renderer_net_predictor.cc revision c2e0dbddbe15c98d52c4786dac06cb8952a8ae6d
1// Copyright (c) 2012 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// See header file for description of RendererNetPredictor class
6
7#include "chrome/renderer/net/renderer_net_predictor.h"
8
9#include <ctype.h>
10
11#include "base/bind.h"
12#include "base/logging.h"
13#include "base/message_loop.h"
14#include "chrome/common/net/predictor_common.h"
15#include "chrome/common/render_messages.h"
16#include "chrome/renderer/net/predictor_queue.h"
17#include "content/public/renderer/render_thread.h"
18
19using content::RenderThread;
20
21// The number of hostnames submitted to Browser DNS resolver per call to
22// SubmitHostsnames() (which reads names from our queue).
23static const size_t kMAX_SUBMISSION_PER_TASK = 30;
24
25RendererNetPredictor::RendererNetPredictor()
26    : c_string_queue_(1000),
27      weak_factory_(this) {
28  Reset();
29}
30
31RendererNetPredictor::~RendererNetPredictor() {
32}
33
34void RendererNetPredictor::Reset() {
35  domain_map_.clear();
36  c_string_queue_.Clear();
37  buffer_full_discard_count_ = 0;
38  numeric_ip_discard_count_ = 0;
39  new_name_count_ = 0;
40}
41
42// Push names into queue quickly!
43void RendererNetPredictor::Resolve(const char* name, size_t length) {
44  if (!length)
45    return;  // Don't store empty strings in buffer.
46  if (is_numeric_ip(name, length))
47    return;  // Numeric IPs have no DNS lookup significance.
48
49  size_t old_size =  c_string_queue_.Size();
50  DnsQueue::PushResult result = c_string_queue_.Push(name, length);
51  if (DnsQueue::SUCCESSFUL_PUSH == result) {
52    if (1 == c_string_queue_.Size()) {
53      DCHECK_EQ(old_size, 0u);
54      if (0 != old_size)
55        return;  // Overkill safety net: Don't send too many InvokeLater's.
56      weak_factory_.InvalidateWeakPtrs();
57      RenderThread::Get()->GetMessageLoop()->PostDelayedTask(
58          FROM_HERE, base::Bind(&RendererNetPredictor::SubmitHostnames,
59                                weak_factory_.GetWeakPtr()),
60          base::TimeDelta::FromMilliseconds(10));
61    }
62    return;
63  }
64  if (DnsQueue::OVERFLOW_PUSH == result) {
65    ++buffer_full_discard_count_;
66    return;
67  }
68  DCHECK(DnsQueue::REDUNDANT_PUSH == result);
69}
70
71// Extract data from the Queue, and then send it off the the Browser process
72// to be resolved.
73void RendererNetPredictor::SubmitHostnames() {
74  // Get all names out of the C_string_queue (into our map)
75  ExtractBufferedNames();
76  // TBD: IT could be that we should only extract about as many names as we are
77  // going to send to the browser.  That would cause a "silly" page with a TON
78  // of URLs to start to overrun the DnsQueue, which will cause the names to
79  // be dropped (not stored in the queue).  By fetching ALL names, we are
80  // taking on a lot of work, which may take a long time to process... perhaps
81  // longer than the page may be visible!?!?!  If we implement a better
82  // mechanism for doing domain_map.clear() (see end of this method), then
83  // we'd automatically flush such pending work from a ridiculously link-filled
84  // page.
85
86  // Don't overload the browser DNS lookup facility, or take too long here,
87  // by only sending off kMAX_SUBMISSION_PER_TASK names to the Browser.
88  // This will help to avoid overloads when a page has a TON of links.
89  DnsPrefetchNames(kMAX_SUBMISSION_PER_TASK);
90  if (new_name_count_ > 0 || 0 < c_string_queue_.Size()) {
91    weak_factory_.InvalidateWeakPtrs();
92    RenderThread::Get()->GetMessageLoop()->PostDelayedTask(
93        FROM_HERE, base::Bind(&RendererNetPredictor::SubmitHostnames,
94                              weak_factory_.GetWeakPtr()),
95        base::TimeDelta::FromMilliseconds(10));
96  } else {
97    // TODO(JAR): Should we only clear the map when we navigate, or reload?
98    domain_map_.clear();
99  }
100}
101
102// Pull some hostnames from the queue, and add them to our map.
103void RendererNetPredictor::ExtractBufferedNames(size_t size_goal) {
104  size_t count(0);  // Number of entries to find (0 means find all).
105  if (size_goal > 0) {
106    if (size_goal <= domain_map_.size())
107      return;  // Size goal was met.
108    count = size_goal - domain_map_.size();
109  }
110
111  std::string name;
112  while (c_string_queue_.Pop(&name)) {
113    DCHECK_NE(name.size(), 0u);
114    // We don't put numeric IP names into buffer.
115    DCHECK(!is_numeric_ip(name.c_str(), name.size()));
116    DomainUseMap::iterator it;
117    it = domain_map_.find(name);
118    if (domain_map_.end() == it) {
119      domain_map_[name] = kPending;
120      ++new_name_count_;
121      if (0 == count) continue;  // Until buffer is empty.
122      if (1 == count) break;  // We found size_goal.
123      DCHECK_GT(count, 1u);
124      --count;
125    } else {
126      DCHECK(kPending == it->second || kLookupRequested == it->second);
127    }
128  }
129}
130
131void RendererNetPredictor::DnsPrefetchNames(size_t max_count) {
132  // We are on the renderer thread, and just need to send things to the browser.
133  chrome_common_net::NameList names;
134  for (DomainUseMap::iterator it = domain_map_.begin();
135    it != domain_map_.end();
136    ++it) {
137    if (0 == (it->second & kLookupRequested)) {
138      it->second |= kLookupRequested;
139      names.push_back(it->first);
140      if (0 == max_count) continue;  // Get all, independent of count.
141      if (1 == max_count) break;
142      --max_count;
143      DCHECK_GE(max_count, 1u);
144    }
145  }
146  DCHECK_GE(new_name_count_, names.size());
147  new_name_count_ -= names.size();
148
149  RenderThread::Get()->Send(new ChromeViewHostMsg_DnsPrefetch(names));
150}
151
152// is_numeric_ip() checks to see if all characters in name are either numeric,
153// or dots.  Such a name will not actually be passed to DNS, as it is an IP
154// address.
155bool RendererNetPredictor::is_numeric_ip(const char* name, size_t length) {
156  // Scan for a character outside our lookup list.
157  while (length-- > 0) {
158    if (!isdigit(*name) && '.' != *name)
159      return false;
160    ++name;
161  }
162  return true;
163}
164