Record the return value of NativeLibraryPreloader.loadLibrary in UMA

base/android/library_loader/library_loader_hooks.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/android/library_loader/library_loader_hooks.h"
 
 #include "base/android/command_line_android.h"
 #include "base/android/jni_string.h"
 #include "base/android/library_loader/library_load_from_apk_status_codes.h"
 #include "base/android/library_loader/library_prefetcher.h"
 #include "base/at_exit.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/sparse_histogram.h"
 #include "jni/LibraryLoader_jni.h"
 
 namespace base {
 namespace android {
 
 namespace {
 
 base::AtExitManager* g_at_exit_manager = NULL;
 const char* g_library_version_number = "";
 LibraryLoadedHook* g_registration_callback = NULL;
@@ skipping 18 matching lines @@
 
   // Low-memory browser loads at fixed address, success or fail.
   LOW_MEMORY_LFA_SUCCESS = 1,
   LOW_MEMORY_LFA_BACKOFF_USED = 2,
 
   MAX_BROWSER_HISTOGRAM_CODE = 3,
 };
 
 RendererHistogramCode g_renderer_histogram_code = NO_PENDING_HISTOGRAM_CODE;
 
+// Indicate whether g_library_preloader_renderer_histogram_code is valid
+bool g_library_preloader_renderer_histogram_code_registered = false;
+
+// The return value of NativeLibraryPreloader.loadLibrary() in child processes.
+int g_library_preloader_renderer_histogram_code = 0;
+
 // The amount of time, in milliseconds, that it took to load the shared
 // libraries in the renderer. Set in
 // RegisterChromiumAndroidLinkerRendererHistogram.
 long g_renderer_library_load_time_ms = 0;
 
 } // namespace
 
 static void RegisterChromiumAndroidLinkerRendererHistogram(
     JNIEnv* env,
     const JavaParamRef<jobject>& jcaller,
     jboolean requested_shared_relro,
     jboolean load_at_fixed_address_failed,
     jlong library_load_time_ms) {
   // Note a pending histogram value for later recording.
   if (requested_shared_relro) {
     g_renderer_histogram_code = load_at_fixed_address_failed
                                 ? LFA_BACKOFF_USED : LFA_SUCCESS;
   } else {
     g_renderer_histogram_code = LFA_NOT_ATTEMPTED;
   }
 
   g_renderer_library_load_time_ms = library_load_time_ms;
 }
 
-void RecordChromiumAndroidLinkerRendererHistogram() {
-  if (g_renderer_histogram_code == NO_PENDING_HISTOGRAM_CODE)
+static void RecordChromiumAndroidLinkerRendererHistogram() {
+  if (g_renderer_histogram_code != NO_PENDING_HISTOGRAM_CODE)
     return;
   // Record and release the pending histogram value.
   UMA_HISTOGRAM_ENUMERATION("ChromiumAndroidLinker.RendererStates",
                             g_renderer_histogram_code,
                             MAX_RENDERER_HISTOGRAM_CODE);
   g_renderer_histogram_code = NO_PENDING_HISTOGRAM_CODE;
 
   // Record how long it took to load the shared libraries.
   UMA_HISTOGRAM_TIMES("ChromiumAndroidLinker.RendererLoadTime",
       base::TimeDelta::FromMilliseconds(g_renderer_library_load_time_ms));
@@ skipping 22 matching lines @@
   // Record the device support for loading a library directly from the APK file.
   UMA_HISTOGRAM_ENUMERATION("ChromiumAndroidLinker.LibraryLoadFromApkStatus",
                             library_load_from_apk_status,
                             LIBRARY_LOAD_FROM_APK_STATUS_CODES_MAX);
 
   // Record how long it took to load the shared libraries.
   UMA_HISTOGRAM_TIMES("ChromiumAndroidLinker.BrowserLoadTime",
                       base::TimeDelta::FromMilliseconds(library_load_time_ms));
 }
 
+static void RecordLibraryPreloaderBrowserHistogram(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& jcaller,
+    jint status) {
+  UMA_HISTOGRAM_SPARSE_SLOWLY(
+      "ChromiumAndroidNativeLibraryPreloader.BrowserStates",
+      status);
+}
+
+static void RegisterLibraryPreloaderRendererHistogram(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& jcaller,
+    jint status) {
+  g_library_preloader_renderer_histogram_code = status;
+  g_library_preloader_renderer_histogram_code_registered = true;
+}
+
+static void RecordLibraryPreloaderRendereHistogram() {
+  if (g_library_preloader_renderer_histogram_code_registered) {
+    UMA_HISTOGRAM_SPARSE_SLOWLY(
+        "ChromiumAndroidNativeLibraryPreloader.RendererStates",

[Alexei Svitkine (slow), 2016/05/26 14:56:29]

I suggest not adding a new histogram prefix unless you expect it will be used a
lot for new metrics.

So perhaps you can nest these under the existing Android.* prefix?

e.g. Android.NativeLibraryPreloader.RendererStates

Also, this is the result of loadLibrary(), right?

So maybe Android.NativeLibraryPreloader.Result.Browser and
Android.NativeLibraryPreloader.Result.Renderer?

The "Browser" and "Renderer" suffixes are a standard way on how to permute a
histogram in UMA and is supported via histogram_suffixes in histograms.xml.

[michaelbai, 2016/05/26 19:10:35]

Done.

+        g_library_preloader_renderer_histogram_code);
+  }
+}
+
+void RecordChromiumAndroidLibraryLoaderRendererHistogram() {
+  RecordChromiumAndroidLinkerRendererHistogram();
+  RecordLibraryPreloaderRendereHistogram();
+}
+
 void SetLibraryLoadedHook(LibraryLoadedHook* func) {
   g_registration_callback = func;
 }
 
 static void InitCommandLine(
     JNIEnv* env,
     const JavaParamRef<jobject>& jcaller,
     const JavaParamRef<jobjectArray>& init_command_line) {
   InitNativeCommandLineFromJavaArray(env, init_command_line);
 }
@@ skipping 43 matching lines @@
   return static_cast<LibraryProcessType>(
       Java_LibraryLoader_getLibraryProcessType(env));
 }
 
 void InitAtExitManager() {
   g_at_exit_manager = new base::AtExitManager();
 }
 
 }  // namespace android
 }  // namespace base