react-native/ReactAndroid/src/main/java/com/facebook/react/cxxbridge/ModuleHolder.java

// Copyright 2004-present Facebook. All Rights Reserved.

package com.facebook.react.cxxbridge;

import javax.annotation.Nullable;
import javax.inject.Provider;

import java.util.concurrent.ExecutionException;

import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactMarker;
import com.facebook.react.common.futures.SimpleSettableFuture;
import com.facebook.react.module.model.Info;
import com.facebook.react.module.model.ReactModuleInfo;
import com.facebook.systrace.Systrace;
import com.facebook.systrace.SystraceMessage;

import static com.facebook.infer.annotation.Assertions.assertNotNull;
import static com.facebook.react.bridge.ReactMarkerConstants.CREATE_MODULE_END;
import static com.facebook.react.bridge.ReactMarkerConstants.CREATE_MODULE_START;
import static com.facebook.systrace.Systrace.TRACE_TAG_REACT_JAVA_BRIDGE;

/**
 * Holder to enable us to lazy create native modules.
 *
 * This works by taking a provider instead of an instance, when it is first required we'll create
 * and initialize it. Initialization currently always happens on the UI thread but this is due to
 * change for performance reasons.
 *
 * Lifecycle events via a {@link LifecycleEventListener} will still always happen on the UI thread.
 */
public class ModuleHolder {

  private final Info mInfo;
  private @Nullable Provider<? extends NativeModule> mProvider;
  private @Nullable NativeModule mModule;
  private boolean mInitializeNeeded;

  public ModuleHolder(
    Class<? extends NativeModule> clazz,
    @Nullable ReactModuleInfo reactModuleInfo,
    Provider<? extends NativeModule> provider) {
    mInfo = reactModuleInfo == null ? new LegacyModuleInfo(clazz) : reactModuleInfo;
    mProvider = provider;

    if (mInfo.needsEagerInit()) {
      mModule = doCreate();
    }
  }

  public synchronized void initialize() {
    if (mModule != null) {
      doInitialize(mModule);
    } else {
      mInitializeNeeded = true;
    }
  }

  public synchronized void destroy() {
    if (mModule != null) {
      mModule.onCatalystInstanceDestroy();
    }
  }

  public Info getInfo() {
    return mInfo;
  }

  public synchronized NativeModule getModule() {
    if (mModule == null) {
      mModule = doCreate();
    }
    return mModule;
  }

  private NativeModule doCreate() {
    NativeModule module = create();
    mProvider = null;
    return module;
  }

  private NativeModule create() {
    boolean isEagerModule = mInfo instanceof LegacyModuleInfo;
    String name = isEagerModule ? ((LegacyModuleInfo) mInfo).mType.getSimpleName() : mInfo.name();
    if (!isEagerModule) {
      ReactMarker.logMarker(CREATE_MODULE_START);
    }
    SystraceMessage.beginSection(TRACE_TAG_REACT_JAVA_BRIDGE, "createModule")
      .arg("name", name)
      .flush();
    NativeModule module = assertNotNull(mProvider).get();
    if (mInitializeNeeded) {
      doInitialize(module);
      mInitializeNeeded = false;
    }
    Systrace.endSection(TRACE_TAG_REACT_JAVA_BRIDGE);
    if (!isEagerModule) {
      ReactMarker.logMarker(CREATE_MODULE_END);
    }
    return module;
  }

  private void doInitialize(NativeModule module) {
    SystraceMessage.Builder section =
      SystraceMessage.beginSection(TRACE_TAG_REACT_JAVA_BRIDGE, "initialize");
    if (module instanceof CxxModuleWrapper) {
      section.arg("className", module.getClass().getSimpleName());
    } else {
      section.arg("name", mInfo.name());
    }
    section.flush();
    callInitializeOnUiThread(module);
    Systrace.endSection(TRACE_TAG_REACT_JAVA_BRIDGE);
  }

  // TODO(t11394264): Use the native module thread here after the old bridge is gone
  private static void callInitializeOnUiThread(final NativeModule module) {
    if (UiThreadUtil.isOnUiThread()) {
      module.initialize();
      return;
    }
    final SimpleSettableFuture<Void> future = new SimpleSettableFuture<>();
    UiThreadUtil.runOnUiThread(new Runnable() {
      @Override
      public void run() {
        Systrace.beginSection(TRACE_TAG_REACT_JAVA_BRIDGE, "initializeOnUiThread");
        try {
          module.initialize();
          future.set(null);
        } catch (Exception e) {
          future.setException(e);
        }
        Systrace.endSection(TRACE_TAG_REACT_JAVA_BRIDGE);
      }
    });
    try {
      future.get();
    } catch (InterruptedException | ExecutionException e) {
      throw new RuntimeException(e);
    }
  }

  private class LegacyModuleInfo implements Info {

    public final Class<?> mType;

    public LegacyModuleInfo(Class<?> type) {
      mType = type;
    }

    public String name() {
      return getModule().getName();
    }

    public boolean canOverrideExistingModule() {
      return getModule().canOverrideExistingModule();
    }

    public boolean supportsWebWorkers() {
      return getModule().supportsWebWorkers();
    }

    public boolean needsEagerInit() {
      return true;
    }
  }
}