Configurable back off for listener recovery

Prior to this commit, DefaultMessageListenerContainer was recovering
on failure using a fixed time interval, potentially in an infinite way.

This commit adds an extra "backoff" property to the container that
permits to fine tune the recovery interval using a BackOff instance.

FixedBackOff provides a fixed interval between two attempts and a
maximum number of retries. ExponentialBackOff increases an initial
interval until a maximum interval has been reached. A BackOff instance
can return a special "STOP" time value that indicates that no further
attemps should be made. DefaultMessageListenerContainer uses this
value to stop the container.

protected method "sleepInbetweenRecoveryAttempts" has been renamed
to "applyBackOff" and now returns a boolean that indicate if the
back off has been applied and a new attempt should now be made.

Issue: SPR-11746

Author: snicoll

spring-core/src/main/java/org/springframework/util/BackOff.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2002-2014 the original author or authors.
+ *
+ * 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 org.springframework.util;
+
+/**
+ * Indicate the rate at which an operation should be retried.
+ *
+ * <p>Users of this interface are expected to use it like this:
+ *
+ * <pre class="code">
+ * {@code
+ *
+ *  long waitInterval = backOff.nextBackOffMillis();
+ *  if (waitInterval == BackOff.STOP) {
+ *    backOff.reset();
+ *    // do not retry operation
+ *  }
+ *  else {
+ *    // sleep, e.g. Thread.sleep(waitInterval)
+ *    // retry operation
+ *  }
+ * }</pre>
+ *
+ * Once the underlying operation has completed successfully, the instance
+ * <b>must</b> be {@link #reset()} before further use. Due to how back off
+ * should be used, implementations do not need to be thread-safe.
+ *
+ * @author Stephane Nicoll
+ * @since 4.1
+ */
+public interface BackOff {
+
+	/**
+	 * Return value of {@link #nextBackOff()} that indicates that the operation
+	 * should not be retried.
+	 */
+	long STOP = -1;
+
+	/**
+	 * Return the number of milliseconds to wait before retrying the operation
+	 * or {@link #STOP} ({@value #STOP}) to indicate that no further attempt
+	 * should be made for the operation.
+	 */
+	long nextBackOff();
+
+	/**
+	 * Reset this instance to its original state.
+	 */
+	void reset();
+
+}

spring-core/src/main/java/org/springframework/util/ExponentialBackOff.java

@@ -0,0 +1,193 @@
+/*
+ * Copyright 2002-2014 the original author or authors.
+ *
+ * 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 org.springframework.util;
+
+/**
+ * Implementation of {@link BackOff} that increases the back off period for each
+ * retry attempt. When the interval has reached the {@link #setMaxInterval(long)
+ * max interval}, it is no longer increased. Stops retrying once the
+ * {@link #setMaxElapsedTime(long) max elapsed time} has been reached.
+ *
+ * <p>Example: The default interval is {@value #DEFAULT_INITIAL_INTERVAL}ms, default
+ * multiplier is {@value #DEFAULT_MULTIPLIER} and the default max interval is
+ * {@value #DEFAULT_MAX_INTERVAL}. For 10 attempts the sequence will be
+ * as follows:
+ *
+ * <pre>
+ * request#     back off
+ *
+ *  1              2000
+ *  2              3000
+ *  3              4500
+ *  4              6750
+ *  5             10125
+ *  6             15187
+ *  7             22780
+ *  8             30000
+ *  9             30000
+ * 10             30000
+ * </pre>
+ *
+ * Note that the default max elapsed time is {@link Long#MAX_VALUE}. Use
+ * {@link #setMaxElapsedTime(long)} to limit the maximum number of time
+ * that an instance should accumulate before returning {@link BackOff#STOP}.
+ *
+ * @author Stephane Nicoll
+ * @since 4.1
+ */
+public class ExponentialBackOff implements BackOff {
+
+	/**
+	 * The default initial interval.
+	 */
+	public static final long DEFAULT_INITIAL_INTERVAL = 2000L;
+
+	/**
+	 * The default multiplier (increases the interval by 50%).
+	 */
+	public static final double DEFAULT_MULTIPLIER = 1.5;
+
+	/**
+	 * The default maximum back off time.
+	 */
+	public static final long DEFAULT_MAX_INTERVAL = 30000L;
+
+	/**
+	 * The default maximum elapsed time.
+	 */
+	public static final long DEFAULT_MAX_ELAPSED_TIME = Long.MAX_VALUE;
+
+
+	private long initialInterval = DEFAULT_INITIAL_INTERVAL;
+
+	private double multiplier = DEFAULT_MULTIPLIER;
+
+	private long maxInterval = DEFAULT_MAX_INTERVAL;
+
+	private long maxElapsedTime = DEFAULT_MAX_ELAPSED_TIME;
+
+	private long currentInterval = -1;
+
+	private long currentElapsedTime = 0;
+
+	/**
+	 * Create an instance with the default settings.
+	 * @see #DEFAULT_INITIAL_INTERVAL
+	 * @see #DEFAULT_MULTIPLIER
+	 * @see #DEFAULT_MAX_INTERVAL
+	 * @see #DEFAULT_MAX_ELAPSED_TIME
+	 */
+	public ExponentialBackOff() {
+	}
+
+	/**
+	 * Create an instance.
+	 * @param initialInterval the initial interval in milliseconds
+	 * @param multiplier the multiplier (should be equal or higher to 1)
+	 */
+	public ExponentialBackOff(long initialInterval, double multiplier) {
+		checkMultiplier(multiplier);
+		this.initialInterval = initialInterval;
+		this.multiplier = multiplier;
+	}
+
+	/**
+	 * The initial interval in milliseconds.
+	 */
+	public void setInitialInterval(long initialInterval) {
+		this.initialInterval = initialInterval;
+	}
+
+	/**
+	 * The value to multiply the current interval with for each retry attempt.
+	 */
+	public void setMultiplier(double multiplier) {
+		checkMultiplier(multiplier);
+		this.multiplier = multiplier;
+	}
+
+	/**
+	 * The maximum back off time.
+	 */
+	public void setMaxInterval(long maxInterval) {
+		this.maxInterval = maxInterval;
+	}
+
+	/**
+	 * The maximum elapsed time in milliseconds after which a call to
+	 * {@link #nextBackOff()} returns {@link BackOff#STOP}.
+	 */
+	public void setMaxElapsedTime(long maxElapsedTime) {
+		this.maxElapsedTime = maxElapsedTime;
+	}
+
+	@Override
+	public long nextBackOff() {
+		if (currentElapsedTime >= maxElapsedTime) {
+			return BackOff.STOP;
+		}
+
+		long nextInterval = computeNextInterval();
+		currentElapsedTime += nextInterval;
+		return nextInterval;
+
+	}
+
+	@Override
+	public void reset() {
+		this.currentInterval = -1;
+		this.currentElapsedTime = 0;
+	}
+
+	private long computeNextInterval() {
+		if (this.currentInterval >= this.maxInterval) {
+			return this.maxInterval;
+		}
+		else if (this.currentInterval < 0) {
+			this.currentInterval = (this.initialInterval < this.maxInterval
+					? this.initialInterval : this.maxInterval);
+		}
+		else {
+			this.currentInterval = multiplyInterval();
+		}
+		return currentInterval;
+	}
+
+	private long multiplyInterval() {
+		long i = this.currentInterval;
+		i *= this.multiplier;
+		return (i > this.maxInterval ? this.maxInterval :i);
+	}
+
+	private void checkMultiplier(double multiplier) {
+		if (multiplier < 1) {
+			throw new IllegalArgumentException("Invalid multiplier '" + multiplier + "'. Should be equal" +
+					"or higher than 1. A multiplier of 1 is equivalent to a fixed interval");
+		}
+	}
+
+	@Override
+	public String toString() {
+		String i = (this.currentInterval < 0 ? "n/a" : this.currentInterval + "ms");
+		final StringBuilder sb = new StringBuilder("ExponentialBackOff{");
+		sb.append("currentInterval=").append(i);
+		sb.append(", multiplier=").append(this.multiplier);
+		sb.append('}');
+		return sb.toString();
+	}
+
+}

spring-core/src/main/java/org/springframework/util/FixedBackOff.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2002-2014 the original author or authors.
+ *
+ * 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 org.springframework.util;
+
+/**
+ * A simple {@link BackOff} implementation that provides a fixed interval
+ * between two attempts and a maximum number of retries.
+ *
+ * @author Stephane Nicoll
+ * @since 4.1
+ */
+public class FixedBackOff implements BackOff {
+
+	/**
+	 * The default recovery interval: 5000 ms = 5 seconds.
+	 */
+	public static final long DEFAULT_INTERVAL = 5000;
+
+	/**
+	 * Constant value indicating an unlimited number of attempts.
+	 */
+	public static final long UNLIMITED_ATTEMPTS = Long.MAX_VALUE;
+
+	private long interval = DEFAULT_INTERVAL;
+
+	private long maxAttempts = UNLIMITED_ATTEMPTS;
+
+	private long currentAttempts = 0;
+
+	/**
+	 * Create an instance with an interval of {@value #DEFAULT_INTERVAL}
+	 * ms and an unlimited number of attempts.
+	 */
+	public FixedBackOff() {
+	}
+
+	/**
+	 * Create an instance.
+	 * @param interval the interval between two attempts
+	 * @param maxAttempts the maximal number of attempts
+	 */
+	public FixedBackOff(long interval, long maxAttempts) {
+		this.interval = interval;
+		this.maxAttempts = maxAttempts;
+	}
+
+	/**
+	 * Set the interval between two attempts in milliseconds.
+	 */
+	public void setInterval(long interval) {
+		this.interval = interval;
+	}
+
+	/**
+	 * Return the interval between two attempts in milliseconds.
+	 */
+	public long getInterval() {
+		return interval;
+	}
+
+	/**
+	 * Set the maximal number of attempts in milliseconds.
+	 */
+	public void setMaxAttempts(long maxAttempts) {
+		this.maxAttempts = maxAttempts;
+	}
+
+	/**
+	 * Return the maximal number of attempts in milliseconds.
+	 */
+	public long getMaxAttempts() {
+		return maxAttempts;
+	}
+
+	@Override
+	public long nextBackOff() {
+		this.currentAttempts++;
+		if (this.currentAttempts <= this.maxAttempts) {
+			return this.interval;
+		}
+		else {
+			return BackOff.STOP;
+		}
+	}
+
+	@Override
+	public void reset() {
+		this.currentAttempts = 0;
+	}
+
+	@Override
+	public String toString() {
+		final StringBuilder sb = new StringBuilder("FixedBackOff{");
+		sb.append("interval=").append(this.interval);
+		String attemptValue = (this.maxAttempts == Long.MAX_VALUE ? "unlimited"
+				: String.valueOf(this.maxAttempts));
+		sb.append(", currentAttempts=").append(this.currentAttempts);
+		sb.append(", maxAttempts=").append(attemptValue);
+		sb.append('}');
+		return sb.toString();
+	}
+
+}