Move InMemoryURLIndex Caching Operations to FILE Thread

chrome/browser/history/url_index_private_data.cc

Index: chrome/browser/history/url_index_private_data.cc
===================================================================
--- chrome/browser/history/url_index_private_data.cc	(revision 125078)
+++ chrome/browser/history/url_index_private_data.cc	(working copy)
@@ -14,11 +14,15 @@
 #include "base/i18n/case_conversion.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/autocomplete/autocomplete.h"
 #include "chrome/browser/history/history_database.h"
+#include "chrome/browser/history/in_memory_url_index.h"
 #include "chrome/common/url_constants.h"
+#include "content/public/browser/notification_details.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_source.h"
 #include "net/base/net_util.h"
 #include "third_party/protobuf/src/google/protobuf/repeated_field.h"
 
@@ -133,6 +137,10 @@
   history_info_map_.clear();
 }
 
+bool URLIndexPrivateData::Empty() const {
+  return history_info_map_.empty();
+}
+
 // Cache Updating --------------------------------------------------------------
 
 bool URLIndexPrivateData::IndexRow(const URLRow& row) {
@@ -902,9 +910,17 @@
 
 // Cache Saving ----------------------------------------------------------------
 
+// static
+void URLIndexPrivateData::WritePrivateDataToCacheFileTask(
+    scoped_ptr<URLIndexPrivateData> private_data,
+    const FilePath& file_path,
+    scoped_refptr<RefCountedBool> succeeded) {
+  DCHECK(private_data.get());
+  DCHECK(!file_path.empty());
+  succeeded->set_value(private_data->SaveToFile(file_path));
+}
+
 bool URLIndexPrivateData::SaveToFile(const FilePath& file_path) {
-  // TODO(mrossetti): Move File IO to another thread.
-  base::ThreadRestrictions::ScopedAllowIO allow_io;
   base::TimeTicks beginning_time = base::TimeTicks::Now();
   InMemoryURLIndexCacheItem index_cache;
   SavePrivateData(&index_cache);
@@ -1022,44 +1038,49 @@
 
 // Cache Restoring -------------------------------------------------------------
 
-bool URLIndexPrivateData::RestoreFromFile(const FilePath& file_path) {
-  // TODO(mrossetti): Figure out how to determine if the cache is up-to-date.
-  // That is: ensure that the database has not been modified since the cache
-  // was last saved. DB file modification date is inadequate. There are no
-  // SQLite table checksums automatically stored.
-  Clear();  // Start with a clean slate.
+// static
+void URLIndexPrivateData::RestoreFromFileTask(const FilePath& file_path,
+                                              URLIndexPrivateData* data) {
+  data = URLIndexPrivateData::RestoreFromFile(file_path);
+}
 
-  // FIXME(mrossetti): Move File IO to another thread.
-  base::ThreadRestrictions::ScopedAllowIO allow_io;
+// static
+URLIndexPrivateData* URLIndexPrivateData::RestoreFromFile(
+    const FilePath& file_path) {
   base::TimeTicks beginning_time = base::TimeTicks::Now();
   if (!file_util::PathExists(file_path))
-    return false;
+    return NULL;
   std::string data;
   // If there is no cache file then simply give up. This will cause us to
   // attempt to rebuild from the history database.
   if (!file_util::ReadFileToString(file_path, &data))
-    return false;
+    return NULL;
 
+  scoped_ptr<URLIndexPrivateData> restored_data(new URLIndexPrivateData);
   InMemoryURLIndexCacheItem index_cache;
   if (!index_cache.ParseFromArray(data.c_str(), data.size())) {
-    LOG(WARNING) << "Failed to parse InMemoryURLIndex cache data read from "
+    LOG(WARNING) << "Failed to parse URLIndexPrivateData cache data read from "
                  << file_path.value();
-    return false;
+    return restored_data.release();
   }
 
-  if (!RestorePrivateData(index_cache)) {
-    Clear();  // Back to square one -- must build from scratch.
-    return false;
+  if (!restored_data->RestorePrivateData(index_cache)) {
+    restored_data.reset();  // Back to square one -- must build from history DB.
+    return NULL;
   }
 
   UMA_HISTOGRAM_TIMES("History.InMemoryURLIndexRestoreCacheTime",
                       base::TimeTicks::Now() - beginning_time);
   UMA_HISTOGRAM_COUNTS("History.InMemoryURLHistoryItems",
-                       history_id_word_map_.size());
+                       restored_data->history_id_word_map_.size());
   UMA_HISTOGRAM_COUNTS("History.InMemoryURLCacheSize", data.size());
-  UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLWords", word_map_.size());
-  UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLChars", char_word_map_.size());
-  return true;
+  UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLWords",
+                             restored_data->word_map_.size());
+  UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLChars",
+                             restored_data->char_word_map_.size());
+  if (restored_data->Empty())
+    restored_data.reset();  // 'No data' is the same as a failed reload.
+  return restored_data.release();
 }
 
 // static