Remove stale-while-revalidate experimental implementation.

net/http/http_cache_transaction.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_transaction.h"
 
 #include "build/build_config.h"
 
 #if defined(OS_POSIX)
 #include <unistd.h>
 #endif
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/format_macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/clock.h"
@@ skipping 144 matching lines @@
 
 void RecordNoStoreHeaderHistogram(int load_flags,
                                   const HttpResponseInfo* response) {
   if (load_flags & LOAD_MAIN_FRAME) {
     UMA_HISTOGRAM_BOOLEAN(
         "Net.MainFrameNoStore",
         response->headers->HasHeaderValue("cache-control", "no-store"));
   }
 }
 
-scoped_ptr<base::Value> NetLogAsyncRevalidationInfoCallback(
-    const NetLog::Source& source,
-    const HttpRequestInfo* request,
-    NetLogCaptureMode capture_mode) {
-  scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
-  source.AddToEventParameters(dict.get());
-
-  dict->SetString("url", request->url.possibly_invalid_spec());
-  dict->SetString("method", request->method);
-  return dict.Pass();
-}
-
 enum ExternallyConditionalizedType {
   EXTERNALLY_CONDITIONALIZED_CACHE_REQUIRES_VALIDATION,
   EXTERNALLY_CONDITIONALIZED_CACHE_USABLE,
   EXTERNALLY_CONDITIONALIZED_MISMATCHED_VALIDATORS,
   EXTERNALLY_CONDITIONALIZED_MAX
 };
 
 }  // namespace
 
 struct HeaderNameAndValue {
@@ skipping 1918 matching lines @@
   return OK;
 }
 
 int HttpCache::Transaction::BeginCacheValidation() {
   DCHECK(mode_ == READ_WRITE);
 
   ValidationType required_validation = RequiresValidation();
 
   bool skip_validation = (required_validation == VALIDATION_NONE);
 
-  if (required_validation == VALIDATION_ASYNCHRONOUS &&
-      !(request_->method == "GET" && (truncated_ || partial_)) && cache_ &&
-      cache_->use_stale_while_revalidate()) {
-    TriggerAsyncValidation();
-    skip_validation = true;
-  }
-
   if (request_->method == "HEAD" &&
       (truncated_ || response_.headers->response_code() == 206)) {
     DCHECK(!partial_);
     if (skip_validation)
       return SetupEntryForRead();
 
     // Bail out!
     next_state_ = STATE_SEND_REQUEST;
     mode_ = NONE;
     return OK;
   }
 
   if (truncated_) {
     // Truncated entries can cause partial gets, so we shouldn't record this
     // load in histograms.
     UpdateTransactionPattern(PATTERN_NOT_COVERED);
     skip_validation = !partial_->initial_validation();
   }
 
   if (partial_.get() && (is_sparse_ || truncated_) &&
       (!partial_->IsCurrentRangeCached() || invalid_range_)) {
     // Force revalidation for sparse or truncated entries. Note that we don't
     // want to ignore the regular validation logic just because a byte range was
     // part of the request.
     skip_validation = false;
   }
 
   if (skip_validation) {
-    // TODO(ricea): Is this pattern okay for asynchronous revalidations?
     UpdateTransactionPattern(PATTERN_ENTRY_USED);
     return SetupEntryForRead();
   } else {
     // Make the network request conditional, to see if we may reuse our cached
     // response.  If we cannot do so, then we just resort to a normal fetch.
     // Our mode remains READ_WRITE for a conditional request.  Even if the
     // conditionalization fails, we don't switch to WRITE mode until we
     // know we won't be falling back to using the cache entry in the
     // LOAD_FROM_CACHE_IF_OFFLINE case.
     if (!ConditionalizeRequest()) {
@@ skipping 159 matching lines @@
   if (response_.unused_since_prefetch &&
       !(effective_load_flags_ & LOAD_PREFETCH) &&
       response_.headers->GetCurrentAge(
           response_.request_time, response_.response_time,
           cache_->clock_->Now()) < TimeDelta::FromMinutes(kPrefetchReuseMins)) {
     // The first use of a resource after prefetch within a short window skips
     // validation.
     return VALIDATION_NONE;
   }
 
-  if (effective_load_flags_ & (LOAD_VALIDATE_CACHE | LOAD_ASYNC_REVALIDATION))
+  if (effective_load_flags_ & LOAD_VALIDATE_CACHE)
     return VALIDATION_SYNCHRONOUS;
 
   if (request_->method == "PUT" || request_->method == "DELETE")
     return VALIDATION_SYNCHRONOUS;
 
   ValidationType validation_required_by_headers =
       response_.headers->RequiresValidation(response_.request_time,
                                             response_.response_time,
                                             cache_->clock_->Now());
 
@@ skipping 233 matching lines @@
   mode_ = NONE;
 }
 
 void HttpCache::Transaction::FixHeadersForHead() {
   if (response_.headers->response_code() == 206) {
     response_.headers->RemoveHeader("Content-Range");
     response_.headers->ReplaceStatusLine("HTTP/1.1 200 OK");
   }
 }
 
-void HttpCache::Transaction::TriggerAsyncValidation() {
-  DCHECK(!request_->upload_data_stream);
-  BoundNetLog async_revalidation_net_log(
-      BoundNetLog::Make(net_log_.net_log(), NetLog::SOURCE_ASYNC_REVALIDATION));
-  net_log_.AddEvent(
-      NetLog::TYPE_HTTP_CACHE_VALIDATE_RESOURCE_ASYNC,
-      async_revalidation_net_log.source().ToEventParametersCallback());
-  async_revalidation_net_log.BeginEvent(
-      NetLog::TYPE_ASYNC_REVALIDATION,
-      base::Bind(
-          &NetLogAsyncRevalidationInfoCallback, net_log_.source(), request_));
-  base::MessageLoop::current()->PostTask(
-      FROM_HERE,
-      base::Bind(&HttpCache::PerformAsyncValidation,
-                 cache_,  // cache_ is a weak pointer.
-                 *request_,
-                 async_revalidation_net_log));
-}
-
 void HttpCache::Transaction::FailRangeRequest() {
   response_ = *new_response_;
   partial_->FixResponseHeaders(response_.headers.get(), false);
 }
 
 int HttpCache::Transaction::SetupEntryForRead() {
   if (network_trans_)
     ResetNetworkTransaction();
   if (partial_.get()) {
     if (truncated_ || is_sparse_ || !invalid_range_) {
@@ skipping 345 matching lines @@
     default:
       NOTREACHED();
   }
 }
 
 void HttpCache::Transaction::OnIOComplete(int result) {
   DoLoop(result);
 }
 
 }  // namespace net