sql/meta_table.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "sql/meta_table.h"
   6
   7 #include "base/logging.h"
   8 #include "base/string_util.h"
   9 #include "sql/connection.h"
  10 #include "sql/statement.h"
  11 #include "sql/transaction.h"
  12
  13 namespace sql {
  14
  15 // Key used in our meta table for version numbers.
  16 static const char kVersionKey[] = "version";
  17 static const char kCompatibleVersionKey[] = "last_compatible_version";
  18
  19 MetaTable::MetaTable() : db_(NULL) {
  20 }
  21
  22 MetaTable::~MetaTable() {
  23 }
  24
  25 // static
  26 bool MetaTable::DoesTableExist(sql::Connection* db) {
  27   DCHECK(db);
  28   return db->DoesTableExist("meta");
  29 }
  30
  31 bool MetaTable::Init(Connection* db, int version, int compatible_version) {
  32   DCHECK(!db_ && db);
  33   db_ = db;
  34
  35   // If values stored are null or missing entirely, 0 will be reported.
  36   // Require new clients to start with a greater initial version.
  37   DCHECK_GT(version, 0);
  38   DCHECK_GT(compatible_version, 0);
  39
  40   // Make sure the table is created an populated atomically.
  41   sql::Transaction transaction(db_);
  42   if (!transaction.Begin())
  43     return false;
  44
  45   if (!DoesTableExist(db)) {
  46     if (!db_->Execute("CREATE TABLE meta"
  47         "(key LONGVARCHAR NOT NULL UNIQUE PRIMARY KEY, value LONGVARCHAR)"))
  48       return false;
  49
  50     // Note: there is no index over the meta table. We currently only have a
  51     // couple of keys, so it doesn't matter. If we start storing more stuff in
  52     // there, we should create an index.
  53     SetVersionNumber(version);
  54     SetCompatibleVersionNumber(compatible_version);
  55   } else {
  56     db_->AddTaggedHistogram("Sqlite.Version", GetVersionNumber());
  57   }
  58   return transaction.Commit();
  59 }
  60
  61 void MetaTable::Reset() {
  62   db_ = NULL;
  63 }
  64
  65 void MetaTable::SetVersionNumber(int version) {
  66   DCHECK_GT(version, 0);
  67   SetValue(kVersionKey, version);
  68 }
  69
  70 int MetaTable::GetVersionNumber() {
  71   int version = 0;
  72   return GetValue(kVersionKey, &version) ? version : 0;
  73 }
  74
  75 void MetaTable::SetCompatibleVersionNumber(int version) {
  76   DCHECK_GT(version, 0);
  77   SetValue(kCompatibleVersionKey, version);
  78 }
  79
  80 int MetaTable::GetCompatibleVersionNumber() {
  81   int version = 0;
  82   return GetValue(kCompatibleVersionKey, &version) ? version : 0;
  83 }
  84
  85 bool MetaTable::SetValue(const char* key, const std::string& value) {
  86   Statement s;
  87   PrepareSetStatement(&s, key);
  88   s.BindString(1, value);
  89   return s.Run();
  90 }
  91
  92 bool MetaTable::SetValue(const char* key, int value) {
  93   Statement s;
  94   PrepareSetStatement(&s, key);
  95   s.BindInt(1, value);
  96   return s.Run();
  97 }
  98
  99 bool MetaTable::SetValue(const char* key, int64 value) {
 100   Statement s;
 101   PrepareSetStatement(&s, key);
 102   s.BindInt64(1, value);
 103   return s.Run();
 104 }
 105
 106 bool MetaTable::GetValue(const char* key, std::string* value) {
 107   Statement s;
 108   if (!PrepareGetStatement(&s, key))
 109     return false;
 110
 111   *value = s.ColumnString(0);
 112   return true;
 113 }
 114
 115 bool MetaTable::GetValue(const char* key, int* value) {
 116   Statement s;
 117   if (!PrepareGetStatement(&s, key))
 118     return false;
 119
 120   *value = s.ColumnInt(0);
 121   return true;
 122 }
 123
 124 bool MetaTable::GetValue(const char* key, int64* value) {
 125   Statement s;
 126   if (!PrepareGetStatement(&s, key))
 127     return false;
 128
 129   *value = s.ColumnInt64(0);
 130   return true;
 131 }
 132
 133 bool MetaTable::DeleteKey(const char* key) {
 134   DCHECK(db_);
 135   Statement s(db_->GetUniqueStatement("DELETE FROM meta WHERE key=?"));
 136   s.BindCString(0, key);
 137   return s.Run();
 138 }
 139
 140 void MetaTable::PrepareSetStatement(Statement* statement, const char* key) {
 141   DCHECK(db_ && statement);
 142   statement->Assign(db_->GetCachedStatement(SQL_FROM_HERE,
 143       "INSERT OR REPLACE INTO meta (key,value) VALUES (?,?)"));
 144   statement->BindCString(0, key);
 145 }
 146
 147 bool MetaTable::PrepareGetStatement(Statement* statement, const char* key) {
 148   DCHECK(db_ && statement);
 149   statement->Assign(db_->GetCachedStatement(SQL_FROM_HERE,
 150       "SELECT value FROM meta WHERE key=?"));
 151   statement->BindCString(0, key);
 152   return statement->Step();
 153 }
 154
 155 }  // namespace sql