1 files changed, 418 insertions, 0 deletions
diff --git a/devtools/shared/webconsole/throttle.js b/devtools/shared/webconsole/throttle.js
new file mode 100644
index 000000000..3a875ee24
--- /dev/null
+++ b/devtools/shared/webconsole/throttle.js
@@ -0,0 +1,418 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ft= javascript ts=2 et sw=2 tw=80: */
+/* 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, Cc} = require("chrome");
+
+const ArrayBufferInputStream = CC("@mozilla.org/io/arraybuffer-input-stream;1",
+                                  "nsIArrayBufferInputStream");
+const BinaryInputStream = CC("@mozilla.org/binaryinputstream;1",
+                             "nsIBinaryInputStream", "setInputStream");
+
+loader.lazyServiceGetter(this, "gActivityDistributor",
+                         "@mozilla.org/network/http-activity-distributor;1",
+                         "nsIHttpActivityDistributor");
+
+const {XPCOMUtils} = require("resource://gre/modules/XPCOMUtils.jsm");
+const {setTimeout} = Cu.import("resource://gre/modules/Timer.jsm", {});
+
+/**
+ * Construct a new nsIStreamListener that buffers data and provides a
+ * method to notify another listener when data is available.  This is
+ * used to throttle network data on a per-channel basis.
+ *
+ * After construction, @see setOriginalListener must be called on the
+ * new object.
+ *
+ * @param {NetworkThrottleQueue} queue the NetworkThrottleQueue to
+ *        which status changes should be reported
+ */
+function NetworkThrottleListener(queue) {
+  this.queue = queue;
+  this.pendingData = [];
+  this.pendingException = null;
+  this.offset = 0;
+  this.responseStarted = false;
+  this.activities = {};
+}
+
+NetworkThrottleListener.prototype = {
+  QueryInterface:
+    XPCOMUtils.generateQI([Ci.nsIStreamListener, Ci.nsIInterfaceRequestor,
+                           Ci.nsISupports]),
+
+  /**
+   * Set the original listener for this object.  The original listener
+   * will receive requests from this object when the queue allows data
+   * through.
+   *
+   * @param {nsIStreamListener} originalListener the original listener
+   *        for the channel, to which all requests will be sent
+   */
+  setOriginalListener: function (originalListener) {
+    this.originalListener = originalListener;
+  },
+
+  /**
+   * @see nsIStreamListener.onStartRequest.
+   */
+  onStartRequest: function (request, context) {
+    this.originalListener.onStartRequest(request, context);
+    this.queue.start(this);
+  },
+
+  /**
+   * @see nsIStreamListener.onStopRequest.
+   */
+  onStopRequest: function (request, context, statusCode) {
+    this.pendingData.push({request, context, statusCode});
+    this.queue.dataAvailable(this);
+  },
+
+  /**
+   * @see nsIStreamListener.onDataAvailable.
+   */
+  onDataAvailable: function (request, context, inputStream, offset, count) {
+    if (this.pendingException) {
+      throw this.pendingException;
+    }
+
+    const bin = new BinaryInputStream(inputStream);
+    const bytes = new ArrayBuffer(count);
+    bin.readArrayBuffer(count, bytes);
+
+    const stream = new ArrayBufferInputStream();
+    stream.setData(bytes, 0, count);
+
+    this.pendingData.push({request, context, stream, count});
+    this.queue.dataAvailable(this);
+  },
+
+  /**
+   * Allow some buffered data from this object to be forwarded to this
+   * object's originalListener.
+   *
+   * @param {Number} bytesPermitted The maximum number of bytes
+   *        permitted to be sent.
+   * @return {Object} an object of the form {length, done}, where
+   *         |length| is the number of bytes actually forwarded, and
+   *         |done| is a boolean indicating whether this particular
+   *         request has been completed.  (A NetworkThrottleListener
+   *         may be queued multiple times, so this does not mean that
+   *         all available data has been sent.)
+   */
+  sendSomeData: function (bytesPermitted) {
+    if (this.pendingData.length === 0) {
+      // Shouldn't happen.
+      return {length: 0, done: true};
+    }
+
+    const {request, context, stream, count, statusCode} = this.pendingData[0];
+
+    if (statusCode !== undefined) {
+      this.pendingData.shift();
+      this.originalListener.onStopRequest(request, context, statusCode);
+      return {length: 0, done: true};
+    }
+
+    if (bytesPermitted > count) {
+      bytesPermitted = count;
+    }
+
+    try {
+      this.originalListener.onDataAvailable(request, context, stream,
+                                            this.offset, bytesPermitted);
+    } catch (e) {
+      this.pendingException = e;
+    }
+
+    let done = false;
+    if (bytesPermitted === count) {
+      this.pendingData.shift();
+      done = true;
+    } else {
+      this.pendingData[0].count -= bytesPermitted;
+    }
+
+    this.offset += bytesPermitted;
+    // Maybe our state has changed enough to emit an event.
+    this.maybeEmitEvents();
+
+    return {length: bytesPermitted, done};
+  },
+
+  /**
+   * Return the number of pending data requests available for this
+   * listener.
+   */
+  pendingCount: function () {
+    return this.pendingData.length;
+  },
+
+  /**
+   * This is called when an http activity event is delivered.  This
+   * object delays the event until the appropriate moment.
+   */
+  addActivityCallback: function (callback, httpActivity, channel, activityType,
+                                 activitySubtype, timestamp, extraSizeData,
+                                 extraStringData) {
+    let datum = {callback, httpActivity, channel, activityType,
+                 activitySubtype, extraSizeData,
+                 extraStringData};
+    this.activities[activitySubtype] = datum;
+
+    if (activitySubtype ===
+        gActivityDistributor.ACTIVITY_SUBTYPE_RESPONSE_COMPLETE) {
+      this.totalSize = extraSizeData;
+    }
+
+    this.maybeEmitEvents();
+  },
+
+  /**
+   * This is called for a download throttler when the latency timeout
+   * has ended.
+   */
+  responseStart: function () {
+    this.responseStarted = true;
+    this.maybeEmitEvents();
+  },
+
+  /**
+   * Check our internal state and emit any http activity events as
+   * needed.  Note that we wait until both our internal state has
+   * changed and we've received the real http activity event from
+   * platform.  This approach ensures we can both pass on the correct
+   * data from the original event, and update the reported time to be
+   * consistent with the delay we're introducing.
+   */
+  maybeEmitEvents: function () {
+    if (this.responseStarted) {
+      this.maybeEmit(gActivityDistributor.ACTIVITY_SUBTYPE_RESPONSE_START);
+      this.maybeEmit(gActivityDistributor.ACTIVITY_SUBTYPE_RESPONSE_HEADER);
+    }
+
+    if (this.totalSize !== undefined && this.offset >= this.totalSize) {
+      this.maybeEmit(gActivityDistributor.ACTIVITY_SUBTYPE_RESPONSE_COMPLETE);
+      this.maybeEmit(gActivityDistributor.ACTIVITY_SUBTYPE_TRANSACTION_CLOSE);
+    }
+  },
+
+  /**
+   * Emit an event for |code|, if the appropriate entry in
+   * |activities| is defined.
+   */
+  maybeEmit: function (code) {
+    if (this.activities[code] !== undefined) {
+      let {callback, httpActivity, channel, activityType,
+           activitySubtype, extraSizeData,
+           extraStringData} = this.activities[code];
+      let now = Date.now() * 1000;
+      callback(httpActivity, channel, activityType, activitySubtype,
+               now, extraSizeData, extraStringData);
+      this.activities[code] = undefined;
+    }
+  },
+};
+
+/**
+ * Construct a new queue that can be used to throttle the network for
+ * a group of related network requests.
+ *
+ * meanBPS {Number} Mean bytes per second.
+ * maxBPS {Number} Maximum bytes per second.
+ * roundTripTimeMean {Number} Mean round trip time in milliseconds.
+ * roundTripTimeMax {Number} Maximum round trip time in milliseconds.
+ */
+function NetworkThrottleQueue(meanBPS, maxBPS,
+                              roundTripTimeMean, roundTripTimeMax) {
+  this.meanBPS = meanBPS;
+  this.maxBPS = maxBPS;
+  this.roundTripTimeMean = roundTripTimeMean;
+  this.roundTripTimeMax = roundTripTimeMax;
+
+  this.pendingRequests = new Set();
+  this.downloadQueue = [];
+  this.previousReads = [];
+
+  this.pumping = false;
+}
+
+NetworkThrottleQueue.prototype = {
+  /**
+   * A helper function that, given a mean and a maximum, returns a
+   * random integer between (mean - (max - mean)) and max.
+   */
+  random: function (mean, max) {
+    return mean - (max - mean) + Math.floor(2 * (max - mean) * Math.random());
+  },
+
+  /**
+   * A helper function that lets the indicating listener start sending
+   * data.  This is called after the initial round trip time for the
+   * listener has elapsed.
+   */
+  allowDataFrom: function (throttleListener) {
+    throttleListener.responseStart();
+    this.pendingRequests.delete(throttleListener);
+    const count = throttleListener.pendingCount();
+    for (let i = 0; i < count; ++i) {
+      this.downloadQueue.push(throttleListener);
+    }
+    this.pump();
+  },
+
+  /**
+   * Notice a new listener object.  This is called by the
+   * NetworkThrottleListener when the request has started.  Initially
+   * a new listener object is put into a "pending" state, until the
+   * round-trip time has elapsed.  This is used to simulate latency.
+   *
+   * @param {NetworkThrottleListener} throttleListener the new listener
+   */
+  start: function (throttleListener) {
+    this.pendingRequests.add(throttleListener);
+    let delay = this.random(this.roundTripTimeMean, this.roundTripTimeMax);
+    if (delay > 0) {
+      setTimeout(() => this.allowDataFrom(throttleListener), delay);
+    } else {
+      this.allowDataFrom(throttleListener);
+    }
+  },
+
+  /**
+   * Note that new data is available for a given listener.  Each time
+   * data is available, the listener will be re-queued.
+   *
+   * @param {NetworkThrottleListener} throttleListener the listener
+   *        which has data available.
+   */
+  dataAvailable: function (throttleListener) {
+    if (!this.pendingRequests.has(throttleListener)) {
+      this.downloadQueue.push(throttleListener);
+      this.pump();
+    }
+  },
+
+  /**
+   * An internal function that permits individual listeners to send
+   * data.
+   */
+  pump: function () {
+    // A redirect will cause two NetworkThrottleListeners to be on a
+    // listener chain.  In this case, we might recursively call into
+    // this method.  Avoid infinite recursion here.
+    if (this.pumping) {
+      return;
+    }
+    this.pumping = true;
+
+    const now = Date.now();
+    const oneSecondAgo = now - 1000;
+
+    while (this.previousReads.length &&
+           this.previousReads[0].when < oneSecondAgo) {
+      this.previousReads.shift();
+    }
+
+    const totalBytes = this.previousReads.reduce((sum, elt) => {
+      return sum + elt.numBytes;
+    }, 0);
+
+    let thisSliceBytes = this.random(this.meanBPS, this.maxBPS);
+    if (totalBytes < thisSliceBytes) {
+      thisSliceBytes -= totalBytes;
+      let readThisTime = 0;
+      while (thisSliceBytes > 0 && this.downloadQueue.length) {
+        let {length, done} = this.downloadQueue[0].sendSomeData(thisSliceBytes);
+        thisSliceBytes -= length;
+        readThisTime += length;
+        if (done) {
+          this.downloadQueue.shift();
+        }
+      }
+      this.previousReads.push({when: now, numBytes: readThisTime});
+    }
+
+    // If there is more data to download, then schedule ourselves for
+    // one second after the oldest previous read.
+    if (this.downloadQueue.length) {
+      const when = this.previousReads[0].when + 1000;
+      setTimeout(this.pump.bind(this), when - now);
+    }
+
+    this.pumping = false;
+  },
+};
+
+/**
+ * Construct a new object that can be used to throttle the network for
+ * a group of related network requests.
+ *
+ * @param {Object} An object with the following attributes:
+ * roundTripTimeMean {Number} Mean round trip time in milliseconds.
+ * roundTripTimeMax {Number} Maximum round trip time in milliseconds.
+ * downloadBPSMean {Number} Mean bytes per second for downloads.
+ * downloadBPSMax {Number} Maximum bytes per second for downloads.
+ * uploadBPSMean {Number} Mean bytes per second for uploads.
+ * uploadBPSMax {Number} Maximum bytes per second for uploads.
+ *
+ * Download throttling will not be done if downloadBPSMean and
+ * downloadBPSMax are <= 0.  Upload throttling will not be done if
+ * uploadBPSMean and uploadBPSMax are <= 0.
+ */
+function NetworkThrottleManager({roundTripTimeMean, roundTripTimeMax,
+                                 downloadBPSMean, downloadBPSMax,
+                                 uploadBPSMean, uploadBPSMax}) {
+  if (downloadBPSMax <= 0 && downloadBPSMean <= 0) {
+    this.downloadQueue = null;
+  } else {
+    this.downloadQueue =
+      new NetworkThrottleQueue(downloadBPSMean, downloadBPSMax,
+                               roundTripTimeMean, roundTripTimeMax);
+  }
+  if (uploadBPSMax <= 0 && uploadBPSMean <= 0) {
+    this.uploadQueue = null;
+  } else {
+    this.uploadQueue = Cc["@mozilla.org/network/throttlequeue;1"]
+      .createInstance(Ci.nsIInputChannelThrottleQueue);
+    this.uploadQueue.init(uploadBPSMean, uploadBPSMax);
+  }
+}
+exports.NetworkThrottleManager = NetworkThrottleManager;
+
+NetworkThrottleManager.prototype = {
+  /**
+   * Create a new NetworkThrottleListener for a given channel and
+   * install it using |setNewListener|.
+   *
+   * @param {nsITraceableChannel} channel the channel to manage
+   * @return {NetworkThrottleListener} the new listener, or null if
+   *         download throttling is not being done.
+   */
+  manage: function (channel) {
+    if (this.downloadQueue) {
+      let listener = new NetworkThrottleListener(this.downloadQueue);
+      let originalListener = channel.setNewListener(listener);
+      listener.setOriginalListener(originalListener);
+      return listener;
+    }
+    return null;
+  },
+
+  /**
+   * Throttle uploads taking place on the given channel.
+   *
+   * @param {nsITraceableChannel} channel the channel to manage
+   */
+  manageUpload: function (channel) {
+    if (this.uploadQueue) {
+      channel = channel.QueryInterface(Ci.nsIThrottledInputChannel);
+      channel.throttleQueue = this.uploadQueue;
+    }
+  },
+};