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sstables: writer: don't require effective_replication_map for sharding metadata

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Currently, we pass an effective_replication_map_ptr to sstable_writer,
so that we can get a stable dht::sharder for writing the sharding metadata.
This is needed because with tablets, the sharder can change dynamically.

However, this is both bad and unnecessary:
 - bad: holding on to an effective_replication_map_ptr is a barrier
   for topology operations, preventing tablet migrations (etc) while
   an sstable is being written
 - unnecessary: tablets don't require sharding metadata at all, since
   two tablets cannot overlap (unlike two sstables from different shards in
   the same node). So the first/last key is sufficient to determine the
   shard/tablet ownership.

Given that, just pass the sharder for vnode sstables, and don't generate
sharding metadata for tablet sstables.
This commit is contained in:
Avi Kivity
2024-01-23 20:21:04 +02:00
parent b88f422a53
commit 8ee75ae8f4
5 changed files with 9 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
replica/table.cc
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@@ -1121,7 +1121,6 @@ table::try_flush_memtable_to_sstable(compaction_group& cg, lw_shared_ptr<memtabl
try {
sstables::sstable_writer_config cfg = get_sstables_manager().configure_writer("memtable");
cfg.backup = incremental_backups_enabled();
cfg.erm = _erm;
auto newtab = make_sstable();
newtabs.push_back(newtab);
@@ -3078,7 +3077,6 @@ public:
}
sstables::sstable_writer_config configure_writer(sstring origin) const override {
auto cfg = _t.get_sstables_manager().configure_writer(std::move(origin));
cfg.erm = _t.get_effective_replication_map();
return cfg;
}
api::timestamp_type min_memtable_timestamp() const override {

4
sstables/mx/writer.cc
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@@ -1472,9 +1472,7 @@ void writer::consume_end_of_stream() {
{ large_data_type::elements_in_collection, std::move(_elements_in_collection_entry) },
}
});
const dht::sharder& sharder = _cfg.erm ? _cfg.erm->get_sharder(_schema)
: _schema.get_sharder(); // Used in tests
_sst.write_scylla_metadata(_shard, sharder, std::move(features), std::move(identifier), std::move(ld_stats), _cfg.origin);
_sst.write_scylla_metadata(_shard, std::move(features), std::move(identifier), std::move(ld_stats), _cfg.origin);
_sst.seal_sstable(_cfg.backup).get();
}

11
sstables/sstables.cc
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@@ -1629,16 +1629,17 @@ sstable::read_scylla_metadata() noexcept {
}
void
sstable::write_scylla_metadata(shard_id shard, const dht::sharder& sharder, sstable_enabled_features features, struct run_identifier identifier,
sstable::write_scylla_metadata(shard_id shard, sstable_enabled_features features, struct run_identifier identifier,
std::optional<scylla_metadata::large_data_stats> ld_stats, sstring origin) {
auto&& first_key = get_first_decorated_key();
auto&& last_key = get_last_decorated_key();
auto sm = create_sharding_metadata(_schema, sharder, first_key, last_key, shard);
auto* sharder_opt = _schema->try_get_static_sharder();
auto sm = sharder_opt ? std::optional(create_sharding_metadata(_schema, *sharder_opt, first_key, last_key, shard)) : std::nullopt;
// sstable write may fail to generate empty metadata if mutation source has only data from other shard.
// see https://github.com/scylladb/scylla/issues/2932 for details on how it can happen.
if (sm.token_ranges.elements.empty()) {
if (sm && sm->token_ranges.elements.empty()) {
throw std::runtime_error(format("Failed to generate sharding metadata for {}", get_filename()));
}
@@ -1646,7 +1647,9 @@ sstable::write_scylla_metadata(shard_id shard, const dht::sharder& sharder, ssta
_components->scylla_metadata.emplace();
}
_components->scylla_metadata->data.set<scylla_metadata_type::Sharding>(std::move(sm));
if (sm) {
_components->scylla_metadata->data.set<scylla_metadata_type::Sharding>(std::move(*sm));
}
_components->scylla_metadata->data.set<scylla_metadata_type::Features>(std::move(features));
_components->scylla_metadata->data.set<scylla_metadata_type::RunIdentifier>(std::move(identifier));
if (ld_stats) {

4
sstables/sstables.hh
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@@ -39,7 +39,7 @@
#include "readers/flat_mutation_reader_fwd.hh"
#include "tracing/trace_state.hh"
#include "utils/updateable_value.hh"
#include "locator/abstract_replication_strategy.hh"
#include "dht/decorated_key.hh"
#include <seastar/util/optimized_optional.hh>
@@ -111,7 +111,6 @@ struct sstable_writer_config {
run_id run_identifier = run_id::create_random_id();
size_t summary_byte_cost;
sstring origin;
locator::effective_replication_map_ptr erm;
private:
explicit sstable_writer_config() {}
@@ -642,7 +641,6 @@ private:
future<> read_scylla_metadata() noexcept;
void write_scylla_metadata(shard_id shard,
const dht::sharder& sharder,
sstable_enabled_features features,
run_identifier identifier,
std::optional<scylla_metadata::large_data_stats> ld_stats,

1
streaming/consumer.cc
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@@ -58,7 +58,6 @@ std::function<future<> (flat_mutation_reader_v2)> make_streaming_consumer(sstrin
schema_ptr s = reader.schema();
auto cfg = cf->get_sstables_manager().configure_writer(origin);
cfg.erm = cf->get_effective_replication_map();
return sst->write_components(std::move(reader), adjusted_estimated_partitions, s,
cfg, encoding_stats{}).then([sst] {
return sst->open_data();