net/base/sdch_dictionary_fetcher.cc

   1 // Copyright 2014 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 "net/base/sdch_dictionary_fetcher.h"
   6
   7 #include <stdint.h>
   8
   9 #include "base/auto_reset.h"
  10 #include "base/bind.h"
  11 #include "base/compiler_specific.h"
  12 #include "base/thread_task_runner_handle.h"
  13 #include "net/base/load_flags.h"
  14 #include "net/url_request/url_request_context.h"
  15 #include "net/url_request/url_request_status.h"
  16 #include "net/url_request/url_request_throttler_manager.h"
  17
  18 namespace {
  19
  20 const int kBufferSize = 4096;
  21
  22 }  // namespace
  23
  24 namespace net {
  25
  26 SdchDictionaryFetcher::SdchDictionaryFetcher(
  27     SdchFetcher::Delegate* consumer,
  28     URLRequestContext* context)
  29     : next_state_(STATE_NONE),
  30       in_loop_(false),
  31       consumer_(consumer),
  32       context_(context),
  33       weak_factory_(this) {
  34   DCHECK(CalledOnValidThread());
  35   DCHECK(consumer);
  36   DCHECK(context);
  37 }
  38
  39 SdchDictionaryFetcher::~SdchDictionaryFetcher() {
  40   DCHECK(CalledOnValidThread());
  41 }
  42
  43 void SdchDictionaryFetcher::Schedule(const GURL& dictionary_url) {
  44   DCHECK(CalledOnValidThread());
  45
  46   // Avoid pushing duplicate copy onto queue. We may fetch this url again later
  47   // and get a different dictionary, but there is no reason to have it in the
  48   // queue twice at one time.
  49   if (!fetch_queue_.empty() && fetch_queue_.back() == dictionary_url) {
  50     SdchManager::SdchErrorRecovery(
  51         SdchManager::DICTIONARY_ALREADY_SCHEDULED_TO_DOWNLOAD);
  52     return;
  53   }
  54   if (attempted_load_.find(dictionary_url) != attempted_load_.end()) {
  55     SdchManager::SdchErrorRecovery(
  56         SdchManager::DICTIONARY_ALREADY_TRIED_TO_DOWNLOAD);
  57     return;
  58   }
  59   attempted_load_.insert(dictionary_url);
  60   fetch_queue_.push(dictionary_url);
  61
  62   next_state_ = STATE_IDLE;
  63
  64   // There are no callbacks to user code from the dictionary fetcher,
  65   // and Schedule() is only called from user code, so this call to DoLoop()
  66   // does not require an |if (in_loop_) return;| guard.
  67   DoLoop(OK);
  68 }
  69
  70 void SdchDictionaryFetcher::Cancel() {
  71   DCHECK(CalledOnValidThread());
  72
  73   next_state_ = STATE_NONE;
  74
  75   while (!fetch_queue_.empty())
  76     fetch_queue_.pop();
  77   attempted_load_.clear();
  78   weak_factory_.InvalidateWeakPtrs();
  79   current_request_.reset(NULL);
  80   buffer_ = NULL;
  81   dictionary_.clear();
  82 }
  83
  84 void SdchDictionaryFetcher::OnResponseStarted(URLRequest* request) {
  85   DCHECK(CalledOnValidThread());
  86   DCHECK_EQ(request, current_request_.get());
  87   DCHECK_EQ(next_state_, STATE_REQUEST_STARTED);
  88
  89   // The response has started, so the stream can be read from.
  90   next_state_ = STATE_REQUEST_READING;
  91
  92   // If this function was synchronously called, the containing
  93   // state machine loop will handle the state transition. Otherwise,
  94   // restart the state machine loop.
  95   if (in_loop_)
  96     return;
  97
  98   DoLoop(request->status().error());
  99 }
 100
 101 void SdchDictionaryFetcher::OnReadCompleted(URLRequest* request,
 102                                             int bytes_read) {
 103   DCHECK(CalledOnValidThread());
 104   DCHECK_EQ(request, current_request_.get());
 105   DCHECK_EQ(next_state_, STATE_REQUEST_READING);
 106
 107   // No state transition is required in this function; the
 108   // completion of the request is detected in DoRead().
 109
 110   if (request->status().is_success())
 111     dictionary_.append(buffer_->data(), bytes_read);
 112
 113   // If this function was synchronously called, the containing
 114   // state machine loop will handle the state transition. Otherwise,
 115   // restart the state machine loop.
 116   if (in_loop_)
 117     return;
 118
 119   DoLoop(request->status().error());
 120 }
 121
 122 int SdchDictionaryFetcher::DoLoop(int rv) {
 123   DCHECK(!in_loop_);
 124   base::AutoReset<bool> auto_reset_in_loop(&in_loop_, true);
 125
 126   do {
 127     State state = next_state_;
 128     next_state_ = STATE_NONE;
 129     switch (state) {
 130       case STATE_IDLE:
 131         rv = DoDispatchRequest(rv);
 132         break;
 133       case STATE_REQUEST_STARTED:
 134         rv = DoRequestStarted(rv);
 135         break;
 136       case STATE_REQUEST_READING:
 137         rv = DoRead(rv);
 138         break;
 139       case STATE_REQUEST_COMPLETE:
 140         rv = DoCompleteRequest(rv);
 141         break;
 142       case STATE_NONE:
 143         NOTREACHED();
 144     }
 145   } while (rv != ERR_IO_PENDING && next_state_ != STATE_NONE);
 146
 147   return rv;
 148 }
 149
 150 int SdchDictionaryFetcher::DoDispatchRequest(int rv) {
 151   DCHECK(CalledOnValidThread());
 152
 153   // |rv| is ignored, as the result from the previous request doesn't
 154   // affect the next request.
 155
 156   if (fetch_queue_.empty() || current_request_.get()) {
 157     next_state_ = STATE_NONE;
 158     return OK;
 159   }
 160
 161   current_request_ = context_->CreateRequest(
 162       fetch_queue_.front(), IDLE, this, NULL);
 163   current_request_->SetLoadFlags(LOAD_DO_NOT_SEND_COOKIES |
 164                                  LOAD_DO_NOT_SAVE_COOKIES);
 165   buffer_ = new IOBuffer(kBufferSize);
 166   fetch_queue_.pop();
 167
 168   next_state_ = STATE_REQUEST_STARTED;
 169   current_request_->Start();
 170
 171   return OK;
 172 }
 173
 174 int SdchDictionaryFetcher::DoRequestStarted(int rv) {
 175   DCHECK(CalledOnValidThread());
 176   DCHECK_EQ(rv, OK);  // Can only come straight from above function.
 177
 178   // The transition to STATE_REQUEST_READING occurs in the
 179   // OnResponseStarted() callback triggered by URLRequest::Start()
 180   // (called in DoDispatchRequest(), above). If that callback did not
 181   // occur synchronously, this routine is executed; it returns ERR_IO_PENDING,
 182   // indicating to the controlling loop that no further work should be done
 183   // until the callback occurs (which will re-invoke DoLoop()).
 184   next_state_ = STATE_REQUEST_STARTED;
 185   return ERR_IO_PENDING;
 186 }
 187
 188 int SdchDictionaryFetcher::DoRead(int rv) {
 189   DCHECK(CalledOnValidThread());
 190
 191   // If there's been an error, abort the current request.
 192   if (rv != OK) {
 193     current_request_.reset();
 194     buffer_ = NULL;
 195     next_state_ = STATE_IDLE;
 196
 197     return OK;
 198   }
 199
 200   next_state_ = STATE_REQUEST_READING;
 201   int bytes_read = 0;
 202   if (!current_request_->Read(buffer_.get(), kBufferSize, &bytes_read)) {
 203     if (current_request_->status().is_io_pending())
 204       return ERR_IO_PENDING;
 205
 206     if (current_request_->status().error() == OK) {
 207       // This "should never happen", but if it does the result will be
 208       // an infinite loop.  It's not clear how to handle a read failure
 209       // without a promise to invoke the callback at some point in the future,
 210       // so the request is failed.
 211       SdchManager::SdchErrorRecovery(SdchManager::DICTIONARY_FETCH_READ_FAILED);
 212       DLOG(FATAL) <<
 213           "URLRequest::Read() returned false without IO pending or error!";
 214       return ERR_FAILED;
 215     }
 216
 217     return current_request_->status().error();
 218   }
 219
 220   if (bytes_read != 0)
 221     dictionary_.append(buffer_->data(), bytes_read);
 222   else
 223     next_state_ = STATE_REQUEST_COMPLETE;
 224
 225   return OK;
 226 }
 227
 228 int SdchDictionaryFetcher::DoCompleteRequest(int rv) {
 229   DCHECK(CalledOnValidThread());
 230
 231   // If the dictionary was successfully fetched, add it to the manager.
 232   if (rv == OK)
 233     consumer_->AddSdchDictionary(dictionary_, current_request_->url());
 234
 235   current_request_.reset();
 236   buffer_ = NULL;
 237   dictionary_.clear();
 238
 239   next_state_ = STATE_IDLE;
 240
 241   return OK;
 242 }
 243
 244 }  // namespace net