[Offline pages] OPMStoreSQL: Upgrade to M55, Upgrade refactoring, conversion refactoring

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"
@@ skipping 15 matching lines @@
 
 // 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"
 
 bool CreateOfflinePagesTable(sql::Connection* db) {
   const char kSql[] = "CREATE TABLE IF NOT EXISTS " OFFLINE_PAGES_TABLE_NAME
                       "(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,"
-                      // TODO(fgorski): Remove. Never used.
-                      " 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
                       " expiration_time INTEGER NOT NULL DEFAULT 0,"
                       " client_namespace VARCHAR NOT NULL,"
                       " client_id VARCHAR NOT NULL,"
                       " online_url VARCHAR NOT NULL,"
-                      // TODO(fgorski): Remove. Never used.
-                      " offline_url VARCHAR NOT NULL DEFAULT '',"
                       " file_path VARCHAR NOT NULL,"
                       " title VARCHAR NOT NULL DEFAULT ''"
                       ")";
   return db->Execute(kSql);
 }
 
-bool RefreshColumnsFrom52To54(sql::Connection* db) {
+bool UpgradeFrom52(sql::Connection* db) {
   if (!db->Execute("ALTER TABLE " OFFLINE_PAGES_TABLE_NAME
                    " RENAME TO temp_" OFFLINE_PAGES_TABLE_NAME)) {
     return false;
   }
   if (!CreateOfflinePagesTable(db))
     return false;
   if (!db->Execute(
           "INSERT INTO " OFFLINE_PAGES_TABLE_NAME
-          " (offline_id, creation_time, file_size, version, last_access_time, "
-          "access_count, status, user_initiated, client_namespace, client_id, "
-          "online_url, offline_url, file_path) "
-          "SELECT offline_id, creation_time, file_size, version, "
-          "last_access_time, "
-          "access_count, status, user_initiated, client_namespace, client_id, "
-          "online_url, offline_url, file_path "
+          " (offline_id, creation_time, file_size, last_access_time, "
+          "access_count, client_namespace, client_id, "
+          "online_url, file_path) "
+          "SELECT "
+          "offline_id, creation_time, file_size, last_access_time, "
+          "access_count, client_namespace, client_id, "
+          "online_url, file_path "
           "FROM temp_" OFFLINE_PAGES_TABLE_NAME)) {
     return false;
   }
   if (!db->Execute("DROP TABLE IF EXISTS temp_" OFFLINE_PAGES_TABLE_NAME))
     return false;
 
   return true;
 }
 
-bool RefreshColumnsFrom53To54(sql::Connection* db) {
+bool UpgradeFrom53(sql::Connection* db) {
   if (!db->Execute("ALTER TABLE " OFFLINE_PAGES_TABLE_NAME
                    " RENAME TO temp_" OFFLINE_PAGES_TABLE_NAME)) {
     return false;
   }
   if (!CreateOfflinePagesTable(db))
     return false;
   if (!db->Execute(
           "INSERT INTO " OFFLINE_PAGES_TABLE_NAME
-          " (offline_id, creation_time, file_size, version, last_access_time, "
-          "access_count, status, user_initiated, client_namespace, client_id, "
-          "online_url, offline_url, file_path, expiration_time) "
-          "SELECT offline_id, creation_time, file_size, version, "
-          "last_access_time, "
-          "access_count, status, user_initiated, client_namespace, client_id, "
-          "online_url, offline_url, file_path, expiration_time "
+          " (offline_id, creation_time, file_size, last_access_time, "
+          "access_count, expiration_time, client_namespace, client_id, "
+          "online_url, file_path) "
+          "SELECT "
+          "offline_id, creation_time, file_size, last_access_time, "
+          "access_count, expiration_time, client_namespace, client_id, "
+          "online_url, file_path "
           "FROM temp_" OFFLINE_PAGES_TABLE_NAME)) {
     return false;
   }
+  if (!db->Execute("DROP TABLE IF EXISTS temp_" OFFLINE_PAGES_TABLE_NAME))
+    return false;
+
+  return true;
+}
+
+bool UpgradeFrom54(sql::Connection* db) {
+  if (!db->Execute("ALTER TABLE " OFFLINE_PAGES_TABLE_NAME
+                   " RENAME TO temp_" OFFLINE_PAGES_TABLE_NAME)) {
+    return false;
+  }
+  if (!CreateOfflinePagesTable(db))
+    return false;
+  if (!db->Execute(

[dewittj, 2016/09/13 18:10:07]

Now that there are 3 copies of this function, it seems like it's time to
refactor this a little to reduce duplication.

[fgorski, 2016/09/13 21:40:21]

Done.

+          "INSERT INTO " OFFLINE_PAGES_TABLE_NAME
+          " (offline_id, creation_time, file_size, last_access_time, "
+          "access_count, expiration_time, client_namespace, client_id, "
+          "online_url, file_path, title) "
+          "SELECT "
+          "offline_id, creation_time, file_size, last_access_time, "
+          "access_count, expiration_time, client_namespace, client_id, "
+          "online_url, file_path, title "
+          "FROM temp_" OFFLINE_PAGES_TABLE_NAME)) {
+    return false;
+  }
   if (!db->Execute("DROP TABLE IF EXISTS temp_" OFFLINE_PAGES_TABLE_NAME))
     return false;
 
   return true;
 }
 
 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(OFFLINE_PAGES_TABLE_NAME)) {
     if (!CreateOfflinePagesTable(db))
       return false;
   }
 
+  // Last Schema update was M55. When making a new Schema update, please update
+  // all methods below to appropriately upgrade from their respective milestones
+  // and add appropriate method to cover changes from M55.

[dewittj, 2016/09/13 18:10:08]

I would like to see somewhere a log of the changes in each version, so that the
upgrade checks are somewhat legible.  If I am reading the code right:
* Initial version lasted through M52
* 53 we added expiration_time
* 54 we added title
* 55 we removed version, status, user_initiated, offline_url.

[romax, 2016/09/13 18:32:14]

I wish these comments can be with those upgrade functions. And originally I was
thinking maybe it's better to keep track of the table version with the table so
that we don't have to check the schema to match with a version. Also I suggest
to use upgrade from X to X+1 and do that for M53ToM54, M54ToM55 while using a
method creating M53 schema as a base. Otherwise it seems to me everytime we
update the schema, we have to change (# of versions - 1) methods while updating
the code?

[fgorski, 2016/09/13 21:40:21]

Done.

   if (!db->DoesColumnExist(OFFLINE_PAGES_TABLE_NAME, "expiration_time")) {
-    if (!RefreshColumnsFrom52To54(db))
+    if (!UpgradeFrom52(db))
       return false;
   } else if (!db->DoesColumnExist(OFFLINE_PAGES_TABLE_NAME, "title")) {
-    if (!RefreshColumnsFrom53To54(db))
+    if (!UpgradeFrom53(db))
+      return false;
+  } else if (db->DoesColumnExist(OFFLINE_PAGES_TABLE_NAME, "offline_url")) {
+    if (!UpgradeFrom54(db))
       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();
 }
 
+base::FilePath GetPathFromString(const std::string& path_string) {

[dewittj, 2016/09/13 18:10:07]

Maybe name this GetPathFromUTF8String (and similar below), this makes it obvious
what the point is.

[fgorski, 2016/09/13 21:40:21]

Done.

+#if defined(OS_POSIX)
+  return base::FilePath(path_string);
+#elif defined(OS_WIN)
+  return base::FilePath(base::UTF8ToWide(path_string));
+#else
+#error Unknown OS
+#endif
+}
+
+std::string GetStringFromPath(const base::FilePath& path) {
+#if defined(OS_POSIX)
+  return path.value();
+#elif defined(OS_WIN)
+  return base::WideToUTF8(path.value());
+#else
+#error Unknown OS
+#endif
+}
+
 // 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(0);
   base::Time creation_time =
       base::Time::FromInternalValue(statement->ColumnInt64(1));
   int64_t file_size = statement->ColumnInt64(2);
-  ClientId client_id(statement->ColumnString(9),
-                     statement->ColumnString(10));
-  GURL url(statement->ColumnString(11));
-#if defined(OS_POSIX)
-  base::FilePath path(statement->ColumnString(13));
-#elif defined(OS_WIN)
-  base::FilePath path(base::UTF8ToWide(statement->ColumnString(13)));
-#else
-#error Unknown OS
-#endif
+  base::Time last_access_time =
+      base::Time::FromInternalValue(statement->ColumnInt64(3));
+  int access_count = statement->ColumnInt(4);
+  base::Time expiration_time =
+      base::Time::FromInternalValue(statement->ColumnInt64(5));
+  ClientId client_id(statement->ColumnString(6), statement->ColumnString(7));
+  GURL url(statement->ColumnString(8));
+  base::FilePath path(GetPathFromString(statement->ColumnString(9)));
+  base::string16 title = statement->ColumnString16(10);
 
   OfflinePageItem item(url, id, client_id, path, file_size, creation_time);
-  item.version = statement->ColumnInt(3);
-  item.last_access_time = base::Time::FromInternalValue(
-      statement->ColumnInt64(4));
-  item.access_count = statement->ColumnInt(5);
-  item.expiration_time =
-      base::Time::FromInternalValue(statement->ColumnInt64(8));
-  item.title = statement->ColumnString16(14);
+  item.last_access_time = last_access_time;
+  item.access_count = access_count;
+  item.expiration_time = expiration_time;
+  item.title = title;
   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, "
+      "file_size, creation_time, last_access_time, access_count, "
       "expiration_time, title)"
       " 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());
-#else
-#error Unknown OS
-#endif
-  statement.BindString(4, path_string);
+  statement.BindString(4, GetStringFromPath(item.file_path));
   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);
-  statement.BindInt64(10, item.expiration_time.ToInternalValue());
-  statement.BindString16(11, item.title);
+  statement.BindInt(8, item.access_count);
+  statement.BindInt64(9, item.expiration_time.ToInternalValue());
+  statement.BindString16(10, item.title);
   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;
@@ skipping 219 matching lines @@
   DCHECK(db_.get());
   if (!db_.get()) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                   base::Bind(callback));
     return false;
   }
   return true;
 }
 
 }  // namespace offline_pages