func TestPrependedBlocks(t *testing.T) {
const BLOCKSIZE = 100
const BLOCK_COUNT = 20
checksum := NewFileChecksumGenerator(BLOCKSIZE)
file1 := io.LimitReader(
readers.NewNonRepeatingSequence(0),
BLOCKSIZE*BLOCK_COUNT,
)
file2 := io.LimitReader(
io.MultiReader(
readers.OneReader(BLOCKSIZE), // Off by one block
readers.NewNonRepeatingSequence(0),
),
BLOCKSIZE*BLOCK_COUNT,
)
output1 := bytes.NewBuffer(nil)
chksum1, _ := checksum.GenerateChecksums(file1, output1)
output2 := bytes.NewBuffer(nil)
chksum2, _ := checksum.GenerateChecksums(file2, output2)
if bytes.Compare(chksum1, chksum2) == 0 {
t.Fatal("Checksums should be different")
}
weaksize, strongSize := checksum.GetChecksumSizes()
sums1, _ := chunks.LoadChecksumsFromReader(output1, weaksize, strongSize)
sums2, _ := chunks.LoadChecksumsFromReader(output2, weaksize, strongSize)
if len(sums1) != len(sums2) {
t.Fatalf("Checksum lengths differ %v vs %v", len(sums1), len(sums2))
}
if sums1[0].Match(sums2[0]) {
t.Error("Chunk sums1[0] should differ from sums2[0]")
}
for i, _ := range sums2 {
if i == 0 {
continue
}
if !sums1[i-1].Match(sums2[i]) {
t.Errorf("Chunk sums1[%v] equal sums2[%v]", i-1, i)
}
}
}
// Each of the data blocks is the same, so the checksums for the blocks should be the same
func TestChecksumBlocksTheSame(t *testing.T) {
const BLOCKSIZE = 100
const BLOCK_COUNT = 20
checksum := NewFileChecksumGenerator(BLOCKSIZE)
output := bytes.NewBuffer(nil)
_, err := checksum.GenerateChecksums(
readers.OneReader(BLOCKSIZE*BLOCK_COUNT),
output,
)
if err != nil {
t.Fatal(err)
}
weakSize, strongSize := checksum.GetChecksumSizes()
if output.Len() != BLOCK_COUNT*(strongSize+weakSize) {
t.Errorf(
"Unexpected output length: %v, expected %v",
output.Len(),
BLOCK_COUNT*(strongSize+weakSize),
)
}
results, err := chunks.LoadChecksumsFromReader(output, weakSize, strongSize)
if err != nil {
t.Fatal(err)
}
if len(results) != BLOCK_COUNT {
t.Fatalf("Results too short! %v", len(results))
}
first := results[0]
for i, chk := range results {
if chk.ChunkOffset != uint(i) {
t.Errorf("Unexpected offset %v on chunk %v", chk.ChunkOffset, i)
}
if !first.Match(chk) {
t.Fatalf("Chunks have different checksums on %v", i)
}
}
}
func BenchmarkStrongComparison(b *testing.B) {
b.ReportAllocs()
b.SetBytes(1)
const BLOCK_SIZE = 8
generator := filechecksum.NewFileChecksumGenerator(BLOCK_SIZE)
b.StartTimer()
results := (&Comparer{}).StartFindMatchingBlocks(
readers.OneReader(b.N+BLOCK_SIZE),
0,
generator,
&NegativeStrongIndex{},
)
for _, ok := <-results; ok; {
}
b.StopTimer()
}