From 971efada741e1d984cd284d591f15adaba03c77b Mon Sep 17 00:00:00 2001
From: fanbingxin <fanbingxin.me@gmail.com>
Date: Thu, 12 Aug 2021 00:33:59 +0800
Subject: [PATCH] kernel: optimize futex with timeout (#80)

---
 kernel/lock.go   | 11 +++++++++--
 kernel/thread.go |  2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/lock.go b/kernel/lock.go
index e7a895a..25c9f9d 100644
--- a/kernel/lock.go
+++ b/kernel/lock.go
@@ -41,8 +41,14 @@ func sleeptimeout(addr *uintptr, val uintptr, ts *linux.Timespec) {
 	deadline := nanosecond() + int64(ts.Nsec) + int64(ts.Sec)*second
 	// check on every timer intr
 	now := nanosecond()
+	t := Mythread()
 	for now < deadline && *addr == val {
-		sleepon(&sleeplock)
+		t.timerKey = uintptr(unsafe.Pointer(&sleeplock))
+		t.sleepKey = uintptr(unsafe.Pointer(addr))
+		t.state = SLEEPING
+		Sched()
+		t.timerKey = 0
+		t.sleepKey = 0
 		now = nanosecond()
 	}
 }
@@ -61,9 +67,10 @@ func sleepon(lock *uintptr) {
 func wakeup(lock *uintptr, n int) {
 	limit := uint(n)
 	cnt := uint(0)
+	lockKey := uintptr(unsafe.Pointer(lock))
 	for i := 0; i < _NTHREDS; i++ {
 		t := &threads[i]
-		if t.sleepKey == uintptr(unsafe.Pointer(lock)) && cnt < limit {
+		if (t.sleepKey == lockKey || t.timerKey == lockKey) && cnt < limit {
 			cnt++
 			t.state = RUNNABLE
 		}
diff --git a/kernel/thread.go b/kernel/thread.go
index 3afc1ca..c9f334e 100644
--- a/kernel/thread.go
+++ b/kernel/thread.go
@@ -73,6 +73,8 @@ type Thread struct {
 	// sysmon 会调用usleep，进而调用sleepon，如果sleepKey是个指针会触发gcWriteBarrier
 	// 而sysmon没有P，会导致空指针
 	sleepKey uintptr
+	// for sleep timeout
+	timerKey uintptr
 
 	// store goroutine tls
 	fsBase uintptr