the opposite: it starts work
* immediately in the background. To the caller, this future implementation feels similar:
* creating one returns immediately, and the caller can use it almost exactly as a "normal"
* asynchronous future or future. The only difference is that with this solution, callbacks
* won't happen until you ask for the result with {@code .get()}. With a normal thread-based,
* async future the callbacks happen at some point in the future regardless of if anything ever
* calls {@code .get()}.
*
* @param The type of the result of the future. See {@link TransformableFuture}.
*/
static class LazyTransformableFuture implements TransformableFuture {
/**
* A function which should trigger the completion of this future with a result. If it does
* not, this is a runtime error.
*
*
This is what makes the future lazy: we can use this to complete the future
* on demand.
*/
private final Completer completer;
private U result;
private Exception exception;
private boolean completed = false;
private boolean cancelled = false;
/**
* Queued up futures which are the result of applying this future's value to some transform
* function ({@link FutureTransform}). Futures are queued up by calling APIs like
* {@link #transformSync(FutureTransform)} and {@link #transformAsync(FutureTransform)}.
*/
private final List> next = new ArrayList<>(1);
private final List doneCallbacks = new ArrayList<>();
private static Logger log = LoggerFactory.getLogger(LazyTransformableFuture.class);
/**
* @param completer Reference to a function which should complete this future when called.
* See {@link #completer}.
*/
LazyTransformableFuture(Completer completer) {
this.completer = completer;
}
void complete(U responses) {
if (isDone()) return;
result = responses;
completed = true;
callDoneCallbacks();
for (LazyTransformingFuture next : this.next) {
try {
next.complete(result);
} catch (Exception e) {
log.warn("Exception caught and ignored while completing next transforming " +
"future.", e);
}
}
}
void completeExceptionally(Exception exception) {
if (isDone()) return;
completed = true;
this.exception = exception;
callDoneCallbacks();
for (LazyTransformingFuture next : this.next) {
try {
next.completeExceptionally(exception);
} catch (Exception e) {
log.warn("Exception caught and ignored while completing next transforming " +
"future with exception.", e);
}
}
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
if (completed) return false;
cancelled = true;
callDoneCallbacks();
return true;
}
@Override
public boolean isCancelled() {
return cancelled;
}
@Override
public boolean isDone() {
return cancelled || completed;
}
@Override
public U get() throws InterruptedException, ExecutionException {
if (cancelled) {
throw new CancellationException();
}
if (!completed) {
completer.triggerFutureCompletion();
if (!completed) {
throw new ExecutionException(new IllegalStateException("Future attempted to " +
"lazily trigger completion, but completer did not actually complete " +
"the future. Check the provided completer function for correctness."));
}
}
if (exception != null) {
throw new ExecutionException(exception);
}
return result;
}
// TODO(ahenning): This ignores the timeout because we aren't doing work in another thread
// I'm not sure that anyone will ever care, but if they did, we would do the same lazy
// stuff, but just do it in another thread which we could interrupt if it took too long.
// In that case we may have to build in interrupt checking during request processing.
@Override
public U get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException,
TimeoutException {
return get();
}
@Override
public TransformableFuture transformSync(FutureTransform futureTransform) {
LazyTransformingFuture future = new LazyTransformingFuture<>(futureTransform, completer);
next.add(future);
return future;
}
@Override
public TransformableFuture transformAsync(
FutureTransform> futureTransform) {
LazyTransformingFuture> future =
new LazyTransformingFuture<>(futureTransform, completer);
next.add(future);
return new NestedTransformableFuture<>(future);
}
@Override
public TransformableFuture transformAsyncIgnoringReturn(
FutureTransform> futureTransform) {
LazyTransformingFuture> future =
new LazyTransformingFuture<>(futureTransform, completer);
next.add(future);
return new NestedTransformableFutureIgnoringReturn(future);
}
@Override
public TransformableFuture whenDoneOrCancelled(FutureDoneCallback callback) {
if (isDone()) {
try {
callback.onDoneOrCancelled();
} catch (Exception e) {
log.warn("Exception caught and ignored while running future done callback.", e);
}
return this;
}
doneCallbacks.add(callback);
return this;
}
private void callDoneCallbacks() {
for (FutureDoneCallback doneCallback : doneCallbacks) {
try {
doneCallback.onDoneOrCancelled();
} catch (Exception e) {
log.warn("Exception caught and ignored while running future done callback.", e);
}
}
}
}
/**
* Wraps a {@link LazyTransformableFuture} and some {@link AbstractLightblueDataRequest
* lightblue requests} which are used to complete this in
* {@link #doQueuedRequestsAndCompleteFutures()}. Naturally, then, that function is used as the
* lazy future's completer function. That function and this implementation are tightly coupled.
*/
class LazyRequestTransformableFuture implements TransformableFuture {
private final LazyTransformableFuture backingFuture =
new LazyTransformableFuture<>(() -> doQueuedRequestsAndCompleteFutures());
final AbstractLightblueDataRequest[] requests;
LazyRequestTransformableFuture(AbstractLightblueDataRequest[] requests) {
this.requests = requests;
}
void complete(LightblueResponses responses) {
backingFuture.complete(responses);
}
void completeExceptionally(Exception exception) {
backingFuture.completeExceptionally(exception);
}
@Override
public TransformableFuture transformSync(
FutureTransform futureTransform) {
return backingFuture.transformSync(futureTransform);
}
@Override
public TransformableFuture transformAsync(
FutureTransform> futureTransform) {
return backingFuture.transformAsync(futureTransform);
}
@Override
public TransformableFuture transformAsyncIgnoringReturn(
FutureTransform> futureTransform) {
return backingFuture.transformAsyncIgnoringReturn(futureTransform);
}
@Override
public TransformableFuture whenDoneOrCancelled(FutureDoneCallback callback) {
backingFuture.whenDoneOrCancelled(callback);
return this;
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
if (!backingFuture.isDone()) {
queuedRequests.remove(this);
}
return backingFuture.cancel(mayInterruptIfRunning);
}
@Override
public boolean isCancelled() {
return backingFuture.isCancelled();
}
@Override
public boolean isDone() {
return backingFuture.isDone();
}
@Override
public LightblueResponses get() throws InterruptedException, ExecutionException {
return backingFuture.get();
}
@Override
public LightblueResponses get(long timeout, TimeUnit unit) throws InterruptedException,
ExecutionException, TimeoutException {
return backingFuture.get(timeout, unit);
}
}
/**
* A simple lazy future implementation which applies some transformation function to the value
* it is completed with.
*
* This is used in {@link #transformSync(FutureTransform)} callbacks of
* {@link TransformableFuture} implementations.
*
* @param The input type used to complete the Future.
* @param The output type as a result of applying the transform function to the input.
*/
static class LazyTransformingFuture implements TransformableFuture {
private final FutureTransform transform;
private final LazyTransformableFuture backingFuture;
LazyTransformingFuture(FutureTransform transform, Completer completer) {
this.transform = transform;
this.backingFuture = new LazyTransformableFuture<>(completer);
}
void complete(T responses) {
if (isDone()) return;
try {
U transformed = transform.transform(responses);
backingFuture.complete(transformed);
} catch (Exception e) {
completeExceptionally(e);
}
}
void completeExceptionally(Exception exception) {
backingFuture.completeExceptionally(exception);
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
return backingFuture.cancel(mayInterruptIfRunning);
}
@Override
public boolean isCancelled() {
return backingFuture.isCancelled();
}
@Override
public boolean isDone() {
return backingFuture.isDone();
}
@Override
public U get() throws InterruptedException, ExecutionException {
return backingFuture.get();
}
/**
* This future is not completed asynchronously so there is no way to "time out" unless we
* introduce another thread for processing requests which I don't think is hugely necessary.
*/
@Override
public U get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException,
TimeoutException {
return backingFuture.get(timeout, unit);
}
@Override
public TransformableFuture transformSync(FutureTransform futureTransform) {
return backingFuture.transformSync(futureTransform);
}
@Override
public TransformableFuture transformAsync(
FutureTransform> futureTransform) {
return backingFuture.transformAsync(futureTransform);
}
@Override
public TransformableFuture transformAsyncIgnoringReturn(
FutureTransform> futureTransform) {
return backingFuture.transformAsyncIgnoringReturn(futureTransform);
}
@Override
public TransformableFuture whenDoneOrCancelled(FutureDoneCallback callback) {
backingFuture.whenDoneOrCancelled(callback);
return this;
}
}
interface Completer {
void triggerFutureCompletion();
}
}