From 0f341fe7f092f704e1c1952c72085eb1ebd2086a Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Wed, 14 Nov 2018 15:19:32 -0500
Subject: use ThreadCall pattern

---
 include/salticidae/event.h | 86 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)

(limited to 'include/salticidae/event.h')

diff --git a/include/salticidae/event.h b/include/salticidae/event.h
index c21644b..da27902 100644
--- a/include/salticidae/event.h
+++ b/include/salticidae/event.h
@@ -25,10 +25,12 @@
 #ifndef _SALTICIDAE_EVENT_H
 #define _SALTICIDAE_EVENT_H
 
+#include <condition_variable>
 #include <unistd.h>
 #include <uv.h>
 #include <sys/eventfd.h>
 
+#include "salticidae/type.h"
 #include "salticidae/queue.h"
 #include "salticidae/util.h"
 #include "salticidae/ref.h"
@@ -177,6 +179,90 @@ class Event {
     operator bool() const { return ev_fd != nullptr || ev_timer != nullptr; }
 };
 
+class ThreadNotifier {
+    std::condition_variable cv;
+    std::mutex mlock;
+    mutex_ul_t ul;
+    bool ready;
+    void *data;
+    public:
+    ThreadNotifier(): ul(mlock), ready(false) {}
+    void *wait() {
+        cv.wait(ul, [this]{ return ready; });
+        return data;
+    }
+    void notify(void *_data) { 
+        {
+            mutex_lg_t _(mlock);
+            ready = true;
+            data = _data;
+        }
+        cv.notify_all();
+    }
+};
+
+class ThreadCall {
+    int ctl_fd[2];
+    EventContext ec;
+    Event ev_listen;
+
+    public:
+    class Handle {
+        std::function<void(Handle &)> callback;
+        ThreadNotifier* notifier;
+        void *result;
+        friend ThreadCall;
+        public:
+        Handle(): notifier(nullptr), result(nullptr) {}
+        void exec() {
+            callback(*this);
+            if (notifier) notifier->notify(result);
+        }
+        void set_result(void *data) { result = data; }
+    };
+
+    ThreadCall() = default;
+    ThreadCall(const ThreadCall &) = delete;
+    ThreadCall(ThreadCall &&) = delete;
+    ThreadCall(EventContext ec): ec(ec) {
+        if (pipe2(ctl_fd, O_NONBLOCK))
+            throw SalticidaeError(std::string("ThreadCall: failed to create pipe"));
+        ev_listen = Event(ec, ctl_fd[0], Event::READ, [this](int fd, int) {
+            Handle *h;
+            read(fd, &h, sizeof(h));
+            h->exec();
+            delete h;
+        });
+        ev_listen.add();
+    }
+
+    ~ThreadCall() {
+        close(ctl_fd[0]);
+        close(ctl_fd[1]);
+    }
+
+    template<typename Func>
+    void *call(Func callback, bool blocking = false) {
+        auto h = new Handle();
+        h->callback = callback;
+        if (blocking)
+        {
+            ThreadNotifier notifier;
+            h->notifier = &notifier;
+            std::atomic_thread_fence(std::memory_order_release);
+            write(ctl_fd[1], &h, sizeof(h));
+            return notifier.wait();
+        }
+        else
+        {
+            std::atomic_thread_fence(std::memory_order_release);
+            write(ctl_fd[1], &h, sizeof(h));
+            return nullptr;
+        }
+    }
+};
+
+
 template<typename T>
 class MPSCQueueEventDriven: public MPSCQueue<T> {
     private:
-- 
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