FetchQuotaWatcher.java

/*
 * Copyright (c) 2015 Spotify AB.
 *
 * 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 com.spotify.heroic.metric;

public interface FetchQuotaWatcher {
    /**
     * Indicates that backend has read {@code n} more datapoints.
     *
     * @param n The number of datapoints read by the backend.
     * @throws com.spotify.heroic.common.QuotaViolationException if quota has been violated.
     */
    void readData(long n);

    /**
     * Indicates if readData quota has been breached or not.
     *
     * @return {@code true} if there is data left to be read, {@code false} otherwise.
     */
    boolean mayReadData();

    /**
     * Get how much data you are allowed to read.
     */
    int getReadDataQuota();

    /**
     * Indicates that backend did access {@code n} more rows
     *
     * @param n The number of rows accessed by the backend.
     */
    void accessedRows(long n);

    /**
     * Special quota watcher indicating no quota should be applied.
     */
    FetchQuotaWatcher NO_QUOTA = new FetchQuotaWatcher() {
        @Override
        public void readData(long n) {
        }

        @Override
        public boolean mayReadData() {
            return true;
        }

        @Override
        public int getReadDataQuota() {
            return Integer.MAX_VALUE;
        }

        @Override
        public void accessedRows(final long n) {
        }
    };
}