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// SPDX-License-Identifier: GPL-3.0-or-later
package lock
import (
"context"
"errors"
"fmt"
"os"
"path/filepath"
"strings"
"sync"
"testing"
"time"
)
func TestAcquireAndRelease(t *testing.T) {
path := filepath.Join(t.TempDir(), "state", "dl.lock")
l, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatal(err)
}
if _, err := os.Stat(path); err != nil {
t.Errorf("lock file missing: %v", err)
}
if b, _ := os.ReadFile(path); !strings.Contains(string(b), fmt.Sprint(os.Getpid())) {
t.Errorf("lock file does not name the holder's pid: %q", b)
}
if err := l.Release(); err != nil {
t.Fatal(err)
}
if _, err := os.Stat(path); !os.IsNotExist(err) {
t.Error("Release left the lock file behind")
}
if err := l.Release(); err != nil {
t.Errorf("a second Release must be harmless: %v", err)
}
}
func TestAcquireFailsWhenHeldAndNotWaiting(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
first, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatal(err)
}
defer first.Release()
if _, err := Acquire(context.Background(), path, false); !errors.Is(err, ErrHeld) {
t.Fatalf("second Acquire err = %v, want ErrHeld", err)
}
}
func TestAcquireWaitsUntilReleased(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
first, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatal(err)
}
go func() {
time.Sleep(150 * time.Millisecond)
first.Release()
}()
start := time.Now()
second, err := Acquire(context.Background(), path, true)
if err != nil {
t.Fatalf("waiting Acquire failed: %v", err)
}
defer second.Release()
if time.Since(start) < 100*time.Millisecond {
t.Error("Acquire returned before the first holder released")
}
}
// TestAcquireRespectsContextCancellation: a waiting Acquire must not
// ignore an interrupt - a cancelled ctx must return promptly with
// ctx.Err(), not poll forever. A regression here would HANG rather than
// fail, so the wait for Acquire's result is itself bounded with its own
// hard timeout: a regression must fail this test, not hang the whole
// suite.
func TestAcquireRespectsContextCancellation(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
held, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatal(err)
}
defer held.Release()
ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
defer cancel()
result := make(chan error, 1)
start := time.Now()
go func() {
_, err := Acquire(ctx, path, true)
result <- err
}()
select {
case err := <-result:
if !errors.Is(err, context.DeadlineExceeded) {
t.Fatalf("Acquire err = %v, want context.DeadlineExceeded", err)
}
if elapsed := time.Since(start); elapsed > 500*time.Millisecond {
t.Errorf("Acquire took %v to notice cancellation, want well under a second", elapsed)
}
case <-time.After(2 * time.Second):
t.Fatal("Acquire ignored context cancellation and is still blocked")
}
}
// TestALockFileWithoutAHolderIsFree: a machine that lost power mid-run
// leaves the lock file behind, but nothing holding it. The text in that
// file is for a human; it must not wedge the next run, whatever it says.
func TestALockFileWithoutAHolderIsFree(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
if err := os.WriteFile(path, []byte("pid 1\nstarted 2020-01-01T00:00:00Z\n"), 0o644); err != nil {
t.Fatal(err)
}
l, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatalf("a lock file nobody holds blocked Acquire: %v", err)
}
defer l.Release()
if b, _ := os.ReadFile(path); !strings.Contains(string(b), fmt.Sprint(os.Getpid())) {
t.Errorf("the lock file still names the old holder: %q", b)
}
}
// TestALockDiesWithItsProcess: the kernel drops an flock when the last
// descriptor closes, however the process ended. A holder that vanishes
// without unlinking - a crash, a kill -9 - must leave the directory usable
// at once. This is the reason the lock is the kernel's rather than a pid
// written into a file and believed.
func TestALockDiesWithItsProcess(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
l, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatal(err)
}
if _, err := Acquire(context.Background(), path, false); !errors.Is(err, ErrHeld) {
t.Fatalf("while held, Acquire err = %v, want ErrHeld", err)
}
// Close the descriptor without unlinking, as a crash would leave it.
if err := l.f.Close(); err != nil {
t.Fatal(err)
}
l.f = nil
if _, err := os.Stat(path); err != nil {
t.Fatalf("the lock file should still be there: %v", err)
}
second, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatalf("a lock file left by a dead holder still blocks Acquire: %v", err)
}
second.Release()
}
// TestOnlyOneAcquireWinsAtOnce: the promise is that a directory is locked
// while krino works in it. Judging a lock stale and recreating it cannot be
// made atomic, so two runs reaching that conclusion together could both
// believe they held it; the kernel's lock has one winner by construction.
func TestOnlyOneAcquireWinsAtOnce(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
for round := 0; round < 20; round++ {
const n = 8
start := make(chan struct{})
var mu sync.Mutex
var won []*Lock
var wg sync.WaitGroup
for i := 0; i < n; i++ {
wg.Add(1)
go func() {
defer wg.Done()
<-start
if l, err := Acquire(context.Background(), path, false); err == nil {
mu.Lock()
won = append(won, l)
mu.Unlock()
}
}()
}
close(start)
wg.Wait()
if len(won) != 1 {
t.Fatalf("round %d: %d callers hold the same lock at once, want 1", round, len(won))
}
for _, l := range won {
if err := l.Release(); err != nil {
t.Fatal(err)
}
}
}
}
// TestHeldErrorNamesTheLockAndHolder: "another krino is working in this
// directory" leaves nothing to act on when the holder is a pid that was
// reused after a crash - the lock is then live for ever as far as krino can
// tell. The error must name the file to remove and the pid it blames.
func TestHeldErrorNamesTheLockAndHolder(t *testing.T) {
path := filepath.Join(t.TempDir(), "dl.lock")
first, err := Acquire(context.Background(), path, false)
if err != nil {
t.Fatal(err)
}
defer first.Release()
_, err = Acquire(context.Background(), path, false)
if !errors.Is(err, ErrHeld) {
t.Fatalf("second Acquire err = %v, want ErrHeld", err)
}
if got := err.Error(); !strings.Contains(got, path) {
t.Errorf("the error does not name the lock file %q: %s", path, got)
}
if got := err.Error(); !strings.Contains(got, fmt.Sprint(os.Getpid())) {
t.Errorf("the error does not name the holder's pid %d: %s", os.Getpid(), got)
}
}
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