Release underlying resources when JS instance is GC'ed on Android

Summary:
[Android] [Added] - Release underlying resources when JS instance is GC'ed on Android

D15826082 was reverted because it introduced a crash in Ads Manager for Android (see P67222724).

This diff fixes the crash and re-applies D15826082. The problem was that `jni::findClassStatic` in the destructor of BlobCollector.cpp couldn't find the Java class `com/facebook/react/modules/blob/BlobModule` and crashed the app.

JNI didn't seem to have access to the Java class loader probably because the destructor was called from a non-Java thread (https://our.intern.facebook.com/intern/wiki/Fbjni/environment-and-thread-management/?vitals_event=wiki_click_navigation_link#threads). The fix is to wrap the code in the destructor inside `ThreadScope::WithClassLoader `, which will allow to run code that has full access to Java as though you were running in a Java thread.

Reviewed By: shergin

Differential Revision: D16122059

fbshipit-source-id: 12f14fa4a58218242a482c2c3e2149bb6770e8ec

RNTester/android/app/BUCK

@@ -25,6 +25,7 @@ rn_android_library(
         react_native_target("java/com/facebook/react:react"),
         react_native_target("java/com/facebook/react/common:build_config"),
         react_native_target("java/com/facebook/react/modules/core:core"),
+        react_native_target("java/com/facebook/react/views/text:text"),
         react_native_target("java/com/facebook/react/shell:shell"),
         react_native_target("jni/prebuilt:android-jsc"),
         # .so files are prebuilt by Gradle with `./gradlew :ReactAndroid:packageReactNdkLibsForBuck`

ReactAndroid/build.gradle

@@ -235,6 +235,7 @@ def getNdkBuildFullPath() {
 task buildReactNdkLib(dependsOn: [prepareJSC, prepareBoost, prepareDoubleConversion, prepareFolly, prepareGlog], type: Exec) {
     inputs.dir("$projectDir/../ReactCommon")
     inputs.dir("src/main/jni")
+    inputs.dir("src/main/java/com/facebook/react/modules/blob")
     outputs.dir("$buildDir/react-ndk/all")
     commandLine(getNdkBuildFullPath(),
             "NDK_DEBUG=" + (nativeBuildType.equalsIgnoreCase("debug") ? "1" : "0"),

ReactAndroid/src/main/java/com/facebook/react/modules/blob/BUCK

@@ -16,6 +16,7 @@ rn_android_library(
     ],
     deps = [
         react_native_dep("libraries/fbcore/src/main/java/com/facebook/common/logging:logging"),
+        react_native_dep("libraries/soloader/java/com/facebook/soloader:soloader"),
         react_native_dep("third-party/java/infer-annotations:infer-annotations"),
         react_native_dep("third-party/java/jsr-305:jsr-305"),
         react_native_dep("third-party/java/okhttp:okhttp3"),
@@ -24,6 +25,7 @@ rn_android_library(
         react_native_target("java/com/facebook/react/bridge:bridge"),
         react_native_target("java/com/facebook/react/common:common"),
         react_native_target("java/com/facebook/react/module/annotations:annotations"),
+        react_native_target("java/com/facebook/react/modules/blob/jni:jni"),
         react_native_target("java/com/facebook/react/modules/network:network"),
         react_native_target("java/com/facebook/react/modules/websocket:websocket"),
     ],

ReactAndroid/src/main/java/com/facebook/react/modules/blob/BlobCollector.java

@@ -0,0 +1,26 @@
+package com.facebook.react.modules.blob;
+
+import com.facebook.react.bridge.JavaScriptContextHolder;
+import com.facebook.react.bridge.ReactContext;
+import com.facebook.soloader.SoLoader;
+
+/* package */ class BlobCollector {
+  static {
+    SoLoader.loadLibrary("reactnativeblob");
+  }
+
+  static void install(final ReactContext reactContext, final BlobModule blobModule) {
+    reactContext.runOnJSQueueThread(
+        new Runnable() {
+          @Override
+          public void run() {
+            JavaScriptContextHolder jsContext = reactContext.getJavaScriptContextHolder();
+            synchronized (jsContext) {
+              nativeInstall(blobModule, jsContext.get());
+            }
+          }
+        });
+  }
+
+  private static native void nativeInstall(Object blobModule, long jsContext);
+}

ReactAndroid/src/main/java/com/facebook/react/modules/blob/BlobModule.java

@@ -12,6 +12,7 @@
 import android.provider.MediaStore;
 import android.webkit.MimeTypeMap;
 import androidx.annotation.Nullable;
+import com.facebook.proguard.annotations.DoNotStrip;
 import com.facebook.react.bridge.Arguments;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
@@ -143,6 +144,11 @@ public BlobModule(ReactApplicationContext reactContext) {
     super(reactContext);
   }
 
+  @Override
+  public void initialize() {
+    BlobCollector.install(getReactApplicationContext(), this);
+  }
+
   @Override
   public String getName() {
     return NAME;
@@ -170,11 +176,16 @@ public String store(byte[] data) {
   }
 
   public void store(byte[] data, String blobId) {
-    mBlobs.put(blobId, data);
+    synchronized (mBlobs) {
+      mBlobs.put(blobId, data);
+    }
   }
 
+  @DoNotStrip
   public void remove(String blobId) {
-    mBlobs.remove(blobId);
+    synchronized (mBlobs) {
+      mBlobs.remove(blobId);
+    }
   }
 
   public @Nullable byte[] resolve(Uri uri) {
@@ -193,17 +204,19 @@ public void remove(String blobId) {
   }
 
   public @Nullable byte[] resolve(String blobId, int offset, int size) {
-    byte[] data = mBlobs.get(blobId);
-    if (data == null) {
-      return null;
-    }
-    if (size == -1) {
-      size = data.length - offset;
-    }
-    if (offset > 0 || size != data.length) {
-      data = Arrays.copyOfRange(data, offset, offset + size);
+    synchronized (mBlobs) {
+      byte[] data = mBlobs.get(blobId);
+      if (data == null) {
+        return null;
+      }
+      if (size == -1) {
+        size = data.length - offset;
+      }
+      if (offset > 0 || size != data.length) {
+        data = Arrays.copyOfRange(data, offset, offset + size);
+      }
+      return data;
     }
-    return data;
   }
 
   public @Nullable byte[] resolve(ReadableMap blob) {

ReactAndroid/src/main/java/com/facebook/react/modules/blob/jni/Android.mk

@@ -0,0 +1,21 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := reactnativeblob
+
+LOCAL_SRC_FILES := $(wildcard $(LOCAL_PATH)/*.cpp)
+
+LOCAL_C_INCLUDES := $(LOCAL_PATH)
+
+LOCAL_CFLAGS += -fvisibility=hidden -fexceptions -frtti
+
+LOCAL_STATIC_LIBRARIES := libjsi libjsireact jscruntime
+LOCAL_SHARED_LIBRARIES := libfolly_json libfb libreactnativejni
+
+include $(BUILD_SHARED_LIBRARY)

ReactAndroid/src/main/java/com/facebook/react/modules/blob/jni/BUCK

@@ -0,0 +1,22 @@
+load("//tools/build_defs/oss:rn_defs.bzl", "ANDROID", "FBJNI_TARGET", "react_native_target", "react_native_xplat_target", "rn_xplat_cxx_library")
+
+rn_xplat_cxx_library(
+    name = "jni",
+    srcs = glob(["*.cpp"]),
+    headers = glob(["*.h"]),
+    header_namespace = "",
+    compiler_flags = ["-fexceptions"],
+    fbandroid_allow_jni_merging = True,
+    platforms = ANDROID,
+    soname = "libreactnativeblob.$(ext)",
+    visibility = [
+        "PUBLIC",
+    ],
+    deps = [
+        "fbsource//xplat/folly:molly",
+        FBJNI_TARGET,
+        react_native_target("jni/react/jni:jni"),
+        react_native_xplat_target("jsi:JSCRuntime"),
+        react_native_xplat_target("jsiexecutor:jsiexecutor"),
+    ],
+)

ReactAndroid/src/main/java/com/facebook/react/modules/blob/jni/BlobCollector.cpp

@@ -0,0 +1,63 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+#include "BlobCollector.h"
+
+#include <fb/fbjni.h>
+#include <memory>
+#include <mutex>
+
+using namespace facebook;
+
+namespace facebook {
+namespace react {
+
+static constexpr auto kBlobModuleJavaDescriptor =
+    "com/facebook/react/modules/blob/BlobModule";
+
+BlobCollector::BlobCollector(
+    jni::global_ref<jobject> blobModule,
+    const std::string &blobId)
+    : blobModule_(blobModule), blobId_(blobId) {}
+
+BlobCollector::~BlobCollector() {
+  jni::ThreadScope::WithClassLoader([&] {
+    static auto removeMethod = jni::findClassStatic(kBlobModuleJavaDescriptor)
+        ->getMethod<void(jstring)>("remove");
+    removeMethod(blobModule_, jni::make_jstring(blobId_).get());
+  });
+}
+
+void BlobCollector::nativeInstall(
+    jni::alias_ref<jhybridobject> jThis,
+    jni::alias_ref<jobject> blobModule,
+    jlong jsContextNativePointer) {
+  auto &runtime = *((jsi::Runtime *) jsContextNativePointer);
+  auto blobModuleRef = jni::make_global(blobModule);
+  runtime.global().setProperty(
+      runtime,
+      "__blobCollectorProvider",
+      jsi::Function::createFromHostFunction(
+          runtime,
+          jsi::PropNameID::forAscii(runtime, "__blobCollectorProvider"),
+          1,
+          [blobModuleRef](
+              jsi::Runtime &rt,
+              const jsi::Value &thisVal,
+              const jsi::Value *args,
+              size_t count) {
+            auto blobId = args[0].asString(rt).utf8(rt);
+            auto blobCollector =
+                std::make_shared<BlobCollector>(blobModuleRef, blobId);
+            return jsi::Object::createFromHostObject(rt, blobCollector);
+          }));
+}
+
+void BlobCollector::registerNatives() {
+  registerHybrid(
+      {makeNativeMethod("nativeInstall", BlobCollector::nativeInstall)});
+}
+
+} // namespace react
+} // namespace facebook

ReactAndroid/src/main/java/com/facebook/react/modules/blob/jni/BlobCollector.h

@@ -0,0 +1,39 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+#pragma once
+
+#include <fb/fbjni.h>
+#include <jsi/jsi.h>
+
+namespace facebook {
+namespace react {
+
+class BlobCollector : public jni::HybridClass<BlobCollector>,
+                      public jsi::HostObject {
+ public:
+  BlobCollector(
+      jni::global_ref<jobject> blobManager,
+      const std::string &blobId);
+  ~BlobCollector();
+
+  static constexpr auto kJavaDescriptor =
+      "Lcom/facebook/react/modules/blob/BlobCollector;";
+
+  static void nativeInstall(
+      jni::alias_ref<jhybridobject> jThis,
+      jni::alias_ref<jobject> blobModule,
+      jlong jsContextNativePointer);
+
+  static void registerNatives();
+
+ private:
+  friend HybridBase;
+
+  jni::global_ref<jobject> blobModule_;
+  const std::string blobId_;
+};
+
+} // namespace react
+} // namespace facebook

ReactAndroid/src/main/java/com/facebook/react/modules/blob/jni/OnLoad.cpp

@@ -0,0 +1,13 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+#include <fb/fbjni.h>
+
+#include "BlobCollector.h"
+
+JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
+  return facebook::jni::initialize(
+      vm, [] { facebook::react::BlobCollector::registerNatives(); });
+}

ReactAndroid/src/main/jni/react/jni/Android.mk

@@ -76,3 +76,5 @@ include $(REACT_SRC_DIR)/turbomodule/core/jni/Android.mk
 # $(call import-module,jscexecutor)
 
 include $(REACT_SRC_DIR)/jscexecutor/Android.mk
+
+include $(REACT_SRC_DIR)/modules/blob/jni/Android.mk