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GC bugfixes, MVCC and transaction refactoring

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Summary:
- GC changed to evaluate old records w.r.t. the oldest transaction's id AND snapshot, as opposed to only id
- MVCC hints exp+aborted race condition prevented
- minor MVCC refactors and cleanups
- minor Transaction refactors and cleanups

Reviewers: buda, dgleich

Reviewed By: buda, dgleich

Subscribers: dtomicevic, pullbot

Differential Revision: https://phabricator.memgraph.io/D434
This commit is contained in:
florijan
2017-06-12 10:21:19 +02:00
parent 025e557204
commit afbb940a05
40 changed files with 798 additions and 783 deletions
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33
src/database/graph_db.cpp
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@@ -34,25 +34,29 @@ GraphDb::GraphDb(const std::string &name, const fs::path &snapshot_db_dir)
gc_scheduler_.Run(std::chrono::seconds(FLAGS_gc_cycle_sec), [this]() {
// main garbage collection logic
// see wiki documentation for logic explanation
const auto next_id = this->tx_engine.count() + 1;
const auto id = this->tx_engine.oldest_active().get_or(next_id);
const auto snapshot = this->tx_engine.GcSnapshot();
{
// This can be run concurrently
this->gc_vertices_.Run(id, this->tx_engine);
this->gc_edges_.Run(id, this->tx_engine);
this->gc_vertices_.Run(snapshot, this->tx_engine);
this->gc_edges_.Run(snapshot, this->tx_engine);
}
// This has to be run sequentially after gc because gc modifies
// version_lists and changes the oldest visible record, on which Refresh
// depends.
{
// This can be run concurrently
this->labels_index_.Refresh(id, this->tx_engine);
this->edge_types_index_.Refresh(id, this->tx_engine);
this->labels_index_.Refresh(snapshot, this->tx_engine);
this->edge_types_index_.Refresh(snapshot, this->tx_engine);
}
this->edge_record_deleter_.FreeExpiredObjects(id);
this->vertex_record_deleter_.FreeExpiredObjects(id);
this->edge_version_list_deleter_.FreeExpiredObjects(id);
this->vertex_version_list_deleter_.FreeExpiredObjects(id);
// we free expired objects with snapshot.back(), which is
// the ID of the oldest active transaction (or next active, if there
// are no currently active). that's legal because that was the
// last possible transaction that could have obtained pointers
// to those records
this->edge_record_deleter_.FreeExpiredObjects(snapshot.back());
this->vertex_record_deleter_.FreeExpiredObjects(snapshot.back());
this->edge_version_list_deleter_.FreeExpiredObjects(snapshot.back());
this->vertex_version_list_deleter_.FreeExpiredObjects(snapshot.back());
});
}
@@ -122,8 +126,9 @@ GraphDb::~GraphDb() {
for (auto &edge : this->edges_.access()) delete edge;
// Free expired records with the maximal possible id from all the deleters.
this->edge_record_deleter_.FreeExpiredObjects(Id::MaximalId());
this->vertex_record_deleter_.FreeExpiredObjects(Id::MaximalId());
this->edge_version_list_deleter_.FreeExpiredObjects(Id::MaximalId());
this->vertex_version_list_deleter_.FreeExpiredObjects(Id::MaximalId());
this->edge_record_deleter_.FreeExpiredObjects(tx::Transaction::MaxId());
this->vertex_record_deleter_.FreeExpiredObjects(tx::Transaction::MaxId());
this->edge_version_list_deleter_.FreeExpiredObjects(tx::Transaction::MaxId());
this->vertex_version_list_deleter_.FreeExpiredObjects(
tx::Transaction::MaxId());
}