ACCUMULO-4847 Fix Retry utility's API (#399)

Create a builder API for Retry and RetryFactory, so that the parameters
(which all have the same type) cannot be easily confused for one another
and cause "sleep-until-heat-death-of-the-universe" bugs.

Also fix a minor bug which is caused by the assumption that nanoTime is
always positive. It is normal for nanoTime to be negative, only the
differences between two times is guaranteed to be positive.

fate/src/main/java/org/apache/accumulo/fate/util/Retry.java

@@ -0,0 +1,357 @@
+/*
+ * 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.accumulo.fate.util;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
+
+import java.util.concurrent.TimeUnit;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+
+/**
+ * Encapsulates the retrying implementation for some operation. Provides bounded retry attempts with a bounded, linear backoff.
+ */
+public class Retry {
+  private static final Logger log = LoggerFactory.getLogger(Retry.class);
+
+  private long maxRetries; // not final for testing
+  private long waitIncrement; // not final for testing
+  private long maxWait; // not final for testing
+  private final long logIntervalNanoSec;
+
+  private long retriesDone;
+  private long currentWait;
+
+  private boolean hasNeverLogged;
+  private long lastRetryLog;
+
+  /**
+   * @param maxRetries
+   *          Maximum times to retry or MAX_RETRY_DISABLED if no maximum
+   * @param startWait
+   *          The amount of time (ms) to wait for the initial retry
+   * @param maxWait
+   *          The maximum wait (ms)
+   * @param waitIncrement
+   *          The amount of time (ms) to increment next wait time by
+   * @param logInterval
+   *          The amount of time (ms) between logging retries
+   */
+  private Retry(long maxRetries, long startWait, long waitIncrement, long maxWait, long logInterval) {
+    this.maxRetries = maxRetries;
+    this.maxWait = maxWait;
+    this.waitIncrement = waitIncrement;
+    this.retriesDone = 0;
+    this.currentWait = startWait;
+    this.logIntervalNanoSec = MILLISECONDS.toNanos(logInterval);
+    this.hasNeverLogged = true;
+    this.lastRetryLog = -1;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  long getMaxRetries() {
+    return maxRetries;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  long getCurrentWait() {
+    return currentWait;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  long getWaitIncrement() {
+    return waitIncrement;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  long getMaxWait() {
+    return maxWait;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  void setMaxRetries(long maxRetries) {
+    this.maxRetries = maxRetries;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  void setStartWait(long startWait) {
+    this.currentWait = startWait;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  void setWaitIncrement(long waitIncrement) {
+    this.waitIncrement = waitIncrement;
+  }
+
+  // Visible for testing
+  @VisibleForTesting
+  void setMaxWait(long maxWait) {
+    this.maxWait = maxWait;
+  }
+
+  public boolean hasInfiniteRetries() {
+    return maxRetries < 0;
+  }
+
+  public long getLogInterval() {
+    return NANOSECONDS.toMillis(logIntervalNanoSec);
+  }
+
+  public boolean canRetry() {
+    return hasInfiniteRetries() || (retriesDone < maxRetries);
+  }
+
+  public void useRetry() {
+    if (!canRetry()) {
+      throw new IllegalStateException("No retries left");
+    }
+
+    retriesDone++;
+  }
+
+  public boolean hasRetried() {
+    return retriesDone > 0;
+  }
+
+  public long retriesCompleted() {
+    return retriesDone;
+  }
+
+  public void waitForNextAttempt() throws InterruptedException {
+    log.debug("Sleeping for {}ms before retrying operation", currentWait);
+    sleep(currentWait);
+    currentWait = Math.min(maxWait, currentWait + waitIncrement);
+  }
+
+  protected void sleep(long wait) throws InterruptedException {
+    Thread.sleep(wait);
+  }
+
+  public void logRetry(Logger log, String message, Throwable t) {
+    // log the first time as debug, and then after every logInterval as a warning
+    long now = System.nanoTime();
+    if (hasNeverLogged) {
+      if (log.isDebugEnabled()) {
+        log.debug(getMessage(message, t));
+      }
+      hasNeverLogged = false;
+      lastRetryLog = now;
+    } else if ((now - lastRetryLog) > logIntervalNanoSec) {
+      log.warn(getMessage(message), t);
+      lastRetryLog = now;
+    } else {
+      if (log.isTraceEnabled()) {
+        log.trace(getMessage(message, t));
+      }
+    }
+  }
+
+  public void logRetry(Logger log, String message) {
+    // log the first time as debug, and then after every logInterval as a warning
+    long now = System.nanoTime();
+    if (hasNeverLogged) {
+      if (log.isDebugEnabled()) {
+        log.debug(getMessage(message));
+      }
+      hasNeverLogged = false;
+      lastRetryLog = now;
+    } else if ((now - lastRetryLog) > logIntervalNanoSec) {
+      log.warn(getMessage(message));
+      lastRetryLog = now;
+    } else {
+      if (log.isTraceEnabled()) {
+        log.trace(getMessage(message));
+      }
+    }
+  }
+
+  private String getMessage(String message) {
+    return message + ", retrying attempt " + (retriesDone + 1) + " (suppressing retry messages for " + getLogInterval() + "ms)";
+  }
+
+  private String getMessage(String message, Throwable t) {
+    return message + ":" + t + ", retrying attempt " + (retriesDone + 1) + " (suppressing retry messages for " + getLogInterval() + "ms)";
+  }
+
+  public interface NeedsRetries {
+    /**
+     * @return this builder with the maximum number of retries set to unlimited
+     */
+    NeedsRetryDelay infiniteRetries();
+
+    /**
+     * @param max
+     *          the maximum number of retries to set
+     * @return this builder with the maximum number of retries set to the provided value
+     */
+    NeedsRetryDelay maxRetries(long max);
+  }
+
+  public interface NeedsRetryDelay {
+    /**
+     * @param duration
+     *          the amount of time to wait before the first retry; input is converted to milliseconds, rounded down to the nearest
+     * @return this builder with the initial wait period set
+     */
+    NeedsTimeIncrement retryAfter(long duration, TimeUnit unit);
+  }
+
+  public interface NeedsTimeIncrement {
+    /**
+     * @param duration
+     *          the amount of additional time to add before each subsequent retry; input is converted to milliseconds, rounded down to the nearest
+     * @return this builder with the increment amount set
+     */
+    NeedsMaxWait incrementBy(long duration, TimeUnit unit);
+  }
+
+  public interface NeedsMaxWait {
+    /**
+     * @param duration
+     *          the maximum amount of time to which the waiting period between retries can be incremented; input is converted to milliseconds, rounded down to
+     *          the nearest
+     * @return this builder with a maximum time limit set
+     */
+    NeedsLogInterval maxWait(long duration, TimeUnit unit);
+  }
+
+  public interface NeedsLogInterval {
+    /**
+     * @param duration
+     *          the minimum time interval between logging that a retry is occurring; input is converted to milliseconds, rounded down to the nearest
+     * @return this builder with a logging interval set
+     */
+    BuilderDone logInterval(long duration, TimeUnit unit);
+  }
+
+  public interface BuilderDone {
+    /**
+     * Create a RetryFactory from this builder which can be used to create many Retry objects with the same settings.
+     *
+     * @return this builder as a factory; intermediate references to this builder cannot be used to change options after this has been called
+     */
+    RetryFactory createFactory();
+
+    /**
+     * Create a single Retry object with the currently configured builder settings.
+     *
+     * @return a retry object from this builder's settings
+     */
+    Retry createRetry();
+  }
+
+  public interface RetryFactory {
+    /**
+     * Create a single Retry object from this factory's settings.
+     *
+     * @return a retry object from this factory's settings
+     */
+    Retry createRetry();
+  }
+
+  public static NeedsRetries builder() {
+    return new RetryFactoryBuilder();
+  }
+
+  private static class RetryFactoryBuilder implements NeedsRetries, NeedsRetryDelay, NeedsTimeIncrement, NeedsMaxWait, NeedsLogInterval, BuilderDone,
+      RetryFactory {
+
+    private boolean modifiable = true;
+    private long maxRetries;
+    private long initialWait;
+    private long maxWait;
+    private long waitIncrement;
+    private long logInterval;
+
+    RetryFactoryBuilder() {}
+
+    private void checkState() {
+      Preconditions.checkState(modifiable, "Cannot modify this builder once 'createFactory()' has been called");
+    }
+
+    @Override
+    public NeedsRetryDelay infiniteRetries() {
+      checkState();
+      this.maxRetries = -1;
+      return this;
+    }
+
+    @Override
+    public NeedsRetryDelay maxRetries(long max) {
+      checkState();
+      Preconditions.checkArgument(max >= 0, "Maximum number of retries must not be negative");
+      this.maxRetries = max;
+      return this;
+    }
+
+    @Override
+    public NeedsTimeIncrement retryAfter(long duration, TimeUnit unit) {
+      checkState();
+      Preconditions.checkArgument(duration >= 0, "Initial waiting period must not be negative");
+      this.initialWait = unit.toMillis(duration);
+      return this;
+    }
+
+    @Override
+    public NeedsMaxWait incrementBy(long duration, TimeUnit unit) {
+      checkState();
+      Preconditions.checkArgument(duration >= 0, "Amount of time to increment the wait between each retry must not be negative");
+      this.waitIncrement = unit.toMillis(duration);
+      return this;
+    }
+
+    @Override
+    public NeedsLogInterval maxWait(long duration, TimeUnit unit) {
+      checkState();
+      this.maxWait = unit.toMillis(duration);
+      Preconditions.checkArgument(maxWait >= initialWait, "Maximum wait between retries must not be less than the initial delay");
+      return this;
+    }
+
+    @Override
+    public BuilderDone logInterval(long duration, TimeUnit unit) {
+      checkState();
+      Preconditions.checkArgument(duration >= 0, "The amount of time between logging retries must not be negative");
+      this.logInterval = unit.toMillis(duration);
+      return this;
+    }
+
+    @Override
+    public RetryFactory createFactory() {
+      this.modifiable = false;
+      return this;
+    }
+
+    @Override
+    public Retry createRetry() {
+      return new Retry(maxRetries, initialWait, waitIncrement, maxWait, logInterval);
+    }
+
+  }
+}