extensions/browser/serial_extension_host_queue.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "extensions/browser/serial_extension_host_queue.h"
   6
   7 #include "base/bind.h"
   8 #include "base/message_loop/message_loop.h"
   9 #include "base/strings/string_number_conversions.h"
  10 #include "base/time/time.h"
  11 #include "components/variations/variations_associated_data.h"
  12 #include "extensions/browser/deferred_start_render_host.h"
  13
  14 namespace extensions {
  15
  16 namespace {
  17
  18 // Gets the number of milliseconds to delay between loading ExtensionHosts. By
  19 // default this is 0, but it can be overridden by field trials.
  20 int GetDelayMs() {
  21   // A sanity check for the maximum delay, to guard against a bad field trial
  22   // config being pushed that delays loading too much (e.g. using wrong units).
  23   static const int kMaxDelayMs = 30 * 1000;
  24   static int delay_ms = -1;
  25   if (delay_ms == -1) {
  26     std::string delay_ms_param =
  27         variations::GetVariationParamValue("ExtensionSpeed", "SerialEHQDelay");
  28     if (delay_ms_param.empty()) {
  29       delay_ms = 0;
  30     } else if (!base::StringToInt(delay_ms_param, &delay_ms)) {
  31       LOG(ERROR) << "Could not parse SerialEHQDelay: " << delay_ms_param;
  32       delay_ms = 0;
  33     } else if (delay_ms < 0 || delay_ms > kMaxDelayMs) {
  34       LOG(ERROR) << "SerialEHQDelay out of range: " << delay_ms;
  35       delay_ms = 0;
  36     }
  37   }
  38   return delay_ms;
  39 }
  40
  41 }  // namespace
  42
  43 SerialExtensionHostQueue::SerialExtensionHostQueue()
  44     : pending_create_(false), ptr_factory_(this) {
  45 }
  46
  47 SerialExtensionHostQueue::~SerialExtensionHostQueue() {
  48 }
  49
  50 void SerialExtensionHostQueue::Add(DeferredStartRenderHost* host) {
  51   queue_.push_back(host);
  52   PostTask();
  53 }
  54
  55 void SerialExtensionHostQueue::Remove(DeferredStartRenderHost* host) {
  56   std::list<DeferredStartRenderHost*>::iterator it =
  57       std::find(queue_.begin(), queue_.end(), host);
  58   if (it != queue_.end())
  59     queue_.erase(it);
  60 }
  61
  62 void SerialExtensionHostQueue::PostTask() {
  63   if (!pending_create_) {
  64     base::MessageLoop::current()->PostDelayedTask(
  65         FROM_HERE, base::Bind(&SerialExtensionHostQueue::ProcessOneHost,
  66                               ptr_factory_.GetWeakPtr()),
  67         base::TimeDelta::FromMilliseconds(GetDelayMs()));
  68     pending_create_ = true;
  69   }
  70 }
  71
  72 void SerialExtensionHostQueue::ProcessOneHost() {
  73   pending_create_ = false;
  74   if (queue_.empty())
  75     return;  // can happen on shutdown
  76
  77   queue_.front()->CreateRenderViewNow();
  78   queue_.pop_front();
  79
  80   if (!queue_.empty())
  81     PostTask();
  82 }
  83
  84 }  // namespace extensions