[core] Implement platform::Factory::sharedFileSource()upstream/map-refactor

1 files changed, 27 insertions, 0 deletions

diff --git a/src/mbgl/platform/factory.cpp b/src/mbgl/platform/factory.cpp
new file mode 100644
index 0000000000..6f595f9866
--- /dev/null
+++ b/src/mbgl/platform/factory.cpp
@@ -0,0 +1,27 @@
+#include <mbgl/platform/factory.hpp>
+#include <mbgl/storage/default_file_source.hpp>
+
+namespace mbgl {
+namespace platform {
+
+std::shared_ptr<FileSource> Factory::sharedFileSource(const FileSourceOptions& options, std::shared_ptr<FileSource> initial) {
+    static std::weak_ptr<FileSource> weak;
+
+    if (initial) {
+        // We can only assign a custom initial value if the weak pointer object has zero references.
+        assert(weak.use_count() == 0);
+        weak = initial;
+    }
+
+    std::shared_ptr<FileSource> strong = weak.lock();
+    if (!strong) {
+        auto defaultFileSource = std::make_shared<DefaultFileSource>(options.cachePath(), options.assetRoot(), options.maximumCacheSize());
+        defaultFileSource->setAccessToken(options.accessToken());
+        weak = strong = defaultFileSource;
+    }
+
+    return strong;
+}
+
+} // namespace platform
+} // namespace mbgl