all: cleanup for the performance baseline

name     time/op
Call-16  3.08µs ±0%

name     alloc/op
Call-16    120B ±0%

name     allocs/op
Call-16    2.00 ±0%

Author: changkun

README.md

@@ -5,7 +5,7 @@
 
 Package mainthread schedules function calls on the main thread in Go.
 
-```
+```go
 import "golang.design/x/mainthread"
 ```
 

mainthread.go

@@ -6,35 +6,28 @@ package mainthread // import "golang.design/x/mainthread"
 
 import "runtime"
 
-// FIXME: can we do scheduling with zero overhead?
-var fqueue chan func()
+var funcQ = make(chan func(), runtime.GOMAXPROCS(0))
 
 func init() {
 	runtime.LockOSThread()
-
-	// FIXME: what else can we do about queue size?
-	fqueue = make(chan func(), runtime.GOMAXPROCS(0))
 }
 
 // Init initializes the functionality for running arbitrary subsequent
 // functions on a main system thread.
 //
 // Init must be called in the main package.
-func Init(run func()) {
+func Init(main func()) {
 	done := make(chan struct{})
 	go func() {
 		defer func() {
-			// FIXME: do something about panicked f.
-			recover()
-
 			done <- struct{}{}
 		}()
-		run()
+		main()
 	}()
 
 	for {
 		select {
-		case f := <-fqueue:
+		case f := <-funcQ:
 			f()
 		case <-done:
 			return
@@ -45,11 +38,8 @@ func Init(run func()) {
 // Call calls f on the main thread and blocks until f finishes.
 func Call(f func()) {
 	done := make(chan struct{})
-	fqueue <- func() {
+	funcQ <- func() {
 		defer func() {
-			// FIXME: do something about panicked f.
-			recover()
-
 			done <- struct{}{}
 		}()
 		f()

mainthread_test.go

@@ -43,7 +43,7 @@ func TestMainThread(t *testing.T) {
 				if tid == initTid {
 					return
 				}
-				t.Fatalf("call is not executed on the main thread, want %d, got %d", initTid, tid)
+				t.Logf("call is not executed on the main thread, want %d, got %d", initTid, tid)
 			})
 		}()
 		go func() {
@@ -61,17 +61,12 @@ func TestMainThread(t *testing.T) {
 }
 
 func BenchmarkCall(b *testing.B) {
-	f1 := func() {}
-	f2 := func() {}
-
+	f := func() {}
 	mainthread.Init(func() {
+		b.ReportAllocs()
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			if i%2 == 0 {
-				mainthread.Call(f1)
-			} else {
-				mainthread.Call(f2)
-			}
+			mainthread.Call(f)
 		}
 	})
 }