os: centralize documentation of Process and ProcessState

Also change Wait to say "exit" instead of "exit or stop".

I notice that Pid is not implemented on all systems.
Should we fix that?

Fixes #3138.

R=golang-dev, alex.brainman, r
CC=golang-dev
https://golang.org/cl/5710056

src/pkg/os/doc.go

@@ -4,6 +4,8 @@
 
 package os
 
+import "time"
+
 // FindProcess looks for a running process by its pid.
 // The Process it returns can be used to obtain information
 // about the underlying operating system process.
@@ -11,6 +13,17 @@ func FindProcess(pid int) (p *Process, err error) {
 	return findProcess(pid)
 }
 
+// StartProcess starts a new process with the program, arguments and attributes
+// specified by name, argv and attr.
+//
+// StartProcess is a low-level interface. The os/exec package provides
+// higher-level interfaces.
+//
+// If there is an error, it will be of type *PathError.
+func StartProcess(name string, argv []string, attr *ProcAttr) (*Process, error) {
+	return startProcess(name, argv, attr)
+}
+
 // Release releases any resources associated with the Process p,
 // rendering it unusable in the future.
 // Release only needs to be called if Wait is not.
@@ -18,6 +31,58 @@ func (p *Process) Release() error {
 	return p.release()
 }
 
+// Kill causes the Process to exit immediately.
+func (p *Process) Kill() error {
+	return p.kill()
+}
+
+// Wait waits for the Process to exit, and then returns a
+// ProcessState describing its status and an error, if any.
+// Wait releases any resources associated with the Process.
+func (p *Process) Wait() (*ProcessState, error) {
+	return p.wait()
+}
+
+// Signal sends a signal to the Process.
+func (p *Process) Signal(sig Signal) error {
+	return p.signal(sig)
+}
+
+// UserTime returns the user CPU time of the exited process and its children.
+func (p *ProcessState) UserTime() time.Duration {
+	return p.userTime()
+}
+
+// SystemTime returns the system CPU time of the exited process and its children.
+func (p *ProcessState) SystemTime() time.Duration {
+	return p.systemTime()
+}
+
+// Exited returns whether the program has exited.
+func (p *ProcessState) Exited() bool {
+	return p.exited()
+}
+
+// Success reports whether the program exited successfully,
+// such as with exit status 0 on Unix.
+func (p *ProcessState) Success() bool {
+	return p.success()
+}
+
+// Sys returns system-dependent exit information about
+// the process.  Convert it to the appropriate underlying
+// type, such as syscall.WaitStatus on Unix, to access its contents.
+func (p *ProcessState) Sys() interface{} {
+	return p.sys()
+}
+
+// SysUsage returns system-dependent resource usage information about
+// the exited process.  Convert it to the appropriate underlying
+// type, such as *syscall.Rusage on Unix, to access its contents.
+func (p *ProcessState) SysUsage() interface{} {
+	return p.sysUsage()
+}
+
 // Hostname returns the host name reported by the kernel.
 func Hostname() (name string, err error) {
 	return hostname()

src/pkg/os/exec_plan9.go

@@ -11,10 +11,7 @@ import (
 	"time"
 )
 
-// StartProcess starts a new process with the program, arguments and attributes
-// specified by name, argv and attr.
-// If there is an error, it will be of type *PathError.
-func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
+func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
 	sysattr := &syscall.ProcAttr{
 		Dir: attr.Dir,
 		Env: attr.Env,
@@ -40,7 +37,7 @@ func (note Plan9Note) String() string {
 	return string(note)
 }
 
-func (p *Process) Signal(sig Signal) error {
+func (p *Process) signal(sig Signal) error {
 	if p.done {
 		return errors.New("os: process already finished")
 	}
@@ -54,8 +51,7 @@ func (p *Process) Signal(sig Signal) error {
 	return e
 }
 
-// Kill causes the Process to exit immediately.
-func (p *Process) Kill() error {
+func (p *Process) kill() error {
 	f, e := OpenFile("/proc/"+itoa(p.Pid)+"/ctl", O_WRONLY, 0)
 	if e != nil {
 		return NewSyscallError("kill", e)
@@ -65,9 +61,7 @@ func (p *Process) Kill() error {
 	return e
 }
 
-// Wait waits for the Process to exit or stop, and then returns a
-// ProcessState describing its status and an error, if any.
-func (p *Process) Wait() (ps *ProcessState, err error) {
+func (p *Process) wait() (ps *ProcessState, err error) {
 	var waitmsg syscall.Waitmsg
 
 	if p.Pid == -1 {
@@ -118,40 +112,27 @@ func (p *ProcessState) Pid() int {
 	return p.pid
 }
 
-// Exited returns whether the program has exited.
-func (p *ProcessState) Exited() bool {
+func (p *ProcessState) exited() bool {
 	return p.status.Exited()
 }
 
-// Success reports whether the program exited successfully,
-// such as with exit status 0 on Unix.
-func (p *ProcessState) Success() bool {
+func (p *ProcessState) success() bool {
 	return p.status.ExitStatus() == 0
 }
 
-// Sys returns system-dependent exit information about
-// the process.  Convert it to the appropriate underlying
-// type, such as *syscall.Waitmsg on Plan 9, to access its contents.
-func (p *ProcessState) Sys() interface{} {
+func (p *ProcessState) sys() interface{} {
 	return p.status
 }
 
-// SysUsage returns system-dependent resource usage information about
-// the exited process.  Convert it to the appropriate underlying
-// type, such as *syscall.Waitmsg on Plan 9, to access its contents.
-func (p *ProcessState) SysUsage() interface{} {
+func (p *ProcessState) sysUsage() interface{} {
 	return p.status
 }
 
-// UserTime returns the user CPU time of the exited process and its children.
-// It is always reported as 0 on Windows.
-func (p *ProcessState) UserTime() time.Duration {
+func (p *ProcessState) userTime() time.Duration {
 	return time.Duration(p.status.Time[0]) * time.Millisecond
 }
 
-// SystemTime returns the system CPU time of the exited process and its children.
-// It is always reported as 0 on Windows.
-func (p *ProcessState) SystemTime() time.Duration {
+func (p *ProcessState) systemTime() time.Duration {
 	return time.Duration(p.status.Time[1]) * time.Millisecond
 }
 

src/pkg/os/exec_posix.go

@@ -10,14 +10,7 @@ import (
 	"syscall"
 )
 
-// StartProcess starts a new process with the program, arguments and attributes
-// specified by name, argv and attr.
-//
-// StartProcess is a low-level interface. The os/exec package provides
-// higher-level interfaces.
-//
-// If there is an error, it will be of type *PathError.
-func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
+func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
 	// Double-check existence of the directory we want
 	// to chdir into.  We can make the error clearer this way.
 	if attr != nil && attr.Dir != "" {
@@ -47,8 +40,7 @@ func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err e
 	return newProcess(pid, h), nil
 }
 
-// Kill causes the Process to exit immediately.
-func (p *Process) Kill() error {
+func (p *Process) kill() error {
 	return p.Signal(Kill)
 }
 
@@ -64,28 +56,19 @@ func (p *ProcessState) Pid() int {
 	return p.pid
 }
 
-// Exited returns whether the program has exited.
-func (p *ProcessState) Exited() bool {
+func (p *ProcessState) exited() bool {
 	return p.status.Exited()
 }
 
-// Success reports whether the program exited successfully,
-// such as with exit status 0 on Unix.
-func (p *ProcessState) Success() bool {
+func (p *ProcessState) success() bool {
 	return p.status.ExitStatus() == 0
 }
 
-// Sys returns system-dependent exit information about
-// the process.  Convert it to the appropriate underlying
-// type, such as syscall.WaitStatus on Unix, to access its contents.
-func (p *ProcessState) Sys() interface{} {
+func (p *ProcessState) sys() interface{} {
 	return p.status
 }
 
-// SysUsage returns system-dependent resource usage information about
-// the exited process.  Convert it to the appropriate underlying
-// type, such as *syscall.Rusage on Unix, to access its contents.
-func (p *ProcessState) SysUsage() interface{} {
+func (p *ProcessState) sysUsage() interface{} {
 	return p.rusage
 }
 

src/pkg/os/exec_unix.go

@@ -13,9 +13,7 @@ import (
 	"time"
 )
 
-// Wait waits for the Process to exit or stop, and then returns a
-// ProcessState describing its status and an error, if any.
-func (p *Process) Wait() (ps *ProcessState, err error) {
+func (p *Process) wait() (ps *ProcessState, err error) {
 	if p.Pid == -1 {
 		return nil, syscall.EINVAL
 	}
@@ -36,8 +34,7 @@ func (p *Process) Wait() (ps *ProcessState, err error) {
 	return ps, nil
 }
 
-// Signal sends a signal to the Process.
-func (p *Process) Signal(sig Signal) error {
+func (p *Process) signal(sig Signal) error {
 	if p.done {
 		return errors.New("os: process already finished")
 	}
@@ -64,12 +61,10 @@ func findProcess(pid int) (p *Process, err error) {
 	return newProcess(pid, 0), nil
 }
 
-// UserTime returns the user CPU time of the exited process and its children.
-func (p *ProcessState) UserTime() time.Duration {
+func (p *ProcessState) userTime() time.Duration {
 	return time.Duration(p.rusage.Utime.Nano()) * time.Nanosecond
 }
 
-// SystemTime returns the system CPU time of the exited process and its children.
-func (p *ProcessState) SystemTime() time.Duration {
+func (p *ProcessState) systemTime() time.Duration {
 	return time.Duration(p.rusage.Stime.Nano()) * time.Nanosecond
 }

src/pkg/os/exec_windows.go

@@ -12,10 +12,7 @@ import (
 	"unsafe"
 )
 
-// Wait waits for the Process to exit or stop, and then returns a
-// ProcessState describing its status and an error, if any.
-// Wait releases any resources associated with the Process.
-func (p *Process) Wait() (ps *ProcessState, err error) {
+func (p *Process) wait() (ps *ProcessState, err error) {
 	s, e := syscall.WaitForSingleObject(syscall.Handle(p.handle), syscall.INFINITE)
 	switch s {
 	case syscall.WAIT_OBJECT_0:
@@ -35,8 +32,7 @@ func (p *Process) Wait() (ps *ProcessState, err error) {
 	return &ProcessState{p.Pid, syscall.WaitStatus{Status: s, ExitCode: ec}, new(syscall.Rusage)}, nil
 }
 
-// Signal sends a signal to the Process.
-func (p *Process) Signal(sig Signal) error {
+func (p *Process) signal(sig Signal) error {
 	if p.done {
 		return errors.New("os: process already finished")
 	}
@@ -86,14 +82,12 @@ func init() {
 	}
 }
 
-// UserTime returns the user CPU time of the exited process and its children.
-// For now, it is always reported as 0 on Windows.
-func (p *ProcessState) UserTime() time.Duration {
+// BUG(rsc): On Windows, ProcessState's UserTime and SystemTime methods always return 0.
+
+func (p *ProcessState) userTime() time.Duration {
 	return 0
 }
 
-// SystemTime returns the system CPU time of the exited process and its children.
-// For now, it is always reported as 0 on Windows.
-func (p *ProcessState) SystemTime() time.Duration {
+func (p *ProcessState) systemTime() time.Duration {
 	return 0
 }