[sql] WARN_UNUSED_RESULT on Execute().

Goal is to encourage callers to handle errors, especially in cases
like schema changes, where dropped errors can result in broken
databases.

Many CREATE INDEX calls where ignoring errors rather than checking if
the index already existed before creating it.  Recoded those to CREATE
INDEX IF NOT EXISTS, which is for exactly this purpose.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/9005036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@115725 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 19 insertions, 20 deletions

diff --git a/chrome/browser/history/thumbnail_database.cc b/chrome/browser/history/thumbnail_database.cc
index 82aed1a..6827077 100644
--- a/chrome/browser/history/thumbnail_database.cc
+++ b/chrome/browser/history/thumbnail_database.cc
@@ -85,12 +85,12 @@ sql::InitStatus ThumbnailDatabase::Init(
                         kCompatibleVersionNumber) ||
       !InitThumbnailTable() ||
       !InitFaviconsTable(&db_, false) ||
-      !InitIconMappingTable(&db_, false)) {
+      !InitFaviconsIndex() ||
+      !InitIconMappingTable(&db_, false) ||
+      !InitIconMappingIndex()) {
     db_.Close();
     return sql::INIT_FAILURE;
   }
-  InitFaviconsIndex();
-  InitIconMappingIndex();
 
   // Version check. We should not encounter a database too old for us to handle
   // in the wild, so we try to continue in that case.
@@ -219,10 +219,10 @@ bool ThumbnailDatabase::InitFaviconsTable(sql::Connection* db,
   return true;
 }
 
-void ThumbnailDatabase::InitFaviconsIndex() {
-  // Add an index on the url column. We ignore errors. Since this is always
-  // called during startup, the index will normally already exist.
-  db_.Execute("CREATE INDEX favicons_url ON favicons(url)");
+bool ThumbnailDatabase::InitFaviconsIndex() {
+  // Add an index on the url column.
+  return
+      db_.Execute("CREATE INDEX IF NOT EXISTS favicons_url ON favicons(url)");
 }
 
 void ThumbnailDatabase::BeginTransaction() {
@@ -236,7 +236,7 @@ void ThumbnailDatabase::CommitTransaction() {
 void ThumbnailDatabase::Vacuum() {
   DCHECK(db_.transaction_nesting() == 0) <<
       "Can not have a transaction when vacuuming.";
-  db_.Execute("VACUUM");
+  ignore_result(db_.Execute("VACUUM"));
 }
 
 void ThumbnailDatabase::SetPageThumbnail(
@@ -605,9 +605,7 @@ bool ThumbnailDatabase::CommitTemporaryIconMappingTable() {
     return false;
 
   // The renamed table needs the index (the temporary table doesn't have one).
-  InitIconMappingIndex();
-
-  return true;
+  return InitIconMappingIndex();
 }
 
 FaviconID ThumbnailDatabase::CopyToTemporaryFaviconTable(FaviconID source) {
@@ -635,8 +633,7 @@ bool ThumbnailDatabase::CommitTemporaryFaviconTable() {
     return false;
 
   // The renamed table needs the index (the temporary table doesn't have one).
-  InitFaviconsIndex();
-  return true;
+  return InitFaviconsIndex();
 }
 
 bool ThumbnailDatabase::NeedsMigrationToTopSites() {
@@ -713,7 +710,8 @@ bool ThumbnailDatabase::RenameAndDropThumbnails(const FilePath& old_db_file,
   if (!meta_table_.Init(&db_, kCurrentVersionNumber, kCompatibleVersionNumber))
     return false;
 
-  InitFaviconsIndex();
+  if (!InitFaviconsIndex())
+    return false;
 
   // Reopen the transaction.
   BeginTransaction();
@@ -738,12 +736,13 @@ bool ThumbnailDatabase::InitIconMappingTable(sql::Connection* db,
   return true;
 }
 
-void ThumbnailDatabase::InitIconMappingIndex() {
-  // Add an index on the url column. We ignore errors. Since this is always
-  // called during startup, the index will normally already exist.
-  db_.Execute("CREATE INDEX icon_mapping_page_url_idx"
-              " ON icon_mapping(page_url)");
-  db_.Execute("CREATE INDEX icon_mapping_icon_id_idx ON icon_mapping(icon_id)");
+bool ThumbnailDatabase::InitIconMappingIndex() {
+  // Add an index on the url column.
+  return
+      db_.Execute("CREATE INDEX IF NOT EXISTS icon_mapping_page_url_idx"
+                  " ON icon_mapping(page_url)") &&
+      db_.Execute("CREATE INDEX IF NOT EXISTS icon_mapping_icon_id_idx"
+                  " ON icon_mapping(icon_id)");
 }
 
 IconMappingID ThumbnailDatabase::AddIconMapping(const GURL& page_url,