1 files changed, 331 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/http2/testsync.go b/vendor/golang.org/x/net/http2/testsync.go
new file mode 100644
index 000000000..61075bd16
--- /dev/null
+++ b/vendor/golang.org/x/net/http2/testsync.go
@@ -0,0 +1,331 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+package http2
+
+import (
+	"context"
+	"sync"
+	"time"
+)
+
+// testSyncHooks coordinates goroutines in tests.
+//
+// For example, a call to ClientConn.RoundTrip involves several goroutines, including:
+//   - the goroutine running RoundTrip;
+//   - the clientStream.doRequest goroutine, which writes the request; and
+//   - the clientStream.readLoop goroutine, which reads the response.
+//
+// Using testSyncHooks, a test can start a RoundTrip and identify when all these goroutines
+// are blocked waiting for some condition such as reading the Request.Body or waiting for
+// flow control to become available.
+//
+// The testSyncHooks also manage timers and synthetic time in tests.
+// This permits us to, for example, start a request and cause it to time out waiting for
+// response headers without resorting to time.Sleep calls.
+type testSyncHooks struct {
+	// active/inactive act as a mutex and condition variable.
+	//
+	//  - neither chan contains a value: testSyncHooks is locked.
+	//  - active contains a value: unlocked, and at least one goroutine is not blocked
+	//  - inactive contains a value: unlocked, and all goroutines are blocked
+	active   chan struct{}
+	inactive chan struct{}
+
+	// goroutine counts
+	total    int                     // total goroutines
+	condwait map[*sync.Cond]int      // blocked in sync.Cond.Wait
+	blocked  []*testBlockedGoroutine // otherwise blocked
+
+	// fake time
+	now    time.Time
+	timers []*fakeTimer
+
+	// Transport testing: Report various events.
+	newclientconn func(*ClientConn)
+	newstream     func(*clientStream)
+}
+
+// testBlockedGoroutine is a blocked goroutine.
+type testBlockedGoroutine struct {
+	f  func() bool   // blocked until f returns true
+	ch chan struct{} // closed when unblocked
+}
+
+func newTestSyncHooks() *testSyncHooks {
+	h := &testSyncHooks{
+		active:   make(chan struct{}, 1),
+		inactive: make(chan struct{}, 1),
+		condwait: map[*sync.Cond]int{},
+	}
+	h.inactive <- struct{}{}
+	h.now = time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC)
+	return h
+}
+
+// lock acquires the testSyncHooks mutex.
+func (h *testSyncHooks) lock() {
+	select {
+	case <-h.active:
+	case <-h.inactive:
+	}
+}
+
+// waitInactive waits for all goroutines to become inactive.
+func (h *testSyncHooks) waitInactive() {
+	for {
+		<-h.inactive
+		if !h.unlock() {
+			break
+		}
+	}
+}
+
+// unlock releases the testSyncHooks mutex.
+// It reports whether any goroutines are active.
+func (h *testSyncHooks) unlock() (active bool) {
+	// Look for a blocked goroutine which can be unblocked.
+	blocked := h.blocked[:0]
+	unblocked := false
+	for _, b := range h.blocked {
+		if !unblocked && b.f() {
+			unblocked = true
+			close(b.ch)
+		} else {
+			blocked = append(blocked, b)
+		}
+	}
+	h.blocked = blocked
+
+	// Count goroutines blocked on condition variables.
+	condwait := 0
+	for _, count := range h.condwait {
+		condwait += count
+	}
+
+	if h.total > condwait+len(blocked) {
+		h.active <- struct{}{}
+		return true
+	} else {
+		h.inactive <- struct{}{}
+		return false
+	}
+}
+
+// goRun starts a new goroutine.
+func (h *testSyncHooks) goRun(f func()) {
+	h.lock()
+	h.total++
+	h.unlock()
+	go func() {
+		defer func() {
+			h.lock()
+			h.total--
+			h.unlock()
+		}()
+		f()
+	}()
+}
+
+// blockUntil indicates that a goroutine is blocked waiting for some condition to become true.
+// It waits until f returns true before proceeding.
+//
+// Example usage:
+//
+//	h.blockUntil(func() bool {
+//		// Is the context done yet?
+//		select {
+//		case <-ctx.Done():
+//		default:
+//			return false
+//		}
+//		return true
+//	})
+//	// Wait for the context to become done.
+//	<-ctx.Done()
+//
+// The function f passed to blockUntil must be non-blocking and idempotent.
+func (h *testSyncHooks) blockUntil(f func() bool) {
+	if f() {
+		return
+	}
+	ch := make(chan struct{})
+	h.lock()
+	h.blocked = append(h.blocked, &testBlockedGoroutine{
+		f:  f,
+		ch: ch,
+	})
+	h.unlock()
+	<-ch
+}
+
+// broadcast is sync.Cond.Broadcast.
+func (h *testSyncHooks) condBroadcast(cond *sync.Cond) {
+	h.lock()
+	delete(h.condwait, cond)
+	h.unlock()
+	cond.Broadcast()
+}
+
+// broadcast is sync.Cond.Wait.
+func (h *testSyncHooks) condWait(cond *sync.Cond) {
+	h.lock()
+	h.condwait[cond]++
+	h.unlock()
+}
+
+// newTimer creates a new fake timer.
+func (h *testSyncHooks) newTimer(d time.Duration) timer {
+	h.lock()
+	defer h.unlock()
+	t := &fakeTimer{
+		hooks: h,
+		when:  h.now.Add(d),
+		c:     make(chan time.Time),
+	}
+	h.timers = append(h.timers, t)
+	return t
+}
+
+// afterFunc creates a new fake AfterFunc timer.
+func (h *testSyncHooks) afterFunc(d time.Duration, f func()) timer {
+	h.lock()
+	defer h.unlock()
+	t := &fakeTimer{
+		hooks: h,
+		when:  h.now.Add(d),
+		f:     f,
+	}
+	h.timers = append(h.timers, t)
+	return t
+}
+
+func (h *testSyncHooks) contextWithTimeout(ctx context.Context, d time.Duration) (context.Context, context.CancelFunc) {
+	ctx, cancel := context.WithCancel(ctx)
+	t := h.afterFunc(d, cancel)
+	return ctx, func() {
+		t.Stop()
+		cancel()
+	}
+}
+
+func (h *testSyncHooks) timeUntilEvent() time.Duration {
+	h.lock()
+	defer h.unlock()
+	var next time.Time
+	for _, t := range h.timers {
+		if next.IsZero() || t.when.Before(next) {
+			next = t.when
+		}
+	}
+	if d := next.Sub(h.now); d > 0 {
+		return d
+	}
+	return 0
+}
+
+// advance advances time and causes synthetic timers to fire.
+func (h *testSyncHooks) advance(d time.Duration) {
+	h.lock()
+	defer h.unlock()
+	h.now = h.now.Add(d)
+	timers := h.timers[:0]
+	for _, t := range h.timers {
+		t := t // remove after go.mod depends on go1.22
+		t.mu.Lock()
+		switch {
+		case t.when.After(h.now):
+			timers = append(timers, t)
+		case t.when.IsZero():
+			// stopped timer
+		default:
+			t.when = time.Time{}
+			if t.c != nil {
+				close(t.c)
+			}
+			if t.f != nil {
+				h.total++
+				go func() {
+					defer func() {
+						h.lock()
+						h.total--
+						h.unlock()
+					}()
+					t.f()
+				}()
+			}
+		}
+		t.mu.Unlock()
+	}
+	h.timers = timers
+}
+
+// A timer wraps a time.Timer, or a synthetic equivalent in tests.
+// Unlike time.Timer, timer is single-use: The timer channel is closed when the timer expires.
+type timer interface {
+	C() <-chan time.Time
+	Stop() bool
+	Reset(d time.Duration) bool
+}
+
+// timeTimer implements timer using real time.
+type timeTimer struct {
+	t *time.Timer
+	c chan time.Time
+}
+
+// newTimeTimer creates a new timer using real time.
+func newTimeTimer(d time.Duration) timer {
+	ch := make(chan time.Time)
+	t := time.AfterFunc(d, func() {
+		close(ch)
+	})
+	return &timeTimer{t, ch}
+}
+
+// newTimeAfterFunc creates an AfterFunc timer using real time.
+func newTimeAfterFunc(d time.Duration, f func()) timer {
+	return &timeTimer{
+		t: time.AfterFunc(d, f),
+	}
+}
+
+func (t timeTimer) C() <-chan time.Time        { return t.c }
+func (t timeTimer) Stop() bool                 { return t.t.Stop() }
+func (t timeTimer) Reset(d time.Duration) bool { return t.t.Reset(d) }
+
+// fakeTimer implements timer using fake time.
+type fakeTimer struct {
+	hooks *testSyncHooks
+
+	mu   sync.Mutex
+	when time.Time      // when the timer will fire
+	c    chan time.Time // closed when the timer fires; mutually exclusive with f
+	f    func()         // called when the timer fires; mutually exclusive with c
+}
+
+func (t *fakeTimer) C() <-chan time.Time { return t.c }
+
+func (t *fakeTimer) Stop() bool {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	stopped := t.when.IsZero()
+	t.when = time.Time{}
+	return stopped
+}
+
+func (t *fakeTimer) Reset(d time.Duration) bool {
+	if t.c != nil || t.f == nil {
+		panic("fakeTimer only supports Reset on AfterFunc timers")
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.hooks.lock()
+	defer t.hooks.unlock()
+	active := !t.when.IsZero()
+	t.when = t.hooks.now.Add(d)
+	if !active {
+		t.hooks.timers = append(t.hooks.timers, t)
+	}
+	return active
+}