Bug 658305 - Use journal_size_limit on places.sqlite.

r=dietrich

toolkit/components/places/Database.cpp

@@ -592,7 +592,17 @@ Database::InitSchema(bool* aDatabaseMigrated)
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  // Grow places in 10MiB increments
+  // The journal is usually free to grow for performance reasons, but it never
+  // shrinks back.  Since the space taken may be problematic, especially on
+  // mobile devices, limit its size.
+  // Since exceeding the limit will cause a truncate, allow a slightly
+  // larger limit than DATABASE_MAX_WAL_SIZE_IN_KIBIBYTES to reduce the number
+  // of times it is needed.
+  nsCAutoString journalSizePragma("PRAGMA journal_size_limit = ");
+  journalSizePragma.AppendInt(DATABASE_MAX_WAL_SIZE_IN_KIBIBYTES * 3);
+  (void)mMainConn->ExecuteSimpleSQL(journalSizePragma);
+
+  // Grow places in 10MiB increments to limit fragmentation on disk.
   (void)mMainConn->SetGrowthIncrement(10 * BYTES_PER_MEBIBYTE, EmptyCString());
 
   // We use our functions during migration, so initialize them now.

toolkit/components/places/tests/unit/test_telemetry.js

@@ -14,7 +14,8 @@ let histograms = {
   PLACES_SORTED_BOOKMARKS_PERC: function (val) do_check_eq(val, 100),
   PLACES_TAGGED_BOOKMARKS_PERC: function (val) do_check_eq(val, 100),
   PLACES_DATABASE_FILESIZE_MB: function (val) do_check_true(val > 0),
-  PLACES_DATABASE_JOURNALSIZE_MB: function (val) do_check_true(val > 0),
+  // The journal may have been truncated.
+  PLACES_DATABASE_JOURNALSIZE_MB: function (val) do_check_true(val >= 0),
   PLACES_DATABASE_PAGESIZE_B: function (val) do_check_eq(val, 32768),
   PLACES_DATABASE_SIZE_PER_PAGE_B: function (val) do_check_true(val > 0),
   PLACES_EXPIRATION_STEPS_TO_CLEAN: function (val) do_check_true(val > 1),