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Library with common components for Flux Capacitor clients and service.
/*
* Copyright (c) Flux Capacitor IP B.V. 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.
* 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.fluxcapacitor.common;
import lombok.extern.slf4j.Slf4j;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.Consumer;
import static io.fluxcapacitor.common.ObjectUtils.newThreadFactory;
import static java.util.concurrent.TimeUnit.SECONDS;
@Slf4j
public class Backlog implements Monitored> {
private final int maxBatchSize;
private final Queue queue = new ConcurrentLinkedQueue<>();
private final ThrowingFunction, CompletableFuture> consumer;
private final ErrorHandler> errorHandler;
private final ExecutorService executorService;
private final AtomicBoolean flushing = new AtomicBoolean();
private final AtomicLong insertPosition = new AtomicLong();
private final AtomicLong flushPosition = new AtomicLong();
private final ConcurrentSkipListMap> results = new ConcurrentSkipListMap<>();
private final Collection>> monitors = new CopyOnWriteArraySet<>();
public static Backlog forConsumer(ThrowingConsumer> consumer) {
return forConsumer(consumer, 1024);
}
public static Backlog forConsumer(ThrowingConsumer> consumer, int maxBatchSize) {
return forConsumer(consumer, maxBatchSize, (e, batch) -> log.error("Consumer {} failed to handle batch of size {}. Continuing with next batch.", consumer, batch.size(), e));
}
public static Backlog forConsumer(ThrowingConsumer> consumer, int maxBatchSize, ErrorHandler> errorHandler) {
return new Backlog<>(list -> {
consumer.accept(list);
return null;
}, maxBatchSize, errorHandler);
}
public static Backlog forAsyncConsumer(ThrowingFunction, CompletableFuture> consumer) {
return forAsyncConsumer(consumer, 1024);
}
public static Backlog forAsyncConsumer(ThrowingFunction, CompletableFuture> consumer, int maxBatchSize) {
return forAsyncConsumer(consumer, maxBatchSize, (e, batch) -> log.error("Consumer {} failed to handle batch of size {}. Continuing with next batch.", consumer, batch.size(), e));
}
public static Backlog forAsyncConsumer(ThrowingFunction, CompletableFuture> consumer, int maxBatchSize, ErrorHandler> errorHandler) {
return new Backlog<>(consumer, maxBatchSize, errorHandler);
}
protected Backlog(ThrowingFunction, CompletableFuture> consumer) {
this(consumer, 1024);
}
protected Backlog(ThrowingFunction, CompletableFuture> consumer, int maxBatchSize) {
this(consumer, maxBatchSize,
(e, batch) -> log.error("Consumer {} failed to handle batch {}. Continuing with next batch.", consumer, batch, e));
}
protected Backlog(ThrowingFunction, CompletableFuture> consumer, int maxBatchSize, ErrorHandler> errorHandler) {
this.maxBatchSize = maxBatchSize;
this.consumer = consumer;
this.executorService = Executors.newSingleThreadExecutor(newThreadFactory("Backlog"));
this.errorHandler = errorHandler;
}
@SafeVarargs
public final CompletableFuture add(T... values) {
Collections.addAll(queue, values);
return values.length == 0 ? CompletableFuture.completedFuture(null)
: awaitFlush(insertPosition.updateAndGet(p -> p + values.length));
}
public CompletableFuture add(Collection values) {
queue.addAll(values);
return values.isEmpty() ? CompletableFuture.completedFuture(null)
: awaitFlush(insertPosition.updateAndGet(p -> p + values.size()));
}
private CompletableFuture awaitFlush(long untilPosition) {
CompletableFuture result = new CompletableFuture<>();
results.put(untilPosition, result);
flushIfNotFlushing();
return result;
}
private void flushIfNotFlushing() {
if (flushing.compareAndSet(false, true)) {
executorService.execute(this::flush);
}
}
private void flush() {
try {
while (!queue.isEmpty()) {
List batch = new ArrayList<>(maxBatchSize);
while (batch.size() < maxBatchSize) {
T value = queue.poll();
if (value == null) {
break;
}
batch.add(value);
}
CompletableFuture future;
try {
future = consumer.apply(batch);
} catch (Throwable e) {
future = CompletableFuture.failedFuture(e);
errorHandler.handleError(e, batch);
}
long lastPosition = flushPosition.addAndGet(batch.size());
if (future == null) {
completeResults(lastPosition, null);
} else {
future.whenComplete((r, e) -> completeResults(lastPosition, e));
}
monitors.forEach(m -> m.accept(batch));
}
flushing.set(false);
if (!queue.isEmpty()) { //a value could've been added after the while loop before flushing was set to false
flushIfNotFlushing();
}
} catch (Throwable e) {
log.error("Failed to flush the backlog", e);
flushing.set(false);
throw e;
}
}
protected void completeResults(long untilPosition, Throwable e) {
var futures = results.headMap(untilPosition, true);
futures.forEach((k, v) -> {
if (e == null) {
v.complete(null);
} else {
v.completeExceptionally(e);
}
});
futures.clear();
}
@Override
public Registration registerMonitor(Consumer> monitor) {
monitors.add(monitor);
return () -> monitors.remove(monitor);
}
public void shutDown() {
try {
executorService.shutdown();
try {
executorService.awaitTermination(1L, SECONDS);
} catch (InterruptedException e) {
log.warn("Shutdown of executor was interrupted", e);
Thread.currentThread().interrupt();
}
} catch (Throwable e) {
log.warn("Failed to shutdown a backlog", e);
}
}
@FunctionalInterface
public interface BatchConsumer {
CompletableFuture accept(List batch) throws Exception;
}
}