Fields

• isTxs :: !( TxSeq ( Validated ( GenTx blk)))

  Transactions currently in the mempool

  NOTE: the total size of the transactions in isTxs may exceed the current capacity ( isCapacity ). When the capacity computed from the ledger has shrunk, we don't remove transactions from the Mempool to satisfy the new lower limit. We let the transactions get removed in the normal way: by becoming invalid w.r.t. the updated ledger state. We treat a Mempool over capacity in the same way as a Mempool at capacity.

• isTxIds :: !( Set ( GenTxId blk))

  The cached IDs of transactions currently in the mempool.

  This allows one to more quickly lookup transactions by ID from a MempoolSnapshot (see snapshotHasTx ).

  This should always be in-sync with the transactions in isTxs .

• isLedgerState :: !( TickedLedgerState blk)

  The cached ledger state after applying the transactions in the Mempool against the chain's ledger state. New transactions will be validated against this ledger.

  INVARIANT: isLedgerState is the ledger resulting from applying the transactions in isTxs against the ledger identified isTip as tip.

• isTip :: !( ChainHash blk)

  The tip of the chain that isTxs was validated against

  This comes from the underlying ledger state ( tickedLedgerState )

• isSlotNo :: ! SlotNo

  The most recent SlotNo that isTxs was validated against

  This comes from applyChainTick ( tickedSlotNo ).

• isLastTicketNo :: ! TicketNo

  The mempool TicketNo counter.

  See vrLastTicketNo for more information.

• isCapacity :: ! MempoolCapacityBytes

  Current maximum capacity of the Mempool. Result of computeMempoolCapacity using the current chain's TickedLedgerState .

  NOTE: this does not correspond to isLedgerState , which is the TickedLedgerState after applying the transactions in the Mempool. There might be a transaction in the Mempool triggering a change in the maximum transaction capacity of a block, which would change the Mempool's capacity (unless overridden). We don't want the Mempool's capacity to depend on its contents. The mempool is assuming all its transactions will be in the next block. So any changes caused by that block will take effect after applying it and will only affect the next block.

Fields

• vrBeforeTip :: ChainHash blk

  The tip of the chain before applying these transactions

• vrSlotNo :: SlotNo

  The slot number of the (imaginary) block the txs will be placed in

• vrBeforeCapacity :: MempoolCapacityBytes

  Capacity of the Mempool. Corresponds to vrBeforeTip and vrBeforeSlotNo , not vrAfter .

• vrValid :: TxSeq ( Validated ( GenTx blk))

  The transactions that were found to be valid (oldest to newest)

• vrValidTxIds :: Set ( GenTxId blk)

  The cached IDs of transactions that were found to be valid (oldest to newest)

• vrNewValid :: Maybe ( Validated ( GenTx blk))

  A new transaction (not previously known) which was found to be valid.

  n.b. This will only contain a valid transaction that was newly added to the mempool (not a previously known valid transaction).

• vrAfter :: TickedLedgerState blk

  The state of the ledger after applying vrValid against the ledger state identifeid by vrBeforeTip .

• vrInvalid :: [(invalidTx, ApplyTxErr blk)]

  The transactions that were invalid, along with their errors

  From oldest to newest.

• vrLastTicketNo :: TicketNo

  The mempool TicketNo counter.

  When validating new transactions, this should be incremented, starting from isLastTicketNo of the InternalState . When validating previously applied transactions, this field should not be affected.