First cut at server timing tests

editor/tools/plugins/com.google.dart.server_test/src/com/google/dart/server/timing/TimingResult.java

Index: editor/tools/plugins/com.google.dart.server_test/src/com/google/dart/server/timing/TimingResult.java
diff --git a/editor/tools/plugins/com.google.dart.server_test/src/com/google/dart/server/timing/TimingResult.java b/editor/tools/plugins/com.google.dart.server_test/src/com/google/dart/server/timing/TimingResult.java
new file mode 100644
index 0000000000000000000000000000000000000000..05a139b4a0a299bcfa622929c34057db9982169e
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.server_test/src/com/google/dart/server/timing/TimingResult.java
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2014, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
+ * 
+ * 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.google.dart.server.timing;
+
+/**
+ * Instances of the class {@code TimingResult} represent the timing information gathered while
+ * executing a given timing test.
+ */
+public class TimingResult {
+  /**
+   * The amount of time spent executing each test, in nanoseconds.
+   */
+  private long[] times;
+
+  /**
+   * The number of nanoseconds in a millisecond.
+   */
+  private static long NANOSECONDS_PER_MILLISECOND = 1000000;
+
+  /**
+   * Initialize a newly created timing result.
+   */
+  public TimingResult(long[] times) {
+    this.times = times;
+  }
+
+  /**
+   * Return the average amount of time spent executing a single iteration, in milliseconds.
+   */
+  public long getAverageTime() {
+    return getTotalTime() / times.length;
+  }
+
+  /**
+   * Return the maximum amount of time spent executing a single iteration, in milliseconds.
+   */
+  public long getMaxTime() {
+    long maxTime = 0L;
+    int count = times.length;
+    for (int i = 0; i < count; i++) {
+      maxTime = Math.max(maxTime, times[i]);
+    }
+    return maxTime / NANOSECONDS_PER_MILLISECOND;
+  }
+
+  /**
+   * Return the maximum amount of time spent executing a single iteration, in milliseconds.
+   */
+  public long getMinTime() {
+    long minTime = Long.MAX_VALUE;
+    int count = times.length;
+    for (int i = 0; i < count; i++) {
+      minTime = Math.min(minTime, times[i]);
+    }
+    return minTime / NANOSECONDS_PER_MILLISECOND;
+  }
+
+  /**
+   * Return the standard deviation of the times.
+   * 
+   * @return the standard deviation of the times
+   */
+  public double getStandardDeviation() {
+    return computeStandardDeviation(toMilliseconds(times));
+  }
+
+  /**
+   * Return the total amount of time spent executing the test, in milliseconds.
+   */
+  public long getTotalTime() {
+    long totalTime = 0L;
+    int count = times.length;
+    for (int i = 0; i < count; i++) {
+      totalTime += times[i];
+    }
+    return totalTime / NANOSECONDS_PER_MILLISECOND;
+  }
+
+  /**
+   * Compute the standard deviation of the given set of values.
+   * 
+   * @param values the values for which a standard deviation is to be computed
+   * @return the standard deviation that was computed
+   */
+  private double computeStandardDeviation(long[] values) {
+    int count = values.length;
+    double sumOfValues = 0.0;
+    for (int i = 0; i < count; i++) {
+      sumOfValues += values[i];
+    }
+    double average = sumOfValues / count;
+    double sumOfDiffSquared = 0.0;
+    for (int i = 0; i < count; i++) {
+      double diff = values[i] - average;
+      sumOfDiffSquared += diff * diff;
+    }
+    // If this were a sample we would divide by (count - 1).
+    return Math.sqrt(sumOfDiffSquared / count);
+  }
+
+  /**
+   * Convert the given times, expressed in nanoseconds, to times expressed in milliseconds.
+   * 
+   * @param values the times in nanoseconds
+   * @return the times in milliseconds
+   */
+  private long[] toMilliseconds(long[] values) {
+    int count = values.length;
+    long[] convertedValues = new long[count];
+    for (int i = 0; i < count; i++) {
+      convertedValues[i] = values[i] / NANOSECONDS_PER_MILLISECOND;
+    }
+    return convertedValues;
+  }
+}