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os: simplify process status

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Since it no longer holds a reference count, just use values.

For #70907

Change-Id: I19a42583988d4f8a9133b1c837356ca0179d688c
Reviewed-on: https://go-review.googlesource.com/c/go/+/638578
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
This commit is contained in:
Ian Lance Taylor 2024-12-22 21:15:30 -08:00 committed by Gopher Robot
parent caf29da4cc
commit e7c9667def
2 changed files with 17 additions and 19 deletions
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34
src/os/exec.go
View File

@ -17,21 +17,19 @@ import (
// ErrProcessDone indicates a [Process] has finished.
var ErrProcessDone = errors.New("os: process already finished")
type processStatus uint64
type processStatus uint32
const (
// PID/handle OK to use.
statusOK processStatus = 0
// statusOK means that the Process is ready to use.
statusOK processStatus = iota
// statusDone indicates that the PID/handle should not be used because
// the process is done (has been successfully Wait'd on).
statusDone processStatus = 1 << 62
statusDone
// statusReleased indicates that the PID/handle should not be used
// because the process is released.
statusReleased processStatus = 1 << 63
processStatusMask = 0x3 << 62
statusReleased
)
// Process stores the information about a process created by [StartProcess].
@ -42,7 +40,7 @@ type Process struct {
//
// This consists of the processStatus fields,
// which indicate if the process is done/released.
state atomic.Uint64
state atomic.Uint32
// Used only when handle is nil
sigMu sync.RWMutex // avoid race between wait and signal
@ -138,7 +136,7 @@ func newDoneProcess(pid int) *Process {
p := &Process{
Pid: pid,
}
p.state.Store(uint64(statusDone)) // No persistent reference, as there is no handle.
p.state.Store(uint32(statusDone)) // No persistent reference, as there is no handle.
runtime.SetFinalizer(p, (*Process).Release)
return p
}
@ -148,9 +146,9 @@ func (p *Process) handleTransientAcquire() (uintptr, processStatus) {
panic("handleTransientAcquire called in invalid mode")
}
state := p.state.Load()
if state&processStatusMask != 0 {
return 0, processStatus(state & processStatusMask)
status := processStatus(p.state.Load())
if status != statusOK {
return 0, status
}
h, ok := p.handle.acquire()
if ok {
@ -161,11 +159,11 @@ func (p *Process) handleTransientAcquire() (uintptr, processStatus) {
// We always set the status to non-zero before closing the handle.
// If we get here the status must have been set non-zero after
// we just checked it above.
state = p.state.Load()
if state&processStatusMask == 0 {
status = processStatus(p.state.Load())
if status == statusOK {
panic("inconsistent process status")
}
return 0, processStatus(state & processStatusMask)
return 0, status
}
func (p *Process) handleTransientRelease() {
@ -187,7 +185,7 @@ func (p *Process) handlePersistentRelease(reason processStatus) processStatus {
for {
state := p.state.Load()
status := processStatus(state & processStatusMask)
status := processStatus(state)
if status != statusOK {
// Both Release and successful Wait will drop the
// Process' persistent reference on the handle. We
@ -196,7 +194,7 @@ func (p *Process) handlePersistentRelease(reason processStatus) processStatus {
// reference is dropped exactly once.
return status
}
if !p.state.CompareAndSwap(state, uint64(reason)) {
if !p.state.CompareAndSwap(state, uint32(reason)) {
continue
}
p.handle.release()
@ -225,7 +223,7 @@ func (p *Process) pidDeactivate(reason processStatus) {
// racing Release and Wait, Wait may successfully wait on the process,
// returning the wait status, while future calls error with "process
// released" rather than "process done".
p.state.CompareAndSwap(0, uint64(reason))
p.state.CompareAndSwap(0, uint32(reason))
}
// ProcAttr holds the attributes that will be applied to a new process

2
src/os/export_linux_test.go
View File

@ -14,5 +14,5 @@ var (
const StatusDone = statusDone
func (p *Process) Status() processStatus {
return processStatus(p.state.Load() & processStatusMask)
return processStatus(p.state.Load())
}