predictors: Extract sql key-value tables into separate class.

chrome/browser/predictors/glowplug_key_value_table.h

+// Copyright 2017 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.
+
+#ifndef CHROME_BROWSER_PREDICTORS_GLOWPLUG_KEY_VALUE_TABLE_H_
+#define CHROME_BROWSER_PREDICTORS_GLOWPLUG_KEY_VALUE_TABLE_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/strings/stringprintf.h"
+#include "sql/statement.h"
+
+namespace google {
+namespace protobuf {
+class MessageLite;
+}
+}
+
+namespace predictors {
+
+namespace internal {
+
+void BindDataToStatement(const std::string& key,
+                         const google::protobuf::MessageLite& data,
+                         sql::Statement* statement);
+
+std::string GetSelectAllSql(const std::string& table_name);
+std::string GetReplaceSql(const std::string& table_name);
+std::string GetDeleteSql(const std::string& table_name);
+std::string GetDeleteAllSql(const std::string& table_name);
+
+}  // namespace internal
+
+template <typename T>
+class GlowplugKeyValueTable {
+ public:
+  GlowplugKeyValueTable(const std::string& table_name, sql::Connection* db);
+  // Virtual for testing.
+  virtual void GetAllData(std::map<std::string, T>* data_map) const;
+  virtual void UpdateData(const std::string& key, const T& data);
+  virtual void DeleteData(const std::vector<std::string>& keys);
+  virtual void DeleteAllData();
+
+ private:
+  const std::string table_name_;
+  sql::Connection* db_;
+
+  DISALLOW_COPY_AND_ASSIGN(GlowplugKeyValueTable);
+};
+
+template <typename T>
+GlowplugKeyValueTable<T>::GlowplugKeyValueTable(const std::string& table_name,
+                                                sql::Connection* db)
+    : table_name_(table_name), db_(db) {}
+
+template <typename T>
+void GlowplugKeyValueTable<T>::GetAllData(
+    std::map<std::string, T>* data_map) const {
+  sql::Statement reader(db_->GetUniqueStatement(
+      ::predictors::internal::GetSelectAllSql(table_name_).c_str()));
+  while (reader.Step()) {
+    auto it = data_map->emplace(reader.ColumnString(0), T()).first;
+    int size = reader.ColumnByteLength(1);
+    const void* blob = reader.ColumnBlob(1);
+    DCHECK(blob);
+    it->second.ParseFromArray(blob, size);
+  }
+}
+
+template <typename T>
+void GlowplugKeyValueTable<T>::UpdateData(const std::string& key,
+                                          const T& data) {
+  sql::Statement inserter(db_->GetUniqueStatement(
+      ::predictors::internal::GetReplaceSql(table_name_).c_str()));
+  ::predictors::internal::BindDataToStatement(key, data, &inserter);
+  inserter.Run();
+}
+
+template <typename T>
+void GlowplugKeyValueTable<T>::DeleteData(
+    const std::vector<std::string>& keys) {
+  auto statement = db_->GetUniqueStatement(
+      ::predictors::internal::GetDeleteSql(table_name_).c_str());
+  for (const auto& key : keys) {
+    sql::Statement deleter(statement);
+    deleter.BindString(0, key);
+    deleter.Run();
+  }
+}
+
+template <typename T>
+void GlowplugKeyValueTable<T>::DeleteAllData() {
+  sql::Statement deleter(db_->GetUniqueStatement(
+      ::predictors::internal::GetDeleteAllSql(table_name_).c_str()));
+  deleter.Run();
+}
+
+}  // namespace predictors
+
+#endif  // CHROME_BROWSER_PREDICTORS_GLOWPLUG_KEY_VALUE_TABLE_H_