From 2aeab259c4d24f87d7788fed338b64d99e0865ec Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Thu, 2 Sep 2021 15:48:04 -0700 Subject: Internal change. PiperOrigin-RevId: 394560866 --- pkg/flipcall/ctrl_futex.go | 5 ++++- pkg/flipcall/flipcall.go | 19 ++++++++++++++++++- 2 files changed, 22 insertions(+), 2 deletions(-) (limited to 'pkg/flipcall') diff --git a/pkg/flipcall/ctrl_futex.go b/pkg/flipcall/ctrl_futex.go index 5d2ee4018..99410628f 100644 --- a/pkg/flipcall/ctrl_futex.go +++ b/pkg/flipcall/ctrl_futex.go @@ -121,7 +121,7 @@ func (ep *Endpoint) ctrlWaitFirst() error { return ep.futexWaitUntilActive() } -func (ep *Endpoint) ctrlRoundTrip() error { +func (ep *Endpoint) ctrlRoundTrip(mayRetainP bool) error { if err := ep.enterFutexWait(); err != nil { return err } @@ -133,6 +133,9 @@ func (ep *Endpoint) ctrlRoundTrip() error { if err := ep.futexWakePeer(); err != nil { return err } + // Since we don't know if the peer Endpoint is in the same process as this + // one (in which case it may need our P to run), we allow our P to be + // retaken regardless of mayRetainP. return ep.futexWaitUntilActive() } diff --git a/pkg/flipcall/flipcall.go b/pkg/flipcall/flipcall.go index f0e4ff487..88588ba0e 100644 --- a/pkg/flipcall/flipcall.go +++ b/pkg/flipcall/flipcall.go @@ -223,6 +223,23 @@ func (ep *Endpoint) RecvFirst() (uint32, error) { // * If ep is a client Endpoint, ep.Connect() has previously been called and // returned nil. func (ep *Endpoint) SendRecv(dataLen uint32) (uint32, error) { + return ep.sendRecv(dataLen, false /* mayRetainP */) +} + +// SendRecvFast is equivalent to SendRecv, but may prevent the caller's runtime +// P from being released, in which case the calling goroutine continues to +// count against GOMAXPROCS while waiting for the peer Endpoint to return +// control to the caller. +// +// SendRecvFast is appropriate if the peer Endpoint is expected to consistently +// return control in a short amount of time (less than ~10ms). +// +// Preconditions: As for SendRecv. +func (ep *Endpoint) SendRecvFast(dataLen uint32) (uint32, error) { + return ep.sendRecv(dataLen, true /* mayRetainP */) +} + +func (ep *Endpoint) sendRecv(dataLen uint32, mayRetainP bool) (uint32, error) { if dataLen > ep.dataCap { panic(fmt.Sprintf("attempting to send packet with datagram length %d (maximum %d)", dataLen, ep.dataCap)) } @@ -233,7 +250,7 @@ func (ep *Endpoint) SendRecv(dataLen uint32) (uint32, error) { // they can only shoot themselves in the foot. *ep.dataLen() = dataLen raceBecomeInactive() - if err := ep.ctrlRoundTrip(); err != nil { + if err := ep.ctrlRoundTrip(mayRetainP); err != nil { return 0, err } raceBecomeActive() -- cgit v1.2.3