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diff --git a/src/main/java/org/elasticsearch/common/StopWatch.java b/src/main/java/org/elasticsearch/common/StopWatch.java
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+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.elasticsearch.common;
+
+import org.elasticsearch.common.unit.TimeValue;
+
+import java.text.NumberFormat;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Simple stop watch, allowing for timing of a number of tasks,
+ * exposing total running time and running time for each named task.
+ * <p/>
+ * <p>Conceals use of <code>System.currentTimeMillis()</code>, improving the
+ * readability of application code and reducing the likelihood of calculation errors.
+ * <p/>
+ * <p>Note that this object is not designed to be thread-safe and does not
+ * use synchronization.
+ * <p/>
+ * <p>This class is normally used to verify performance during proof-of-concepts
+ * and in development, rather than as part of production applications.
+ *
+ *
+ */
+public class StopWatch {
+
+    /**
+     * Identifier of this stop watch.
+     * Handy when we have output from multiple stop watches
+     * and need to distinguish between them in log or console output.
+     */
+    private final String id;
+
+    private boolean keepTaskList = true;
+
+    private final List<TaskInfo> taskList = new LinkedList<TaskInfo>();
+
+    /**
+     * Start time of the current task
+     */
+    private long startTimeMillis;
+
+    /**
+     * Is the stop watch currently running?
+     */
+    private boolean running;
+
+    /**
+     * Name of the current task
+     */
+    private String currentTaskName;
+
+    private TaskInfo lastTaskInfo;
+
+    private int taskCount;
+
+    /**
+     * Total running time
+     */
+    private long totalTimeMillis;
+
+    /**
+     * Construct a new stop watch. Does not start any task.
+     */
+    public StopWatch() {
+        this.id = "";
+    }
+
+    /**
+     * Construct a new stop watch with the given id.
+     * Does not start any task.
+     *
+     * @param id identifier for this stop watch.
+     *           Handy when we have output from multiple stop watches
+     *           and need to distinguish between them.
+     */
+    public StopWatch(String id) {
+        this.id = id;
+    }
+
+    /**
+     * Determine whether the TaskInfo array is built over time. Set this to
+     * "false" when using a StopWatch for millions of intervals, or the task
+     * info structure will consume excessive memory. Default is "true".
+     */
+    public StopWatch keepTaskList(boolean keepTaskList) {
+        this.keepTaskList = keepTaskList;
+        return this;
+    }
+
+    /**
+     * Start an unnamed task. The results are undefined if {@link #stop()}
+     * or timing methods are called without invoking this method.
+     *
+     * @see #stop()
+     */
+    public StopWatch start() throws IllegalStateException {
+        return start("");
+    }
+
+    /**
+     * Start a named task. The results are undefined if {@link #stop()}
+     * or timing methods are called without invoking this method.
+     *
+     * @param taskName the name of the task to start
+     * @see #stop()
+     */
+    public StopWatch start(String taskName) throws IllegalStateException {
+        if (this.running) {
+            throw new IllegalStateException("Can't start StopWatch: it's already running");
+        }
+        this.startTimeMillis = System.currentTimeMillis();
+        this.running = true;
+        this.currentTaskName = taskName;
+        return this;
+    }
+
+    /**
+     * Stop the current task. The results are undefined if timing
+     * methods are called without invoking at least one pair
+     * {@link #start()} / {@link #stop()} methods.
+     *
+     * @see #start()
+     */
+    public StopWatch stop() throws IllegalStateException {
+        if (!this.running) {
+            throw new IllegalStateException("Can't stop StopWatch: it's not running");
+        }
+        long lastTime = System.currentTimeMillis() - this.startTimeMillis;
+        this.totalTimeMillis += lastTime;
+        this.lastTaskInfo = new TaskInfo(this.currentTaskName, lastTime);
+        if (this.keepTaskList) {
+            this.taskList.add(lastTaskInfo);
+        }
+        ++this.taskCount;
+        this.running = false;
+        this.currentTaskName = null;
+        return this;
+    }
+
+    /**
+     * Return whether the stop watch is currently running.
+     */
+    public boolean isRunning() {
+        return this.running;
+    }
+
+    /**
+     * Return the time taken by the last task.
+     */
+    public TimeValue lastTaskTime() throws IllegalStateException {
+        if (this.lastTaskInfo == null) {
+            throw new IllegalStateException("No tests run: can't get last interval");
+        }
+        return this.lastTaskInfo.getTime();
+    }
+
+    /**
+     * Return the name of the last task.
+     */
+    public String lastTaskName() throws IllegalStateException {
+        if (this.lastTaskInfo == null) {
+            throw new IllegalStateException("No tests run: can't get last interval");
+        }
+        return this.lastTaskInfo.getTaskName();
+    }
+
+    /**
+     * Return the total time for all tasks.
+     */
+    public TimeValue totalTime() {
+        return new TimeValue(totalTimeMillis, TimeUnit.MILLISECONDS);
+    }
+
+    /**
+     * Return the number of tasks timed.
+     */
+    public int taskCount() {
+        return taskCount;
+    }
+
+    /**
+     * Return an array of the data for tasks performed.
+     */
+    public TaskInfo[] taskInfo() {
+        if (!this.keepTaskList) {
+            throw new UnsupportedOperationException("Task info is not being kept!");
+        }
+        return this.taskList.toArray(new TaskInfo[this.taskList.size()]);
+    }
+
+    /**
+     * Return a short description of the total running time.
+     */
+    public String shortSummary() {
+        return "StopWatch '" + this.id + "': running time  = " + totalTime();
+    }
+
+    /**
+     * Return a string with a table describing all tasks performed.
+     * For custom reporting, call getTaskInfo() and use the task info directly.
+     */
+    public String prettyPrint() {
+        StringBuilder sb = new StringBuilder(shortSummary());
+        sb.append('\n');
+        if (!this.keepTaskList) {
+            sb.append("No task info kept");
+        } else {
+            sb.append("-----------------------------------------\n");
+            sb.append("ms     %     Task name\n");
+            sb.append("-----------------------------------------\n");
+            NumberFormat nf = NumberFormat.getNumberInstance(Locale.ROOT);
+            nf.setMinimumIntegerDigits(5);
+            nf.setGroupingUsed(false);
+            NumberFormat pf = NumberFormat.getPercentInstance(Locale.ROOT);
+            pf.setMinimumIntegerDigits(3);
+            pf.setGroupingUsed(false);
+            for (TaskInfo task : taskInfo()) {
+                sb.append(nf.format(task.getTime().millis())).append("  ");
+                sb.append(pf.format(task.getTime().secondsFrac() / totalTime().secondsFrac())).append("  ");
+                sb.append(task.getTaskName()).append("\n");
+            }
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Return an informative string describing all tasks performed
+     * For custom reporting, call <code>getTaskInfo()</code> and use the task info directly.
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder(shortSummary());
+        if (this.keepTaskList) {
+            for (TaskInfo task : taskInfo()) {
+                sb.append("; [").append(task.getTaskName()).append("] took ").append(task.getTime());
+                long percent = Math.round((100.0f * task.getTime().millis()) / totalTime().millis());
+                sb.append(" = ").append(percent).append("%");
+            }
+        } else {
+            sb.append("; no task info kept");
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Inner class to hold data about one task executed within the stop watch.
+     */
+    public static class TaskInfo {
+
+        private final String taskName;
+
+        private final TimeValue timeValue;
+
+        private TaskInfo(String taskName, long timeMillis) {
+            this.taskName = taskName;
+            this.timeValue = new TimeValue(timeMillis, TimeUnit.MILLISECONDS);
+        }
+
+        /**
+         * Return the name of this task.
+         */
+        public String getTaskName() {
+            return taskName;
+        }
+
+        /**
+         * Return the time this task took.
+         */
+        public TimeValue getTime() {
+            return timeValue;
+        }
+    }
+
+}