add an async subscriber impl with thread pool

2026-01-13 03:00:32 +00:00
parent d2ef352ce9
commit 6d5e0f92ad
11 changed files with 425 additions and 0 deletions
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <memory>
+#include <unordered_map>
+#include <vector>
+
+#include "subscriber.hpp"
+#include "thread_pool.hpp"
+
+template <typename TEventId, typename TEventInfo>
+class Subscribable {
+    using TSubscriber = Subscriber<TEventId, TEventInfo>;
+
+   private:
+    std::unordered_map<TEventId, std::vector<std::shared_ptr<TSubscriber>>>
+        subscribersMap_;
+
+   public:
+    void subscribe(const TEventId& eventId,
+                   std::shared_ptr<TSubscriber> subscriber) {
+        subscribersMap_[eventId].push_back(subscriber);
+    }
+
+    void unsubscribe(const TEventId& eventId,
+                     std::shared_ptr<TSubscriber> subscriber) {
+        auto entry = subscribersMap_.find(eventId);
+        if (entry == subscribersMap_.end()) {
+            return;
+        }
+
+        std::erase(entry->second, subscriber);
+        if (entry->second.empty()) {
+            subscribersMap_.erase(entry);
+        }
+    }
+
+    void notify(const TEventId& eventId, const TEventInfo& eventInfo,
+                ThreadPool& threadPool) const {
+        auto entry = subscribersMap_.find(eventId);
+        if (entry == subscribersMap_.end()) {
+            return;
+        }
+
+        // edge case: if a subscriber unsubscribes itself during notification
+        // this modifies the vector and makes my iterators invalid
+        auto subscribersCopy = entry->second;
+        for (auto& subscriber : subscribersCopy) {
+            // Enqueue each notification as a separate task in the thread pool
+            // capture by value next to copy the shared_ptr
+            threadPool.enqueue([subscriber, eventId, eventInfo]() {
+                subscriber->onNotification(eventId, eventInfo);
+            });
+        }
+    }
+};