import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

devtools/server/performance/memory.js

@@ -0,0 +1,425 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const { Cc, Ci, Cu } = require("chrome");
+const { reportException } = require("devtools/shared/DevToolsUtils");
+const { Class } = require("sdk/core/heritage");
+const { expectState } = require("devtools/server/actors/common");
+loader.lazyRequireGetter(this, "events", "sdk/event/core");
+loader.lazyRequireGetter(this, "EventTarget", "sdk/event/target", true);
+loader.lazyRequireGetter(this, "DeferredTask",
+  "resource://gre/modules/DeferredTask.jsm", true);
+loader.lazyRequireGetter(this, "StackFrameCache",
+  "devtools/server/actors/utils/stack", true);
+loader.lazyRequireGetter(this, "ThreadSafeChromeUtils");
+loader.lazyRequireGetter(this, "HeapSnapshotFileUtils",
+  "devtools/shared/heapsnapshot/HeapSnapshotFileUtils");
+loader.lazyRequireGetter(this, "ChromeActor", "devtools/server/actors/chrome",
+                         true);
+loader.lazyRequireGetter(this, "ChildProcessActor",
+                         "devtools/server/actors/child-process", true);
+
+/**
+ * A class that returns memory data for a parent actor's window.
+ * Using a tab-scoped actor with this instance will measure the memory footprint of its
+ * parent tab. Using a global-scoped actor instance however, will measure the memory
+ * footprint of the chrome window referenced by its root actor.
+ *
+ * To be consumed by actor's, like MemoryActor using this module to
+ * send information over RDP, and TimelineActor for using more light-weight
+ * utilities like GC events and measuring memory consumption.
+ */
+var Memory = exports.Memory = Class({
+  extends: EventTarget,
+
+  /**
+   * Requires a root actor and a StackFrameCache.
+   */
+  initialize: function (parent, frameCache = new StackFrameCache()) {
+    this.parent = parent;
+    this._mgr = Cc["@mozilla.org/memory-reporter-manager;1"]
+                  .getService(Ci.nsIMemoryReporterManager);
+    this.state = "detached";
+    this._dbg = null;
+    this._frameCache = frameCache;
+
+    this._onGarbageCollection = this._onGarbageCollection.bind(this);
+    this._emitAllocations = this._emitAllocations.bind(this);
+    this._onWindowReady = this._onWindowReady.bind(this);
+
+    events.on(this.parent, "window-ready", this._onWindowReady);
+  },
+
+  destroy: function () {
+    events.off(this.parent, "window-ready", this._onWindowReady);
+
+    this._mgr = null;
+    if (this.state === "attached") {
+      this.detach();
+    }
+  },
+
+  get dbg() {
+    if (!this._dbg) {
+      this._dbg = this.parent.makeDebugger();
+    }
+    return this._dbg;
+  },
+
+  /**
+   * Attach to this MemoryBridge.
+   *
+   * This attaches the MemoryBridge's Debugger instance so that you can start
+   * recording allocations or take a census of the heap. In addition, the
+   * MemoryBridge will start emitting GC events.
+   */
+  attach: expectState("detached", function () {
+    this.dbg.addDebuggees();
+    this.dbg.memory.onGarbageCollection = this._onGarbageCollection.bind(this);
+    this.state = "attached";
+  }, "attaching to the debugger"),
+
+  /**
+   * Detach from this MemoryBridge.
+   */
+  detach: expectState("attached", function () {
+    this._clearDebuggees();
+    this.dbg.enabled = false;
+    this._dbg = null;
+    this.state = "detached";
+  }, "detaching from the debugger"),
+
+  /**
+   * Gets the current MemoryBridge attach/detach state.
+   */
+  getState: function () {
+    return this.state;
+  },
+
+  _clearDebuggees: function () {
+    if (this._dbg) {
+      if (this.isRecordingAllocations()) {
+        this.dbg.memory.drainAllocationsLog();
+      }
+      this._clearFrames();
+      this.dbg.removeAllDebuggees();
+    }
+  },
+
+  _clearFrames: function () {
+    if (this.isRecordingAllocations()) {
+      this._frameCache.clearFrames();
+    }
+  },
+
+  /**
+   * Handler for the parent actor's "window-ready" event.
+   */
+  _onWindowReady: function ({ isTopLevel }) {
+    if (this.state == "attached") {
+      this._clearDebuggees();
+      if (isTopLevel && this.isRecordingAllocations()) {
+        this._frameCache.initFrames();
+      }
+      this.dbg.addDebuggees();
+    }
+  },
+
+  /**
+   * Returns a boolean indicating whether or not allocation
+   * sites are being tracked.
+   */
+  isRecordingAllocations: function () {
+    return this.dbg.memory.trackingAllocationSites;
+  },
+
+  /**
+   * Save a heap snapshot scoped to the current debuggees' portion of the heap
+   * graph.
+   *
+   * @param {Object|null} boundaries
+   *
+   * @returns {String} The snapshot id.
+   */
+  saveHeapSnapshot: expectState("attached", function (boundaries = null) {
+    // If we are observing the whole process, then scope the snapshot
+    // accordingly. Otherwise, use the debugger's debuggees.
+    if (!boundaries) {
+      boundaries = this.parent instanceof ChromeActor || this.parent instanceof ChildProcessActor
+        ? { runtime: true }
+        : { debugger: this.dbg };
+    }
+    const path = ThreadSafeChromeUtils.saveHeapSnapshot(boundaries);
+    return HeapSnapshotFileUtils.getSnapshotIdFromPath(path);
+  }, "saveHeapSnapshot"),
+
+  /**
+   * Take a census of the heap. See js/src/doc/Debugger/Debugger.Memory.md for
+   * more information.
+   */
+  takeCensus: expectState("attached", function () {
+    return this.dbg.memory.takeCensus();
+  }, "taking census"),
+
+  /**
+   * Start recording allocation sites.
+   *
+   * @param {number} options.probability
+   *                 The probability we sample any given allocation when recording allocations.
+   *                 Must be between 0 and 1 -- defaults to 1.
+   * @param {number} options.maxLogLength
+   *                 The maximum number of allocation events to keep in the
+   *                 log. If new allocs occur while at capacity, oldest
+   *                 allocations are lost. Must fit in a 32 bit signed integer.
+   * @param {number} options.drainAllocationsTimeout
+   *                 A number in milliseconds of how often, at least, an `allocation` event
+   *                 gets emitted (and drained), and also emits and drains on every GC event,
+   *                 resetting the timer.
+   */
+  startRecordingAllocations: expectState("attached", function (options = {}) {
+    if (this.isRecordingAllocations()) {
+      return this._getCurrentTime();
+    }
+
+    this._frameCache.initFrames();
+
+    this.dbg.memory.allocationSamplingProbability = options.probability != null
+      ? options.probability
+      : 1.0;
+
+    this.drainAllocationsTimeoutTimer = typeof options.drainAllocationsTimeout === "number" ? options.drainAllocationsTimeout : null;
+
+    if (this.drainAllocationsTimeoutTimer != null) {
+      if (this._poller) {
+        this._poller.disarm();
+      }
+      this._poller = new DeferredTask(this._emitAllocations, this.drainAllocationsTimeoutTimer);
+      this._poller.arm();
+    }
+
+    if (options.maxLogLength != null) {
+      this.dbg.memory.maxAllocationsLogLength = options.maxLogLength;
+    }
+    this.dbg.memory.trackingAllocationSites = true;
+
+    return this._getCurrentTime();
+  }, "starting recording allocations"),
+
+  /**
+   * Stop recording allocation sites.
+   */
+  stopRecordingAllocations: expectState("attached", function () {
+    if (!this.isRecordingAllocations()) {
+      return this._getCurrentTime();
+    }
+    this.dbg.memory.trackingAllocationSites = false;
+    this._clearFrames();
+
+    if (this._poller) {
+      this._poller.disarm();
+      this._poller = null;
+    }
+
+    return this._getCurrentTime();
+  }, "stopping recording allocations"),
+
+  /**
+   * Return settings used in `startRecordingAllocations` for `probability`
+   * and `maxLogLength`. Currently only uses in tests.
+   */
+  getAllocationsSettings: expectState("attached", function () {
+    return {
+      maxLogLength: this.dbg.memory.maxAllocationsLogLength,
+      probability: this.dbg.memory.allocationSamplingProbability
+    };
+  }, "getting allocations settings"),
+
+  /**
+   * Get a list of the most recent allocations since the last time we got
+   * allocations, as well as a summary of all allocations since we've been
+   * recording.
+   *
+   * @returns Object
+   *          An object of the form:
+   *
+   *            {
+   *              allocations: [<index into "frames" below>, ...],
+   *              allocationsTimestamps: [
+   *                <timestamp for allocations[0]>,
+   *                <timestamp for allocations[1]>,
+   *                ...
+   *              ],
+   *              allocationSizes: [
+   *                <bytesize for allocations[0]>,
+   *                <bytesize for allocations[1]>,
+   *                ...
+   *              ],
+   *              frames: [
+   *                {
+   *                  line: <line number for this frame>,
+   *                  column: <column number for this frame>,
+   *                  source: <filename string for this frame>,
+   *                  functionDisplayName: <this frame's inferred function name function or null>,
+   *                  parent: <index into "frames">
+   *                },
+   *                ...
+   *              ],
+   *            }
+   *
+   *          The timestamps' unit is microseconds since the epoch.
+   *
+   *          Subsequent `getAllocations` request within the same recording and
+   *          tab navigation will always place the same stack frames at the same
+   *          indices as previous `getAllocations` requests in the same
+   *          recording. In other words, it is safe to use the index as a
+   *          unique, persistent id for its frame.
+   *
+   *          Additionally, the root node (null) is always at index 0.
+   *
+   *          We use the indices into the "frames" array to avoid repeating the
+   *          description of duplicate stack frames both when listing
+   *          allocations, and when many stacks share the same tail of older
+   *          frames. There shouldn't be any duplicates in the "frames" array,
+   *          as that would defeat the purpose of this compression trick.
+   *
+   *          In the future, we might want to split out a frame's "source" and
+   *          "functionDisplayName" properties out the same way we have split
+   *          frames out with the "frames" array. While this would further
+   *          compress the size of the response packet, it would increase CPU
+   *          usage to build the packet, and it should, of course, be guided by
+   *          profiling and done only when necessary.
+   */
+  getAllocations: expectState("attached", function () {
+    if (this.dbg.memory.allocationsLogOverflowed) {
+      // Since the last time we drained the allocations log, there have been
+      // more allocations than the log's capacity, and we lost some data. There
+      // isn't anything actionable we can do about this, but put a message in
+      // the browser console so we at least know that it occurred.
+      reportException("MemoryBridge.prototype.getAllocations",
+                      "Warning: allocations log overflowed and lost some data.");
+    }
+
+    const allocations = this.dbg.memory.drainAllocationsLog();
+    const packet = {
+      allocations: [],
+      allocationsTimestamps: [],
+      allocationSizes: [],
+    };
+    for (let { frame: stack, timestamp, size } of allocations) {
+      if (stack && Cu.isDeadWrapper(stack)) {
+        continue;
+      }
+
+      // Safe because SavedFrames are frozen/immutable.
+      let waived = Cu.waiveXrays(stack);
+
+      // Ensure that we have a form, size, and index for new allocations
+      // because we potentially haven't seen some or all of them yet. After this
+      // loop, we can rely on the fact that every frame we deal with already has
+      // its metadata stored.
+      let index = this._frameCache.addFrame(waived);
+
+      packet.allocations.push(index);
+      packet.allocationsTimestamps.push(timestamp);
+      packet.allocationSizes.push(size);
+    }
+
+    return this._frameCache.updateFramePacket(packet);
+  }, "getting allocations"),
+
+  /*
+   * Force a browser-wide GC.
+   */
+  forceGarbageCollection: function () {
+    for (let i = 0; i < 3; i++) {
+      Cu.forceGC();
+    }
+  },
+
+  /**
+   * Force an XPCOM cycle collection. For more information on XPCOM cycle
+   * collection, see
+   * https://developer.mozilla.org/en-US/docs/Interfacing_with_the_XPCOM_cycle_collector#What_the_cycle_collector_does
+   */
+  forceCycleCollection: function () {
+    Cu.forceCC();
+  },
+
+  /**
+   * A method that returns a detailed breakdown of the memory consumption of the
+   * associated window.
+   *
+   * @returns object
+   */
+  measure: function () {
+    let result = {};
+
+    let jsObjectsSize = {};
+    let jsStringsSize = {};
+    let jsOtherSize = {};
+    let domSize = {};
+    let styleSize = {};
+    let otherSize = {};
+    let totalSize = {};
+    let jsMilliseconds = {};
+    let nonJSMilliseconds = {};
+
+    try {
+      this._mgr.sizeOfTab(this.parent.window, jsObjectsSize, jsStringsSize, jsOtherSize,
+                          domSize, styleSize, otherSize, totalSize, jsMilliseconds, nonJSMilliseconds);
+      result.total = totalSize.value;
+      result.domSize = domSize.value;
+      result.styleSize = styleSize.value;
+      result.jsObjectsSize = jsObjectsSize.value;
+      result.jsStringsSize = jsStringsSize.value;
+      result.jsOtherSize = jsOtherSize.value;
+      result.otherSize = otherSize.value;
+      result.jsMilliseconds = jsMilliseconds.value.toFixed(1);
+      result.nonJSMilliseconds = nonJSMilliseconds.value.toFixed(1);
+    } catch (e) {
+      reportException("MemoryBridge.prototype.measure", e);
+    }
+
+    return result;
+  },
+
+  residentUnique: function () {
+    return this._mgr.residentUnique;
+  },
+
+  /**
+   * Handler for GC events on the Debugger.Memory instance.
+   */
+  _onGarbageCollection: function (data) {
+    events.emit(this, "garbage-collection", data);
+
+    // If `drainAllocationsTimeout` set, fire an allocations event with the drained log,
+    // which will restart the timer.
+    if (this._poller) {
+      this._poller.disarm();
+      this._emitAllocations();
+    }
+  },
+
+
+  /**
+   * Called on `drainAllocationsTimeoutTimer` interval if and only if set during `startRecordingAllocations`,
+   * or on a garbage collection event if drainAllocationsTimeout was set.
+   * Drains allocation log and emits as an event and restarts the timer.
+   */
+  _emitAllocations: function () {
+    events.emit(this, "allocations", this.getAllocations());
+    this._poller.arm();
+  },
+
+  /**
+   * Accesses the docshell to return the current process time.
+   */
+  _getCurrentTime: function () {
+    return (this.parent.isRootActor ? this.parent.docShell : this.parent.originalDocShell).now();
+  },
+
+});