net/http: eliminate more arbitrary timeouts in tests

Change-Id: I5b3158ecd0eb20dc433a53a2b03eb4551cbb3f7d
Reviewed-on: https://go-review.googlesource.com/c/go/+/477196
Auto-Submit: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Damien Neil <dneil@google.com>

src/net/http/clientserver_test.go

@@ -1283,24 +1283,28 @@ func testInterruptWithPanic(t *testing.T, mode testMode, panicValue any) {
 	}
 	wantStackLogged := panicValue != nil && panicValue != ErrAbortHandler
 
-	if err := waitErrCondition(5*time.Second, 10*time.Millisecond, func() error {
+	waitCondition(t, 10*time.Millisecond, func(d time.Duration) bool {
 		gotLog := logOutput()
 		if !wantStackLogged {
 			if gotLog == "" {
-				return nil
+				return true
 			}
-			return fmt.Errorf("want no log output; got: %s", gotLog)
+			t.Fatalf("want no log output; got: %s", gotLog)
 		}
 		if gotLog == "" {
-			return fmt.Errorf("wanted a stack trace logged; got nothing")
+			if d > 0 {
+				t.Logf("wanted a stack trace logged; got nothing after %v", d)
+			}
+			return false
 		}
 		if !strings.Contains(gotLog, "created by ") && strings.Count(gotLog, "\n") < 6 {
-			return fmt.Errorf("output doesn't look like a panic stack trace. Got: %s", gotLog)
+			if d > 0 {
+				t.Logf("output doesn't look like a panic stack trace after %v. Got: %s", d, gotLog)
+			}
+			return false
 		}
-		return nil
-	}); err != nil {
-		t.Fatal(err)
-	}
+		return true
+	})
 }
 
 type lockedBytesBuffer struct {

src/net/http/main_test.go

@@ -140,29 +140,15 @@ func afterTest(t testing.TB) {
 	t.Errorf("Test appears to have leaked %s:\n%s", bad, stacks)
 }
 
-// waitCondition reports whether fn eventually returned true,
-// checking immediately and then every checkEvery amount,
-// until waitFor has elapsed, at which point it returns false.
-func waitCondition(waitFor, checkEvery time.Duration, fn func() bool) bool {
-	deadline := time.Now().Add(waitFor)
-	for time.Now().Before(deadline) {
-		if fn() {
-			return true
-		}
-		time.Sleep(checkEvery)
+// waitCondition waits for fn to return true,
+// checking immediately and then at exponentially increasing intervals.
+func waitCondition(t testing.TB, delay time.Duration, fn func(time.Duration) bool) {
+	t.Helper()
+	start := time.Now()
+	var since time.Duration
+	for !fn(since) {
+		time.Sleep(delay)
+		delay = 2*delay - (delay / 2) // 1.5x, rounded up
+		since = time.Since(start)
 	}
-	return false
-}
-
-// waitErrCondition is like waitCondition but with errors instead of bools.
-func waitErrCondition(waitFor, checkEvery time.Duration, fn func() error) error {
-	deadline := time.Now().Add(waitFor)
-	var err error
-	for time.Now().Before(deadline) {
-		if err = fn(); err == nil {
-			return nil
-		}
-		time.Sleep(checkEvery)
-	}
-	return err
 }

src/net/http/serve_test.go

@@ -5439,12 +5439,16 @@ func testServerSetKeepAlivesEnabledClosesConns(t *testing.T, mode testMode) {
 	ts.Config.SetKeepAlivesEnabled(false)
 
 	var idle1 int
-	if !waitCondition(2*time.Second, 10*time.Millisecond, func() bool {
+	waitCondition(t, 10*time.Millisecond, func(d time.Duration) bool {
 		idle1 = tr.IdleConnCountForTesting("http", addr)
-		return idle1 == 0
-	}) {
-		t.Fatalf("idle count after SetKeepAlivesEnabled called = %v; want 0", idle1)
-	}
+		if idle1 != 0 {
+			if d > 0 {
+				t.Logf("idle count %v after SetKeepAlivesEnabled called = %v; waiting for 0", d, idle1)
+			}
+			return false
+		}
+		return true
+	})
 
 	a3 := get()
 	if a3 == a2 {
@@ -5604,9 +5608,15 @@ func testServerKeepAlivesEnabled(t *testing.T, mode testMode) {
 	srv := cst.ts.Config
 	srv.SetKeepAlivesEnabled(false)
 	for try := 0; try < 2; try++ {
-		if !waitCondition(2*time.Second, 10*time.Millisecond, srv.ExportAllConnsIdle) {
-			t.Fatalf("request %v: test server has active conns", try)
-		}
+		waitCondition(t, 10*time.Millisecond, func(d time.Duration) bool {
+			if !srv.ExportAllConnsIdle() {
+				if d > 0 {
+					t.Logf("test server still has active conns after %v", d)
+				}
+				return false
+			}
+			return true
+		})
 		conns := 0
 		var info httptrace.GotConnInfo
 		ctx := httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{