[core] OfflineDatabase pack API

- introduce `OfflineDatabase::pack()` standing for incremental vacuum
- make pack optional at offline region deletion
- update `OfflineDatabase.DeleteRegion` test accordingly to the items above

2 files changed, 15 insertions, 4 deletions

diff --git a/platform/default/include/mbgl/storage/offline_database.hpp b/platform/default/include/mbgl/storage/offline_database.hpp
index f097cd5440..ac997bf6ad 100644
--- a/platform/default/include/mbgl/storage/offline_database.hpp
+++ b/platform/default/include/mbgl/storage/offline_database.hpp
@@ -74,7 +74,7 @@ public:
     expected<OfflineRegionMetadata, std::exception_ptr>
     updateMetadata(const int64_t regionID, const OfflineRegionMetadata&);
 
-    std::exception_ptr deleteRegion(OfflineRegion&&);
+    std::exception_ptr deleteRegion(OfflineRegion&&, bool pack = true);
     std::exception_ptr invalidateRegion(int64_t regionID);
 
     // Return value is (response, stored size)
@@ -93,6 +93,7 @@ public:
     uint64_t getOfflineMapboxTileCount();
     bool exceedsOfflineMapboxTileCountLimit(const Resource&);
     void markUsedResources(int64_t regionID, const std::list<Resource>&);
+    std::exception_ptr pack();
 
 private:
     void initialize();
diff --git a/platform/default/src/mbgl/storage/offline_database.cpp b/platform/default/src/mbgl/storage/offline_database.cpp
index 4f813e906d..fef524ce57 100644
--- a/platform/default/src/mbgl/storage/offline_database.cpp
+++ b/platform/default/src/mbgl/storage/offline_database.cpp
@@ -197,6 +197,7 @@ void OfflineDatabase::migrateToVersion6() {
 }
 
 void OfflineDatabase::vacuum() {
+    assert(db);
     if (getPragma<int64_t>("PRAGMA auto_vacuum") != 2 /*INCREMENTAL*/) {
         db->exec("PRAGMA auto_vacuum = INCREMENTAL");
         db->exec("VACUUM");
@@ -883,7 +884,7 @@ OfflineDatabase::updateMetadata(const int64_t regionID, const OfflineRegionMetad
     return unexpected<std::exception_ptr>(std::current_exception());
 }
 
-std::exception_ptr OfflineDatabase::deleteRegion(OfflineRegion&& region) try {
+std::exception_ptr OfflineDatabase::deleteRegion(OfflineRegion&& region, bool pack) try {
     {
         mapbox::sqlite::Query query{ getStatement("DELETE FROM regions WHERE id = ?") };
         query.bind(1, region.getID());
@@ -892,10 +893,10 @@ std::exception_ptr OfflineDatabase::deleteRegion(OfflineRegion&& region) try {
 
     evict(0);
     assert(db);
-    vacuum();
+    if (pack) vacuum();
 
     // Ensure that the cached offlineTileCount value is recalculated.
-    offlineMapboxTileCount = {};
+    offlineMapboxTileCount = nullopt;
     return nullptr;
 } catch (...) {
     handleError("delete region");
@@ -1303,6 +1304,15 @@ void OfflineDatabase::markUsedResources(int64_t regionID, const std::list<Resour
     handleError("mark resources as used");
 }
 
+std::exception_ptr OfflineDatabase::pack() try {
+    if (!db) initialize();
+    vacuum();
+    return nullptr;
+} catch (...) {
+    handleError("pack storage");
+    return std::current_exception();
+}
+
 std::exception_ptr OfflineDatabase::resetDatabase() try {
     removeExisting();
     initialize();