https://github.com/ReactiveX/RxJava: Reactive Extensions for Java
  • David Karnok 
Copyright (c) 2016-present, RxJava Contributors.
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.

/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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.reactivex.internal.fuseable;

import io.reactivex.annotations.*;


A minimalist queue interface without the method bloat of java.util.Collection and java.util.Queue.

Type parameters:
  • <T> – the value type to offer and poll, not null
/**
 * A minimalist queue interface without the method bloat of java.util.Collection and java.util.Queue.
 *
 * @param <T> the value type to offer and poll, not null
 */
public interface SimpleQueue<T> {

    
Atomically enqueue a single.

Params:
  • value – the value to enqueue, not null
Returns:true if successful, false if the value was not enqueued
likely due to reaching the queue capacity)
/**
     * Atomically enqueue a single.
     * @param value the value to enqueue, not null
     * @return true if successful, false if the value was not enqueued
     * likely due to reaching the queue capacity)
     */
    boolean offer(@NonNull T value);

    
Atomically enqueue two values.

Params:
  • v1 – the first value to enqueue, not null
  • v2 – the second value to enqueue, not null
Returns:true if successful, false if the value was not enqueued
likely due to reaching the queue capacity)
/**
     * Atomically enqueue two values.
     * @param v1 the first value to enqueue, not null
     * @param v2 the second value to enqueue, not null
     * @return true if successful, false if the value was not enqueued
     * likely due to reaching the queue capacity)
     */
    boolean offer(@NonNull T v1, @NonNull T v2);

    
Tries to dequeue a value (non-null) or returns null if
the queue is empty.

 If the producer uses offer(Object, Object) and when polling in pairs, if the first poll() returns a non-null item, the second poll() is guaranteed to return a non-null item as well. 
Throws:
  • Exception – if some pre-processing of the dequeued
item (usually through fused functions) throws.
Returns:the item or null to indicate an empty queue
/**
     * Tries to dequeue a value (non-null) or returns null if
     * the queue is empty.
     * <p>
     * If the producer uses {@link #offer(Object, Object)} and
     * when polling in pairs, if the first poll() returns a non-null
     * item, the second poll() is guaranteed to return a non-null item
     * as well.
     * @return the item or null to indicate an empty queue
     * @throws Exception if some pre-processing of the dequeued
     * item (usually through fused functions) throws.
     */
    @Nullable
    T poll() throws Exception;

    
Returns true if the queue is empty.

 Note however that due to potential fused functions in poll() it is possible this method returns false but then poll() returns null because the fused function swallowed the available item(s). 
Returns:true if the queue is empty
/**
     * Returns true if the queue is empty.
     * <p>
     * Note however that due to potential fused functions in {@link #poll()}
     * it is possible this method returns false but then poll() returns null
     * because the fused function swallowed the available item(s).
     * @return true if the queue is empty
     */
    boolean isEmpty();

    
Removes all enqueued items from this queue.

/**
     * Removes all enqueued items from this queue.
     */
    void clear();
}