Deriving private keys from BIP32 paths, public keys from private keys,
scripts from public keys, and addresses from scripts are some of the
most CPU-intensive tasks the wallet performs. Once the wallet inevitably
accumulates thousands of used paths, startup times become painful due to
needing to re-derive these data items for every used path in the wallet
upon every startup. Introduce a persistent cache to avoid the need to
re-derive these items every time the wallet is opened.
Introduce _get_keypair_from_path and _get_pubkey_from_path methods to
allow cached public keys to be used rather than always deriving them on
the fly.
Change many code paths that were calling CPU-intensive methods of
BTCEngine so that instead they call _get_key_from_path,
_get_keypair_from_path, _get_pubkey_from_path, get_script_from_path,
and/or get_address_from_path, all of which can take advantage of the new
cache.
Hoist _populate_script_map from BIP32Wallet into BaseWallet, rename it
to _populate_maps, and have it populate the new _addr_map in addition to
the existing _script_map. Have the constructor of each concrete wallet
subclass pass to _populate_maps the paths it contributes. Additionally,
do not implement yield_known_paths by iterating over _script_map, but
rather have each wallet subclass contribute its own paths to the
generator returned by yield_known_paths.
Sometimes calling code is only interested in the balance or UTXOs at a
single mixdepth. In these cases, it is wasteful to get the balance or
UTXOs at all mixdepths, only to throw away the returned information
about all but the single mixdepth of interest. Implement new methods in
BaseWallet to get the balance or UTXOs at a single mixdepth.
Also, correct an apparent oversight due to apparently misplaced
indentation: the maxheight parameter of get_balance_by_mixdepth was
ignored unless the include_disabled parameter was passed as False. It
appears that the intention was for include_disabled and maxheight to be
independent filters on the returned information.
Matt Whitlock
roshii