Mempool Transactions
Zecwallet Lite now supports instant notifications of incoming transactions by scanning the mempool! This is available in v1.7.2, which is downloadable from www.zecwallet.co or from the iOS App store or Play App store
Efficiently scanning the mempool
Zecwallet implements mempool scanning via a new LightwalletD API that streams transactions in the mempool to the client, where they are scanned to see if they belong to the wallet.
Up until now, fetching mempool transactions was very inefficient, especially on the battery, since it effectively required polling LightwalletD for new transactions every few seconds.
The new LightwalletD API uses a long-lived stream (which is a gRPC feature) that keeps a persistent, low-power stream open to the LightwalletD server. As soon as LightwalletD sees a new transaction in the mempool, it streams it to the client, which then scans it.
- This is very battery efficient, allowing the Wifi/Cellular Radio to operate in low-power mode
- It is efficient, since there is no duplication of data, no polling and no waking up the CPU/Radio every few seconds
- It allows the transactions to be scanned as soon as they are in the mempool, updating Zecwallet near-instant.
- A great side effect of this API is that it allows the client to monitor when new blocks are mined. This means that the wallet is always up-to-date with the zcash chain.
Next Steps
This new mempool API allows the wallet to keep up-to-date with the chain tip much more efficiently, which will allow Zecwallet to detect reorgs early. This will, in turn allow more recent funds to be spent - i.e., You won’t have to wait for confirmations to spend your funds anymore. The next version of Zecwallet will allow spending funds with just 1 confirmation.