func TestReturnsErrorsWhenSyncing(t *testing.T) {
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{
[]byte{}, []byte{},
})
expectedError := errors.New("BOOM")
fakeDataFile.WriteBlockFunc = func(id uint16, data []byte) error {
return expectedError
}
buffer := dbio.NewDataBuffer(fakeDataFile, 2)
buffer.FetchBlock(0)
buffer.FetchBlock(1)
if err := buffer.Sync(); err != nil {
t.Fatal("Unexpected error", err)
}
buffer.MarkAsDirty(1)
err := buffer.Sync()
if err == nil {
t.Fatal("Error not raised")
} else if err != expectedError {
t.Fatal("Unknown error raised")
}
}
func TestEvictsBlocksAfterFillingInAllFrames(t *testing.T) {
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{
[]byte{}, []byte{}, []byte{},
})
readCount := 0
original := fakeDataFile.ReadBlockFunc
fakeDataFile.ReadBlockFunc = func(id uint16, data []byte) error {
readCount += 1
return original(id, data)
}
buffer := dbio.NewDataBuffer(fakeDataFile, 2)
// From this point on, we fetch blocks in a way to ensure that we have multiple
// hits on different blocks and also force a couple cache misses
for blockId := 0; blockId < 3; blockId++ {
for i := 0; i < 10; i++ {
buffer.FetchBlock(uint16(blockId))
}
}
// Fetch block 1 again to ensure it is still in memory
buffer.FetchBlock(uint16(1))
if readCount != 3 {
t.Errorf("Read from datafile more than three times (total: %d times)", readCount)
}
// Force 2 cache misses
buffer.FetchBlock(0)
buffer.FetchBlock(1)
if readCount != 5 {
t.Error("Read from cache but should not do that")
}
}
func TestSimpleJSONDB_InitializesDataFile(t *testing.T) {
firstDataBlock := make([]byte, 10)
blocksBitMapBlock := make([]byte, dbio.DATABLOCK_SIZE)
bTreeRootBlock := make([]byte, 2)
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{
firstDataBlock,
blocksBitMapBlock,
nil,
nil,
bTreeRootBlock,
})
jsondb.NewWithDataFile(fakeDataFile)
if !utils.SlicesEqual(firstDataBlock[0:2], []byte{0x00, 0x03}) {
t.Error("Did not set the next available data block pointer to 3")
}
if !utils.SlicesEqual(firstDataBlock[2:4], []byte{0x00, 0x03}) {
t.Error("Did not set the first record block pointer to 3")
}
blocksBitMap := dbio.NewBitMapFromBytes(blocksBitMapBlock)
for i := 0; i < 4; i++ {
val, err := blocksBitMap.Get(i)
if err != nil {
t.Fatal(err)
}
if !val {
t.Errorf("Expected block %d to be flagged as used", i)
}
}
}
func TestFetchesBlockFromDataFile(t *testing.T) {
fakeDataBlock := []byte{0x10, 0xF0}
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{nil, fakeDataBlock})
dataBlock, err := dbio.NewDataBuffer(fakeDataFile, 1).FetchBlock(1)
if err != nil {
t.Fatal("Unexpected error", err)
}
if dataBlock.ID != 1 {
t.Errorf("ID doesn't match (expected %d got %d)", 1, dataBlock.ID)
}
if !utils.SlicesEqual(dataBlock.Data[0:2], fakeDataBlock) {
t.Errorf("Data blocks do not match (expected %x got %x)", fakeDataBlock, dataBlock.Data[0:2])
}
}
func TestSavesDirtyFramesOnSync(t *testing.T) {
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{
[]byte{}, []byte{}, []byte{},
})
blocksThatWereWritten := []uint16{}
fakeDataFile.WriteBlockFunc = func(id uint16, data []byte) error {
blocksThatWereWritten = append(blocksThatWereWritten, id)
return nil
}
buffer := dbio.NewDataBuffer(fakeDataFile, 3)
// Read the 3 blocks and flag two as dirty
buffer.FetchBlock(0)
buffer.MarkAsDirty(0)
buffer.FetchBlock(1)
// Not dirty
buffer.FetchBlock(2)
buffer.MarkAsDirty(2)
if err := buffer.Sync(); err != nil {
t.Fatal(err)
}
if len(blocksThatWereWritten) != 2 {
t.Fatalf("Should have written 2 blocks, wrote %v", blocksThatWereWritten)
}
if blocksThatWereWritten[0] != 0 && blocksThatWereWritten[1] != 0 {
t.Errorf("Should have written the block 0, wrote %v", blocksThatWereWritten)
}
if blocksThatWereWritten[0] != 2 && blocksThatWereWritten[1] != 2 {
t.Errorf("Should have written the block 2, wrote %v", blocksThatWereWritten)
}
blocksThatWereWritten = []uint16{}
if err := buffer.Sync(); err != nil {
t.Fatal(err)
}
if len(blocksThatWereWritten) != 0 {
t.Fatalf("Blocks have already been writen, wrote %v again", blocksThatWereWritten)
}
}
func TestFetchBlockCachesData(t *testing.T) {
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{nil, []byte{}})
readCount := 0
original := fakeDataFile.ReadBlockFunc
fakeDataFile.ReadBlockFunc = func(id uint16, data []byte) error {
readCount += 1
return original(id, data)
}
buffer := dbio.NewDataBuffer(fakeDataFile, 1)
for i := 0; i < 10; i++ {
buffer.FetchBlock(1)
}
if readCount > 1 {
t.Errorf("Read from datafile more than once (total: %d times)", readCount)
}
}
func TestSavesDirtyFramesWhenEvicting(t *testing.T) {
fakeDataBlock := []byte{0x00, 0x01, 0x02}
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{
fakeDataBlock, []byte{}, []byte{}, []byte{},
})
blockThatWasWritten := uint16(999)
bytesWritten := []byte{}
fakeDataFile.WriteBlockFunc = func(id uint16, data []byte) error {
blockThatWasWritten = id
bytesWritten = data
return nil
}
buffer := dbio.NewDataBuffer(fakeDataFile, 2)
// Read the first 2 blocks and flag the first one as dirty
buffer.FetchBlock(0)
buffer.FetchBlock(1)
buffer.MarkAsDirty(0)
// Evict the frame 1 by loading a third frame
buffer.FetchBlock(2)
// Evict the frame 0 by loading a fourth frame
buffer.FetchBlock(3)
if blockThatWasWritten == 999 {
t.Fatalf("Block was not saved to disk (%d)", blockThatWasWritten)
}
if blockThatWasWritten != 0 {
t.Errorf("Unknown block saved to disk (%d)", blockThatWasWritten)
}
if !utils.SlicesEqual(bytesWritten[0:3], fakeDataBlock) {
t.Errorf("Invalid data saved to disk %x", bytesWritten[0:3])
}
}
func TestDiscardsUnmodifiedFrames(t *testing.T) {
fakeDataFile := utils.NewFakeDataFileWithBlocks([][]byte{
[]byte{}, []byte{}, []byte{},
})
wroteToDisk := false
fakeDataFile.WriteBlockFunc = func(id uint16, data []byte) error {
wroteToDisk = true
return nil
}
buffer := dbio.NewDataBuffer(fakeDataFile, 2)
// Read the first 2 blocks
buffer.FetchBlock(0)
buffer.FetchBlock(1)
// Evict the first frame (by loading a third frame)
buffer.FetchBlock(2)
if wroteToDisk {
t.Fatal("No blocks should have been saved to disk")
}
}