use state machine management for exec.Pid()

Signed-off-by: Lifubang <lifubang@acmcoder.com>

runtime/v1/linux/proc/exec_state.go

@@ -31,6 +31,7 @@ type execState interface {
 	Delete(context.Context) error
 	Kill(context.Context, uint32, bool) error
 	SetExited(int)
+	Pid() int
 }
 
 type execCreatedState struct {
@@ -82,6 +83,12 @@ func (s *execCreatedState) SetExited(status int) {
 	}
 }
 
+func (s *execCreatedState) Pid() int {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+	return s.p.pidv()
+}
+
 type execRunningState struct {
 	p *execProcess
 }
@@ -120,6 +127,12 @@ func (s *execRunningState) SetExited(status int) {
 	}
 }
 
+func (s *execRunningState) Pid() int {
+	s.p.mu.Lock()
+	defer s.p.mu.Unlock()
+	return s.p.pidv()
+}
+
 type execStoppedState struct {
 	p *execProcess
 }
@@ -157,3 +170,7 @@ func (s *execStoppedState) Kill(ctx context.Context, sig uint32, all bool) error
 func (s *execStoppedState) SetExited(status int) {
 	// no op
 }
+
+func (s *execStoppedState) Pid() int {
+	return s.p.pidv()
+}