Do not leave pool lock after panic from nil context

refs #13

pool.go

@@ -276,10 +276,10 @@ func (p *Pool) TryAcquire(ctx context.Context) (*Resource, error) {
 // will return ErrNotAvailable if no resource is available.
 func (p *Pool) doAcquire(ctx context.Context, block bool) (*Resource, error) {
 	startNano := nanotime()
-	p.cond.L.Lock()
 	if doneChan := ctx.Done(); doneChan != nil {
 		select {
 		case <-ctx.Done():
+			p.cond.L.Lock()
 			p.canceledAcquireCount += 1
 			p.cond.L.Unlock()
 			return nil, ctx.Err()
@@ -287,6 +287,8 @@ func (p *Pool) doAcquire(ctx context.Context, block bool) (*Resource, error) {
 		}
 	}
 
+	p.cond.L.Lock()
+
 	emptyAcquire := false
 
 	for {

pool_test.go

@@ -192,6 +192,20 @@ func TestPoolTryAcquireDoesNotBlock(t *testing.T) {
 	assert.Equal(t, 1, createCounter.Value())
 }
 
+func TestPoolAcquireNilContextDoesNotLeavePoolLocked(t *testing.T) {
+	constructor, createCounter := createConstructor()
+	pool := puddle.NewPool(constructor, stubDestructor, 10)
+
+	assert.Panics(t, func() { pool.Acquire(nil) })
+
+	res, err := pool.Acquire(context.Background())
+	require.NoError(t, err)
+	assert.Equal(t, 1, res.Value())
+	res.Release()
+
+	assert.Equal(t, 1, createCounter.Value())
+}
+
 func TestPoolAcquireContextAlreadyCanceled(t *testing.T) {
 	constructor := func(ctx context.Context) (interface{}, error) {
 		panic("should never be called")