Give plugins ability to defer service readiness

Author: halfgaar

flashmq_plugin.cpp

@@ -17,6 +17,7 @@ See LICENSE for license details.
 #include "subscriptionstore.h"
 #include "globals.h"
 #include "utils.h"
+#include "mainapp.h"
 
 void flashmq_logf(int level, const char *str, ...)
 {
@@ -311,3 +312,37 @@ void flashmq_get_client_pointer(const std::weak_ptr<Session> &session, std::weak
     if (!sessionLocked) return;
     clientOut = sessionLocked->makeSharedClient();
 }
+
+void flashmq_defer_thread_ready()
+{
+    auto d = ThreadGlobals::getThreadData();
+
+    if (!d)
+    {
+        Logger::getInstance()->log(LOG_ERROR) << "Calling flashmq_defer_thread_ready from custom thread.";
+        return;
+    }
+
+    d->deferThreadReady = true;
+}
+
+void flashmq_signal_thread_ready()
+{
+    const auto d = ThreadGlobals::getThreadData();
+
+    if (!d)
+    {
+        Logger::getInstance()->log(LOG_ERROR) << "Calling flashmq_signal_thread_ready from custom thread.";
+        return;
+    }
+
+    if (!d->deferThreadReady)
+        return;
+
+    std::shared_ptr<MainApp> lockedMainApp = d->mMainApp.lock();
+
+    if (!lockedMainApp)
+        return;
+
+    lockedMainApp->queueThreadInitDecrement();
+}

flashmq_public.h

@@ -298,6 +298,30 @@ uint32_t API flashmq_add_task(std::function<void()> f, uint32_t delay_in_ms);
  */
 void API flashmq_remove_task(uint32_t id);
 
+/**
+ * @brief Use this if you don't want your thread to be signalled ready after flashmq_plugin_init().
+ *
+ * Normally, when threads return from flashmq_plugin_init(), the worker thread signals to the main thread it's done. Once
+ * all threads have done this, the listeners are created and systemd is notified. You may want to defer this, until all
+ * your auth data is loaded, for instance.
+ *
+ * One simple solution to queue back this event is to use flashmq_add_task() to poll on a timer and check if your data is
+ * loaded, and run flashmq_signal_thread_ready() when it's ready.
+ *
+ * [Introduced in FlashMQ 1.26.0]
+ */
+void API flashmq_defer_thread_ready();
+
+/**
+ * @brief Counterpart to flashmq_defer_thread_ready().
+ *
+ * There is no timeout action. If you don't do this, FlashMQ will never be ready. When starting from systemd unit of
+ * type 'notify', it will be restarted after a set time.
+ *
+ * [Introduced in FlashMQ 1.26.0]
+ */
+void API flashmq_signal_thread_ready();
+
 }
 
 #endif // FLASHMQ_PUBLIC_H

threaddata.h

@@ -120,6 +120,7 @@ class ThreadData
 public:
     Settings settingsLocalCopy; // Is updated on reload, within the thread loop.
     Authentication authentication;
+    bool deferThreadReady = false;
     bool running = true;
     bool finished = false;
     bool allWillsQueued = false;

threadloop.cpp

@@ -40,7 +40,7 @@ void do_thread_work(std::shared_ptr<ThreadData> threadData)
 
         auto lockedMainApp = threadData->mMainApp.lock();
 
-        if (lockedMainApp)
+        if (!threadData->deferThreadReady && lockedMainApp)
         {
             lockedMainApp->queueThreadInitDecrement();
         }