internal/trace: remove redundant info from Event.String

Remove redundant information from state transition events. They
currently mention the proc and goroutine id that is transitioning twice.

Also reorder the reason to appear after the from->to state transition
information since it is a detail that is not available for all
transition.

Before example:

M=6164541440 P=3 G=17 StateTransition Time=7169014471424 Resource=Goroutine(17) Reason="chan receive" GoID=17 Running->Waiting
M=6166261760 P=3 G=10 StateTransition Time=7169908799040 Resource=Proc(4) Reason="" ProcID=4 Idle->Idle

After example:

M=6164541440 P=3 G=17 StateTransition Time=7169014471424 GoID=17 Running->Waiting Reason="chan receive"
M=6166261760 P=3 G=10 StateTransition Time=7169908799040 ProcID=4 Idle->Idle Reason=""

Change-Id: I6a6a696487ff2905f7c98dae7e887b998a2cb298
Reviewed-on: https://go-review.googlesource.com/c/go/+/697356
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>

diff --git a/src/internal/trace/event.go b/src/internal/trace/event.go
index a47f71b65e70f5e6fa570e2fa3ebb658143fff57..321e4e21fb35fc1092a422e7d03f752ff945528d 100644 (file)
--- a/src/internal/trace/event.go
+++ b/src/internal/trace/event.go
@@ -843,7 +843,6 @@ func (e Event) String() string {
                fmt.Fprintf(&sb, " Task=%d Category=%q Message=%q", l.Task, l.Category, l.Message)
        case EventStateTransition:
                s := e.StateTransition()
-               fmt.Fprintf(&sb, " Resource=%s Reason=%q", s.Resource, s.Reason)
                switch s.Resource.Kind {
                case ResourceGoroutine:
                        id := s.Resource.Goroutine()
@@ -854,6 +853,7 @@ func (e Event) String() string {
                        old, new := s.Proc()
                        fmt.Fprintf(&sb, " ProcID=%d %s->%s", id, old, new)
                }
+               fmt.Fprintf(&sb, " Reason=%q", s.Reason)
                if s.Stack != NoStack {
                        fmt.Fprintln(&sb)
                        fmt.Fprintln(&sb, "TransitionStack=")