f872c93ad1
Summary: Command id is necessary in remote produce to identify an ongoing pull because a transaction can have multiple commands that all belong under the same plan and tx id. Reviewers: teon.banek, mtomic, buda Reviewed By: teon.banek Subscribers: pullbot Differential Revision: https://phabricator.memgraph.io/D1386
74 lines
2.9 KiB
C++
74 lines
2.9 KiB
C++
#pragma once
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#include <atomic>
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#include "communication/rpc/client_pool.hpp"
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#include "data_structures/concurrent/concurrent_map.hpp"
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#include "io/network/endpoint.hpp"
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#include "transactions/commit_log.hpp"
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#include "transactions/engine.hpp"
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#include "transactions/transaction.hpp"
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namespace tx {
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/** Distributed worker transaction engine. Connects to a MasterEngine (single
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* source of truth) to obtain transactional info. Caches most info locally. Can
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* begin/advance/end transactions on the master. */
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class WorkerEngine : public Engine {
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public:
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/// The wait time between two releases of local transaction objects that have
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/// expired on the master.
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static constexpr std::chrono::seconds kCacheReleasePeriod{1};
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explicit WorkerEngine(communication::rpc::ClientPool &master_client_pool);
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~WorkerEngine();
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Transaction *Begin() override;
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CommandId Advance(TransactionId id) override;
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CommandId UpdateCommand(TransactionId id) override;
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void Commit(const Transaction &t) override;
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void Abort(const Transaction &t) override;
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CommitLog::Info Info(TransactionId tid) const override;
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Snapshot GlobalGcSnapshot() override;
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Snapshot GlobalActiveTransactions() override;
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TransactionId GlobalLast() const override;
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TransactionId LocalLast() const override;
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void LocalForEachActiveTransaction(
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std::function<void(Transaction &)> f) override;
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TransactionId LocalOldestActive() const override;
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Transaction *RunningTransaction(TransactionId tx_id) override;
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// Caches the transaction for the given info an returs a ptr to it.
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Transaction *RunningTransaction(TransactionId tx_id,
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const Snapshot &snapshot);
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void EnsureNextIdGreater(TransactionId tx_id) override;
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void GarbageCollectCommitLog(tx::TransactionId tx_id) override;
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/// Clears the cache of local transactions that have expired. The signature of
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/// this method is dictated by `distributed::TransactionalCacheCleaner`.
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void ClearTransactionalCache(TransactionId oldest_active) const;
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private:
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// Local caches.
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mutable ConcurrentMap<TransactionId, Transaction *> active_;
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std::atomic<TransactionId> local_last_{0};
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// Mutable because just getting info can cause a cache fill.
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mutable CommitLog clog_;
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// Communication to the transactional master.
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communication::rpc::ClientPool &master_client_pool_;
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// Used for clearing of caches of transactions that have expired.
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// Initialize the oldest_active_ with 1 because there's never a tx with id=0
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std::atomic<TransactionId> oldest_active_{1};
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// Removes a single transaction from the cache, if present.
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void ClearSingleTransaction(TransactionId tx_Id) const;
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// Updates the oldest active transaction to the one from the snapshot. If the
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// snapshot is empty, it's set to the given alternative.
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void UpdateOldestActive(const Snapshot &snapshot, TransactionId alternative);
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};
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} // namespace tx
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