diff options
Diffstat (limited to 'src/runtime/chan.go')
| -rw-r--r-- | src/runtime/chan.go | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/src/runtime/chan.go b/src/runtime/chan.go index b14ebc31d2..ae26be3c42 100644 --- a/src/runtime/chan.go +++ b/src/runtime/chan.go @@ -36,6 +36,7 @@ type hchan struct { buf unsafe.Pointer // points to an array of dataqsiz elements elemsize uint16 closed uint32 + timer *timer // timer feeding this chan elemtype *_type // element type sendx uint // send index recvx uint // receive index @@ -426,12 +427,19 @@ func closechan(c *hchan) { } // empty reports whether a read from c would block (that is, the channel is -// empty). It uses a single atomic read of mutable state. +// empty). It is atomically correct and sequentially consistent at the moment +// it returns, but since the channel is unlocked, the channel may become +// non-empty immediately afterward. func empty(c *hchan) bool { // c.dataqsiz is immutable. if c.dataqsiz == 0 { return atomic.Loadp(unsafe.Pointer(&c.sendq.first)) == nil } + // c.timer is also immutable (it is set after make(chan) but before any channel operations). + // All timer channels have dataqsiz > 0. + if c.timer != nil { + c.timer.maybeRunChan() + } return atomic.Loaduint(&c.qcount) == 0 } @@ -470,6 +478,10 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool) throw("unreachable") } + if c.timer != nil { + c.timer.maybeRunChan() + } + // Fast path: check for failed non-blocking operation without acquiring the lock. if !block && empty(c) { // After observing that the channel is not ready for receiving, we observe whether the @@ -570,11 +582,16 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool) mysg.elem = ep mysg.waitlink = nil gp.waiting = mysg + mysg.g = gp mysg.isSelect = false mysg.c = c gp.param = nil c.recvq.enqueue(mysg) + if c.timer != nil { + blockTimerChan(c) + } + // Signal to anyone trying to shrink our stack that we're about // to park on a channel. The window between when this G's status // changes and when we set gp.activeStackChans is not safe for @@ -586,6 +603,9 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool) if mysg != gp.waiting { throw("G waiting list is corrupted") } + if c.timer != nil { + unblockTimerChan(c) + } gp.waiting = nil gp.activeStackChans = false if mysg.releasetime > 0 { @@ -728,6 +748,9 @@ func chanlen(c *hchan) int { if c == nil { return 0 } + if c.timer != nil { + c.timer.maybeRunChan() + } return int(c.qcount) } |