Generic Transaction Pool
An extensible and performant implementation of Ethereum Transaction Pool.
The pool stores ordered, verified transactions according to some pluggable
The pool also allows you to construct a set of
pending transactions according
to some notion of
The pool is generic over transactions and should make no assumptions about them.
The only thing we can rely on is the
Scoring that defines:
- the ordering of transactions from a single sender
- the priority of the transaction compared to other transactions from different senders
NOTE: the transactions from a single sender are not ordered by priority,
but still when constructing pending set we always need to maintain the ordering
txs always needs to be included after
txs even if it has higher priority)
- Possibility to handle tens of thousands of transactions
- Fast insertions and replacements
O(per-sender + log(senders))
- Reasonably fast removal of stalled transactions
- Reasonably fast construction of pending set
O(txs * (log(senders) + log(per-sender))
The removal performance could be improved by trading some memory. Currently
SmallVec is used
to store senders transactions, instead we could use
VecDeque and efficiently
the best transactions.
The pending set construction and insertion complexity could be reduced by introducing
a notion of
nonce - an absolute, numeric ordering of transactions.
We don't do that because of possible implications of EIP208 where nonce might not be
- The pool groups transactions from particular sender together
and stores them ordered by
Scoringwithin that group i.e.
- Additionaly we maintain the best and the worst transaction from each sender
priority) ordered by
priority. It means that we can easily identify the best transaction inside the entire pool and the worst transaction.
- Whenever new transaction is inserted to the queue:
- first check all the limits (overall, memory, per-sender)
- retrieve all transactions from a sender
- binary search for position to insert the transaction
- decide if we are replacing existing transaction (3 outcomes: drop, replace, insert)
- update best and worst transaction from that sender if affected
- Pending List construction:
- Take the best transaction (by priority) from all senders to the List
- Replace the transaction with next transaction (by ordering) from that sender (if any)
A transactions ordering abstraction.
The Error type.
Light pool status. This status is cheap to compute and can be called frequently.
A no-op implementation of
Transaction Pool options.
An iterator over all pending (ready) transactions.
NOTE: the transactions are not removed from the queue.
You might remove them later by calling
A transaction pool.
A full queue status.
To compute this status it is required to provide
Internal representation of transaction.
An iterator over all pending (ready) transactions in unoredered fashion.
The kind of an error.
Transaction pool listener.
A readiness indicator.
Already verified transaction that can be safely queued.