Increase page size for SyncData DB from 4K to maximum supported 32K

sync/syncable/directory_backing_store.cc

 // Copyright 2012 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 "sync/syncable/directory_backing_store.h"
 
 #include "build/build_config.h"
 
 #include <limits>
 
 #include "base/base64.h"
 #include "base/logging.h"
+#include "base/metrics/field_trial.h"
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "sql/connection.h"
 #include "sql/statement.h"
 #include "sql/transaction.h"
 #include "sync/internal_api/public/base/node_ordinal.h"
 #include "sync/protocol/bookmark_specifics.pb.h"
 #include "sync/protocol/sync.pb.h"
@@ skipping 145 matching lines @@
 }  // namespace
 
 ///////////////////////////////////////////////////////////////////////////////
 // DirectoryBackingStore implementation.
 
 DirectoryBackingStore::DirectoryBackingStore(const string& dir_name)
   : db_(new sql::Connection()),
     dir_name_(dir_name),
     needs_column_refresh_(false) {
   db_->set_histogram_tag("SyncDirectory");
-  db_->set_page_size(4096);
   db_->set_cache_size(32);
+  if (IsSyncBackingDatabase32KEnabled()) {
+    db_->set_page_size(32768);
+  } else {
+    db_->set_page_size(4096);
+  }
 }
 
 DirectoryBackingStore::DirectoryBackingStore(const string& dir_name,
                                              sql::Connection* db)
   : db_(db),
     dir_name_(dir_name),
     needs_column_refresh_(false) {
 }
 
 DirectoryBackingStore::~DirectoryBackingStore() {
@@ skipping 111 matching lines @@
         return false;
       DCHECK_EQ(db_->GetLastChangeCount(), 1);
       s2.Reset(true);
     }
   }
 
   return transaction.Commit();
 }
 
 bool DirectoryBackingStore::InitializeTables() {
+  int page_size = 0;
+  if (IsSyncBackingDatabase32KEnabled() &&
+      GetDatabasePageSize(&page_size) &&
+      page_size == 4096) {
+    IncreasePageSizeTo32K();
+  }
   sql::Transaction transaction(db_.get());
   if (!transaction.Begin())
     return false;
 
   int version_on_disk = GetVersion();
 
   // Upgrade from version 67. Version 67 was widely distributed as the original
   // Bookmark Sync release. Version 68 removed unique naming.
   if (version_on_disk == 67) {
     if (MigrateVersion67To68())
@@ skipping 1265 matching lines @@
     query.append(ColumnName(i));
     values.append("?");
   }
   query.append(" ) ");
   values.append(" )");
   query.append(values);
   save_statement->Assign(db_->GetUniqueStatement(
       base::StringPrintf(query.c_str(), "metas").c_str()));
 }
 
+// Get page size for the database.
+bool DirectoryBackingStore::GetDatabasePageSize(int* page_size) {
+  sql::Statement s(db_->GetUniqueStatement("PRAGMA page_size"));
+  if (!s.Step())
+    return false;
+  *page_size = s.ColumnInt(0);
+  return true;
+}
+
+bool DirectoryBackingStore::IsSyncBackingDatabase32KEnabled() {
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("SyncBackingDatabase32K");
+  return group_name == "Enabled";
+}
+
+bool DirectoryBackingStore::IncreasePageSizeTo32K() {
+  if (!db_->Execute("PRAGMA page_size=32768;") ||
+      !Vacuum()) {
+    return false;
+  }
+  return true;
+}
+
+bool DirectoryBackingStore::Vacuum() {
+  DCHECK_EQ(db_->transaction_nesting(), 0);
+  if (!db_->Execute("VACUUM;")) {
+    return false;
+  }
+  return true;
+}
+
 }  // namespace syncable
 }  // namespace syncer