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Hack to load OPTIONS file for read_amp_bytes_per_bit (#7659) 

Summary:
A temporary hack to work around a bug in 6.10, 6.11, 6.12, 6.13 and
6.14. The bug will write out 8 bytes to OPTIONS file from the starting
address of BlockBasedTableOptions.read_amp_bytes_per_bit which is
actually a uint32. Consequently, the value of read_amp_bytes_per_bit
written in the OPTIONS file is wrong. From 6.15, RocksDB will
try to parse the read_amp_bytes_per_bit from OPTIONS file as a uint32.
To be able to load OPTIONS file generated by affected releases before
the fix, we need to manually parse read_amp_bytes_per_bit with this hack.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7659

Test Plan:
Generate a db with current 6.14.fb (head at b6db05dbb5). Maybe use db_stress.

Checkout this PR, run
```
 ~/rocksdb/ldb --db=. --try_load_options --ignore_unknown_options idump --count_only
```
Expect success, and should not see
```
Failed: Invalid argument: Error parsing read_amp_bytes_per_bit:17179869184
```

Also
make check

Reviewed By: anand1976

Differential Revision: D24954752

Pulled By: riversand963

fbshipit-source-id: c7b802fc3e52acd050a4fc1cd475016122234394
This commit is contained in:
Yanqin Jin 2020-11-13 11:51:24 -08:00 committed by Facebook GitHub Bot
parent e300ce211d
commit 9aa1b1dc19
2 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
options/options_test.cc
View File

@ -846,7 +846,12 @@ TEST_F(OptionsTest, GetBlockBasedTableOptionsFromString) {
"block_cache=1M;block_cache_compressed=1k;block_size=1024;"
"block_size_deviation=8;block_restart_interval=4;"
"format_version=5;whole_key_filtering=1;"
"filter_policy=bloomfilter:4.567:false;",
"filter_policy=bloomfilter:4.567:false;"
// A bug caused read_amp_bytes_per_bit to be a large integer in OPTIONS
// file generated by 6.10 to 6.14. Though bug is fixed in these releases,
// we need to handle the case of loading OPTIONS file generated before the
// fix.
"read_amp_bytes_per_bit=17179869185;",
&new_opt));
ASSERT_TRUE(new_opt.cache_index_and_filter_blocks);
ASSERT_EQ(new_opt.index_type, BlockBasedTableOptions::kHashSearch);
@ -867,6 +872,9 @@ TEST_F(OptionsTest, GetBlockBasedTableOptionsFromString) {
EXPECT_EQ(bfp->GetMillibitsPerKey(), 4567);
EXPECT_EQ(bfp->GetWholeBitsPerKey(), 5);
EXPECT_EQ(bfp->GetMode(), BloomFilterPolicy::kAutoBloom);
// Verify that only the lower 32bits are stored in
// new_opt.read_amp_bytes_per_bit.
EXPECT_EQ(1U, new_opt.read_amp_bytes_per_bit);
// unknown option
Status s = GetBlockBasedTableOptionsFromString(

17
table/block_based/block_based_table_factory.cc
View File

@ -360,7 +360,22 @@ static std::unordered_map<std::string, OptionTypeInfo>
{"read_amp_bytes_per_bit",
{offsetof(struct BlockBasedTableOptions, read_amp_bytes_per_bit),
OptionType::kUInt32T, OptionVerificationType::kNormal,
OptionTypeFlags::kNone}},
OptionTypeFlags::kNone,
[](const ConfigOptions& /*opts*/, const std::string& /*name*/,
const std::string& value, char* addr) {
// A workaround to fix a bug in 6.10, 6.11, 6.12, 6.13
// and 6.14. The bug will write out 8 bytes to OPTIONS file from the
// starting address of BlockBasedTableOptions.read_amp_bytes_per_bit
// which is actually a uint32. Consequently, the value of
// read_amp_bytes_per_bit written in the OPTIONS file is wrong.
// From 6.15, RocksDB will try to parse the read_amp_bytes_per_bit
// from OPTIONS file as a uint32. To be able to load OPTIONS file
// generated by affected releases before the fix, we need to
// manually parse read_amp_bytes_per_bit with this special hack.
uint64_t read_amp_bytes_per_bit = ParseUint64(value);
EncodeFixed32(addr, static_cast<uint32_t>(read_amp_bytes_per_bit));
return Status::OK();
}}},
{"enable_index_compression",
{offsetof(struct BlockBasedTableOptions, enable_index_compression),
OptionType::kBoolean, OptionVerificationType::kNormal,