com.facebook.react.bridge.webworkers.WebWorkers.java Source code

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Here is the source code for com.facebook.react.bridge.webworkers.WebWorkers.java

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/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

package com.facebook.react.bridge.webworkers;

import java.io.File;
import java.io.IOException;

import com.facebook.proguard.annotations.DoNotStrip;
import com.facebook.react.bridge.queue.MessageQueueThread;
import com.facebook.react.bridge.queue.MessageQueueThreadImpl;
import com.facebook.react.bridge.queue.ProxyQueueThreadExceptionHandler;
import com.facebook.react.common.build.ReactBuildConfig;

import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;
import okio.Okio;
import okio.Sink;

@DoNotStrip
public class WebWorkers {

    /**
     * Creates a new MessageQueueThread for a background web worker owned by the JS thread with the
     * given MessageQueueThread.
     */
    @DoNotStrip
    public static MessageQueueThread createWebWorkerThread(int id, MessageQueueThread ownerThread) {
        return MessageQueueThreadImpl.startNewBackgroundThread("web-worker-" + id,
                new ProxyQueueThreadExceptionHandler(ownerThread));
    }

    /**
     * Utility method used to help develop web workers on debug builds. In release builds, worker
     * scripts need to be packaged with the app, but in dev mode we want to fetch/reload the worker
     * script on the fly from the packager. This method fetches the given URL *synchronously* and
     * writes it to the specified temp file.
     *
     * This is exposed from Java only because we don't want to add a C++ networking library dependency
     *
     * NB: The caller is responsible for deleting the file specified by outFileName when they're done
     * with it.
     * NB: We write to a temp file instead of returning a String because, depending on the size of the
     * worker script, allocating the full script string on the Java heap can cause an OOM.
     */
    public static void downloadScriptToFileSync(String url, String outFileName) {
        if (!ReactBuildConfig.DEBUG) {
            throw new RuntimeException(
                    "For security reasons, downloading scripts is only allowed in debug builds.");
        }

        OkHttpClient client = new OkHttpClient();
        final File out = new File(outFileName);

        Request request = new Request.Builder().url(url).build();

        try {
            Response response = client.newCall(request).execute();

            Sink output = Okio.sink(out);
            Okio.buffer(response.body().source()).readAll(output);
        } catch (IOException e) {
            throw new RuntimeException("Exception downloading web worker script to file", e);
        }
    }
}