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/*******************************************************************************
 * Copyright 2011 Netflix
 * 
 * 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.netflix.dyno.connectionpool.impl;

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

import com.netflix.dyno.connectionpool.RetryPolicy;

/**
 * Simple implementation of {@link RetryPolicy} that ensures an operation can be re tried at most N times.
 * 
 * Note that RetryNTimes (2) means that a total of 2 + 1 = 3 attempts will be allowed before giving up.
 * 
 * @author poberai
 *
 */
public class RetryNTimes implements RetryPolicy {

	private int n; 
	private final AtomicReference state = new AtomicReference<>(new RetryState(0, false));
	private final boolean allowCrossZoneFallback;
	
	public RetryNTimes(int n, boolean allowFallback) {
		this.n = n;
		this.allowCrossZoneFallback = allowFallback;
	}

	@Override
	public void begin() {
	}

	@Override
	public void success() {
		boolean success = false;
		RetryState rs = state.get();
		while (!success) {
			success = state.compareAndSet(rs, new RetryState(rs.count + 1, true));
		}
	}

	@Override
	public void failure(Exception e) {
		boolean success = false;
		RetryState rs = state.get();
		while (!success) {
			success = state.compareAndSet(rs, new RetryState(rs.count + 1, false));
		}
	}

	@Override
	public boolean allowRetry() {
		final RetryState rs = state.get();
		return !rs.success && rs.count <= n;
	}

	@Override
	public int getAttemptCount() {
		return state.get().count;
	}

	@Override
	public boolean allowCrossZoneFallback() {
		return allowCrossZoneFallback;
	}

	@Override
	public String toString() {
		return "RetryNTimes{" +
				"n=" + n +
				", state=" + state.get() +
				", allowCrossZoneFallback=" + allowCrossZoneFallback +
				'}';
	}

	public static class RetryFactory implements RetryPolicyFactory {
		
		int n; 
		boolean allowCrossZoneFallback;
		
		public RetryFactory(int n) {
			this(n, true);
		}
		
		public RetryFactory(int n, boolean allowFallback) {
			this.n = n;
			this.allowCrossZoneFallback = allowFallback;
		}
		
		@Override
		public RetryPolicy getRetryPolicy() {
			return new RetryNTimes(n, allowCrossZoneFallback);
		}

		@Override
		public String toString() {
			return "RetryFactory{" +
					"n=" + n +
					", allowCrossZoneFallback=" + allowCrossZoneFallback +
					'}';
		}
	}

	private class RetryState {
		private final int count;
		private final boolean success;

		public RetryState(final int count, final boolean success) {
			this.count = count;
			this.success = success;
		}

		@Override
		public String toString() {
			return "RetryState{" +
					"count=" + count +
					", success=" + success +
					'}';
		}
	}
}