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Do not block try lock on state mutex #2387

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koct9i wants to merge 1 commit into from
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Do not block try lock on state mutex #2387

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6 changes: 4 additions & 2 deletions pkg/lockfile/lockfile.go
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Original file line number Diff line number Diff line change
Expand Up @@ -417,10 +417,12 @@ func (l *LockFile) tryLock(lType rawfilelock.LockType) error {
success = l.rwMutex.TryLock()
rwMutexUnlocker = l.rwMutex.Unlock
}
if !success {
if !success || !l.stateMutex.TryLock() {
if success {
rwMutexUnlocker()
}
return fmt.Errorf("resource temporarily unavailable")
}
l.stateMutex.Lock()
defer l.stateMutex.Unlock()
if l.counter == 0 {
// If we're the first reference on the lock, we need to open the file again.
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49 changes: 49 additions & 0 deletions pkg/lockfile/lockfile_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -277,6 +277,55 @@ func TestTryReadLockFile(t *testing.T) {
assert.Nil(t, <-errChan)
}

func TestTryLockState(t *testing.T) {
l, err := getTempLockfile()
require.NoError(t, err, "creating lock")
defer os.Remove(l.name)

// Take a write lock somewhere.
cmd, wc, rc, err := subLock(l)
require.NoError(t, err)
_, err = io.Copy(io.Discard, rc)
require.NoError(t, err)

err = l.TryRLock()
assert.NotNil(t, err)

// Lock and hold state mutex.
locked := make(chan bool)
go func() {
locked <- false
l.RLock()
locked <- true
l.Unlock()
locked <- false
}()

assert.False(t, <-locked)

// Wait state mutex is locked.
for !l.stateMutex.TryLock() {
l.stateMutex.Unlock()
time.Sleep(100 * time.Millisecond)
}

// Try locks should fail without blocking.
errChan := make(chan error)
go func() {
errChan <- l.TryRLock()
errChan <- l.TryLock()
}()
assert.NotNil(t, <-errChan)
assert.NotNil(t, <-errChan)

wc.Close()
err = cmd.Wait()
require.NoError(t, err)

assert.True(t, <-locked)
assert.False(t, <-locked)
}

func TestLockfileRead(t *testing.T) {
l, err := getTempLockfile()
require.Nil(t, err, "error getting temporary lock file")
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