org.apache.flink.runtime.state.InternalPriorityQueue Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.flink.runtime.state;
import org.apache.flink.annotation.Internal;
import org.apache.flink.util.CloseableIterator;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Collection;
/**
* Interface for collection that gives in order access to elements w.r.t their priority.
*
* @param type of elements in the ordered set.
*/
@Internal
public interface InternalPriorityQueue {
/**
* Retrieves and removes the first element (w.r.t. the order) of this set,
* or returns {@code null} if this set is empty.
*
* @return the first element of this ordered set, or {@code null} if this set is empty.
*/
@Nullable
T poll();
/**
* Retrieves, but does not remove, the element (w.r.t. order) of this set,
* or returns {@code null} if this set is empty.
*
* @return the first element (w.r.t. order) of this ordered set, or {@code null} if this set is empty.
*/
@Nullable
T peek();
/**
* Adds the given element to the set, if it is not already contained.
*
* @param toAdd the element to add to the set.
* @return true if the operation changed the head element or if it is unclear if the head element changed.
* Only returns false if the head element was not changed by this operation.
*/
boolean add(@Nonnull T toAdd);
/**
* Removes the given element from the set, if is contained in the set.
*
* @param toRemove the element to remove.
* @return true if the operation changed the head element or if it is unclear if the head element changed.
* Only returns false if the head element was not changed by this operation.
*/
boolean remove(@Nonnull T toRemove);
/**
* Check if the set contains any elements.
*
* @return true if the set is empty, i.e. no element is contained.
*/
boolean isEmpty();
/**
* Returns the number of elements in this set.
*
* @return the number of elements in this set.
*/
@Nonnegative
int size();
/**
* Adds all the given elements to the set.
*/
void addAll(@Nullable Collection toAdd);
/**
* Iterator over all elements, no order guaranteed. Iterator must be closed after usage.
*/
@Nonnull
CloseableIterator iterator();
}