tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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heap-snapshot-file.js (2508B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 
      5 "use strict";
      6 
      7 const { Actor } = require("resource://devtools/shared/protocol.js");
      8 const {
      9  heapSnapshotFileSpec,
     10 } = require("resource://devtools/shared/specs/heap-snapshot-file.js");
     11 
     12 loader.lazyRequireGetter(
     13  this,
     14  "DevToolsUtils",
     15  "resource://devtools/shared/DevToolsUtils.js"
     16 );
     17 loader.lazyRequireGetter(
     18  this,
     19  "HeapSnapshotFileUtils",
     20  "resource://devtools/shared/heapsnapshot/HeapSnapshotFileUtils.js"
     21 );
     22 
     23 /**
     24 * The HeapSnapshotFileActor handles transferring heap snapshot files from the
     25 * server to the client. This has to be a global actor in the parent process
     26 * because child processes are sandboxed and do not have access to the file
     27 * system.
     28 */
     29 exports.HeapSnapshotFileActor = class HeapSnapshotFileActor extends Actor {
     30  constructor(conn) {
     31    super(conn, heapSnapshotFileSpec);
     32 
     33    if (
     34      Services.appinfo.processType !== Services.appinfo.PROCESS_TYPE_DEFAULT
     35    ) {
     36      const err = new Error(
     37        "Attempt to create a HeapSnapshotFileActor in a " +
     38          "child process! The HeapSnapshotFileActor *MUST* " +
     39          "be in the parent process!"
     40      );
     41      DevToolsUtils.reportException("HeapSnapshotFileActor's constructor", err);
     42    }
     43  }
     44 
     45  /**
     46   * @see MemoryFront.prototype.transferHeapSnapshot
     47   *
     48   * @param {string} snapshotId
     49   *        The ID returned by MemoryActor's saveHeapSnapshot method.
     50   * @param {Function} startBulkSend
     51   *        Function provided by protocol.js Actor framework to initiate
     52   *        the bulk reply. This methods returns a promise resolving to
     53   *        a StreamCopier instance, whose `copyFrom` method allows
     54   *        to send the data back to the client via an input stream.
     55   */
     56  async transferHeapSnapshot(snapshotId, startBulkSend) {
     57    const snapshotFilePath =
     58      HeapSnapshotFileUtils.getHeapSnapshotTempFilePath(snapshotId);
     59    if (!snapshotFilePath) {
     60      throw new Error(`No heap snapshot with id: ${snapshotId}`);
     61    }
     62 
     63    const streamPromise = DevToolsUtils.openFileStream(snapshotFilePath);
     64 
     65    const { size } = await IOUtils.stat(snapshotFilePath);
     66    const bulkPromise = startBulkSend(size);
     67 
     68    const [bulk, stream] = await Promise.all([bulkPromise, streamPromise]);
     69 
     70    try {
     71      await bulk.copyFrom(stream);
     72    } finally {
     73      stream.close();
     74    }
     75  }
     76 };