chrome/renderer/net/renderer_net_predictor.cc

   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/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
  19 using content::RenderThread;
  20
  21 // The number of hostnames submitted to Browser DNS resolver per call to
  22 // SubmitHostsnames() (which reads names from our queue).
  23 static const size_t kMAX_SUBMISSION_PER_TASK = 30;
  24
  25 RendererNetPredictor::RendererNetPredictor()
  26     : c_string_queue_(1000),
  27       weak_factory_(this) {
  28   Reset();
  29 }
  30
  31 RendererNetPredictor::~RendererNetPredictor() {
  32 }
  33
  34 void 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!
  43 void 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.
  73 void 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.
 103 void 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
 131 void 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.
 155 bool 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 }