Sparse IO: Allow failover to network in debug builds

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>
@@ skipping 1512 matching lines @@
 
 int HttpCache::Transaction::DoCacheQueryData() {
   next_state_ = STATE_CACHE_QUERY_DATA_COMPLETE;
 
   // Balanced in DoCacheQueryDataComplete.
   return ResetCacheIOStart(
       entry_->disk_entry->ReadyForSparseIO(io_callback_));
 }
 
 int HttpCache::Transaction::DoCacheQueryDataComplete(int result) {
-  DCHECK_EQ(OK, result);
+  // Note: a backend may not support Sparse IO, in this case it is expected that
+  // header validation will fail and transition to STATE_SEND_REQUEST.

[rvargas (doing something else), 2013/08/23 17:54:13]

I would prefer if you return a specific error code from the backend and do an
explicit transition to whatever you need here.

[pasko, 2013/08/26 15:42:51]

Done.

   if (!cache_.get())
     return ERR_UNEXPECTED;
 
   return ValidateEntryHeadersAndContinue();
 }
 
 int HttpCache::Transaction::DoCacheReadData() {
   DCHECK(entry_);
   next_state_ = STATE_CACHE_READ_DATA_COMPLETE;
 
@@ skipping 1051 matching lines @@
 void HttpCache::Transaction::ResetNetworkTransaction() {
   DCHECK(!old_network_trans_load_timing_);
   DCHECK(network_trans_);
   LoadTimingInfo load_timing;
   if (network_trans_->GetLoadTimingInfo(&load_timing))
     old_network_trans_load_timing_.reset(new LoadTimingInfo(load_timing));
   network_trans_.reset();
 }
 
 }  // namespace net