SimpleCache: merge the first and second stream in one file

net/disk_cache/simple/simple_util.cc

Index: net/disk_cache/simple/simple_util.cc
diff --git a/net/disk_cache/simple/simple_util.cc b/net/disk_cache/simple/simple_util.cc
index 4a89f9b5eb61c61bf01e08104648a15c7482f24c..23f7ec95d136e805d330993a8d76ace5e9718dfa 100644
--- a/net/disk_cache/simple/simple_util.cc
+++ b/net/disk_cache/simple/simple_util.cc
@@ -98,10 +98,24 @@ int64 GetFileSizeFromKeyAndDataSize(const std::string& key, int32 data_size) {
       sizeof(SimpleFileEOF);
 }
 
-int64 GetFileOffsetFromKeyAndDataOffset(const std::string& key,
-                                        int data_offset) {
+int GetFileIndexFromStreamIndex(int stream_index) {
+  return (stream_index == 2) ? 1 : 0;
+}
+
+int GetLastEOFRecordOffset(int file_index, const int data_size[]) {
+  if (file_index == 0)
+    return data_size[0] + data_size[1] + sizeof(SimpleFileEOF);

[Deprecated (see juliatuttle), 2013/09/16 20:01:52]

This looks like it's vulnerable to an integer overflow if someone manages to
cache a 2+ GB resource in stream 1 -- the stream 0 offset could easily end up
negative.  (For that matter, caching something that is INT_MAX could still make
the offset of the last SimpleFileHeader's worth of the resource negative.)

[pasko, 2013/09/17 10:06:34]

This should be fine.

Currently Write operations will start failing after reaching 1/8 of the cache
size, which itself is itself an int32, so this leaves a maximum of 256MiB of
data per entry stream.

+  return data_size[2];
+}
+
+int64 GetFileOffsetFromDataOffset(const std::string& key,
+                                  int data_offset,
+                                  int index,
+                                  int stream_1_size) {
   const int64 headers_size = sizeof(disk_cache::SimpleFileHeader) + key.size();
-  return headers_size + data_offset;
+  const int64 additional_offset =
+      index == 0 ? stream_1_size + sizeof(SimpleFileEOF) : 0;
+  return headers_size + data_offset + additional_offset;
 }
 
 // TODO(clamy, gavinp): this should go in base