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crl-release-24.3: sstable: fix improper buffer reuse in copyDataBlocks #4182

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Nov 26, 2024
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crl-release-24.3: sstable: fix improper buffer reuse in copyDataBlocks #4182

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14 changes: 7 additions & 7 deletions sstable/colblk_writer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1090,7 +1090,7 @@ func shouldFlushWithoutLatestKV(
func (w *RawColumnWriter) copyDataBlocks(
ctx context.Context, blocks []indexEntry, rh objstorage.ReadHandle,
) error {
buf := make([]byte, 0, 256<<10)
const readSizeTarget = 256 << 10
readAndFlushBlocks := func(firstBlockIdx, lastBlockIdx int) error {
if firstBlockIdx > lastBlockIdx {
panic("pebble: readAndFlushBlocks called with invalid block range")
Expand All @@ -1103,9 +1103,9 @@ func (w *RawColumnWriter) copyDataBlocks(
// blocks in one request.
lastBH := blocks[lastBlockIdx].bh
blocksToReadLen := lastBH.Offset + lastBH.Length + block.TrailerLen - blocks[firstBlockIdx].bh.Offset
if blocksToReadLen > uint64(cap(buf)) {
buf = make([]byte, 0, blocksToReadLen)
}
// We need to create a new buffer for each read, as w.enqueuePhysicalBlock passes
// a pointer to the buffer to the write queue.
buf := make([]byte, 0, blocksToReadLen)
if err := rh.ReadAt(ctx, buf[:blocksToReadLen], int64(blocks[firstBlockIdx].bh.Offset)); err != nil {
return err
}
Expand All @@ -1120,8 +1120,8 @@ func (w *RawColumnWriter) copyDataBlocks(
}
return nil
}
// Iterate through blocks until we have enough to fill cap(buf). When we have more than
// one block in blocksToRead and adding the next block would exceed the buffer capacity,
// Iterate through blocks until we have enough to fill readSizeTarget. When we have more than
// one block in blocksToRead and adding the next block would exceed the target buffer capacity,
// we read and flush existing blocks in blocksToRead. This allows us to read as many
// blocks in one IO request as possible, while still utilizing the write queue in this
// writer.
Expand All @@ -1133,7 +1133,7 @@ func (w *RawColumnWriter) copyDataBlocks(
start := i
// Note the i++ in the initializing condition; this means we will always flush at least
// one block.
for i++; i < len(blocks) && (blocks[i].bh.Length+blocks[i].bh.Offset+block.TrailerLen-blocks[start].bh.Offset) <= uint64(cap(buf)); i++ {
for i++; i < len(blocks) && (blocks[i].bh.Length+blocks[i].bh.Offset+block.TrailerLen-blocks[start].bh.Offset) <= uint64(readSizeTarget); i++ {
}
// i points to one index past the last block we want to read.
if err := readAndFlushBlocks(start, i-1); err != nil {
Expand Down
30 changes: 26 additions & 4 deletions sstable/copier_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,10 @@ import (

func TestCopySpan(t *testing.T) {
fs := vfs.NewMem()
blockCache := cache.New(1 << 20 /* 1 MB */)
blockCache := cache.New(2 << 20 /* 1 MB */)
cacheID := cache.ID(1)
fileNameToNum := make(map[string]base.FileNum)
nextFileNum := base.FileNum(1)
defer blockCache.Unref()

keySchema := colblk.DefaultKeySchema(testkeys.Comparer, 16)
Expand All @@ -35,6 +38,8 @@ func TestCopySpan(t *testing.T) {
if err != nil {
return err.Error()
}
fileNameToNum[d.CmdArgs[0].Key] = nextFileNum
nextFileNum++
tableFormat := TableFormatMax
blockSize := 1
var indexBlockSize int
Expand Down Expand Up @@ -92,15 +97,28 @@ func TestCopySpan(t *testing.T) {
if err != nil {
return err.Error()
}
r, err := NewReader(context.TODO(), readable, ReaderOptions{
var start, end []byte
for _, arg := range d.CmdArgs[1:] {
switch arg.Key {
case "start":
start = []byte(arg.FirstVal(t))
case "end":
end = []byte(arg.FirstVal(t))
}
}
rOpts := ReaderOptions{
Comparer: testkeys.Comparer,
KeySchemas: KeySchemas{keySchema.Name: &keySchema},
})
}
rOpts.internal.CacheOpts.Cache = blockCache
rOpts.internal.CacheOpts.CacheID = cacheID
rOpts.internal.CacheOpts.FileNum = base.DiskFileNum(fileNameToNum[d.CmdArgs[0].Key])
r, err := NewReader(context.TODO(), readable, rOpts)
defer r.Close()
if err != nil {
return err.Error()
}
iter, err := r.NewIter(block.NoTransforms, nil, nil)
iter, err := r.NewIter(block.NoTransforms, start, end)
if err != nil {
return err.Error()
}
Expand All @@ -126,6 +144,8 @@ func TestCopySpan(t *testing.T) {
return err.Error()
}
writable := objstorageprovider.NewFileWritable(output)
fileNameToNum[outputFile] = nextFileNum
nextFileNum++

f, err := fs.Open(inputFile)
if err != nil {
Expand All @@ -140,6 +160,8 @@ func TestCopySpan(t *testing.T) {
KeySchemas: KeySchemas{keySchema.Name: &keySchema},
}
rOpts.internal.CacheOpts.Cache = blockCache
rOpts.internal.CacheOpts.CacheID = cacheID
rOpts.internal.CacheOpts.FileNum = base.DiskFileNum(fileNameToNum[inputFile])
r, err := NewReader(context.TODO(), readable, rOpts)
if err != nil {
return err.Error()
Expand Down
14 changes: 2 additions & 12 deletions sstable/testdata/copy_span
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Original file line number Diff line number Diff line change
Expand Up @@ -92,10 +92,8 @@ c.SET.4:baz
d.SET.5:foobar
----

iter test3
iter test3 start=c
----
a#0,SET: foo
b#0,SET: bar
c#0,SET: baz
d#0,SET: foobar

Expand Down Expand Up @@ -134,18 +132,10 @@ i.SET.5:foo
j.SET.5:foo
----

iter test32
iter test32 start=c end=e
----
a#0,SET: foo
b#0,SET: bar
c#0,SET: baz
d#0,SET: foobar
e#0,SET: foo
f#0,SET: foo
g#0,SET: foo
h#0,SET: foo
i#0,SET: foo
j#0,SET: foo

copy-span test32 test33 b.SET.10 cc.SET.0
----
Expand Down