Android: Add API for getting native histograms.

The function getAndReset returns a map which holds the name of a histogram and its samples.

This CL depends on: https://codereview.webrtc.org/1915523002/

BUG=

Review-Url: https://codereview.webrtc.org/1952223007
Cr-Commit-Position: refs/heads/master@{#12848}

webrtc/api/androidtests/src/org/webrtc/PeerConnectionTest.java

@@ -10,6 +10,8 @@
 
 package org.webrtc;
 
+import org.webrtc.Metrics;
+import org.webrtc.Metrics.HistogramInfo;
 import org.webrtc.PeerConnection.IceConnectionState;
 import org.webrtc.PeerConnection.IceGatheringState;
 import org.webrtc.PeerConnection.SignalingState;
@@ -530,6 +532,7 @@ public class PeerConnectionTest extends ActivityTestCase {
 
   @MediumTest
   public void testCompleteSession() throws Exception {
+    Metrics.enable();
     // Allow loopback interfaces too since our Android devices often don't
     // have those.
     PeerConnectionFactory.Options options = new PeerConnectionFactory.Options();
@@ -741,6 +744,7 @@ public class PeerConnectionTest extends ActivityTestCase {
     answeringExpectations.expectStateChange(DataChannel.State.CLOSED);
     answeringExpectations.dataChannel.close();
     offeringExpectations.dataChannel.close();
+    getMetrics();
 
     // Free the Java-land objects, collect them, and sleep a bit to make sure we
     // don't get late-arrival crashes after the Java-land objects have been
@@ -968,6 +972,18 @@ public class PeerConnectionTest extends ActivityTestCase {
     System.gc();
   }
 
+  private static void getMetrics() {
+    Metrics metrics = Metrics.getAndReset();
+    assertTrue(metrics.map.size() > 0);
+    // Test for example that the configured video codec is recorded when a
+    // VideoSendStream is created.
+    String name = "WebRTC.Video.Encoder.CodecType";
+    assertTrue(metrics.map.containsKey(name));
+    HistogramInfo info = metrics.map.get(name);
+    assertEquals(1, info.samples.size());       // samples: <sample value, # of events>
+    assertTrue(info.samples.containsValue(2));  // <codec type, 2>, same codec configured
+  }
+
   private static void shutdownPC(
       PeerConnection pc, ObserverExpectations expectations) {
     if (expectations.dataChannel != null) {

webrtc/api/api.gyp

@@ -39,6 +39,7 @@
             'java/jni/androidmediadecoder_jni.h',
             'java/jni/androidmediaencoder_jni.cc',
             'java/jni/androidmediaencoder_jni.h',
+            'java/jni/androidmetrics_jni.cc',
             'java/jni/androidnetworkmonitor_jni.cc',
             'java/jni/androidnetworkmonitor_jni.h',
             'java/jni/androidvideocapturer_jni.cc',

webrtc/api/java/jni/androidmetrics_jni.cc

@@ -0,0 +1,59 @@
+/*
+ *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <map>
+#include <memory>
+
+#include "webrtc/api/java/jni/classreferenceholder.h"
+#include "webrtc/api/java/jni/jni_helpers.h"
+#include "webrtc/api/java/jni/native_handle_impl.h"
+#include "webrtc/system_wrappers/include/metrics_default.h"
+
+// Enables collection of native histograms.
+namespace webrtc_jni {
+JOW(void, Metrics_nativeEnable)(JNIEnv* jni, jclass) {
+  webrtc::metrics::Enable();
+}
+
+// Gets and clears native histograms.
+JOW(jobject, Metrics_nativeGetAndReset)(JNIEnv* jni, jclass) {
+  jclass j_metrics_class = FindClass(jni, "org/webrtc/Metrics");
+  jmethodID j_add =
+      GetMethodID(jni, j_metrics_class, "add",
+                  "(Ljava/lang/String;Lorg/webrtc/Metrics$HistogramInfo;)V");
+  jclass j_info_class = FindClass(jni, "org/webrtc/Metrics$HistogramInfo");
+  jmethodID j_add_sample = GetMethodID(jni, j_info_class, "addSample", "(II)V");
+
+  // Create |Metrics|.
+  jobject j_metrics = jni->NewObject(
+      j_metrics_class, GetMethodID(jni, j_metrics_class, "<init>", "()V"));
+
+  std::map<std::string, std::unique_ptr<webrtc::metrics::SampleInfo>>
+      histograms;
+  webrtc::metrics::GetAndReset(&histograms);
+  for (const auto& kv : histograms) {
+    // Create and add samples to |HistogramInfo|.
+    jobject j_info = jni->NewObject(
+        j_info_class, GetMethodID(jni, j_info_class, "<init>", "(III)V"),
+        kv.second->min, kv.second->max,
+        static_cast<int>(kv.second->bucket_count));
+    for (const auto& sample : kv.second->samples) {
+      jni->CallVoidMethod(j_info, j_add_sample, sample.first, sample.second);
+    }
+    // Add |HistogramInfo| to |Metrics|.
+    jstring j_name = jni->NewStringUTF(kv.first.c_str());
+    jni->CallVoidMethod(j_metrics, j_add, j_name, j_info);
+    jni->DeleteLocalRef(j_name);
+    jni->DeleteLocalRef(j_info);
+  }
+  CHECK_EXCEPTION(jni);
+  return j_metrics;
+}
+}  // namespace webrtc_jni

webrtc/api/java/jni/classreferenceholder.cc

@@ -69,6 +69,8 @@ ClassReferenceHolder::ClassReferenceHolder(JNIEnv* jni) {
   LoadClass(jni, "org/webrtc/MediaSource$State");
   LoadClass(jni, "org/webrtc/MediaStream");
   LoadClass(jni, "org/webrtc/MediaStreamTrack$State");
+  LoadClass(jni, "org/webrtc/Metrics");
+  LoadClass(jni, "org/webrtc/Metrics$HistogramInfo");
   LoadClass(jni, "org/webrtc/NetworkMonitor");
   LoadClass(jni, "org/webrtc/NetworkMonitorAutoDetect$ConnectionType");
   LoadClass(jni, "org/webrtc/NetworkMonitorAutoDetect$IPAddress");

webrtc/api/java/src/org/webrtc/Metrics.java

@@ -0,0 +1,77 @@
+/*
+ *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+import java.util.HashMap;
+import java.util.Map;
+
+// Java-side of androidmetrics_jni.cc.
+//
+// Rtc histograms can be queried through the API, getAndReset().
+// The returned map holds the name of a histogram and its samples.
+//
+// Example of |map| with one histogram:
+// |name|: "WebRTC.Video.InputFramesPerSecond"
+//     |min|: 1
+//     |max|: 100
+//     |bucketCount|: 50
+//     |samples|: [30]:1
+//
+// Most histograms are not updated frequently (e.g. most video metrics are an
+// average over the call and recorded when a stream is removed).
+// The metrics can for example be retrieved when a peer connection is closed.
+
+public class Metrics {
+  static {
+    System.loadLibrary("jingle_peerconnection_so");
+  }
+  public final Map<String, HistogramInfo> map =
+       new HashMap<String, HistogramInfo>();  // <name, HistogramInfo>
+
+  /**
+   * Class holding histogram information.
+   */
+  public static class HistogramInfo {
+    public final int min;
+    public final int max;
+    public final int bucketCount;
+    public final Map<Integer, Integer> samples =
+        new HashMap<Integer, Integer>();  // <value, # of events>
+
+    public HistogramInfo(int min, int max, int bucketCount) {
+      this.min = min;
+      this.max = max;
+      this.bucketCount = bucketCount;
+    }
+
+    public void addSample(int value, int numEvents) {
+      samples.put(value, numEvents);
+    }
+  }
+
+  private void add(String name, HistogramInfo info) {
+    map.put(name, info);
+  }
+
+  // Enables gathering of metrics (which can be fetched with getAndReset()).
+  // Must be called before PeerConnectionFactory is created.
+  public static void enable() {
+    nativeEnable();
+  }
+
+  // Gets and clears native histograms.
+  public static Metrics getAndReset() {
+    return nativeGetAndReset();
+  }
+
+  private static native void nativeEnable();
+  private static native Metrics nativeGetAndReset();
+}