Bug 1821004 - Add summary.java-heap memory report. r=geckoview-reviewers,owlish

Android's memory profiler can show current java-heap size. Android M+
can get this usages from API. So this fix adds this entry to
about:memory.

Differential Revision: https://phabricator.services.mozilla.com/D172211

mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoAppShell.java

@@ -40,6 +40,7 @@ import android.net.Network;
 import android.net.NetworkInfo;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.Debug;
 import android.os.LocaleList;
 import android.os.Looper;
 import android.os.PowerManager;
@@ -1595,6 +1596,26 @@ public class GeckoAppShell {
     return id == 0 ? info.nonLocalizedLabel.toString() : context.getString(id);
   }
 
+  @WrapForJNI(calledFrom = "gecko")
+  private static int getMemoryUsage(final String stateName) {
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
+      // No API to get Java heap usages.
+      return -1;
+    }
+
+    final Debug.MemoryInfo memInfo = new Debug.MemoryInfo();
+    Debug.getMemoryInfo(memInfo);
+    final String usage = memInfo.getMemoryStat(stateName);
+    if (usage == null) {
+      return -1;
+    }
+    try {
+      return Integer.parseInt(usage);
+    } catch (final NumberFormatException e) {
+      return -1;
+    }
+  }
+
   @WrapForJNI
   public static native boolean isParentProcess();
 

xpcom/base/nsMemoryReporterManager.cpp

@@ -43,6 +43,11 @@
 #include "mozilla/ipc/UtilityProcessManager.h"
 #include "mozilla/ipc/FileDescriptorUtils.h"
 
+#ifdef MOZ_WIDGET_ANDROID
+#  include "mozilla/java/GeckoAppShellWrappers.h"
+#  include "mozilla/jni/Utils.h"
+#endif
+
 #ifdef XP_WIN
 #  include "mozilla/MemoryInfo.h"
 
@@ -1606,6 +1611,35 @@ NS_IMPL_ISUPPORTS(DMDReporter, nsIMemoryReporter)
 
 #endif  // MOZ_DMD
 
+#ifdef MOZ_WIDGET_ANDROID
+class AndroidMemoryReporter final : public nsIMemoryReporter {
+ public:
+  NS_DECL_ISUPPORTS
+
+  AndroidMemoryReporter() = default;
+
+  NS_IMETHOD
+  CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
+                 bool aAnonymize) override {
+    if (!jni::IsAvailable() || jni::GetAPIVersion() < 23) {
+      return NS_OK;
+    }
+
+    int32_t heap = java::GeckoAppShell::GetMemoryUsage("summary.java-heap"_ns);
+    if (heap > 0) {
+      MOZ_COLLECT_REPORT("java-heap", KIND_OTHER, UNITS_BYTES, heap * 1024,
+                         "The private Java Heap usage");
+    }
+    return NS_OK;
+  }
+
+ private:
+  ~AndroidMemoryReporter() = default;
+};
+
+NS_IMPL_ISUPPORTS(AndroidMemoryReporter, nsIMemoryReporter)
+#endif
+
 /**
  ** nsMemoryReporterManager implementation
  **/
@@ -1695,6 +1729,10 @@ nsMemoryReporterManager::Init() {
   RegisterStrongReporter(new WindowsAddressSpaceReporter());
 #endif
 
+#ifdef MOZ_WIDGET_ANDROID
+  RegisterStrongReporter(new AndroidMemoryReporter());
+#endif
+
 #ifdef XP_UNIX
   nsMemoryInfoDumper::Initialize();
 #endif