Avoid double-resumption of task on active connection close. Fixes #1376.

With a concurrent read operation, the libevent active TCP connection close function could result in a double-resumption of the read task, if the close happened in the same event loop round as a read-ready or close event on the socket.

source/vibe/core/drivers/libevent2_tcp.d

@@ -660,7 +660,7 @@ package nothrow extern(C)
 
 		auto f = ctx.readOwner;
 		try {
-			if (f && f.running)
+			if (f && f.running && ctx.state != ConnectionState.activeClose)
 				ctx.core.resumeTask(f);
 		} catch (UncaughtException e) {
 			logWarn("Got exception when resuming task onSocketRead: %s", e.msg);
@@ -698,7 +698,8 @@ package nothrow extern(C)
 			string errorMessage;
 			if (status & BEV_EVENT_EOF) {
 				logDebug("Connection was closed (fd %d).", ctx.socketfd);
-				ctx.state = ConnectionState.passiveClose;
+				if (ctx.state != ConnectionState.activeClose)
+					ctx.state = ConnectionState.passiveClose;
 				evbuffer* buf = bufferevent_get_input(buf_event);
 				if (evbuffer_get_length(buf) == 0) free_event = true;
 			} else if (status & BEV_EVENT_TIMEOUT) {
@@ -719,7 +720,7 @@ package nothrow extern(C)
 
 			ctx.core.eventException = ex;
 
-			if (ctx.readOwner && ctx.readOwner.running) {
+			if (ctx.readOwner && ctx.readOwner.running && ctx.state != ConnectionState.activeClose) {
 				logTrace("resuming corresponding task%s...", ex is null ? "" : " with exception");
 				if (ctx.readOwner.fiber.state == Fiber.State.EXEC) ctx.exception = ex;
 				else ctx.core.resumeTask(ctx.readOwner, ex);

tests/vibe.core.net.1376/dub.sdl

@@ -0,0 +1,4 @@
+name "tests"
+description "TCP disconnect task issue"
+dependency "vibe-d:core" path="../../"
+versions "VibeDefaultMain"

tests/vibe.core.net.1376/source/app.d

@@ -0,0 +1,29 @@
+import vibe.core.core;
+import vibe.core.net;
+import core.time : msecs;
+
+shared static this()
+{
+	listenTCP(11375,(conn){
+		auto td = runTask({
+			ubyte [3] buf;
+			try {
+				conn.read(buf);
+				assert(false, "Expected read() to throw an exception.");
+			} catch (Exception) {} // expected
+		});
+		conn.close();
+	});
+
+	runTask({
+		auto conn = connectTCP("127.0.0.1", 11375);
+		conn.write("a");
+		conn.close();
+
+		conn = connectTCP("127.0.0.1", 11375);
+		conn.close();
+
+		sleep(50.msecs);
+		exitEventLoop();
+	});
+}