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Reactive streams branch move reactive classes out of dataloader helper #159

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merged 4 commits into from
May 24, 2024
Merged

Reactive streams branch move reactive classes out of dataloader helper #159

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91d3036
This moves the reactive code pout into its own package because DataLo…
bbakerman May 24, 2024
e98621b
renamed classes inline with their counterparts
bbakerman May 24, 2024
6523015
made them non public and created a static factory support class
bbakerman May 24, 2024
170ccf8
reorged method placement
bbakerman May 24, 2024
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256 changes: 15 additions & 241 deletions src/main/java/org/dataloader/DataLoaderHelper.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
import org.dataloader.annotations.GuardedBy;
import org.dataloader.annotations.Internal;
import org.dataloader.impl.CompletableFutureKit;
import org.dataloader.impl.DataLoaderAssertionException;
import org.dataloader.reactive.ReactiveSupport;
import org.dataloader.scheduler.BatchLoaderScheduler;
import org.dataloader.stats.StatisticsCollector;
import org.dataloader.stats.context.IncrementBatchLoadCountByStatisticsContext;
Expand All @@ -12,13 +12,11 @@
import org.dataloader.stats.context.IncrementLoadCountStatisticsContext;
import org.dataloader.stats.context.IncrementLoadErrorCountStatisticsContext;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;

import java.time.Clock;
import java.time.Instant;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
Expand Down Expand Up @@ -510,7 +508,7 @@ private CompletableFuture<List<V>> invokeMapBatchLoader(List<K> keys, BatchLoade

private CompletableFuture<List<V>> invokeBatchPublisher(List<K> keys, List<Object> keyContexts, List<CompletableFuture<V>> queuedFutures, BatchLoaderEnvironment environment) {
CompletableFuture<List<V>> loadResult = new CompletableFuture<>();
Subscriber<V> subscriber = new DataLoaderSubscriber(loadResult, keys, keyContexts, queuedFutures);
Subscriber<V> subscriber = ReactiveSupport.batchSubscriber(loadResult, keys, keyContexts, queuedFutures, helperIntegration());

BatchLoaderScheduler batchLoaderScheduler = loaderOptions.getBatchLoaderScheduler();
if (batchLoadFunction instanceof BatchPublisherWithContext) {
Expand All @@ -537,7 +535,7 @@ private CompletableFuture<List<V>> invokeBatchPublisher(List<K> keys, List<Objec

private CompletableFuture<List<V>> invokeMappedBatchPublisher(List<K> keys, List<Object> keyContexts, List<CompletableFuture<V>> queuedFutures, BatchLoaderEnvironment environment) {
CompletableFuture<List<V>> loadResult = new CompletableFuture<>();
Subscriber<Map.Entry<K, V>> subscriber = new DataLoaderMapEntrySubscriber(loadResult, keys, keyContexts, queuedFutures);
Subscriber<Map.Entry<K, V>> subscriber = ReactiveSupport.mappedBatchSubscriber(loadResult, keys, keyContexts, queuedFutures, helperIntegration());

BatchLoaderScheduler batchLoaderScheduler = loaderOptions.getBatchLoaderScheduler();
if (batchLoadFunction instanceof MappedBatchPublisherWithContext) {
Expand Down Expand Up @@ -625,246 +623,22 @@ private static <T> DispatchResult<T> emptyDispatchResult() {
return (DispatchResult<T>) EMPTY_DISPATCH_RESULT;
}

/**********************************************************************************************
* ********************************************************************************************
* <p>
* The reactive support classes start here
*
* @param <T> for two
**********************************************************************************************
**********************************************************************************************
*/
private abstract class DataLoaderSubscriberBase<T> implements Subscriber<T> {

final CompletableFuture<List<V>> valuesFuture;
final List<K> keys;
final List<Object> callContexts;
final List<CompletableFuture<V>> queuedFutures;

List<K> clearCacheKeys = new ArrayList<>();
List<V> completedValues = new ArrayList<>();
boolean onErrorCalled = false;
boolean onCompleteCalled = false;

DataLoaderSubscriberBase(
CompletableFuture<List<V>> valuesFuture,
List<K> keys,
List<Object> callContexts,
List<CompletableFuture<V>> queuedFutures
) {
this.valuesFuture = valuesFuture;
this.keys = keys;
this.callContexts = callContexts;
this.queuedFutures = queuedFutures;
}

@Override
public void onSubscribe(Subscription subscription) {
subscription.request(keys.size());
}

@Override
public void onNext(T v) {
assertState(!onErrorCalled, () -> "onError has already been called; onNext may not be invoked.");
assertState(!onCompleteCalled, () -> "onComplete has already been called; onNext may not be invoked.");
}

@Override
public void onComplete() {
assertState(!onErrorCalled, () -> "onError has already been called; onComplete may not be invoked.");
onCompleteCalled = true;
}

@Override
public void onError(Throwable throwable) {
assertState(!onCompleteCalled, () -> "onComplete has already been called; onError may not be invoked.");
onErrorCalled = true;

stats.incrementBatchLoadExceptionCount(new IncrementBatchLoadExceptionCountStatisticsContext<>(keys, callContexts));
}

/*
* A value has arrived - how do we complete the future that's associated with it in a common way
*/
void onNextValue(K key, V value, Object callContext, List<CompletableFuture<V>> futures) {
if (value instanceof Try) {
// we allow the batch loader to return a Try so we can better represent a computation
// that might have worked or not.
//noinspection unchecked
Try<V> tryValue = (Try<V>) value;
if (tryValue.isSuccess()) {
futures.forEach(f -> f.complete(tryValue.get()));
} else {
stats.incrementLoadErrorCount(new IncrementLoadErrorCountStatisticsContext<>(key, callContext));
futures.forEach(f -> f.completeExceptionally(tryValue.getThrowable()));
clearCacheKeys.add(key);
}
} else {
futures.forEach(f -> f.complete(value));
private ReactiveSupport.HelperIntegration<K> helperIntegration() {
return new ReactiveSupport.HelperIntegration<>() {
@Override
public StatisticsCollector getStats() {
return stats;
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very weird diff

}
}

Throwable unwrapThrowable(Throwable ex) {
if (ex instanceof CompletionException) {
ex = ex.getCause();
@Override
public void clearCacheView(K key) {
dataLoader.clear(key);
}
return ex;
}
}

private class DataLoaderSubscriber extends DataLoaderSubscriberBase<V> {

private int idx = 0;

private DataLoaderSubscriber(
CompletableFuture<List<V>> valuesFuture,
List<K> keys,
List<Object> callContexts,
List<CompletableFuture<V>> queuedFutures
) {
super(valuesFuture, keys, callContexts, queuedFutures);
}

// onNext may be called by multiple threads - for the time being, we pass 'synchronized' to guarantee
// correctness (at the cost of speed).
@Override
public synchronized void onNext(V value) {
super.onNext(value);

if (idx >= keys.size()) {
// hang on they have given us more values than we asked for in keys
// we cant handle this
return;
}
K key = keys.get(idx);
Object callContext = callContexts.get(idx);
CompletableFuture<V> future = queuedFutures.get(idx);
onNextValue(key, value, callContext, List.of(future));

completedValues.add(value);
idx++;
}


@Override
public synchronized void onComplete() {
super.onComplete();
if (keys.size() != completedValues.size()) {
// we have more or less values than promised
// we will go through all the outstanding promises and mark those that
// have not finished as failed
for (CompletableFuture<V> queuedFuture : queuedFutures) {
if (!queuedFuture.isDone()) {
queuedFuture.completeExceptionally(new DataLoaderAssertionException("The size of the promised values MUST be the same size as the key list"));
}
}
@Override
public void clearCacheEntriesOnExceptions(List<K> keys) {
possiblyClearCacheEntriesOnExceptions(keys);
}
possiblyClearCacheEntriesOnExceptions(clearCacheKeys);
valuesFuture.complete(completedValues);
}

@Override
public synchronized void onError(Throwable ex) {
super.onError(ex);
ex = unwrapThrowable(ex);
// Set the remaining keys to the exception.
for (int i = idx; i < queuedFutures.size(); i++) {
K key = keys.get(i);
CompletableFuture<V> future = queuedFutures.get(i);
if (! future.isDone()) {
future.completeExceptionally(ex);
// clear any cached view of this key because it failed
dataLoader.clear(key);
}
}
valuesFuture.completeExceptionally(ex);
}

}

private class DataLoaderMapEntrySubscriber extends DataLoaderSubscriberBase<Map.Entry<K, V>> {

private final Map<K, Object> callContextByKey;
private final Map<K, List<CompletableFuture<V>>> queuedFuturesByKey;
private final Map<K, V> completedValuesByKey = new HashMap<>();


private DataLoaderMapEntrySubscriber(
CompletableFuture<List<V>> valuesFuture,
List<K> keys,
List<Object> callContexts,
List<CompletableFuture<V>> queuedFutures
) {
super(valuesFuture, keys, callContexts, queuedFutures);
this.callContextByKey = new HashMap<>();
this.queuedFuturesByKey = new HashMap<>();
for (int idx = 0; idx < queuedFutures.size(); idx++) {
K key = keys.get(idx);
Object callContext = callContexts.get(idx);
CompletableFuture<V> queuedFuture = queuedFutures.get(idx);
callContextByKey.put(key, callContext);
queuedFuturesByKey.computeIfAbsent(key, k -> new ArrayList<>()).add(queuedFuture);
}
}


@Override
public synchronized void onNext(Map.Entry<K, V> entry) {
super.onNext(entry);
K key = entry.getKey();
V value = entry.getValue();

Object callContext = callContextByKey.get(key);
List<CompletableFuture<V>> futures = queuedFuturesByKey.getOrDefault(key, List.of());

onNextValue(key, value, callContext, futures);

// did we have an actual key for this value - ignore it if they send us one outside the key set
if (!futures.isEmpty()) {
completedValuesByKey.put(key, value);
}
}

@Override
public synchronized void onComplete() {
super.onComplete();

possiblyClearCacheEntriesOnExceptions(clearCacheKeys);
List<V> values = new ArrayList<>(keys.size());
for (K key : keys) {
V value = completedValuesByKey.get(key);
values.add(value);

List<CompletableFuture<V>> futures = queuedFuturesByKey.getOrDefault(key, List.of());
for (CompletableFuture<V> future : futures) {
if (! future.isDone()) {
// we have a future that never came back for that key
// but the publisher is done sending in data - it must be null
// e.g. for key X when found no value
future.complete(null);
}
}
}
valuesFuture.complete(values);
}

@Override
public synchronized void onError(Throwable ex) {
super.onError(ex);
ex = unwrapThrowable(ex);
// Complete the futures for the remaining keys with the exception.
for (int idx = 0; idx < queuedFutures.size(); idx++) {
K key = keys.get(idx);
List<CompletableFuture<V>> futures = queuedFuturesByKey.get(key);
if (!completedValuesByKey.containsKey(key)) {
for (CompletableFuture<V> future : futures) {
future.completeExceptionally(ex);
}
// clear any cached view of this key because they all failed
dataLoader.clear(key);
}
}
valuesFuture.completeExceptionally(ex);
}
};
}
}
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