mirror of https://github.com/facebook/rocksdb.git
21d5a8f54f
Summary:
### Summary: The sst_dump tool occur IO Error when reading data in PlainTable, as shown in the follow
```bash
❯ ./sst_dump --file=/tmp/write_example --command=scan --show_properties --verify_checksum
options.env is 0x60000282dc00
Process /tmp/write_example/001630.sst
Sst file format: plain table
/tmp/filepicker_example/001630.sst: IO error: While pread offset 0 len 758: /tmp/filepicker_example/001630.sst: Bad address
Process /tmp/filepicker_example/001624.sst
```
#### Reason
The root cause is that `fopts.use_mmap_reads` is false, `NewRandomAccessFile` will produce an `PosixRandomAccessFile` file. but `soptions_.use_mmap_reads` is true, This will result in unexpected calls in the `MmapDataIfNeeded` function.
```c++
Status SstFileDumper::GetTableReader(const std::string& file_path) {
...
if (s.ok()) {
if (magic_number == kPlainTableMagicNumber ||
magic_number == kLegacyPlainTableMagicNumber ||
magic_number == kCuckooTableMagicNumber) {
soptions_.use_mmap_reads = true;
...
// WARN: fopts.use_mmap_reads is false
fs->NewRandomAccessFile(file_path, fopts, &file, nullptr);
file_.reset(new RandomAccessFileReader(std::move(file), file_path));
}
...
}
if (s.ok()) {
// soptions_.use_mmap_reads is true
s = NewTableReader(ioptions_, soptions_, internal_comparator_, file_size,
&table_reader_);
}
return s;
}
```
The following read logic was executed on a `PosixRandomAccessFile` file, Eventually, `PosixRandomAccessFile::Read` will be called with a `nullptr` `scratch`
```c++
Status PlainTableReader::MmapDataIfNeeded() {
if (file_info_.is_mmap_mode) {
// Get mmapped memory.
// Executing the following logic on the PosixRandomAccessFile file is incorrect
return file_info_.file->Read(
IOOptions(), 0, static_cast<size_t>(file_size_), &file_info_.file_data,
nullptr, nullptr, Env::IO_TOTAL /* rate_limiter_priority */);
}
return Status::OK();
}
```
#### Fix:
When parsing PlainTable, set the variable `fopts.use_mmap_reads` equal `soptions_.use_mmap_reads`, When the `soptions_.use_mmap_reads` is true, `NewRandomAccessFile` will produce an `PosixMmapReadableFile` file. This will work correctly in the `MmapDataIfNeeded` function
```
❯ ./sst_dump --file=/tmp/write_example --command=scan --show_properties --verify_checksum
options.env is 0x6000009323e0
Process /tmp/write_example/001630.sst
Sst file format: plain table
from [] to []
'keys496' seq:0, type:1 => values1496
'keys497' seq:0, type:1 => values1497
'keys498' seq:0, type:1 => values1498
Table Properties:
------------------------------
# data blocks: 1
# entries: 3
# deletions: 0
# merge operands: 0
# range deletions: 0
raw key size: 45
raw average key size: 15.000000
raw value size: 42
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/12223
Reviewed By: cbi42
Differential Revision: D52706238
Pulled By: ajkr
fbshipit-source-id: 2f9f518ec81d1cbde00bd65ab6bd304796836c0a
|
||
|---|---|---|
| .. | ||
| adaptive | ||
| block_based | ||
| cuckoo | ||
| plain | ||
| block_fetcher.cc | ||
| block_fetcher.h | ||
| block_fetcher_test.cc | ||
| cleanable_test.cc | ||
| compaction_merging_iterator.cc | ||
| compaction_merging_iterator.h | ||
| format.cc | ||
| format.h | ||
| get_context.cc | ||
| get_context.h | ||
| internal_iterator.h | ||
| iter_heap.h | ||
| iterator.cc | ||
| iterator_wrapper.h | ||
| merger_test.cc | ||
| merging_iterator.cc | ||
| merging_iterator.h | ||
| meta_blocks.cc | ||
| meta_blocks.h | ||
| mock_table.cc | ||
| mock_table.h | ||
| multiget_context.h | ||
| persistent_cache_helper.cc | ||
| persistent_cache_helper.h | ||
| persistent_cache_options.h | ||
| scoped_arena_iterator.h | ||
| sst_file_dumper.cc | ||
| sst_file_dumper.h | ||
| sst_file_reader.cc | ||
| sst_file_reader_test.cc | ||
| sst_file_writer.cc | ||
| sst_file_writer_collectors.h | ||
| table_builder.h | ||
| table_factory.cc | ||
| table_properties.cc | ||
| table_properties_internal.h | ||
| table_reader.h | ||
| table_reader_bench.cc | ||
| table_test.cc | ||
| two_level_iterator.cc | ||
| two_level_iterator.h | ||
| unique_id.cc | ||
| unique_id_impl.h | ||