Support external event loops via non-blocking poll() alt. to run() (#762)

* Support external event loops via non-blocking poll() alternative to run()

* Removed tabs

* Reinstated setting of timepoint in Loop::run()/poll() for consistency with libuv

src/Asio.h

@@ -22,6 +22,10 @@ struct Loop : boost::asio::io_service {
     void run() {
         boost::asio::io_service::run();
     }
+
+    void poll() {
+        boost::asio::io_service::poll();
+    }
 };
 
 struct Timer {

src/Epoll.cpp

@@ -9,55 +9,69 @@ std::recursive_mutex cbMutex;
 void (*callbacks[16])(Poll *, int, int);
 int cbHead = 0;
 
-void Loop::run() {
-    timepoint = std::chrono::system_clock::now();
-    while (numPolls) {
-        for (std::pair<Poll *, void (*)(Poll *)> c : closing) {
-            numPolls--;
+void Loop::doEpoll(int epollTimeout) {
+    for (std::pair<Poll *, void (*)(Poll *)> c : closing) {
+        numPolls--;
 
-            c.second(c.first);
+        c.second(c.first);
 
-            if (!numPolls) {
-                closing.clear();
-                return;
-            }
+        if (!numPolls) {
+            closing.clear();
+            return;
         }
-        closing.clear();
+    }
+    closing.clear();
 
-        int numFdReady = epoll_wait(epfd, readyEvents, 1024, delay);
-        timepoint = std::chrono::system_clock::now();
+    int numFdReady = epoll_wait(epfd, readyEvents, 1024, epollTimeout);
+    timepoint = std::chrono::system_clock::now();
 
-        if (preCb) {
-            preCb(preCbData);
-        }
+    if (preCb) {
+        preCb(preCbData);
+    }
 
-        for (int i = 0; i < numFdReady; i++) {
-            Poll *poll = (Poll *) readyEvents[i].data.ptr;
-            int status = -bool(readyEvents[i].events & EPOLLERR);
-            callbacks[poll->state.cbIndex](poll, status, readyEvents[i].events);
-        }
+    for (int i = 0; i < numFdReady; i++) {
+        Poll *poll = (Poll *) readyEvents[i].data.ptr;
+        int status = -bool(readyEvents[i].events & EPOLLERR);
+        callbacks[poll->state.cbIndex](poll, status, readyEvents[i].events);
+    }
+
+    while (timers.size() && timers[0].timepoint < timepoint) {
+        Timer *timer = timers[0].timer;
+        cancelledLastTimer = false;
+        timers[0].cb(timers[0].timer);
 
-        while (timers.size() && timers[0].timepoint < timepoint) {
-            Timer *timer = timers[0].timer;
-            cancelledLastTimer = false;
-            timers[0].cb(timers[0].timer);
-
-            if (cancelledLastTimer) {
-                continue;
-            }
-
-            int repeat = timers[0].nextDelay;
-            auto cb = timers[0].cb;
-            timers.erase(timers.begin());
-            if (repeat) {
-                timer->start(cb, repeat, repeat);
-            }
+        if (cancelledLastTimer) {
+            continue;
         }
 
-        if (postCb) {
-            postCb(postCbData);
+        int repeat = timers[0].nextDelay;
+        auto cb = timers[0].cb;
+        timers.erase(timers.begin());
+        if (repeat) {
+            timer->start(cb, repeat, repeat);
         }
     }
+
+    if (postCb) {
+        postCb(postCbData);
+    }
+}
+
+void Loop::run() {
+    // updated for consistency with libuv impl. behaviour
+    timepoint = std::chrono::system_clock::now();
+    while (numPolls) {
+        doEpoll(delay);
+    }
+}
+
+void Loop::poll() {
+    if (numPolls) {
+        doEpoll(0);
+    } else {
+        // updated for consistency with libuv impl. behaviour
+        timepoint = std::chrono::system_clock::now();
+    }
 }
 
 }

src/Epoll.h

@@ -34,7 +34,7 @@ struct Loop {
     int epfd;
     int numPolls = 0;
     bool cancelledLastTimer;
-    int delay = -1;
+    int delay = -1;  // delay to next timer expiry, or -1 if no timers pending
     epoll_event readyEvents[1024];
     std::chrono::system_clock::time_point timepoint;
     std::vector<Timepoint> timers;
@@ -58,8 +58,12 @@ struct Loop {
         delete this;
     }
 
+    void doEpoll(int epollTimeout);
+
     void run();
 
+    void poll();
+
     int getEpollFd() {
         return epfd;
     }

src/Hub.h

@@ -67,6 +67,7 @@ public:
     }
 
     using uS::Node::run;
+    using uS::Node::poll;
     using uS::Node::getLoop;
     using Group<SERVER>::onConnection;
     using Group<CLIENT>::onConnection;

src/Libuv.h

@@ -24,6 +24,10 @@ struct Loop : uv_loop_t {
     void run() {
         uv_run(this, UV_RUN_DEFAULT);
     }
+
+    void poll() {
+        uv_run(this, UV_RUN_NOWAIT);
+    }
 };
 
 struct Async {

src/Node.cpp

@@ -64,6 +64,10 @@ void Node::run() {
     loop->run();
 }
 
+void Node::poll() {
+    loop->poll();
+}
+
 Node::~Node() {
     delete [] nodeData->recvBufferMemoryBlock;
     SSL_CTX_free(nodeData->clientContext);

src/Node.h

@@ -78,8 +78,13 @@ protected:
 public:
     Node(int recvLength = 1024, int prePadding = 0, int postPadding = 0, bool useDefaultLoop = false);
     ~Node();
+
+    /* Blocking */
     void run();
 
+    /* Non-blocking */
+    void poll();
+
     Loop *getLoop() {
         return loop;
     }