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leveldb: rename functions and add comments

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This commit is contained in:
Michael B. 2023-12-05 16:33:50 +01:00
parent b05aa997ab
commit 78a3e94bd7
1 changed files with 16 additions and 12 deletions
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28
format/leveldb/leveldb_ldb.go
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@ -96,7 +96,7 @@ func ldbDecode(d *decode.D) any {
d.SeekAbs(metaIndexOffset * 8)
var metaHandles []BlockHandle
readBlock("metaindex", metaIndexSize, readKeyValueContent, func(d *decode.D) {
readBlock("metaindex", metaIndexSize, readKeyValueContents, func(d *decode.D) {
// BlockHandle
// https://github.com/google/leveldb/blob/main/table/format.cc#L24
handle := BlockHandle{
@ -110,7 +110,7 @@ func ldbDecode(d *decode.D) any {
d.SeekAbs(indexOffset * 8)
var dataHandles []BlockHandle
readBlock("index", indexSize, readKeyValueContent, func(d *decode.D) {
readBlock("index", indexSize, readKeyValueContents, func(d *decode.D) {
// BlockHandle
// https://github.com/google/leveldb/blob/main/table/format.cc#L24
handle := BlockHandle{
@ -137,7 +137,7 @@ func ldbDecode(d *decode.D) any {
d.FieldArray("data", func(d *decode.D) {
for _, handle := range dataHandles {
d.SeekAbs(int64(handle.Offset) * 8)
readBlock("data_block", int64(handle.Size), readKeyValueContent, nil, d)
readBlock("data_block", int64(handle.Size), readKeyValueContents, nil, d)
}
})
}
@ -147,8 +147,10 @@ func ldbDecode(d *decode.D) any {
// Readers
func readBlock(name string, size int64, readBlockContent func(size int64, valueCallbackFn func(d *decode.D), d *decode.D), valueCallbackFn func(d *decode.D), d *decode.D) {
// ReadBlock: https://github.com/google/leveldb/blob/main/table/format.cc#L69
// Read block contents as well as compression + crc bytes following it.
// The function `readBlockContents` gets the uncompressed bytebuffer.
// https://github.com/google/leveldb/blob/main/table/format.cc#L69
func readBlock(name string, size int64, readBlockContents func(size int64, valueCallbackFn func(d *decode.D), d *decode.D), valueCallbackFn func(d *decode.D), d *decode.D) {
d.FieldStruct(name, func(d *decode.D) {
start := d.Pos()
br := d.RawLen(size * 8)
@ -163,7 +165,7 @@ func readBlock(name string, size int64, readBlockContent func(size int64, valueC
d.SeekAbs(start)
if compressionType == compressionTypeNone {
d.FieldStruct("uncompressed", func(d *decode.D) {
readBlockContent(size, valueCallbackFn, d)
readBlockContents(size, valueCallbackFn, d)
})
} else {
compressedSize := size
@ -180,7 +182,7 @@ func readBlock(name string, size int64, readBlockContent func(size int64, valueC
d.Fatalf("Unsupported compression type: %x", compressionType)
}
d.FieldStructRootBitBufFn("uncompressed", bitio.NewBitReader(bb.Bytes(), -1), func(d *decode.D) {
readBlockContent(int64(bb.Len()), valueCallbackFn, d)
readBlockContents(int64(bb.Len()), valueCallbackFn, d)
})
d.FieldRawLen("compressed", compressedSize*8)
}
@ -188,9 +190,10 @@ func readBlock(name string, size int64, readBlockContent func(size int64, valueC
})
}
func readKeyValueContent(size int64, valueCallbackFn func(d *decode.D), d *decode.D) {
// https://github.com/google/leveldb/blob/main/table/block_builder.cc#L16
// https://github.com/google/leveldb/blob/main/table/block.cc
// Read content encoded as a sequence of key/value-entries and a trailer of restarts.
// https://github.com/google/leveldb/blob/main/table/block_builder.cc#L16
// https://github.com/google/leveldb/blob/main/table/block.cc
func readKeyValueContents(size int64, valueCallbackFn func(d *decode.D), d *decode.D) {
uint32Size := int64(32)
uint64Size := int64(64)
start := d.Pos()
@ -237,10 +240,11 @@ func readKeyValueContent(size int64, valueCallbackFn func(d *decode.D), d *decod
})
}
// Read content encoded in the "filter" or "stats" Meta Block format.
// https://github.com/google/leveldb/blob/main/doc/table_format.md#filter-meta-block
// https://github.com/google/leveldb/blob/main/table/filter_block.cc
func readMetaContent(size int64, valueCallbackFn func(d *decode.D), d *decode.D) {
// TK(2023-12-04)
// https://github.com/google/leveldb/blob/main/doc/table_format.md#filter-meta-block
// https://github.com/google/leveldb/blob/main/table/filter_block.cc
d.FieldRawLen("raw", size*8)
}