bloblru: add test for GetOrCompute
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1 changed files with 67 additions and 0 deletions
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@ -1,11 +1,14 @@
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package bloblru
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import (
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"context"
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"fmt"
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"math/rand"
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"testing"
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"github.com/restic/restic/internal/restic"
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rtest "github.com/restic/restic/internal/test"
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"golang.org/x/sync/errgroup"
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)
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func TestCache(t *testing.T) {
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@ -52,6 +55,70 @@ func TestCache(t *testing.T) {
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rtest.Equals(t, cacheSize, c.free)
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}
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func TestCacheGetOrCompute(t *testing.T) {
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var id1, id2 restic.ID
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id1[0] = 1
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id2[0] = 2
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const (
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kiB = 1 << 10
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cacheSize = 64*kiB + 3*overhead
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)
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c := New(cacheSize)
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e := fmt.Errorf("broken")
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_, err := c.GetOrCompute(id1, func() ([]byte, error) {
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return nil, e
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})
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rtest.Equals(t, e, err, "expected error was not returned")
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// fill buffer
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data1 := make([]byte, 10*kiB)
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blob, err := c.GetOrCompute(id1, func() ([]byte, error) {
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return data1, nil
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})
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rtest.OK(t, err)
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rtest.Equals(t, &data1[0], &blob[0], "wrong buffer returend")
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// now the buffer should be returned without calling the compute function
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blob, err = c.GetOrCompute(id1, func() ([]byte, error) {
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return nil, e
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})
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rtest.OK(t, err)
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rtest.Equals(t, &data1[0], &blob[0], "wrong buffer returend")
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// check concurrency
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wg, _ := errgroup.WithContext(context.TODO())
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wait := make(chan struct{})
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calls := make(chan struct{}, 10)
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// start a bunch of blocking goroutines
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for i := 0; i < 10; i++ {
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wg.Go(func() error {
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buf, err := c.GetOrCompute(id2, func() ([]byte, error) {
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// block to ensure that multiple requests are waiting in parallel
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<-wait
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calls <- struct{}{}
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return make([]byte, 42), nil
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})
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if len(buf) != 42 {
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return fmt.Errorf("wrong buffer")
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}
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return err
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})
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}
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close(wait)
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rtest.OK(t, wg.Wait())
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close(calls)
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count := 0
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for range calls {
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count++
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}
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rtest.Equals(t, 1, count, "expected exactly one call of the compute function")
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}
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func BenchmarkAdd(b *testing.B) {
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const (
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MiB = 1 << 20
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