initial add of SQL based storage

components/offline_pages/offline_page_metadata_store_sql.cc

+// Copyright 2016 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 "components/offline_pages/offline_page_metadata_store_sql.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/sequenced_task_runner.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/thread_task_runner_handle.h"
+#include "components/offline_pages/offline_page_item.h"
+#include "sql/connection.h"
+#include "sql/statement.h"
+#include "sql/transaction.h"
+
+namespace offline_pages {
+
+namespace {
+
+// This is a macro instead of a const so that
+// it can be used inline in other SQL statements below.
+#define OFFLINE_PAGES_TABLE_NAME "offlinepages_v1"
+
+const char kOfflinePagesColumns[] =
+    "(offline_id INTEGER PRIMARY KEY NOT NULL,"
+    " creation_time INTEGER NOT NULL,"
+    " file_size INTEGER NOT NULL,"
+    " version INTEGER NOT NULL,"
+    " last_access_time INTEGER NOT NULL,"
+    " access_count INTEGER NOT NULL,"
+    " status INTEGER NOT NULL DEFAULT 0,"
+    // A note on this field:  It will be NULL for now and is reserved for
+    // later use.  We will treat NULL as "Unknown" in any subsequent queries
+    // for user_initiated values.
+    " user_initiated INTEGER,"  // this is actually a boolean
+    " client_namespace VARCHAR NOT NULL,"
+    " client_id VARCHAR NOT NULL,"
+    " online_url VARCHAR NOT NULL,"
+    " offline_url VARCHAR NOT NULL DEFAULT \"\","

[Scott Hess - ex-Googler, 2016/05/03 18:09:03]

Use '' (double single quotes).  SQL uses double-quoted strings to quote
identifiers.  SQLite interprets double-quoted strings as strings in contexts
where it cannot be resolved to an identifier, for compatibility with other SQL
systems.

http://stackoverflow.com/questions/1992314/what-is-the-difference-between-sin...

[bburns, 2016/05/03 19:39:32]

Done.

+    " file_path VARCHAR NOT NULL"
+    ")";
+
+// This is cloned from //content/browser/appcache/appcache_database.cc
+struct TableInfo {
+  const char* table_name;
+  const char* columns;
+};
+
+const TableInfo kOfflinePagesTable{OFFLINE_PAGES_TABLE_NAME,
+                                   kOfflinePagesColumns};
+
+// This enum is used to define the indices for the columns in each row
+// that hold the different pieces of offline page.
+enum : int {
+  OP_OFFLINE_ID = 0,
+  OP_CREATION_TIME,
+  OP_FILE_SIZE,
+  OP_VERSION,
+  OP_LAST_ACCESS_TIME,
+  OP_ACCESS_COUNT,
+  OP_STATUS,
+  OP_USER_INITIATED,
+  OP_CLIENT_NAMESPACE,
+  OP_CLIENT_ID,
+  OP_ONLINE_URL,
+  OP_OFFLINE_URL,
+  OP_FILE_PATH
+};
+
+bool CreateTable(sql::Connection* db, const TableInfo& table_info) {
+  std::string sql("CREATE TABLE ");
+  sql += table_info.table_name;
+  sql += table_info.columns;
+  return db->Execute(sql.c_str());
+}
+
+bool CreateSchema(sql::Connection* db) {
+  // If you create a transaction but don't Commit() it is automatically
+  // rolled back by its destructor when it falls out of scope.
+  sql::Transaction transaction(db);
+  if (!transaction.Begin())
+    return false;
+  if (db->DoesTableExist(kOfflinePagesTable.table_name))
+    return true;
+
+  if (!CreateTable(db, kOfflinePagesTable))
+    return false;
+
+  // TODO(bburns): Add indices here.
+  return transaction.Commit();
+}
+
+bool DeleteByOfflineId(sql::Connection* db, int64_t offline_id) {
+  static const char kSql[] =
+      "DELETE FROM " OFFLINE_PAGES_TABLE_NAME " WHERE offline_id=?";
+  sql::Statement statement(db->GetCachedStatement(SQL_FROM_HERE, kSql));
+  statement.BindInt64(0, offline_id);
+  return statement.Run();
+}
+
+// Create an offline page item from a SQL result.  Expects complete rows with
+// all columns present.
+OfflinePageItem MakeOfflinePageItem(sql::Statement* statement) {
+  int64_t id = statement->ColumnInt64(OP_OFFLINE_ID);
+  GURL url(statement->ColumnString(OP_ONLINE_URL));
+  ClientId client_id(statement->ColumnString(OP_CLIENT_NAMESPACE),
+                     statement->ColumnString(OP_CLIENT_ID));
+#if defined(OS_POSIX)
+  base::FilePath path(statement->ColumnString(OP_FILE_PATH));
+#elif defined(OS_WIN)
+  base::FilePath path(base::UTF8ToWide(statement->ColumnString(OP_FILE_PATH)));
+#else
+#error Unknown OS
+#endif
+  int64_t file_size = statement->ColumnInt64(OP_FILE_SIZE);
+  base::Time creation_time =
+      base::Time::FromInternalValue(statement->ColumnInt64(OP_CREATION_TIME));
+
+  OfflinePageItem item(url, id, client_id, path, file_size, creation_time);
+  item.last_access_time = base::Time::FromInternalValue(
+      statement->ColumnInt64(OP_LAST_ACCESS_TIME));
+  item.version = statement->ColumnInt(OP_VERSION);
+  item.access_count = statement->ColumnInt(OP_ACCESS_COUNT);
+  return item;
+}
+
+bool InsertOrReplace(sql::Connection* db, const OfflinePageItem& item) {
+  const char kSql[] =
+      "INSERT OR REPLACE INTO " OFFLINE_PAGES_TABLE_NAME
+      " (offline_id, online_url, client_namespace, client_id, file_path, "
+      "file_size, creation_time, last_access_time, version, access_count)"
+      " VALUES "
+      " (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)";
+
+  sql::Statement statement(db->GetCachedStatement(SQL_FROM_HERE, kSql));
+  statement.BindInt64(0, item.offline_id);
+  statement.BindString(1, item.url.spec());
+  statement.BindString(2, item.client_id.name_space);
+  statement.BindString(3, item.client_id.id);
+#if defined(OS_POSIX)
+  std::string path_string = item.file_path.value();
+#elif defined(OS_WIN)
+  std::string path_string = base::WideToUTF8(item.file_path.value());

[Scott Hess - ex-Googler, 2016/05/03 18:09:03]

Missing the #else/#error Unknown OS.

[bburns, 2016/05/03 19:39:32]

oops, sorry I missed that in the earlier review...

Done.

+#endif
+  statement.BindString(4, path_string);
+  statement.BindInt64(5, item.file_size);
+  statement.BindInt64(6, item.creation_time.ToInternalValue());
+  statement.BindInt64(7, item.last_access_time.ToInternalValue());
+  statement.BindInt(8, item.version);
+  statement.BindInt(9, item.access_count);
+  return statement.Run();
+}
+
+bool InitDatabase(sql::Connection* db, base::FilePath path) {
+  db->set_page_size(4096);
+  db->set_cache_size(500);
+  db->set_histogram_tag("OfflinePageMetadata");
+  db->set_exclusive_locking();
+
+  base::File::Error err;
+  if (!base::CreateDirectoryAndGetError(path.DirName(), &err)) {
+    LOG(ERROR) << "Failed to create offline pages db directory: "
+               << base::File::ErrorToString(err);
+    return false;
+  }
+  if (!db->Open(path)) {
+    LOG(ERROR) << "Failed to open database";
+    return false;
+  }
+  db->Preload();
+
+  return CreateSchema(db);
+}
+
+}  // anonymous namespace
+
+OfflinePageMetadataStoreSQL::OfflinePageMetadataStoreSQL(
+    scoped_refptr<base::SequencedTaskRunner> background_task_runner,
+    const base::FilePath& path)
+    : background_task_runner_(std::move(background_task_runner)),
+      db_file_path_(path.AppendASCII("OfflinePages.db")) {}
+
+OfflinePageMetadataStoreSQL::~OfflinePageMetadataStoreSQL() {
+  if (db_.get() &&
+      !background_task_runner_->DeleteSoon(FROM_HERE, db_.release())) {
+    DLOG(WARNING) << "SQL database will not be deleted.";
+  }
+}
+
+void OfflinePageMetadataStoreSQL::LoadSync(
+    sql::Connection* db,
+    const base::FilePath& path,
+    scoped_refptr<base::SingleThreadTaskRunner> runner,
+    const LoadCallback& callback) {
+  if (!InitDatabase(db, path)) {
+    NotifyLoadResult(runner, callback, STORE_INIT_FAILED,
+                     std::vector<OfflinePageItem>());
+    return;
+  }
+
+  const char kSql[] = "SELECT * FROM " OFFLINE_PAGES_TABLE_NAME;
+
+  sql::Statement statement(db->GetCachedStatement(SQL_FROM_HERE, kSql));
+
+  std::vector<OfflinePageItem> result;
+  while (statement.Step()) {
+    result.push_back(MakeOfflinePageItem(&statement));
+  }
+
+  if (statement.Succeeded()) {
+    NotifyLoadResult(runner, callback, LOAD_SUCCEEDED, result);
+  } else {
+    NotifyLoadResult(runner, callback, STORE_LOAD_FAILED,
+                     std::vector<OfflinePageItem>());
+  }
+}
+
+void OfflinePageMetadataStoreSQL::AddOrUpdateOfflinePageSync(
+    const OfflinePageItem& offline_page,
+    sql::Connection* db,
+    scoped_refptr<base::SingleThreadTaskRunner> runner,
+    const UpdateCallback& callback) {
+  // TODO(bburns): add UMA metrics here (and for levelDB).
+  bool ok = InsertOrReplace(db, offline_page);
+  runner->PostTask(FROM_HERE, base::Bind(callback, ok));
+}
+
+void OfflinePageMetadataStoreSQL::RemoveOfflinePagesSync(
+    const std::vector<int64_t>& offline_ids,
+    sql::Connection* db,
+    scoped_refptr<base::SingleThreadTaskRunner> runner,
+    const UpdateCallback& callback) {
+  // TODO(bburns): add UMA metrics here (and for levelDB).
+
+  // If you create a transaction but don't Commit() it is automatically
+  // rolled back by its destructor when it falls out of scope.
+  sql::Transaction transaction(db);
+  if (!transaction.Begin()) {
+    runner->PostTask(FROM_HERE, base::Bind(callback, false));
+    return;
+  }
+  for (auto offline_id : offline_ids) {
+    if (!DeleteByOfflineId(db, offline_id)) {
+      runner->PostTask(FROM_HERE, base::Bind(callback, false));
+      return;
+    }
+  }
+
+  bool success = transaction.Commit();
+  runner->PostTask(FROM_HERE, base::Bind(callback, success));
+}
+
+void OfflinePageMetadataStoreSQL::ResetSync(
+    std::unique_ptr<sql::Connection> db,
+    scoped_refptr<base::SingleThreadTaskRunner> runner,
+    const ResetCallback& callback) {
+  const char kSql[] = "DELETE * FROM " OFFLINE_PAGES_TABLE_NAME;
+  sql::Statement statement(db->GetCachedStatement(SQL_FROM_HERE, kSql));
+  runner->PostTask(FROM_HERE, base::Bind(callback, statement.Run()));
+}
+
+void OfflinePageMetadataStoreSQL::NotifyLoadResult(
+    scoped_refptr<base::SingleThreadTaskRunner> runner,
+    const LoadCallback& callback,
+    LoadStatus status,
+    const std::vector<OfflinePageItem>& result) {
+  // TODO(bburns): Switch to SQL specific UMA metrics.
+  UMA_HISTOGRAM_ENUMERATION("OfflinePages.LoadStatus", status,
+                            OfflinePageMetadataStore::LOAD_STATUS_COUNT);
+  if (status == LOAD_SUCCEEDED) {
+    UMA_HISTOGRAM_COUNTS("OfflinePages.SavedPageCount", result.size());
+  } else {
+    DVLOG(1) << "Offline pages database loading failed: " << status;
+  }
+  runner->PostTask(FROM_HERE, base::Bind(callback, status, result));
+}
+
+void OfflinePageMetadataStoreSQL::Load(const LoadCallback& callback) {
+  db_.reset(new sql::Connection());
+  background_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreSQL::LoadSync, db_.get(),
+                 db_file_path_, base::ThreadTaskRunnerHandle::Get(), callback));
+}
+
+void OfflinePageMetadataStoreSQL::AddOrUpdateOfflinePage(
+    const OfflinePageItem& offline_page,
+    const UpdateCallback& callback) {
+  DCHECK(db_.get());
+  background_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreSQL::AddOrUpdateOfflinePageSync,
+                 offline_page, db_.get(), base::ThreadTaskRunnerHandle::Get(),
+                 callback));
+}
+
+void OfflinePageMetadataStoreSQL::RemoveOfflinePages(
+    const std::vector<int64_t>& offline_ids,
+    const UpdateCallback& callback) {
+  DCHECK(db_.get());
+
+  if (offline_ids.empty()) {
+    // Nothing to do, but post a callback instead of calling directly
+    // to preserve the async style behavior to prevent bugs.
+    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
+                                                  base::Bind(callback, true));
+    return;
+  }
+
+  background_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreSQL::RemoveOfflinePagesSync,
+                 offline_ids, db_.get(), base::ThreadTaskRunnerHandle::Get(),
+                 callback));
+}
+
+void OfflinePageMetadataStoreSQL::Reset(const ResetCallback& callback) {
+  background_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreSQL::ResetSync, base::Passed(&db_),
+                 base::ThreadTaskRunnerHandle::Get(), callback));
+}
+
+}  // namespace offline_pages