[core] Suppress network requests for invisible tiles

If the render source does not need rendering, we set necessity for its tiles to `optional`, and thus suppress network requests on tiles expiration.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/mbgl/renderer/tile_pyramid.cpp b/src/mbgl/renderer/tile_pyramid.cpp
index 2bf6e2e1a9..586d3b5a8a 100644
--- a/src/mbgl/renderer/tile_pyramid.cpp
+++ b/src/mbgl/renderer/tile_pyramid.cpp
@@ -68,6 +68,10 @@ void TilePyramid::update(const std::vector<Immutable<style::LayerProperties>>& l
     if (!needsRendering) {
         if (!needsRelayout) {
             for (auto& entry : tiles) {
+                // These tiles are invisible, we set optional necessity
+                // for them and thus suppress network requests on
+                // tiles expiration (see `OnlineFileRequest`).
+                entry.second->setNecessity(TileNecessity::Optional);
                 cache.add(entry.first, std::move(entry.second));
             }
         }