diff options
Diffstat (limited to 'libgo/go/runtime/netpoll.go')
| -rw-r--r-- | libgo/go/runtime/netpoll.go | 64 |
1 files changed, 41 insertions, 23 deletions
diff --git a/libgo/go/runtime/netpoll.go b/libgo/go/runtime/netpoll.go index d2fb77569d6..5157e4dd9e2 100644 --- a/libgo/go/runtime/netpoll.go +++ b/libgo/go/runtime/netpoll.go @@ -36,18 +36,27 @@ import ( // func netpollIsPollDescriptor(fd uintptr) bool // Reports whether fd is a file descriptor used by the poller. +// Error codes returned by runtime_pollReset and runtime_pollWait. +// These must match the values in internal/poll/fd_poll_runtime.go. +const ( + pollNoError = 0 // no error + pollErrClosing = 1 // descriptor is closed + pollErrTimeout = 2 // I/O timeout + pollErrNotPollable = 3 // general error polling descriptor +) + // pollDesc contains 2 binary semaphores, rg and wg, to park reader and writer // goroutines respectively. The semaphore can be in the following states: // pdReady - io readiness notification is pending; // a goroutine consumes the notification by changing the state to nil. // pdWait - a goroutine prepares to park on the semaphore, but not yet parked; // the goroutine commits to park by changing the state to G pointer, -// or, alternatively, concurrent io notification changes the state to READY, +// or, alternatively, concurrent io notification changes the state to pdReady, // or, alternatively, concurrent timeout/close changes the state to nil. // G pointer - the goroutine is blocked on the semaphore; -// io notification or timeout/close changes the state to READY or nil respectively +// io notification or timeout/close changes the state to pdReady or nil respectively // and unparks the goroutine. -// nil - nothing of the above. +// nil - none of the above. const ( pdReady uintptr = 1 pdWait uintptr = 2 @@ -110,6 +119,7 @@ func poll_runtime_pollServerInit() { func netpollGenericInit() { if atomic.Load(&netpollInited) == 0 { + lockInit(&netpollInitLock, lockRankNetpollInit) lock(&netpollInitLock) if netpollInited == 0 { netpollinit() @@ -180,42 +190,49 @@ func (c *pollCache) free(pd *pollDesc) { unlock(&c.lock) } +// poll_runtime_pollReset, which is internal/poll.runtime_pollReset, +// prepares a descriptor for polling in mode, which is 'r' or 'w'. +// This returns an error code; the codes are defined above. //go:linkname poll_runtime_pollReset internal..z2fpoll.runtime_pollReset func poll_runtime_pollReset(ctx uintptr, mode int) int { pd := (*pollDesc)(unsafe.Pointer(ctx)) - err := netpollcheckerr(pd, int32(mode)) - if err != 0 { - return err + errcode := netpollcheckerr(pd, int32(mode)) + if errcode != pollNoError { + return errcode } if mode == 'r' { pd.rg = 0 } else if mode == 'w' { pd.wg = 0 } - return 0 + return pollNoError } +// poll_runtime_pollWait, which is internal/poll.runtime_pollWait, +// waits for a descriptor to be ready for reading or writing, +// according to mode, which is 'r' or 'w'. +// This returns an error code; the codes are defined above. //go:linkname poll_runtime_pollWait internal..z2fpoll.runtime_pollWait func poll_runtime_pollWait(ctx uintptr, mode int) int { pd := (*pollDesc)(unsafe.Pointer(ctx)) - err := netpollcheckerr(pd, int32(mode)) - if err != 0 { - return err + errcode := netpollcheckerr(pd, int32(mode)) + if errcode != pollNoError { + return errcode } // As for now only Solaris, illumos, and AIX use level-triggered IO. if GOOS == "solaris" || GOOS == "illumos" || GOOS == "aix" || GOOS == "hurd" { netpollarm(pd, mode) } for !netpollblock(pd, int32(mode), false) { - err = netpollcheckerr(pd, int32(mode)) - if err != 0 { - return err + errcode = netpollcheckerr(pd, int32(mode)) + if errcode != pollNoError { + return errcode } // Can happen if timeout has fired and unblocked us, // but before we had a chance to run, timeout has been reset. // Pretend it has not happened and retry. } - return 0 + return pollNoError } //go:linkname poll_runtime_pollWaitCanceled internal..z2fpoll.runtime_pollWaitCanceled @@ -368,18 +385,18 @@ func netpollready(toRun *gList, pd *pollDesc, mode int32) { func netpollcheckerr(pd *pollDesc, mode int32) int { if pd.closing { - return 1 // ErrFileClosing or ErrNetClosing + return pollErrClosing } if (mode == 'r' && pd.rd < 0) || (mode == 'w' && pd.wd < 0) { - return 2 // ErrTimeout + return pollErrTimeout } // Report an event scanning error only on a read event. // An error on a write event will be captured in a subsequent // write call that is able to report a more specific error. if mode == 'r' && pd.everr { - return 3 // ErrNotPollable + return pollErrNotPollable } - return 0 + return pollNoError } func netpollblockcommit(gp *g, gpp unsafe.Pointer) bool { @@ -406,7 +423,7 @@ func netpollblock(pd *pollDesc, mode int32, waitio bool) bool { gpp = &pd.wg } - // set the gpp semaphore to WAIT + // set the gpp semaphore to pdWait for { old := *gpp if old == pdReady { @@ -421,13 +438,13 @@ func netpollblock(pd *pollDesc, mode int32, waitio bool) bool { } } - // need to recheck error states after setting gpp to WAIT + // need to recheck error states after setting gpp to pdWait // this is necessary because runtime_pollUnblock/runtime_pollSetDeadline/deadlineimpl // do the opposite: store to closing/rd/wd, membarrier, load of rg/wg if waitio || netpollcheckerr(pd, mode) == 0 { gopark(netpollblockcommit, unsafe.Pointer(gpp), waitReasonIOWait, traceEvGoBlockNet, 5) } - // be careful to not lose concurrent READY notification + // be careful to not lose concurrent pdReady notification old := atomic.Xchguintptr(gpp, 0) if old > pdWait { throw("runtime: corrupted polldesc") @@ -447,7 +464,7 @@ func netpollunblock(pd *pollDesc, mode int32, ioready bool) *g { return nil } if old == 0 && !ioready { - // Only set READY for ioready. runtime_pollWait + // Only set pdReady for ioready. runtime_pollWait // will check for timeout/cancel before waiting. return nil } @@ -456,7 +473,7 @@ func netpollunblock(pd *pollDesc, mode int32, ioready bool) *g { new = pdReady } if atomic.Casuintptr(gpp, old, new) { - if old == pdReady || old == pdWait { + if old == pdWait { old = 0 } return (*g)(unsafe.Pointer(old)) @@ -535,6 +552,7 @@ func (c *pollCache) alloc() *pollDesc { } pd := c.first c.first = pd.link + lockInit(&pd.lock, lockRankPollDesc) unlock(&c.lock) return pd } |