From efcd876b501a70152811039e454ec5600fecd42d Mon Sep 17 00:00:00 2001 From: Arve Knudsen Date: Fri, 20 Oct 2023 16:16:10 +0200 Subject: [PATCH] Ensure deterministic execution, for tests Signed-off-by: Arve Knudsen --- tsdb/postings_for_matchers_cache.go | 17 ++++++++++++++--- tsdb/postings_for_matchers_cache_test.go | 2 +- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/tsdb/postings_for_matchers_cache.go b/tsdb/postings_for_matchers_cache.go index 6b99487710..865224f7f3 100644 --- a/tsdb/postings_for_matchers_cache.go +++ b/tsdb/postings_for_matchers_cache.go @@ -93,6 +93,11 @@ func (p *postingsForMatcherPromise) result(ctx context.Context) (index.Postings, case <-ctx.Done(): return nil, ctx.Err() case <-p.done: + // Checking context error is necessary for deterministic tests, + // as channel selection order is random + if ctx.Err() != nil { + return nil, ctx.Err() + } if p.err != nil { return nil, p.err } @@ -107,12 +112,18 @@ func (c *PostingsForMatchersCache) postingsForMatchersPromise(ix IndexPostingsRe key := matchersKey(ms) oldPromise, loaded := c.calls.LoadOrStore(key, promise) if loaded { - promise = oldPromise.(*postingsForMatcherPromise) - return promise.result + // promise was not stored, we return a previously stored promise, that's possibly being fulfilled in another goroutine + close(promise.done) + return oldPromise.(*postingsForMatcherPromise).result } + + // promise was stored, close its channel after fulfilment defer close(promise.done) - // FIXME: do we need to cancel the call to postingsForMatchers if all the callers waiting for the result have cancelled their context? + // Don't let context cancellation fail the promise, since it may be used by multiple goroutines, each with + // its own context. Also, keep the call independent of this particular context, since the promise will be reused. + // FIXME: do we need to cancel the call to postingsForMatchers if all the callers waiting for the result have + // cancelled their context? if postings, err := c.postingsForMatchers(context.Background(), ix, ms...); err != nil { promise.err = err } else { diff --git a/tsdb/postings_for_matchers_cache_test.go b/tsdb/postings_for_matchers_cache_test.go index d196dcdab8..41ccaacd47 100644 --- a/tsdb/postings_for_matchers_cache_test.go +++ b/tsdb/postings_for_matchers_cache_test.go @@ -352,7 +352,7 @@ func TestPostingsForMatchersCache(t *testing.T) { ctx1, cancel := context.WithCancel(context.Background()) cancel() _, err := c.PostingsForMatchers(ctx1, indexForPostingsMock{}, true, matchers...) - require.Equal(t, context.Canceled, err) + require.ErrorIs(t, err, context.Canceled) ctx2 := context.Background() actualPostings, err := c.PostingsForMatchers(ctx2, indexForPostingsMock{}, true, matchers...)