Use kXXH3 as default checksum (CPU efficiency) (#10778)

Summary:
Since this has been supported for about a year, I think it's time to make it the default. This should improve CPU efficiency slightly on most hardware.

A current DB performance comparison using buck+clang build:
```
TEST_TMPDIR=/dev/shm ./db_bench -checksum_type={1,4} -benchmarks=fillseq[-X1000] -num=3000000 -disable_wal
```
kXXH3 (+0.2% DB write throughput):
`fillseq [AVG    1000 runs] : 822149 (± 1004) ops/sec;   91.0 (± 0.1) MB/sec`
kCRC32c:
`fillseq [AVG    1000 runs] : 820484 (± 1203) ops/sec;   90.8 (± 0.1) MB/sec`

Micro benchmark comparison:
```
./db_bench --benchmarks=xxh3[-X20],crc32c[-X20]
```
Machine 1, buck+clang build:
`xxh3 [AVG    20 runs] : 3358616 (± 19091) ops/sec; 13119.6 (± 74.6) MB/sec`
`crc32c [AVG    20 runs] : 2578725 (± 7742) ops/sec; 10073.1 (± 30.2) MB/sec`

Machine 2, make+gcc build, DEBUG_LEVEL=0 PORTABLE=0:
`xxh3 [AVG    20 runs] : 6182084 (± 137223) ops/sec; 24148.8 (± 536.0) MB/sec`
`crc32c [AVG    20 runs] : 5032465 (± 42454) ops/sec; 19658.1 (± 165.8) MB/sec`

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10778

Test Plan: make check, unit tests updated

Reviewed By: ajkr

Differential Revision: D40112510

Pulled By: pdillinger

fbshipit-source-id: e59a8d50a60346137732f8668ba7cfac93be2b37

HISTORY.md

@@ -34,6 +34,7 @@
 * Sanitize min_write_buffer_number_to_merge to 1 if atomic flush is enabled to prevent unexpected data loss when WAL is disabled in a multi-column-family setting (#10773).
 
 ### Public API changes
+* Make kXXH3 checksum the new default, because it is faster on common hardware, especially with kCRC32c affected by a performance bug in some versions of clang (https://github.com/facebook/rocksdb/issues/9891). DBs written with this new setting can be read by RocksDB 6.27 and newer.
 * Refactor the classes, APIs and data structures for block cache tracing to allow a user provided trace writer to be used. Introduced an abstract BlockCacheTraceWriter class that takes a structured BlockCacheTraceRecord. The BlockCacheTraceWriter implementation can then format and log the record in whatever way it sees fit. The default BlockCacheTraceWriterImpl does file tracing using a user provided TraceWriter. More details in rocksdb/includb/block_cache_trace_writer.h.
 
 ## 7.7.0 (09/18/2022)

db/db_test_util.cc

@@ -487,8 +487,10 @@ Options DBTestBase::GetOptions(
     case kInfiniteMaxOpenFiles:
       options.max_open_files = -1;
       break;
-    case kXXH3Checksum: {
+    case kCRC32cChecksum: {
-      table_options.checksum = kXXH3;
+      // Old default was CRC32c, but XXH3 (new default) is faster on common
+      // hardware
+      table_options.checksum = kCRC32c;
       // Thrown in here for basic coverage:
       options.DisableExtraChecks();
       break;

db/db_test_util.h

@@ -1048,7 +1048,7 @@ class DBTestBase : public testing::Test {
     kUniversalCompactionMultiLevel = 20,
     kCompressedBlockCache = 21,
     kInfiniteMaxOpenFiles = 22,
-    kXXH3Checksum = 23,
+    kCRC32cChecksum = 23,
     kFIFOCompaction = 24,
     kOptimizeFiltersForHits = 25,
     kRowCache = 26,

include/rocksdb/table.h

@@ -251,7 +251,7 @@ struct BlockBasedTableOptions {
   // Use the specified checksum type. Newly created table files will be
   // protected with this checksum type. Old table files will still be readable,
   // even though they have different checksum type.
-  ChecksumType checksum = kCRC32c;
+  ChecksumType checksum = kXXH3;
 
   // Disable block cache. If this is set to true,
   // then no block cache should be used, and the block_cache should

table/table_test.cc

@@ -2256,7 +2256,8 @@ TEST_P(BlockBasedTableTest, BadChecksumType) {
   // Corrupt checksum type (123 is invalid)
   auto& sink = *c.TEST_GetSink();
   size_t len = sink.contents_.size();
-  ASSERT_EQ(sink.contents_[len - Footer::kNewVersionsEncodedLength], kCRC32c);
+  ASSERT_EQ(sink.contents_[len - Footer::kNewVersionsEncodedLength],
+            table_options.checksum);
   sink.contents_[len - Footer::kNewVersionsEncodedLength] = char{123};
 
   // (Re-)Open table file with bad checksum type

tools/check_format_compatible.sh

@@ -125,7 +125,7 @@ EOF
 
 # To check for DB forward compatibility with loading options (old version
 # reading data from new), as well as backward compatibility
-declare -a db_forward_with_options_refs=("6.6.fb" "6.7.fb" "6.8.fb" "6.9.fb" "6.10.fb" "6.11.fb" "6.12.fb" "6.13.fb" "6.14.fb" "6.15.fb" "6.16.fb" "6.17.fb" "6.18.fb" "6.19.fb" "6.20.fb" "6.21.fb" "6.22.fb" "6.23.fb" "6.24.fb" "6.25.fb" "6.26.fb" "6.27.fb" "6.28.fb" "6.29.fb" "7.0.fb" "7.1.fb" "7.2.fb" "7.3.fb" "7.4.fb" "7.5.fb" "7.6.fb")
+declare -a db_forward_with_options_refs=("6.27.fb" "6.28.fb" "6.29.fb" "7.0.fb" "7.1.fb" "7.2.fb" "7.3.fb" "7.4.fb" "7.5.fb" "7.6.fb")
 # To check for DB forward compatibility without loading options (in addition
 # to the "with loading options" set), as well as backward compatibility
 declare -a db_forward_no_options_refs=() # N/A at the moment
@@ -133,7 +133,7 @@ declare -a db_forward_no_options_refs=() # N/A at the moment
 # To check for SST ingestion backward compatibility (new version reading
 # data from old) (ldb ingest_extern_sst added in 5.16.x, back-ported to
 # 5.14.x, 5.15.x)
-declare -a ext_backward_only_refs=("5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb")
+declare -a ext_backward_only_refs=("5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb" "6.6.fb" "6.7.fb" "6.8.fb" "6.9.fb" "6.10.fb" "6.11.fb" "6.12.fb" "6.13.fb" "6.14.fb" "6.15.fb" "6.16.fb" "6.17.fb" "6.18.fb" "6.19.fb" "6.20.fb" "6.21.fb" "6.22.fb" "6.23.fb" "6.24.fb" "6.25.fb" "6.26.fb")
 # To check for SST ingestion forward compatibility (old version reading
 # data from new) as well as backward compatibility
 declare -a ext_forward_refs=("${db_forward_no_options_refs[@]}" "${db_forward_with_options_refs[@]}")