/* * Copyright 2015 MongoDB, Inc. * * 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 com.mongodb.async.client; import com.mongodb.MongoException; import com.mongodb.async.AsyncBatchCursor; import com.mongodb.async.SingleResultCallback; import java.util.List; final class MongoIterableSubscription<TResult> extends AbstractSubscription<TResult> { private final MongoIterable<TResult> mongoIterable; /* protected by `this` */ private boolean isReading; private boolean completed; /* protected by `this` */ private volatile AsyncBatchCursor<TResult> batchCursor; MongoIterableSubscription(final MongoIterable<TResult> mongoIterable, final Observer<? super TResult> observer) { super(observer); this.mongoIterable = mongoIterable; observer.onSubscribe(this); } @Override void requestInitialData() { mongoIterable.batchSize(getBatchSize()); mongoIterable.batchCursor(new SingleResultCallback<AsyncBatchCursor<TResult>>() { @Override public void onResult(final AsyncBatchCursor<TResult> result, final Throwable t) { if (t != null) { onError(t); } else if (result != null) { batchCursor = result; requestMoreData(); } else { onError(new MongoException("Unexpected error, no AsyncBatchCursor returned from the MongoIterable.")); } } }); } @Override boolean checkCompleted() { return completed; } @Override void postTerminate() { if (batchCursor != null) { batchCursor.close(); } } @Override void requestMoreData() { boolean mustRead = false; synchronized (this) { if (!isReading && !isTerminated() && batchCursor != null) { isReading = true; mustRead = true; } } if (mustRead) { batchCursor.setBatchSize(getBatchSize()); batchCursor.next(new SingleResultCallback<List<TResult>>() { @Override public void onResult(final List<TResult> result, final Throwable t) { synchronized (MongoIterableSubscription.this) { isReading = false; if (t == null && result == null) { completed = true; } } if (t != null) { onError(t); } else { addToQueue(result); } } }); } } /** * Returns the batchSize to be used with the cursor. * * <p>Anything less than 2 would close the cursor so that is the minimum batchSize and `Integer.MAX_VALUE` is the maximum * batchSize.</p> * * @return the batchSize to use */ private int getBatchSize() { long requested = getRequested(); if (requested <= 1) { return 2; } else if (requested < Integer.MAX_VALUE) { return (int) requested; } else { return Integer.MAX_VALUE; } } }