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restic/internal/bloblru/cache_test.go
2024-05-05 12:00:25 +02:00

147 lines
3.1 KiB
Go

package bloblru
import (
"context"
"fmt"
"math/rand"
"testing"
"github.com/restic/restic/internal/restic"
rtest "github.com/restic/restic/internal/test"
"golang.org/x/sync/errgroup"
)
func TestCache(t *testing.T) {
var id1, id2, id3 restic.ID
id1[0] = 1
id2[0] = 2
id3[0] = 3
const (
kiB = 1 << 10
cacheSize = 64*kiB + 3*overhead
)
c := New(cacheSize)
addAndCheck := func(id restic.ID, exp []byte) {
c.Add(id, exp)
blob, ok := c.Get(id)
rtest.Assert(t, ok, "blob %v added but not found in cache", id)
rtest.Equals(t, &exp[0], &blob[0])
rtest.Equals(t, exp, blob)
}
// Our blobs have len 1 but larger cap. The cache should check the cap,
// since it more reliably indicates the amount of memory kept alive.
addAndCheck(id1, make([]byte, 1, 32*kiB))
addAndCheck(id2, make([]byte, 1, 30*kiB))
addAndCheck(id3, make([]byte, 1, 10*kiB))
_, ok := c.Get(id2)
rtest.Assert(t, ok, "blob %v not present", id2)
_, ok = c.Get(id1)
rtest.Assert(t, !ok, "blob %v present, but should have been evicted", id1)
c.Add(id1, make([]byte, 1+c.size))
_, ok = c.Get(id1)
rtest.Assert(t, !ok, "blob %v too large but still added to cache")
c.c.Remove(id1)
c.c.Remove(id3)
c.c.Remove(id2)
rtest.Equals(t, cacheSize, c.size)
rtest.Equals(t, cacheSize, c.free)
}
func TestCacheGetOrCompute(t *testing.T) {
var id1, id2 restic.ID
id1[0] = 1
id2[0] = 2
const (
kiB = 1 << 10
cacheSize = 64*kiB + 3*overhead
)
c := New(cacheSize)
e := fmt.Errorf("broken")
_, err := c.GetOrCompute(id1, func() ([]byte, error) {
return nil, e
})
rtest.Equals(t, e, err, "expected error was not returned")
// fill buffer
data1 := make([]byte, 10*kiB)
blob, err := c.GetOrCompute(id1, func() ([]byte, error) {
return data1, nil
})
rtest.OK(t, err)
rtest.Equals(t, &data1[0], &blob[0], "wrong buffer returend")
// now the buffer should be returned without calling the compute function
blob, err = c.GetOrCompute(id1, func() ([]byte, error) {
return nil, e
})
rtest.OK(t, err)
rtest.Equals(t, &data1[0], &blob[0], "wrong buffer returend")
// check concurrency
wg, _ := errgroup.WithContext(context.TODO())
wait := make(chan struct{})
calls := make(chan struct{}, 10)
// start a bunch of blocking goroutines
for i := 0; i < 10; i++ {
wg.Go(func() error {
buf, err := c.GetOrCompute(id2, func() ([]byte, error) {
// block to ensure that multiple requests are waiting in parallel
<-wait
calls <- struct{}{}
return make([]byte, 42), nil
})
if len(buf) != 42 {
return fmt.Errorf("wrong buffer")
}
return err
})
}
close(wait)
rtest.OK(t, wg.Wait())
close(calls)
count := 0
for range calls {
count++
}
rtest.Equals(t, 1, count, "expected exactly one call of the compute function")
}
func BenchmarkAdd(b *testing.B) {
const (
MiB = 1 << 20
nblobs = 64
)
c := New(64 * MiB)
buf := make([]byte, 8*MiB)
ids := make([]restic.ID, nblobs)
sizes := make([]int, nblobs)
r := rand.New(rand.NewSource(100))
for i := range ids {
r.Read(ids[i][:])
sizes[i] = r.Intn(8 * MiB)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
c.Add(ids[i%nblobs], buf[:sizes[i%nblobs]])
}
}