[core] Clearing ambient cache can skip vacuum

5 files changed, 50 insertions, 14 deletions

diff --git a/include/mbgl/storage/default_file_source.hpp b/include/mbgl/storage/default_file_source.hpp
index 88f318581b..e3b5bc9fbc 100644
--- a/include/mbgl/storage/default_file_source.hpp
+++ b/include/mbgl/storage/default_file_source.hpp
@@ -212,14 +212,21 @@ public:
     /*
      * Erase resources from the ambient cache, freeing storage space.
      *
-     * Erases the ambient cache, freeing resources. This operation can be
-     * potentially slow because it will trigger a VACUUM on SQLite,
-     * forcing the database to move pages on the filesystem.
+     * Erases the ambient cache, freeing resources.
+     *
+     * If the |pack| argument is `true`, this operation includes database
+     * file packing. This operation can be potentially slow because it triggers
+     * a VACUUM on SQLite, forcing the database to move pages on the
+     * filesystem.
+     *
+     * If the |pack| argument is `false` the database file packing is skipped and the
+     * database file does not shrink after this operation completes. Database file
+     * packing can be done later with `packDatabase()`.
      *
      * Resources overlapping with offline regions will not be affected
      * by this call.
      */
-    void clearAmbientCache(std::function<void (std::exception_ptr)>);
+    void clearAmbientCache(std::function<void(std::exception_ptr)>, bool pack = true);
 
     /*
      * Sets the maximum size in bytes for the ambient cache.
diff --git a/platform/default/include/mbgl/storage/offline_database.hpp b/platform/default/include/mbgl/storage/offline_database.hpp
index ac997bf6ad..717d232e32 100644
--- a/platform/default/include/mbgl/storage/offline_database.hpp
+++ b/platform/default/include/mbgl/storage/offline_database.hpp
@@ -58,10 +58,10 @@ public:
     // lookup, it will not get downloaded again.
     std::exception_ptr invalidateAmbientCache();
 
-    // Clear the tile cache, freeing resources. This operation can be
-    // potentially slow because it will trigger a VACUUM on SQLite,
-    // forcing the database to move pages on the filesystem.
-    std::exception_ptr clearAmbientCache();
+    // Clear the tile cache, freeing resources. If |pack| is `true`,
+    // this operation can be slow because it will trigger a VACUUM on
+    // SQLite, forcing the database to move pages on the filesystem.
+    std::exception_ptr clearAmbientCache(bool pack = true);
 
     expected<OfflineRegions, std::exception_ptr> listRegions();
 
diff --git a/platform/default/src/mbgl/storage/default_file_source.cpp b/platform/default/src/mbgl/storage/default_file_source.cpp
index 36acb748de..c476ab3886 100644
--- a/platform/default/src/mbgl/storage/default_file_source.cpp
+++ b/platform/default/src/mbgl/storage/default_file_source.cpp
@@ -198,8 +198,8 @@ public:
         callback(offlineDatabase->invalidateAmbientCache());
     }
 
-    void clearAmbientCache(std::function<void (std::exception_ptr)> callback) {
-        callback(offlineDatabase->clearAmbientCache());
+    void clearAmbientCache(std::function<void(std::exception_ptr)> callback, bool pack) {
+        callback(offlineDatabase->clearAmbientCache(pack));
     }
 
     void setMaximumAmbientCacheSize(uint64_t size, std::function<void (std::exception_ptr)> callback) {
@@ -367,8 +367,8 @@ void DefaultFileSource::invalidateAmbientCache(std::function<void (std::exceptio
     impl->actor().invoke(&Impl::invalidateAmbientCache, std::move(callback));
 }
 
-void DefaultFileSource::clearAmbientCache(std::function<void(std::exception_ptr)> callback) {
-    impl->actor().invoke(&Impl::clearAmbientCache, std::move(callback));
+void DefaultFileSource::clearAmbientCache(std::function<void(std::exception_ptr)> callback, bool pack) {
+    impl->actor().invoke(&Impl::clearAmbientCache, std::move(callback), pack);
 }
 
 void DefaultFileSource::setMaximumAmbientCacheSize(uint64_t size, std::function<void (std::exception_ptr)> callback) {
diff --git a/platform/default/src/mbgl/storage/offline_database.cpp b/platform/default/src/mbgl/storage/offline_database.cpp
index fef524ce57..c9b74a71f7 100644
--- a/platform/default/src/mbgl/storage/offline_database.cpp
+++ b/platform/default/src/mbgl/storage/offline_database.cpp
@@ -682,7 +682,7 @@ std::exception_ptr OfflineDatabase::invalidateAmbientCache() try {
     return std::current_exception();
 }
 
-std::exception_ptr OfflineDatabase::clearAmbientCache() try {
+std::exception_ptr OfflineDatabase::clearAmbientCache(bool pack) try {
     // clang-format off
     mapbox::sqlite::Query tileQuery{ getStatement(
         "DELETE FROM tiles "
@@ -705,7 +705,7 @@ std::exception_ptr OfflineDatabase::clearAmbientCache() try {
 
     resourceQuery.run();
 
-    vacuum();
+    if (pack) vacuum();
 
     return nullptr;
 } catch (...) {
diff --git a/test/storage/offline_database.test.cpp b/test/storage/offline_database.test.cpp
index 9d798d0a62..9db344d89c 100644
--- a/test/storage/offline_database.test.cpp
+++ b/test/storage/offline_database.test.cpp
@@ -952,6 +952,35 @@ TEST(OfflineDatabase, TEST_REQUIRES_WRITE(ClearAmbientCache)) {
     EXPECT_EQ(0u, log.uncheckedCount());
 }
 
+TEST(OfflineDatabase, TEST_REQUIRES_WRITE(Pack)) {
+    FixtureLog log;
+    deleteDatabaseFiles();
+
+    OfflineDatabase db(filename);
+    size_t initialSize = util::read_file(filename).size();
+
+    Response response;
+    response.data = randomString(.5 * 1024 * 1024);
+
+    for (unsigned i = 0; i < 50; ++i) {
+        const Resource tile = Resource::tile("mapbox://tile_" + std::to_string(i), 1, 0, 0, 0, Tileset::Scheme::XYZ);
+        db.put(tile, response);
+
+        const Resource style = Resource::style("mapbox://style_" + std::to_string(i));
+        db.put(style, response);
+    }
+    size_t populatedSize = util::read_file(filename).size();
+    ASSERT_GT(populatedSize, initialSize);
+
+    db.clearAmbientCache(false /*pack*/);
+    EXPECT_EQ(populatedSize, util::read_file(filename).size());
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    db.pack();
+    EXPECT_EQ(initialSize, util::read_file(filename).size());
+    EXPECT_EQ(0u, log.uncheckedCount());
+}
+
 TEST(OfflineDatabase, CreateRegionInfiniteMaxZoom) {
     FixtureLog log;
     OfflineDatabase db(":memory:");