[core] Add unit tests for ambient cache size

test/storage/offline_database.test.cpp

@@ -714,19 +714,22 @@ TEST(OfflineDatabase, TEST_REQUIRES_WRITE(DeleteRegion)) {
         EXPECT_LT(sizeWithOneRegion, sizeWithTwoRegions);
         db.runPackDatabaseAutomatically(true);
         db.deleteRegion(std::move(*region2));
-        // The size of the database has shrunk right away.
+
+        // After clearing the cache, the size of the database
+        // should get back to the original size.
+        db.clearAmbientCache();
+
+        // The size of the database has shrunk right away after deleted region
+        // is evicted from an ambient cache.
         const size_t sizeWithoutRegions = util::read_file(filename).size();
-        ASSERT_EQ(0u, db.listRegions().value().size());
-        EXPECT_LT(sizeWithoutRegions, sizeWithOneRegion);
 
         // The tiles from the offline region will migrate to the
         // ambient cache and shrink the database to the maximum
         // size defined by default.
         EXPECT_LE(sizeWithoutRegions, util::DEFAULT_MAX_CACHE_SIZE);
 
-        // After clearing the cache, the size of the database
-        // should get back to the original size.
-        db.clearAmbientCache();
+        ASSERT_EQ(0u, db.listRegions().value().size());
+        EXPECT_LT(sizeWithoutRegions, sizeWithOneRegion);
     }
 
     EXPECT_EQ(initialSize, util::read_file(filename).size());
@@ -1059,7 +1062,8 @@ TEST(OfflineDatabase, PutEvictsLeastRecentlyUsedResources) {
     Response response;
     response.data = randomString(1024);
 
-    for (uint32_t i = 1; i <= 100; i++) {
+    // Add 101 resource to ambient cache, 1 over defined limit.
+    for (uint32_t i = 1; i <= 101; ++i) {
         Resource resource = Resource::style("http://example.com/"s + util::toString(i));
         db.put(resource, response);
         EXPECT_TRUE(bool(db.get(resource))) << i;
@@ -1070,6 +1074,45 @@ TEST(OfflineDatabase, PutEvictsLeastRecentlyUsedResources) {
     EXPECT_EQ(0u, log.uncheckedCount());
 }
 
+TEST(OfflineDatabase, OfflineRegionDoesNotAffectAmbientCacheSize) {
+    FixtureLog log;
+    OfflineDatabase db(":memory:");
+    unsigned dataSize = 1024u * 100u;
+    unsigned numberOfCachedResources = 2u;
+    unsigned databasePage = 4096u;
+    unsigned pageOverhead = numberOfCachedResources * databasePage;
+
+    // 200KB ambient cache limit + database page overhead.
+    db.setMaximumAmbientCacheSize(dataSize * numberOfCachedResources + pageOverhead);
+
+    Response response;
+    response.data = randomString(dataSize);
+
+    // First 100KB ambient cache resource.
+    db.put(Resource::style("http://example.com/ambient1.json"s), response);
+
+    OfflineTilePyramidRegionDefinition definition(
+        "http://example.com/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0, false);
+    auto region = db.createRegion(definition, OfflineRegionMetadata());
+
+    // 1MB of offline region data.
+    for (std::size_t i = 0; i < 5; ++i) {
+        const Resource tile = Resource::tile("mapbox://tile_" + std::to_string(i), 1, 0, 0, 0, Tileset::Scheme::XYZ);
+        db.putRegionResource(region->getID(), tile, response);
+
+        const Resource style = Resource::style("mapbox://style_" + std::to_string(i));
+        db.putRegionResource(region->getID(), style, response);
+    }
+
+    // Second 100KB ambient cache resource.
+    db.put(Resource::style("http://example.com/ambient2.json"s), response);
+
+    // Offline region resources should not affect ambient cache size.
+    EXPECT_TRUE(bool(db.get(Resource::style("http://example.com/ambient1.json"s))));
+    EXPECT_TRUE(bool(db.get(Resource::style("http://example.com/ambient2.json"s))));
+    EXPECT_EQ(0u, log.uncheckedCount());
+}
+
 TEST(OfflineDatabase, PutRegionResourceDoesNotEvict) {
     FixtureLog log;
     OfflineDatabase db(":memory:");
@@ -1098,7 +1141,8 @@ TEST(OfflineDatabase, PutFailsWhenEvictionInsuffices) {
     db.setMaximumAmbientCacheSize(1024 * 100);
 
     Response big;
-    big.data = randomString(1024 * 100);
+    // One page over the cache size.
+    big.data = randomString(1024 * 100 + 4096);
 
     EXPECT_FALSE(db.put(Resource::style("http://example.com/big"), big).first);