Function TestPackerBoundarySplits

pkg/blobserver/blobpacked/blobpacked_test.go:970–1092

(t *testing.T)

}

func TestPackerBoundarySplits(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping slow test")
	}
	// Test a file of three chunk sizes, totalling near the 16 MB
	// boundary:
	//    - 1st chunk is 6 MB. ("blobA")
	//    - 2nd chunk is 6 MB. ("blobB")
	//    - 3rd chunk ("blobC") is binary-searched (up to 4MB) to find
	//      which size causes the packer to write two zip files.

	// During the test we set zip overhead boundaries to 0, to
	// force the test to into its pathological misprediction code paths,
	// where it needs to back up and rewrite the zip with one part less.
	// That's why the test starts with two zip files: so there's at
	// least one that can be removed to make room.
	defer setIntTemporarily(&zipPerEntryOverhead, 0)()

	const sizeAB = 12 << 20
	const maxBlobSize = 16 << 20
	bytesAB := randBytes(sizeAB)
	blobA := &test.Blob{Contents: string(bytesAB[:sizeAB/2])}
	blobB := &test.Blob{Contents: string(bytesAB[sizeAB/2:])}
	refA := blobA.BlobRef()
	refB := blobB.BlobRef()
	bytesCFull := randBytes(maxBlobSize - sizeAB) // will be sliced down

	// Mechanism to verify we hit the back-up code path:
	var (
		mu                    sync.Mutex
		sawTruncate           blob.Ref
		stoppedBeforeOverflow bool
	)
	testHookSawTruncate = func(after blob.Ref) {
		if after != refB {
			t.Errorf("unexpected truncate point %v", after)
		}
		mu.Lock()
		defer mu.Unlock()
		sawTruncate = after
	}
	testHookStopBeforeOverflowing = func() {
		mu.Lock()
		defer mu.Unlock()
		stoppedBeforeOverflow = true
	}
	defer func() {
		testHookSawTruncate = nil
		testHookStopBeforeOverflowing = nil
	}()

	generatesTwoZips := func(sizeC int) (ret bool) {
		large := new(test.Fetcher)
		s := &storage{
			small: new(test.Fetcher),
			large: large,
			meta:  sorted.NewMemoryKeyValue(),
			log: test.NewLogger(t, "blobpacked: ",