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Block access tracing: Trace referenced key for Get on non-data blocks. (
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facebook#5548)

Summary:
This PR traces the referenced key for Get for all types of blocks. This is useful when evaluating hybrid row-block caches.
Pull Request resolved: facebook#5548

Test Plan: make clean && USE_CLANG=1 make check -j32

Differential Revision: D16157979

Pulled By: HaoyuHuang

fbshipit-source-id: f6327411c9deb74e35e22a35f66cdbae09ab9d87
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@HaoyuHuang @facebook-github-bot
HaoyuHuang authored and facebook-github-bot committed Jul 17, 2019
1 parent 22ce462 commit 8a008d4
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Showing 9 changed files with 386 additions and 77 deletions.
58 changes: 35 additions & 23 deletions table/block_based/block_based_table_reader.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1983,10 +1983,12 @@ CachableEntry<UncompressionDict> BlockBasedTable::GetUncompressionDict(
/*block_size=*/usage, rep_->cf_id_for_tracing(),
/*cf_name=*/"", rep_->level_for_tracing(),
rep_->sst_number_for_tracing(), lookup_context->caller, is_cache_hit,
/*no_insert=*/no_io, lookup_context->get_id);
/*no_insert=*/no_io, lookup_context->get_id,
lookup_context->get_from_user_specified_snapshot,
/*referenced_key=*/"");
block_cache_tracer_->WriteBlockAccess(access_record, cache_key,
rep_->cf_name_for_tracing(),
/*referenced_key=*/nullptr);
lookup_context->referenced_key);
}
return {dict, cache_handle ? rep_->table_options.block_cache.get() : nullptr,
cache_handle, false /* own_value */};
Expand Down Expand Up @@ -2237,7 +2239,6 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
Slice key /* key to the block cache */;
Slice ckey /* key to the compressed block cache */;
bool is_cache_hit = false;
bool no_insert = true;
if (block_cache != nullptr || block_cache_compressed != nullptr) {
// create key for block cache
if (block_cache != nullptr) {
Expand Down Expand Up @@ -2265,7 +2266,6 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
// Can't find the block from the cache. If I/O is allowed, read from the
// file.
if (block_entry->GetValue() == nullptr && !no_io && ro.fill_cache) {
no_insert = false;
Statistics* statistics = rep_->ioptions.statistics;
const bool maybe_compressed =
block_type != BlockType::kFilter && rep_->blocks_maybe_compressed;
Expand Down Expand Up @@ -2332,11 +2332,11 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
assert(false);
break;
}
if (BlockCacheTraceHelper::ShouldTraceReferencedKey(
bool no_insert = no_io || !ro.fill_cache;
if (BlockCacheTraceHelper::IsGetOrMultiGetOnDataBlock(
trace_block_type, lookup_context->caller)) {
// Defer logging the access to Get() and MultiGet() to trace additional
// information, e.g., the referenced key,
// referenced_key_exist_in_block.
// information, e.g., referenced_key_exist_in_block.

// Make a copy of the block key here since it will be logged later.
lookup_context->FillLookupContext(
Expand All @@ -2351,10 +2351,12 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
/*block_size=*/usage, rep_->cf_id_for_tracing(),
/*cf_name=*/"", rep_->level_for_tracing(),
rep_->sst_number_for_tracing(), lookup_context->caller, is_cache_hit,
no_insert, lookup_context->get_id);
no_insert, lookup_context->get_id,
lookup_context->get_from_user_specified_snapshot,
/*referenced_key=*/"");
block_cache_tracer_->WriteBlockAccess(access_record, key,
rep_->cf_name_for_tracing(),
/*referenced_key=*/nullptr);
lookup_context->referenced_key);
}
}

Expand Down Expand Up @@ -3288,12 +3290,18 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
// First check the full filter
// If full filter not useful, Then go into each block
uint64_t tracing_get_id = get_context->get_tracing_get_id();
BlockCacheLookupContext lookup_context{TableReaderCaller::kUserGet,
tracing_get_id};
BlockCacheLookupContext lookup_context{
TableReaderCaller::kUserGet, tracing_get_id,
/*get_from_user_specified_snapshot=*/read_options.snapshot != nullptr};
if (block_cache_tracer_ && block_cache_tracer_->is_tracing_enabled()) {
// Trace the key since it contains both user key and sequence number.
lookup_context.referenced_key = key.ToString();
lookup_context.get_from_user_specified_snapshot =
read_options.snapshot != nullptr;
}
const bool may_match =
FullFilterKeyMayMatch(read_options, filter, key, no_io, prefix_extractor,
get_context, &lookup_context);

if (!may_match) {
RecordTick(rep_->ioptions.statistics, BLOOM_FILTER_USEFUL);
PERF_COUNTER_BY_LEVEL_ADD(bloom_filter_useful, 1, rep_->level);
Expand Down Expand Up @@ -3347,7 +3355,9 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
}

BlockCacheLookupContext lookup_data_block_context{
TableReaderCaller::kUserGet, tracing_get_id};
TableReaderCaller::kUserGet, tracing_get_id,
/*get_from_user_specified_snapshot=*/read_options.snapshot !=
nullptr};
bool does_referenced_key_exist = false;
DataBlockIter biter;
uint64_t referenced_data_size = 0;
Expand Down Expand Up @@ -3406,7 +3416,7 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
if (does_referenced_key_exist) {
referenced_key = biter.key();
} else {
referenced_key = ExtractUserKey(key);
referenced_key = key;
}
BlockCacheTraceRecord access_record(
rep_->ioptions.env->NowMicros(),
Expand All @@ -3417,6 +3427,7 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
lookup_data_block_context.is_cache_hit,
lookup_data_block_context.no_insert,
lookup_data_block_context.get_id,
lookup_data_block_context.get_from_user_specified_snapshot,
/*referenced_key=*/"", referenced_data_size,
lookup_data_block_context.num_keys_in_block,
does_referenced_key_exist);
Expand Down Expand Up @@ -3460,8 +3471,9 @@ void BlockBasedTable::MultiGet(const ReadOptions& read_options,
if (!sst_file_range.empty() && sst_file_range.begin()->get_context) {
tracing_mget_id = sst_file_range.begin()->get_context->get_tracing_get_id();
}
BlockCacheLookupContext lookup_context{TableReaderCaller::kUserMultiGet,
tracing_mget_id};
BlockCacheLookupContext lookup_context{
TableReaderCaller::kUserMultiGet, tracing_mget_id,
/*get_from_user_specified_snapshot=*/read_options.snapshot != nullptr};
FullFilterKeysMayMatch(read_options, filter, &sst_file_range, no_io,
prefix_extractor, &lookup_context);

Expand Down Expand Up @@ -3492,11 +3504,8 @@ void BlockBasedTable::MultiGet(const ReadOptions& read_options,
{
MultiGetRange data_block_range(sst_file_range, sst_file_range.begin(),
sst_file_range.end());
BlockCacheLookupContext lookup_compression_dict_context(
TableReaderCaller::kUserMultiGet);
auto uncompression_dict_storage = GetUncompressionDict(nullptr, no_io,
sst_file_range.begin()->get_context,
&lookup_compression_dict_context);
auto uncompression_dict_storage = GetUncompressionDict(
nullptr, no_io, sst_file_range.begin()->get_context, &lookup_context);
const UncompressionDict& uncompression_dict =
uncompression_dict_storage.GetValue() == nullptr
? UncompressionDict::GetEmptyDict()
Expand Down Expand Up @@ -3591,7 +3600,9 @@ void BlockBasedTable::MultiGet(const ReadOptions& read_options,
uint64_t referenced_data_size = 0;
bool does_referenced_key_exist = false;
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet, tracing_mget_id);
TableReaderCaller::kUserMultiGet, tracing_mget_id,
/*get_from_user_specified_snapshot=*/read_options.snapshot !=
nullptr);
if (first_block) {
if (!block_handles[idx_in_batch].IsNull() ||
!results[idx_in_batch].IsEmpty()) {
Expand Down Expand Up @@ -3685,7 +3696,7 @@ void BlockBasedTable::MultiGet(const ReadOptions& read_options,
if (does_referenced_key_exist) {
referenced_key = biter->key();
} else {
referenced_key = ExtractUserKey(key);
referenced_key = key;
}
BlockCacheTraceRecord access_record(
rep_->ioptions.env->NowMicros(),
Expand All @@ -3696,6 +3707,7 @@ void BlockBasedTable::MultiGet(const ReadOptions& read_options,
lookup_data_block_context.is_cache_hit,
lookup_data_block_context.no_insert,
lookup_data_block_context.get_id,
lookup_data_block_context.get_from_user_specified_snapshot,
/*referenced_key=*/"", referenced_data_size,
lookup_data_block_context.num_keys_in_block,
does_referenced_key_exist);
Expand Down
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