MainThreadPost.cpp

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// Publishes the event queue as the IMainThreadPost capability, so the thread
// module can hand results back to the main thread without depending on event.
 
#include "common/MainThreadPost.h"
#include "common/Capability.h"
#include "common/Module.h"
#include "platform_event/PlatformEvent.h"
 
#include <string>
 
namespace eve::platform_event {
namespace {
 
class EventQueuePoster : public eve::caps::IMainThreadPost {
public:
    void prepare() override { resolve(); }
 
    void postToMainThread(std::string name, std::string data) override {
        // Never touch the module registry here: this runs on a worker thread.
        // prepare() is contracted to have resolved the queue already.
        PlatformEvent *ev = queue_;
        if (!ev) return;
        ev->pushData(std::move(name), std::move(data));
    }
 
private:
    void resolve() {
        if (queue_) return;
        PlatformEvent *ev = eve::ModuleManager::getInstance<PlatformEvent>("PlatformEvent");
        if (!ev) ev = PlatformEvent::create();
        queue_ = ev;
    }
 
    PlatformEvent *queue_ = nullptr;
};
 
struct Register {
    Register() {
        static EventQueuePoster poster;
        eve::cap::provide<eve::caps::IMainThreadPost>(&poster);
    }
} g_register;
 
}  // namespace
}  // namespace eve::platform_event