Let prefetched resources skip cache revalidation once for a short duration.

net/http/http_cache.cc

 // 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 "net/http/http_cache.h"
 
 #include <algorithm>
 
 #include "base/compiler_specific.h"
 
@@ skipping 11 matching lines @@
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/pickle.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/worker_pool.h"
+#include "base/time/default_clock.h"
 #include "base/time/time.h"
 #include "net/base/cache_type.h"
 #include "net/base/io_buffer.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_delegate.h"
 #include "net/base/upload_data_stream.h"
 #include "net/disk_cache/disk_cache.h"
 #include "net/http/disk_based_cert_cache.h"
 #include "net/http/disk_cache_based_quic_server_info.h"
@@ skipping 312 matching lines @@
                    base::Unretained(network_delegate),
                    static_cast<URLRequest*>(NULL)));
     // The above use of base::Unretained is safe because the NetworkDelegate has
     // to live at least as long as the HttpNetworkSession which has to live as
     // least as long as the HttpNetworkLayer which has to live at least as long
     // this HttpCache object.
   }
 
   DCHECK_EQ(0, request_.load_flags & LOAD_ASYNC_REVALIDATION);
   request_.load_flags |= LOAD_ASYNC_REVALIDATION;
-  start_time_ = base::Time::Now();
+  start_time_ = cache_->clock()->Now();
   // This use of base::Unretained is safe because |transaction_| is owned by
   // this object.
   read_callback_ = base::Bind(&AsyncValidation::OnRead, base::Unretained(this));
   // This use of base::Unretained is safe as above.
   int rv = transaction_->Start(
       &request_,
       base::Bind(&AsyncValidation::OnStarted, base::Unretained(this)),
       net_log);
 
   if (rv == ERR_IO_PENDING)
@@ skipping 57 matching lines @@
 void HttpCache::AsyncValidation::Terminate(int result) {
   if (result == ERR_SSL_CLIENT_AUTH_CERT_NEEDED || IsCertificateError(result)) {
     // We should not attempt to access this resource asynchronously again until
     // the certificate problem has been resolved.
     // TODO(ricea): For ERR_SSL_CLIENT_AUTH_CERT_NEEDED, mark the entry as
     // requiring synchronous revalidation rather than just deleting it. Other
     // certificate errors cause the resource to be considered uncacheable
     // anyway.
     cache_->DoomEntry(transaction_->key(), transaction_.get());
   }
-  base::TimeDelta duration = base::Time::Now() - start_time_;
+  base::TimeDelta duration = cache_->clock()->Now() - start_time_;
   UMA_HISTOGRAM_TIMES("HttpCache.AsyncValidationDuration", duration);
   transaction_->net_log().EndEventWithNetErrorCode(
       NetLog::TYPE_ASYNC_REVALIDATION, result);
   cache_->DeleteAsyncValidation(cache_->GenerateCacheKey(&request_));
   // |this| is deleted.
 }
 
 //-----------------------------------------------------------------------------
 HttpCache::HttpCache(const net::HttpNetworkSession::Params& params,
                      BackendFactory* backend_factory)
     : net_log_(params.net_log),
       backend_factory_(backend_factory),
       building_backend_(false),
       bypass_lock_for_test_(false),
       use_stale_while_revalidate_(params.use_stale_while_revalidate),
       mode_(NORMAL),
       network_layer_(new HttpNetworkLayer(new HttpNetworkSession(params))),
+      clock_(new base::DefaultClock()),
       weak_factory_(this) {
   SetupQuicServerInfoFactory(network_layer_->GetSession());
 }
 
 
 // This call doesn't change the shared |session|'s QuicServerInfoFactory because
 // |session| is shared.
 HttpCache::HttpCache(HttpNetworkSession* session,
                      BackendFactory* backend_factory)
     : net_log_(session->net_log()),
       backend_factory_(backend_factory),
       building_backend_(false),
       bypass_lock_for_test_(false),
       use_stale_while_revalidate_(session->params().use_stale_while_revalidate),
       mode_(NORMAL),
       network_layer_(new HttpNetworkLayer(session)),
+      clock_(new base::DefaultClock()),
       weak_factory_(this) {
 }
 
 HttpCache::HttpCache(HttpTransactionFactory* network_layer,
                      NetLog* net_log,
                      BackendFactory* backend_factory)
     : net_log_(net_log),
       backend_factory_(backend_factory),
       building_backend_(false),
       bypass_lock_for_test_(false),
       use_stale_while_revalidate_(false),
       mode_(NORMAL),
       network_layer_(network_layer),
+      clock_(new base::DefaultClock()),
       weak_factory_(this) {
   SetupQuicServerInfoFactory(network_layer_->GetSession());
   HttpNetworkSession* session = network_layer_->GetSession();
   if (session)
     use_stale_while_revalidate_ = session->params().use_stale_while_revalidate;
 }
 
 HttpCache::~HttpCache() {
   // Transactions should see an invalid cache after this point; otherwise they
   // could see an inconsistent object (half destroyed).
@@ skipping 907 matching lines @@
     building_backend_ = false;
     DeletePendingOp(pending_op);
   }
 
   // The cache may be gone when we return from the callback.
   if (!item->DoCallback(result, disk_cache_.get()))
     item->NotifyTransaction(result, NULL);
 }
 
 }  // namespace net