Histogram versions and extended error codes for SQLite databases.

sql/meta_table.cc

 // Copyright (c) 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 "sql/meta_table.h"
 
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "sql/connection.h"
 #include "sql/statement.h"
@@ skipping 34 matching lines @@
   if (!DoesTableExist(db)) {
     if (!db_->Execute("CREATE TABLE meta"
         "(key LONGVARCHAR NOT NULL UNIQUE PRIMARY KEY, value LONGVARCHAR)"))
       return false;
 
     // Note: there is no index over the meta table. We currently only have a
     // couple of keys, so it doesn't matter. If we start storing more stuff in
     // there, we should create an index.
     SetVersionNumber(version);
     SetCompatibleVersionNumber(compatible_version);
+  } else {
+    // At this point, the highest version is Web, at 50, then
+    // History at 25, then a tie for 6.  100 leaves some room for
+    // growth.
+    // TODO(shess): Another option would be to use |version| as the cap.
+    static size_t kSqliteVersionMax = 100;

[jar (doing other things), 2013/05/07 23:46:41]

This fits wonderfully into a UMA_HISTOGRAM_SPARSE_SLOWLY.  It will use less
memory, and never grow too old.

+    db_->AddLinearHistogram(".Version", GetVersionNumber(), kSqliteVersionMax);
   }
   return transaction.Commit();
 }
 
 void MetaTable::Reset() {
   db_ = NULL;
 }
 
 void MetaTable::SetVersionNumber(int version) {
   DCHECK_GT(version, 0);
@@ skipping 79 matching lines @@
 
 bool MetaTable::PrepareGetStatement(Statement* statement, const char* key) {
   DCHECK(db_ && statement);
   statement->Assign(db_->GetCachedStatement(SQL_FROM_HERE,
       "SELECT value FROM meta WHERE key=?"));
   statement->BindCString(0, key);
   return statement->Step();
 }
 
 }  // namespace sql