From ef218ac4d8ec01ae866419df881a32a307b7ec22 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 1 Aug 2012 05:00:00 +0200
Subject: [PATCH] implement epoll (Jamie Turner)

---
 fd.c       | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 taskimpl.h |   7 +++
 2 files changed, 129 insertions(+), 1 deletion(-)

diff --git a/fd.c b/fd.c
index f3d5950..3fe387e 100644
--- a/fd.c
+++ b/fd.c
@@ -1,7 +1,14 @@
 #include "taskimpl.h"
+#if USE_EPOLL
+#include <sys/epoll.h>
+#else
 #include <sys/poll.h>
+#endif
 #include <fcntl.h>
 
+#if USE_EPOLL
+static int epfd;
+#else
 enum
 {
 	MAXFD = 1024
@@ -10,11 +17,69 @@ enum
 static struct pollfd pollfd[MAXFD];
 static Task *polltask[MAXFD];
 static int npollfd;
+#endif
+
 static int startedfdtask;
 static Tasklist sleeping;
 static int sleepingcounted;
 static uvlong nsec(void);
 
+#if USE_EPOLL
+
+void
+fdtask(void *v)
+{
+	struct epoll_event events[1000];
+	int i, ms, nevents;
+	Task *t;
+	uvlong now;
+
+	USED(v);
+	tasksystem();
+	taskname("fdtask");
+	for(;;){
+		/* let everyone else run */
+		while(taskyield() > 0)
+			;
+		/* we're the only one runnable - poll for i/o */
+		errno = 0;
+		taskstate("epoll");
+		if((t=sleeping.head) == nil)
+			ms = -1;
+		else{
+			/* sleep at most 5s */
+			now = nsec();
+			if(now >= t->alarmtime)
+				ms = 0;
+			else if(now+5*1000*1000*1000LL >= t->alarmtime)
+				ms = (t->alarmtime - now)/1000000;
+			else
+				ms = 5000;
+		}
+		if((nevents = epoll_wait(epfd, events, 1000, ms)) < 0){
+			if(errno == EINTR)
+				continue;
+			fprint(2, "epoll: %s\n", strerror(errno));
+			taskexitall(0);
+		}
+
+		/* wake up the guys who deserve it */
+		for(i=0; i<nevents; i++){
+			taskready((Task *)events[i].data.ptr);
+		}
+
+		now = nsec();
+		while((t=sleeping.head) && now >= t->alarmtime){
+			deltask(&sleeping, t);
+			if(!t->system && --sleepingcounted == 0)
+				taskcount--;
+			taskready(t);
+		}
+	}
+}
+
+#else
+
 void
 fdtask(void *v)
 {
@@ -60,7 +125,7 @@ fdtask(void *v)
 				polltask[i] = polltask[npollfd];
 			}
 		}
-		
+
 		now = nsec();
 		while((t=sleeping.head) && now >= t->alarmtime){
 			deltask(&sleeping, t);
@@ -71,6 +136,8 @@ fdtask(void *v)
 	}
 }
 
+#endif
+
 uint
 taskdelay(uint ms)
 {
@@ -79,6 +146,11 @@ taskdelay(uint ms)
 	
 	if(!startedfdtask){
 		startedfdtask = 1;
+#if USE_EPOLL
+		epfd = epoll_create(1);
+		if(epfd < 0)
+			abort();
+#endif
 		taskcreate(fdtask, 0, 32768);
 	}
 
@@ -113,6 +185,53 @@ taskdelay(uint ms)
 	return (nsec() - now)/1000000;
 }
 
+#if USE_EPOLL
+
+void
+fdwait(int fd, int rw)
+{
+	struct epoll_event ev;
+	int bits, duped, r;
+
+	if(!startedfdtask){
+		startedfdtask = 1;
+		epfd = epoll_create(1);
+		if(epfd < 0)
+			abort();
+		taskcreate(fdtask, 0, 32768);
+	}
+
+	taskstate("fdwait for %s", rw=='r' ? "read" : rw=='w' ? "write" : "error");
+	bits = 0;
+	switch(rw){
+	case 'r':
+		bits |= EPOLLIN | EPOLLPRI;
+		break;
+	case 'w':
+		bits |= EPOLLOUT;
+		break;
+	}
+
+	memset(&ev, 0, sizeof(ev));
+	ev.events = bits;
+	ev.data.ptr = taskrunning;
+	r = epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev);
+	duped = 0;
+	if(r < 0 || errno == EEXIST){
+		duped = 1;
+		fd = dup(fd);
+		r = epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev);
+		if(r != 0)
+			abort();
+	}
+	taskswitch();
+	epoll_ctl(epfd, EPOLL_CTL_DEL, fd, &ev);
+	if(duped)
+		close(fd);
+}
+
+#else
+
 void
 fdwait(int fd, int rw)
 {
@@ -147,6 +266,8 @@ fdwait(int fd, int rw)
 	taskswitch();
 }
 
+#endif
+
 /* Like fdread but always calls fdwait before reading. */
 int
 fdread1(int fd, void *buf, int n)
diff --git a/taskimpl.h b/taskimpl.h
index 4fd7ba6..84a2d35 100644
--- a/taskimpl.h
+++ b/taskimpl.h
@@ -26,6 +26,13 @@
 #endif
 #endif
 
+#define USE_EPOLL 1
+
+#if !defined(__linux)
+#undef USE_EPOLL
+#define USE_EPOLL 0
+#endif
+
 #include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>