SimpleCache: read small files all at once.

net/disk_cache/simple/simple_entry_impl.h

Index: net/disk_cache/simple/simple_entry_impl.h
diff --git a/net/disk_cache/simple/simple_entry_impl.h b/net/disk_cache/simple/simple_entry_impl.h
index 7ab6c38e4ef1bd55d1ba8a60a258dbfee94afca0..efd673aae5d54088dd6d1d43ba087fba30892d96 100644
--- a/net/disk_cache/simple/simple_entry_impl.h
+++ b/net/disk_cache/simple/simple_entry_impl.h
@@ -301,9 +301,11 @@ class NET_EXPORT_PRIVATE SimpleEntryImpl : public Entry,
       int result,
       std::unique_ptr<SimpleSynchronousEntry::CRCRequest> crc_result) const;
 
-  // Called after completion of asynchronous IO and receiving file metadata for
-  // the entry in |entry_stat|. Updates the metadata in the entry and in the
-  // index to make them available on next IO operations.
+  // Called after completion of an operation, to either incoproprate file info
+  // received from I/O done on the worker pool, or to simply bump the
+  // timestamps. Updates the metadata both in |this| and in the index.
+  // Stream size information in particular may be important for following
+  // operations.
   void UpdateDataFromEntryStat(const SimpleEntryStat& entry_stat);
 
   int64_t GetDiskUsage() const;
@@ -312,8 +314,14 @@ class NET_EXPORT_PRIVATE SimpleEntryImpl : public Entry,
   void RecordReadIsParallelizable(const SimpleEntryOperation& operation) const;
   void RecordWriteDependencyType(const SimpleEntryOperation& operation) const;
 
-  // Reads from the stream 0 data kept in memory.
-  int ReadStream0Data(net::IOBuffer* buf, int offset, int buf_len);
+  // Completes a read from the stream data kept in memory, logging metrics
+  // and updating metadata as appropriate. If |callback| is non-null, it will

[pasko, 2017/08/09 12:28:22]

nit: s/as appropriate//

[Maks Orlovich, 2017/08/09 15:25:02]

Done.

+  // be posted to with the return code.

[pasko, 2017/08/09 12:28:22]

s/posted to/posted to the current task runner/ ? ... since a callback cannot be
posted to (though it may be that my English is lacking here, lemme know)

[Maks Orlovich, 2017/08/09 15:25:02]

Done.

+  void ReadFromBufferAndPostReply(net::GrowableIOBuffer* in_buf,
+                                  int offset,
+                                  int buf_len,
+                                  net::IOBuffer* out_buf,
+                                  const CompletionCallback& callback);
 
   // Copies data from |buf| to the internal in-memory buffer for stream 0. If
   // |truncate| is set to true, the target buffer will be truncated at |offset|
@@ -341,6 +349,7 @@ class NET_EXPORT_PRIVATE SimpleEntryImpl : public Entry,
   const base::FilePath path_;
   const uint64_t entry_hash_;
   const bool use_optimistic_operations_;
+  bool is_initial_stream1_read_;  // used for metrics only.
   std::string key_;
 
   // |last_used_|, |last_modified_| and |data_size_| are copied from the
@@ -403,6 +412,11 @@ class NET_EXPORT_PRIVATE SimpleEntryImpl : public Entry,
   // used to write HTTP headers, the memory consumption of keeping it in memory
   // is acceptable.
   scoped_refptr<net::GrowableIOBuffer> stream_0_data_;
+
+  // Sometimes stream 1 data is prefetched when stream 0 is first read.
+  // If a write to the stream occurs on the entry the prefetch buffer is
+  // discarded. It may also be null if it wasn't prefetched in the first place.
+  scoped_refptr<net::GrowableIOBuffer> stream_1_prefetch_data_;
 };
 
 }  // namespace disk_cache