1 files changed, 106 insertions, 0 deletions
diff --git a/src/mbgl/storage/shared_request_base.hpp b/src/mbgl/storage/shared_request_base.hpp
new file mode 100644
index 0000000000..d7ed00264a
--- /dev/null
+++ b/src/mbgl/storage/shared_request_base.hpp
@@ -0,0 +1,106 @@
+#ifndef MBGL_STORAGE_DEFAULT_SHARED_REQUEST_BASE
+#define MBGL_STORAGE_DEFAULT_SHARED_REQUEST_BASE
+
+#include <mbgl/storage/resource.hpp>
+#include <mbgl/storage/file_cache.hpp>
+#include <mbgl/storage/default_file_source_impl.hpp>
+#include <mbgl/storage/request.hpp>
+#include <mbgl/util/util.hpp>
+#include <mbgl/util/noncopyable.hpp>
+
+#include <string>
+#include <set>
+#include <vector>
+#include <cassert>
+
+typedef struct uv_loop_s uv_loop_t;
+
+namespace mbgl {
+
+class Request;
+class Response;
+class DefaultFileSource;
+
+class SharedRequestBase : private util::noncopyable {
+protected:
+    MBGL_STORE_THREAD(tid)
+
+public:
+    SharedRequestBase(DefaultFileSource::Impl *source_, const Resource &resource_)
+        : resource(resource_), source(source_) {}
+
+    virtual void start(uv_loop_t *loop, std::shared_ptr<const Response> response = nullptr) = 0;
+    virtual void cancel() = 0;
+
+    void notify(std::shared_ptr<const Response> response, FileCache::Hint hint) {
+        MBGL_VERIFY_THREAD(tid);
+
+        if (source) {
+            source->notify(this, observers, response, hint);
+        }
+    }
+
+    void subscribe(Request *request) {
+        MBGL_VERIFY_THREAD(tid);
+
+        observers.insert(request);
+    }
+
+    void unsubscribe(Request *request) {
+        MBGL_VERIFY_THREAD(tid);
+
+        observers.erase(request);
+
+        if (abandoned()) {
+            // There are no observers anymore. We are initiating cancelation.
+            if (source) {
+                // First, remove this SharedRequestBase from the source.
+                source->notify(this, observers, nullptr, FileCache::Hint::No);
+            }
+
+            // Then, initiate cancelation of this request
+            cancel();
+        }
+    }
+
+    bool abandoned() const {
+        return observers.empty();
+    }
+
+    std::vector<Request *> removeAllInEnvironment(const Environment &env) {
+        MBGL_VERIFY_THREAD(tid);
+
+        std::vector<Request *> result;
+
+        // Removes all Requests in the supplied environment and returns a list
+        // of them.
+        util::erase_if(observers, [&](Request *req) -> bool {
+            if (&req->env == &env) {
+                result.push_back(req);
+                return true;
+            } else {
+                return false;
+            }
+        });
+
+        return result;
+    }
+
+protected:
+    virtual ~SharedRequestBase() {
+        MBGL_VERIFY_THREAD(tid);
+    }
+
+public:
+    const Resource resource;
+
+protected:
+    DefaultFileSource::Impl *source = nullptr;
+
+private:
+    std::set<Request *> observers;
+};
+
+}
+
+#endif