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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <iterator>
#include "chrome/browser/predictors/resource_prefetcher.h"
#include "base/stl_util.h"
#include "content/public/browser/browser_thread.h"
#include "net/base/io_buffer.h"
namespace {
// The size of the buffer used to read the resource.
static const size_t kResourceBufferSizeBytes = 50000;
} // namespace
namespace predictors {
ResourcePrefetcher::Request::Request(const GURL& i_resource_url)
: resource_url(i_resource_url),
prefetch_status(PREFETCH_STATUS_NOT_STARTED),
usage_status(USAGE_STATUS_NOT_REQUESTED) {
}
ResourcePrefetcher::Request::Request(const Request& other)
: resource_url(other.resource_url),
prefetch_status(other.prefetch_status),
usage_status(other.usage_status) {
}
ResourcePrefetcher::ResourcePrefetcher(
Delegate* delegate,
const ResourcePrefetchPredictorConfig& config,
const NavigationID& navigation_id,
PrefetchKeyType key_type,
scoped_ptr<RequestVector> requests)
: state_(INITIALIZED),
delegate_(delegate),
config_(config),
navigation_id_(navigation_id),
key_type_(key_type),
request_vector_(requests.Pass()) {
CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
DCHECK(request_vector_.get());
std::copy(request_vector_->begin(), request_vector_->end(),
std::back_inserter(request_queue_));
}
ResourcePrefetcher::~ResourcePrefetcher() {
// Delete any pending net::URLRequests.
STLDeleteContainerPairFirstPointers(inflight_requests_.begin(),
inflight_requests_.end());
}
void ResourcePrefetcher::Start() {
CHECK(CalledOnValidThread());
CHECK_EQ(state_, INITIALIZED);
state_ = RUNNING;
TryToLaunchPrefetchRequests();
}
void ResourcePrefetcher::Stop() {
CHECK(CalledOnValidThread());
if (state_ == FINISHED)
return;
state_ = STOPPED;
}
void ResourcePrefetcher::TryToLaunchPrefetchRequests() {
CHECK(state_ == RUNNING || state_ == STOPPED);
// Try to launch new requests if the state is RUNNING.
if (state_ == RUNNING) {
bool request_available = true;
// Loop through the requests while we are under the
// max_prefetches_inflight_per_host_per_navigation limit, looking for a URL
// for which the max_prefetches_inflight_per_host_per_navigation limit has
// not been reached. Try to launch as many requests as possible.
while ((static_cast<int>(inflight_requests_.size()) <
config_.max_prefetches_inflight_per_navigation) &&
request_available) {
std::list<Request*>::iterator request_it = request_queue_.begin();
for (; request_it != request_queue_.end(); ++request_it) {
const std::string& host = (*request_it)->resource_url.host();
std::map<std::string, int>::iterator host_it =
host_inflight_counts_.find(host);
if (host_it == host_inflight_counts_.end() ||
host_it->second <
config_.max_prefetches_inflight_per_host_per_navigation)
break;
}
request_available = request_it != request_queue_.end();
if (request_available) {
SendRequest(*request_it);
request_queue_.erase(request_it);
}
}
}
// If the inflight_requests_ is empty, we cant launch any more. Finish.
if (inflight_requests_.empty()) {
CHECK(host_inflight_counts_.empty());
CHECK(request_queue_.empty() || state_ == STOPPED);
state_ = FINISHED;
delegate_->ResourcePrefetcherFinished(this, request_vector_.release());
}
}
void ResourcePrefetcher::SendRequest(Request* request) {
request->prefetch_status = Request::PREFETCH_STATUS_STARTED;
net::URLRequest* url_request =
new net::URLRequest(request->resource_url,
this,
delegate_->GetURLRequestContext());
inflight_requests_[url_request] = request;
host_inflight_counts_[url_request->original_url().host()] += 1;
url_request->set_method("GET");
url_request->set_first_party_for_cookies(navigation_id_.main_frame_url);
url_request->set_referrer(navigation_id_.main_frame_url.spec());
url_request->set_priority(net::LOW);
StartURLRequest(url_request);
}
void ResourcePrefetcher::StartURLRequest(net::URLRequest* request) {
request->Start();
}
void ResourcePrefetcher::FinishRequest(net::URLRequest* request,
Request::PrefetchStatus status) {
std::map<net::URLRequest*, Request*>::iterator request_it =
inflight_requests_.find(request);
CHECK(request_it != inflight_requests_.end());
const std::string host = request->original_url().host();
std::map<std::string, int>::iterator host_it = host_inflight_counts_.find(
host);
CHECK_GT(host_it->second, 0);
host_it->second -= 1;
if (host_it->second == 0)
host_inflight_counts_.erase(host);
request_it->second->prefetch_status = status;
inflight_requests_.erase(request_it);
delete request;
TryToLaunchPrefetchRequests();
}
void ResourcePrefetcher::ReadFullResponse(net::URLRequest* request) {
bool status = true;
while (status) {
int bytes_read = 0;
scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(
kResourceBufferSizeBytes));
status = request->Read(buffer, kResourceBufferSizeBytes, &bytes_read);
if (status) {
status = ShouldContinueReadingRequest(request, bytes_read);
} else if (request->status().error()) {
FinishRequest(request, Request::PREFETCH_STATUS_FAILED);
return;
}
}
}
bool ResourcePrefetcher::ShouldContinueReadingRequest(net::URLRequest* request,
int bytes_read) {
if (bytes_read == 0) { // When bytes_read == 0, no more data.
if (request->was_cached())
FinishRequest(request, Request::PREFETCH_STATUS_FROM_CACHE);
else
FinishRequest(request, Request::PREFETCH_STATUS_FROM_NETWORK);
return false;
}
return true;
}
void ResourcePrefetcher::OnReceivedRedirect(net::URLRequest* request,
const GURL& new_url,
bool* defer_redirect) {
FinishRequest(request, Request::PREFETCH_STATUS_REDIRECTED);
}
void ResourcePrefetcher::OnAuthRequired(net::URLRequest* request,
net::AuthChallengeInfo* auth_info) {
FinishRequest(request, Request::PREFETCH_STATUS_AUTH_REQUIRED);
}
void ResourcePrefetcher::OnCertificateRequested(
net::URLRequest* request,
net::SSLCertRequestInfo* cert_request_info) {
FinishRequest(request, Request::PREFETCH_STATUS_CERT_REQUIRED);
}
void ResourcePrefetcher::OnSSLCertificateError(net::URLRequest* request,
const net::SSLInfo& ssl_info,
bool fatal) {
FinishRequest(request, Request::PREFETCH_STATUS_CERT_ERROR);
}
void ResourcePrefetcher::OnResponseStarted(net::URLRequest* request) {
if (request->status().error()) {
FinishRequest(request, Request::PREFETCH_STATUS_FAILED);
return;
}
// TODO(shishir): Do not read cached entries, or ones that are not cacheable.
ReadFullResponse(request);
}
void ResourcePrefetcher::OnReadCompleted(net::URLRequest* request,
int bytes_read) {
if (request->status().error()) {
FinishRequest(request, Request::PREFETCH_STATUS_FAILED);
return;
}
if (ShouldContinueReadingRequest(request, bytes_read))
ReadFullResponse(request);
}
} // namespace predictors
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