From 43a123c1ae6613b3efeed291fa552ecd909d3acf Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Tue, 16 Apr 2024 21:23:18 +0200 Subject: Adding upstream version 1.20.14. Signed-off-by: Daniel Baumann --- src/sync/cond_test.go | 316 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 316 insertions(+) create mode 100644 src/sync/cond_test.go (limited to 'src/sync/cond_test.go') diff --git a/src/sync/cond_test.go b/src/sync/cond_test.go new file mode 100644 index 0000000..859cae5 --- /dev/null +++ b/src/sync/cond_test.go @@ -0,0 +1,316 @@ +// Copyright 2011 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 sync_test + +import ( + "reflect" + "runtime" + . "sync" + "testing" + "time" +) + +func TestCondSignal(t *testing.T) { + var m Mutex + c := NewCond(&m) + n := 2 + running := make(chan bool, n) + awake := make(chan bool, n) + for i := 0; i < n; i++ { + go func() { + m.Lock() + running <- true + c.Wait() + awake <- true + m.Unlock() + }() + } + for i := 0; i < n; i++ { + <-running // Wait for everyone to run. + } + for n > 0 { + select { + case <-awake: + t.Fatal("goroutine not asleep") + default: + } + m.Lock() + c.Signal() + m.Unlock() + <-awake // Will deadlock if no goroutine wakes up + select { + case <-awake: + t.Fatal("too many goroutines awake") + default: + } + n-- + } + c.Signal() +} + +func TestCondSignalGenerations(t *testing.T) { + var m Mutex + c := NewCond(&m) + n := 100 + running := make(chan bool, n) + awake := make(chan int, n) + for i := 0; i < n; i++ { + go func(i int) { + m.Lock() + running <- true + c.Wait() + awake <- i + m.Unlock() + }(i) + if i > 0 { + a := <-awake + if a != i-1 { + t.Fatalf("wrong goroutine woke up: want %d, got %d", i-1, a) + } + } + <-running + m.Lock() + c.Signal() + m.Unlock() + } +} + +func TestCondBroadcast(t *testing.T) { + var m Mutex + c := NewCond(&m) + n := 200 + running := make(chan int, n) + awake := make(chan int, n) + exit := false + for i := 0; i < n; i++ { + go func(g int) { + m.Lock() + for !exit { + running <- g + c.Wait() + awake <- g + } + m.Unlock() + }(i) + } + for i := 0; i < n; i++ { + for i := 0; i < n; i++ { + <-running // Will deadlock unless n are running. + } + if i == n-1 { + m.Lock() + exit = true + m.Unlock() + } + select { + case <-awake: + t.Fatal("goroutine not asleep") + default: + } + m.Lock() + c.Broadcast() + m.Unlock() + seen := make([]bool, n) + for i := 0; i < n; i++ { + g := <-awake + if seen[g] { + t.Fatal("goroutine woke up twice") + } + seen[g] = true + } + } + select { + case <-running: + t.Fatal("goroutine did not exit") + default: + } + c.Broadcast() +} + +func TestRace(t *testing.T) { + x := 0 + c := NewCond(&Mutex{}) + done := make(chan bool) + go func() { + c.L.Lock() + x = 1 + c.Wait() + if x != 2 { + t.Error("want 2") + } + x = 3 + c.Signal() + c.L.Unlock() + done <- true + }() + go func() { + c.L.Lock() + for { + if x == 1 { + x = 2 + c.Signal() + break + } + c.L.Unlock() + runtime.Gosched() + c.L.Lock() + } + c.L.Unlock() + done <- true + }() + go func() { + c.L.Lock() + for { + if x == 2 { + c.Wait() + if x != 3 { + t.Error("want 3") + } + break + } + if x == 3 { + break + } + c.L.Unlock() + runtime.Gosched() + c.L.Lock() + } + c.L.Unlock() + done <- true + }() + <-done + <-done + <-done +} + +func TestCondSignalStealing(t *testing.T) { + for iters := 0; iters < 1000; iters++ { + var m Mutex + cond := NewCond(&m) + + // Start a waiter. + ch := make(chan struct{}) + go func() { + m.Lock() + ch <- struct{}{} + cond.Wait() + m.Unlock() + + ch <- struct{}{} + }() + + <-ch + m.Lock() + m.Unlock() + + // We know that the waiter is in the cond.Wait() call because we + // synchronized with it, then acquired/released the mutex it was + // holding when we synchronized. + // + // Start two goroutines that will race: one will broadcast on + // the cond var, the other will wait on it. + // + // The new waiter may or may not get notified, but the first one + // has to be notified. + done := false + go func() { + cond.Broadcast() + }() + + go func() { + m.Lock() + for !done { + cond.Wait() + } + m.Unlock() + }() + + // Check that the first waiter does get signaled. + select { + case <-ch: + case <-time.After(2 * time.Second): + t.Fatalf("First waiter didn't get broadcast.") + } + + // Release the second waiter in case it didn't get the + // broadcast. + m.Lock() + done = true + m.Unlock() + cond.Broadcast() + } +} + +func TestCondCopy(t *testing.T) { + defer func() { + err := recover() + if err == nil || err.(string) != "sync.Cond is copied" { + t.Fatalf("got %v, expect sync.Cond is copied", err) + } + }() + c := Cond{L: &Mutex{}} + c.Signal() + var c2 Cond + reflect.ValueOf(&c2).Elem().Set(reflect.ValueOf(&c).Elem()) // c2 := c, hidden from vet + c2.Signal() +} + +func BenchmarkCond1(b *testing.B) { + benchmarkCond(b, 1) +} + +func BenchmarkCond2(b *testing.B) { + benchmarkCond(b, 2) +} + +func BenchmarkCond4(b *testing.B) { + benchmarkCond(b, 4) +} + +func BenchmarkCond8(b *testing.B) { + benchmarkCond(b, 8) +} + +func BenchmarkCond16(b *testing.B) { + benchmarkCond(b, 16) +} + +func BenchmarkCond32(b *testing.B) { + benchmarkCond(b, 32) +} + +func benchmarkCond(b *testing.B, waiters int) { + c := NewCond(&Mutex{}) + done := make(chan bool) + id := 0 + + for routine := 0; routine < waiters+1; routine++ { + go func() { + for i := 0; i < b.N; i++ { + c.L.Lock() + if id == -1 { + c.L.Unlock() + break + } + id++ + if id == waiters+1 { + id = 0 + c.Broadcast() + } else { + c.Wait() + } + c.L.Unlock() + } + c.L.Lock() + id = -1 + c.Broadcast() + c.L.Unlock() + done <- true + }() + } + for routine := 0; routine < waiters+1; routine++ { + <-done + } +} -- cgit v1.2.3