[SimpleCache] Prefetch stream 1 so that the first read is faster

net/disk_cache/simple/simple_synchronous_entry.h

 // Copyright (c) 2013 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.
 
 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_SYNCHRONOUS_ENTRY_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_SYNCHRONOUS_ENTRY_H_
 
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 61 matching lines @@
   int32_t data_size_[kSimpleEntryStreamCount];
   int32_t sparse_data_size_;
 };
 
 struct SimpleEntryCreationResults {
   explicit SimpleEntryCreationResults(SimpleEntryStat entry_stat);
   ~SimpleEntryCreationResults();
 
   SimpleSynchronousEntry* sync_entry;
   scoped_refptr<net::GrowableIOBuffer> stream_0_data;
+  scoped_refptr<net::GrowableIOBuffer> stream_1_prefetch_data;
   SimpleEntryStat entry_stat;
   uint32_t stream_0_crc32;
   int result;
 };
 
 // Worker thread interface to the very simple cache. This interface is not
 // thread safe, and callers must ensure that it is only ever accessed from
 // a single thread between synchronization points.
 class SimpleSynchronousEntry {
  public:
@@ skipping 181 matching lines @@
   void CloseFile(int index);
   void CloseFiles();
 
   // Read the header and key at the beginning of the file, and validate that
   // they are correct. If this entry was opened with a key, the key is checked
   // for a match. If not, then the |key_| member is set based on the value in
   // this header. Records histograms if any check is failed.
   bool CheckHeaderAndKey(int file_index);
 
   // Returns a net error, i.e. net::OK on success.
-  int InitializeForOpen(SimpleEntryStat* out_entry_stat,
-                        scoped_refptr<net::GrowableIOBuffer>* stream_0_data,
-                        uint32_t* out_stream_0_crc32);
+  int InitializeForOpen(
+      SimpleEntryStat* out_entry_stat,
+      scoped_refptr<net::GrowableIOBuffer>* stream_0_data,
+      uint32_t* out_stream_0_crc32,
+      scoped_refptr<net::GrowableIOBuffer>* stream_1_prefetch_data);
 
   // Writes the header and key to a newly-created stream file. |index| is the
   // index of the stream. Returns true on success; returns false and sets
   // |*out_result| on failure.
   bool InitializeCreatedFile(int index, CreateEntryResult* out_result);
 
   // Returns a net error, including net::OK on success and net::FILE_EXISTS
   // when the entry already exists.
   int InitializeForCreate(SimpleEntryStat* out_entry_stat);
 
@@ skipping 93 matching lines @@
   int64_t sparse_tail_offset_;
 
   // True if the entry was created, or false if it was opened. Used to log
   // SimpleCache.*.EntryCreatedWithStream2Omitted only for created entries.
   bool files_created_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_SYNCHRONOUS_ENTRY_H_