cmd/go: rename flag counters and add buildmode values separately

Rename the subcommand flag counter names from
go/flag/<subcommand>/<flagname> to go/<subcommand>/flag/<flagname>.

Also remove the special case that adds counters for buildmode flag
values and instead add an additional counter for the flag values.
The new counter has the form go/<subcommand>/flag/buildmode:<flagvalue>.
We use a new CountFlagValue function that's been added to the
internal/telemetry package to help with this.

Finally add the go/invocations counter

Change-Id: I995b6b0009ba0f58faeb3e2a75f3b137e4136209
Reviewed-on: https://go-review.googlesource.com/c/go/+/583917
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

3 files changed, 26 insertions, 14 deletions

diff --git a/src/cmd/go/main.go b/src/cmd/go/main.go
index 86f3c65a92..72656dd903 100644
--- a/src/cmd/go/main.go
+++ b/src/cmd/go/main.go
@@ -98,6 +98,7 @@ func main() {
 
 	flag.Usage = base.Usage
 	flag.Parse()
+	telemetry.Inc("go/invocations")
 	telemetry.CountFlags("go/flag:", *flag.CommandLine)
 
 	args := flag.Args()
@@ -252,14 +253,9 @@ func invoke(cmd *base.Command, args []string) {
 	} else {
 		base.SetFromGOFLAGS(&cmd.Flag)
 		cmd.Flag.Parse(args[1:])
-		prefix := "go/flag:" + strings.ReplaceAll(cfg.CmdName, " ", "-") + "-"
-		cmd.Flag.Visit(func(f *flag.Flag) {
-			counterName := prefix + f.Name
-			if f.Name == "buildmode" { // Special case: there is a limited set of buildmode values
-				counterName += "-" + f.Value.String()
-			}
-			telemetry.Inc(counterName)
-		})
+		flagCounterPrefix := "go/" + strings.ReplaceAll(cfg.CmdName, " ", "-") + "/flag"
+		telemetry.CountFlags(flagCounterPrefix+":", cmd.Flag)
+		telemetry.CountFlagValue(flagCounterPrefix+"/", cmd.Flag, "buildmode")
 		args = cmd.Flag.Args()
 	}
 
diff --git a/src/cmd/internal/telemetry/telemetry.go b/src/cmd/internal/telemetry/telemetry.go
index d31f0eeff3..2420a07708 100644
--- a/src/cmd/internal/telemetry/telemetry.go
+++ b/src/cmd/internal/telemetry/telemetry.go
@@ -59,3 +59,18 @@ func NewStackCounter(name string, depth int) *counter.StackCounter {
 func CountFlags(prefix string, flagSet flag.FlagSet) {
 	counter.CountFlags(prefix, flagSet)
 }
+
+// CountFlagValue creates a counter for the flag value
+// if it is set and increments the counter. The name of the
+// counter is the concatenation of prefix, the flagName, ":",
+// and value.String() for the flag's value.
+func CountFlagValue(prefix string, flagSet flag.FlagSet, flagName string) {
+	// TODO(matloob): Maybe pass in a list of flagNames if we end up counting
+	// values for more than one?
+	// TODO(matloob): Add this to x/telemetry?
+	flagSet.Visit(func(f *flag.Flag) {
+		if f.Name == flagName {
+			counter.New(prefix + f.Name + ":" + f.Value.String()).Inc()
+		}
+	})
+}
diff --git a/src/cmd/internal/telemetry/telemetry_bootstrap.go b/src/cmd/internal/telemetry/telemetry_bootstrap.go
index 2e127bec28..01549b6970 100644
--- a/src/cmd/internal/telemetry/telemetry_bootstrap.go
+++ b/src/cmd/internal/telemetry/telemetry_bootstrap.go
@@ -12,9 +12,10 @@ type dummyCounter struct{}
 
 func (dc dummyCounter) Inc() {}
 
-func Start()                                              {}
-func StartWithUpload()                                    {}
-func Inc(name string)                                     {}
-func NewCounter(name string) dummyCounter                 { return dummyCounter{} }
-func NewStackCounter(name string, depth int) dummyCounter { return dummyCounter{} }
-func CountFlags(name string, flagSet flag.FlagSet)        {}
+func Start()                                                              {}
+func StartWithUpload()                                                    {}
+func Inc(name string)                                                     {}
+func NewCounter(name string) dummyCounter                                 { return dummyCounter{} }
+func NewStackCounter(name string, depth int) dummyCounter                 { return dummyCounter{} }
+func CountFlags(name string, flagSet flag.FlagSet)                        {}
+func CountFlagValue(prefix string, flagSet flag.FlagSet, flagName string) {}