RFC: use some in-memory state in SimpleCache to quickly cache-miss some CantConditionalize cases

net/disk_cache/simple/simple_index_file.cc

 // 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.
 
 #include "net/disk_cache/simple/simple_index_file.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/files/file.h"
@@ skipping 322 matching lines @@
                      (base::TimeTicks::Now() - start_time));
   }
 }
 
 bool SimpleIndexFile::IndexMetadata::CheckIndexMetadata() {
   if (entry_count_ > kMaxEntriesInIndex ||
       magic_number_ != kSimpleIndexMagicNumber) {
     return false;
   }
 
-  static_assert(kSimpleVersion == 7, "index metadata reader out of date");
+  static_assert(kSimpleVersion == 8, "index metadata reader out of date");
   // No |reason_| is saved in the version 6 file format.
   if (version_ == 6)
     return reason_ == SimpleIndex::INDEX_WRITE_REASON_MAX;
-  return version_ == 7 && reason_ < SimpleIndex::INDEX_WRITE_REASON_MAX;
+  return (version_ == 7 || version_ == 8) &&
+         reason_ < SimpleIndex::INDEX_WRITE_REASON_MAX;
 }
 
 SimpleIndexFile::SimpleIndexFile(
     const scoped_refptr<base::SingleThreadTaskRunner>& cache_thread,
     const scoped_refptr<base::TaskRunner>& worker_pool,
     net::CacheType cache_type,
     const base::FilePath& cache_directory)
     : cache_thread_(cache_thread),
       worker_pool_(worker_pool),
       cache_type_(cache_type),
@@ skipping 194 matching lines @@
   if (!index_metadata.CheckIndexMetadata()) {
     LOG(ERROR) << "Invalid index_metadata on Simple Cache Index.";
     return;
   }
 
   entries->reserve(index_metadata.entry_count() + kExtraSizeForMerge);
   while (entries->size() < index_metadata.entry_count()) {
     uint64_t hash_key;
     EntryMetadata entry_metadata;
     if (!pickle_it.ReadUInt64(&hash_key) ||
-        !entry_metadata.Deserialize(&pickle_it)) {
+        !entry_metadata.Deserialize(&pickle_it,
+                                    index_metadata.has_memory_entry_data())) {
       LOG(WARNING) << "Invalid EntryMetadata in Simple Index file.";
       entries->clear();
       return;
     }
     SimpleIndex::InsertInEntrySet(hash_key, entry_metadata, entries);
   }
 
   int64_t cache_last_modified;
   if (!pickle_it.ReadInt64(&cache_last_modified)) {
     entries->clear();
@@ skipping 32 matching lines @@
 bool SimpleIndexFile::LegacyIsIndexFileStale(
     base::Time cache_last_modified,
     const base::FilePath& index_file_path) {
   base::Time index_mtime;
   if (!simple_util::GetMTime(index_file_path, &index_mtime))
     return true;
   return index_mtime < cache_last_modified;
 }
 
 }  // namespace disk_cache