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Process cemented elections with exclusive lock to avoid races

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This commit is contained in:
Piotr Wójcik 2024-10-18 14:17:04 +02:00
commit 82d9d2d323
2 changed files with 38 additions and 16 deletions
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42
nano/node/active_elections.cpp
View file

@ -31,11 +31,24 @@ nano::active_elections::active_elections (nano::node & node_a, nano::confirming_
// Cementing blocks might implicitly confirm dependent elections
confirming_set.batch_cemented.add ([this] (auto const & cemented) {
auto transaction = node.ledger.tx_begin_read ();
for (auto const & [block, confirmation_root, source_election] : cemented)
std::deque<block_cemented_result> results;
{
transaction.refresh_if_needed ();
block_cemented (transaction, block, confirmation_root, source_election);
// Process all cemented blocks while holding the lock to avoid races where an election for a block that is already cemented is inserted
nano::lock_guard<nano::mutex> guard{ mutex };
for (auto const & [block, confirmation_root, source_election] : cemented)
{
auto result = block_cemented (block, confirmation_root, source_election);
results.push_back (result);
}
}
{
// TODO: This could be offloaded to a separate notification worker, profiling is needed
auto transaction = node.ledger.tx_begin_read ();
for (auto const & [status, votes] : results)
{
transaction.refresh_if_needed ();
notify_observers (transaction, status, votes);
}
}
});
@ -83,16 +96,17 @@ void nano::active_elections::stop ()
clear ();
}
void nano::active_elections::block_cemented (nano::secure::transaction const & transaction, std::shared_ptr<nano::block> const & block, nano::block_hash const & confirmation_root, std::shared_ptr<nano::election> const & source_election)
auto nano::active_elections::block_cemented (std::shared_ptr<nano::block> const & block, nano::block_hash const & confirmation_root, std::shared_ptr<nano::election> const & source_election) -> block_cemented_result
{
debug_assert (!mutex.try_lock ());
debug_assert (node.block_confirmed (block->hash ()));
// Dependent elections are implicitly confirmed when their block is cemented
auto dependend_election = election (block->qualified_root ());
auto dependend_election = election_impl (block->qualified_root ());
if (dependend_election)
{
node.stats.inc (nano::stat::type::active_elections, nano::stat::detail::confirm_dependent);
dependend_election->try_confirm (block->hash ());
dependend_election->try_confirm (block->hash ()); // TODO: This should either confirm or cancel the election
}
nano::election_status status;
@ -126,7 +140,7 @@ void nano::active_elections::block_cemented (nano::secure::transaction const & t
nano::log::arg{ "confirmation_root", confirmation_root },
nano::log::arg{ "source_election", source_election });
notify_observers (transaction, status, votes);
return { status, votes };
}
void nano::active_elections::notify_observers (nano::secure::transaction const & transaction, nano::election_status const & status, std::vector<nano::vote_with_weight_info> const & votes) const
@ -443,11 +457,17 @@ bool nano::active_elections::active (nano::block const & block_a) const
return roots.get<tag_root> ().find (block_a.qualified_root ()) != roots.get<tag_root> ().end ();
}
std::shared_ptr<nano::election> nano::active_elections::election (nano::qualified_root const & root_a) const
std::shared_ptr<nano::election> nano::active_elections::election (nano::qualified_root const & root) const
{
std::shared_ptr<nano::election> result;
nano::lock_guard<nano::mutex> lock{ mutex };
auto existing = roots.get<tag_root> ().find (root_a);
return election_impl (root);
}
std::shared_ptr<nano::election> nano::active_elections::election_impl (nano::qualified_root const & root) const
{
debug_assert (!mutex.try_lock ());
std::shared_ptr<nano::election> result;
auto existing = roots.get<tag_root> ().find (root);
if (existing != roots.get<tag_root> ().end ())
{
result = existing->election;

12
nano/node/active_elections.hpp
View file

@ -105,7 +105,7 @@ public:
bool active (nano::qualified_root const &) const;
std::shared_ptr<nano::election> election (nano::qualified_root const &) const;
// Returns a list of elections sorted by difficulty
std::vector<std::shared_ptr<nano::election>> list_active (std::size_t = std::numeric_limits<std::size_t>::max ());
std::vector<std::shared_ptr<nano::election>> list_active (std::size_t max_count = std::numeric_limits<std::size_t>::max ());
bool erase (nano::block const &);
bool erase (nano::qualified_root const &);
bool empty () const;
@ -133,11 +133,13 @@ private:
void request_confirm (nano::unique_lock<nano::mutex> &);
// Erase all blocks from active and, if not confirmed, clear digests from network filters
void cleanup_election (nano::unique_lock<nano::mutex> & lock_a, std::shared_ptr<nano::election>);
nano::stat::type completion_type (nano::election const & election) const;
// Returns a list of elections sorted by difficulty, mutex must be locked
std::vector<std::shared_ptr<nano::election>> list_active_impl (std::size_t) const;
using block_cemented_result = std::pair<nano::election_status, std::vector<nano::vote_with_weight_info>>;
block_cemented_result block_cemented (std::shared_ptr<nano::block> const & block, nano::block_hash const & confirmation_root, std::shared_ptr<nano::election> const & source_election);
void notify_observers (nano::secure::transaction const &, nano::election_status const & status, std::vector<nano::vote_with_weight_info> const & votes) const;
void block_cemented (nano::secure::transaction const &, std::shared_ptr<nano::block> const & block, nano::block_hash const & confirmation_root, std::shared_ptr<nano::election> const & source_election);
std::shared_ptr<nano::election> election_impl (nano::qualified_root const &) const;
std::vector<std::shared_ptr<nano::election>> list_active_impl (std::size_t max_count) const;
private: // Dependencies
active_elections_config const & config;