110 lines
2.0 KiB
C++
110 lines
2.0 KiB
C++
#pragma once
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#include <atomic>
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#include <vector>
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#include "transaction.hpp"
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#include "transaction_cache.hpp"
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#include "commit_log.hpp"
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#include "utils/counters/simple_counter.hpp"
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#include "threading/sync/spinlock.hpp"
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#include "threading/sync/lockable.hpp"
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namespace tx
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{
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class TransactionError : std::runtime_error
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{
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public:
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using std::runtime_error::runtime_error;
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};
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class Engine : Lockable<SpinLock>
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{
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public:
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using sptr = std::shared_ptr<Engine>;
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Engine() : counter(0) {}
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const Transaction& begin()
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{
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auto guard = this->acquire_unique();
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auto id = Id(counter.next());
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auto t = new Transaction(id, active);
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active.insert(id);
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cache.put(id, t);
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return *t;
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}
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const Transaction& advance(const Id& id)
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{
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auto guard = this->acquire_unique();
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auto* t = cache.get(id);
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if(t == nullptr)
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throw TransactionError("transaction does not exist");
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// this is a new command
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t->cid++;
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return *t;
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}
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void commit(const Transaction& t)
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{
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auto guard = this->acquire_unique();
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CommitLog::get().set_committed(t.id);
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finalize(t);
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}
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void abort(const Transaction& t)
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{
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auto guard = this->acquire_unique();
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CommitLog::get().set_aborted(t.id);
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finalize(t);
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}
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Id last_known_active()
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{
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auto guard = this->acquire_unique();
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return active.front();
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}
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// total number of transactions started from the beginning of time
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uint64_t count()
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{
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auto guard = this->acquire_unique();
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return counter.count();
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}
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// the number of currently active transactions
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size_t size()
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{
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auto guard = this->acquire_unique();
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return active.size();
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}
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private:
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void finalize(const Transaction& t)
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{
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active.remove(t.id);
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// remove transaction from cache
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cache.del(t.id);
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}
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SimpleCounter<uint64_t> counter;
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Snapshot<Id> active;
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TransactionCache<uint64_t> cache;
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};
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}
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