/*
 * 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.
 */
Hints subsystem consists of several components. Hint encodes all the required metadata and the mutation being hinted. HintsBuffer provides a temporary buffer for writing the hints to in a concurrent manner, before we flush them to disk. HintsBufferPool is responsible for submitting HintsBuffer instances for flushing when they exceed their capacity, and for maitaining a reserve HintsBuffer instance, and creating extra ones if flushing cannot keep up with arrival rate. HintsWriteExecutor is a single-threaded executor that performs all the writing to disk. HintsDispatchExecutor is a multi-threaded executor responsible for dispatch of the hints to their destinations. HintsStore tracks the state of all hints files (written and being written to) for a given host id destination. HintsCatalog maintains the mapping of host ids to HintsStore instances, and provides some aggregate APIs. HintsService wraps the catalog, the pool, and the two executors, acting as a front-end for hints. /**
 * Hints subsystem consists of several components.
 *
 * {@link org.apache.cassandra.hints.Hint} encodes all the required metadata and the mutation being hinted.
 *
 * {@link org.apache.cassandra.hints.HintsBuffer} provides a temporary buffer for writing the hints to in a concurrent manner,
 * before we flush them to disk.
 *
 * {@link org.apache.cassandra.hints.HintsBufferPool} is responsible for submitting {@link org.apache.cassandra.hints.HintsBuffer}
 * instances for flushing when they exceed their capacity, and for maitaining a reserve {@link org.apache.cassandra.hints.HintsBuffer}
 * instance, and creating extra ones if flushing cannot keep up with arrival rate.
 *
 * {@link org.apache.cassandra.hints.HintsWriteExecutor} is a single-threaded executor that performs all the writing to disk.
 *
 * {@link org.apache.cassandra.hints.HintsDispatchExecutor} is a multi-threaded executor responsible for dispatch of
 * the hints to their destinations.
 *
 * {@link org.apache.cassandra.hints.HintsStore} tracks the state of all hints files (written and being written to)
 * for a given host id destination.
 *
 * {@link org.apache.cassandra.hints.HintsCatalog} maintains the mapping of host ids to {@link org.apache.cassandra.hints.HintsStore}
 * instances, and provides some aggregate APIs.
 *
 * {@link org.apache.cassandra.hints.HintsService} wraps the catalog, the pool, and the two executors, acting as a front-end
 * for hints.
 */
package org.apache.cassandra.hints;