This matches the recent change made to bitcoin core wallet, and
follows roughly a year after the minimum mempool relay fee/kB was
dropped to the same value.
This commit is the result of several big changes being made to the
wallet. In particular, the "handshake" (initial sync to the chain
server) was quite racy and required proper synchronization. To make
fixing this race easier, several other changes were made to the
internal wallet data structures and much of the RPC server ended up
being rewritten.
First, all account support has been removed. The previous Account
struct has been replaced with a Wallet structure, which includes a
keystore for saving keys, and a txstore for storing relevant
transactions. This decision has been made since it is the opinion of
myself and other developers that bitcoind accounts are fundamentally
broken (as accounts implemented by bitcoind support both arbitrary
address groupings as well as moving balances between accounts -- these
are fundamentally incompatible features), and since a BIP0032 keystore
is soon planned to be implemented (at which point, "accounts" can
return as HD extended keys). With the keystore handling the grouping
of related keys, there is no reason have many different Account
structs, and the AccountManager has been removed as well. All RPC
handlers that take an account option will only work with "" (the
default account) or "*" if the RPC allows specifying all accounts.
Second, much of the RPC server has been cleaned up. The global
variables for the RPC server and chain server client have been moved
to part of the rpcServer struct, and the handlers for each RPC method
that are looked up change depending on which components have been set.
Passthrough requests are also no longer handled specially, but when
the chain server is set, a handler to perform the passthrough will be
returned if the method is not otherwise a wallet RPC. The
notification system for websocket clients has also been rewritten so
wallet components can send notifications through channels, rather than
requiring direct access to the RPC server itself, or worse still,
sending directly to a websocket client's send channel. In the future,
this will enable proper registration of notifications, rather than
unsolicited broadcasts to every connected websocket client (see
issue #84).
Finally, and the main reason why much of this cleanup was necessary,
the races during intial sync with the chain server have been fixed.
Previously, when the 'Handshake' was run, a rescan would occur which
would perform modifications to Account data structures as
notifications were received. Synchronization was provided with a
single binary semaphore which serialized all access to wallet and
account data. However, the Handshake itself was not able to run with
this lock (or else notifications would block), and many data races
would occur as both notifications were being handled. If GOMAXPROCS
was ever increased beyond 1, btcwallet would always immediately crash
due to invalid addresses caused by the data races on startup. To fix
this, the single lock for all wallet access has been replaced with
mutexes for both the keystore and txstore. Handling of btcd
notifications and client requests may now occur simultaneously.
GOMAXPROCS has also been set to the number of logical CPUs at the
beginning of main, since with the data races fixed, there's no reason
to prevent the extra parallelism gained by increasing it.
Closes#78.
Closes#101.
Closes#110.
This package is used solely for the storage of private and public
keys, and the addresses they represent. Since "wallet" is an
overloaded term and a working wallet requires transaction history as
well, rename this package and its data structures to more clearly
reflect what it is for.
When a BIP0032 wallet is implemented and multiple address chains can
be supported by a single keystore, the Account structure will
represent a single wallet (and be renamed to reflect that change),
rather than keeping the collection of Account structs as currently
managed by the AccountManager. In preperation for this, and to remove
a global variable, move the fee increment for created transactions to
this structure. When setting the fee, look it up from the default
account.
Pass the RPC client to the notification handlers. Update the last
seen block for blockconnected notifications in the client structure
directly, protecting access with a mutex.
The Credit and Debits structures are simple wrappers around an
embedded *txstore.TxRecord, as well as an output index in the case of
Credit. This means that a Credit is at most two words, while a Debits
struct is just one. To avoid the unnecessary garbage of creating
Credit and Debits structures on the heap (where the underlying
TxRecord likely already is), simply pass around everywhere as
non-pointer types, and modify the receivers for all Credit and Debits
methods to non-pointer receivers since none of them ever modify the
value.
Unspent inputs were being sorted multiple times in an inner loop.
This change moves the sort outside the loop so it is only performed
once. While here, also move the transaction confirmation filter
outside the inner loop, as these can be calculated just once.
This change is the result of using the errcheck tool
(https://github.com/kisielk/errcheck) to find all unchecked errors,
both unassigned and those assigned to the blank identifier.
Every returned error is now handled in some manner. These include:
- Logging errors that would otherwise be missed
- Returning errors to the caller for further processing
- Checking error values to determine what to do next
- Panicking for truely exceptional "impossible" errors
On the subject of panics, they are a sharp tool and should be used
sparingly. That being said, I have added them to check errors that
were previously explicitly ignored, because they were expected to
always return without failure. This could be due to fake error paths
(i.e. writing to a bytes.Buffer panics for OOM and should never return
an error) or previous logic asserts that an error case is impossible.
Rather than leaving these unhandled and letting code fail later,
either with incorrect results or a nil pointer dereference, it now
produces a stack trace at the error emit site, which I find far more
useful when debugging.
While here, a bunch of dead code was removed, including code to move
pre-0.1.1 uxto and transaction history account files to the new
directory (as they would be unreadable anyways) and a big chunk of
commented out rpcclient code.
This is an intial pass at converting the btcwallet and deps codebases
to pass a network by their parameters, rather than by a magic number
to identify the network. The parameters in params.go have been
updated to embed a *btcnet.Params, and all previous uses of cfg.Net()
have been replaced with activeNet.{Params,Net} (where activeNet is
the global var for the active network).
Although dependancy packages have not yet been updated from using
btcwire.BitcoinNet to btcnet.Params, the parameters are now accessible
at all callsites, and individual packages can be updated to use btcnet
without requiring updates in each external btc* package at once.
While here, the exported API for btcwallet internal library packages
(txstore and wallet) have been updated to pass full network parameters
rather than the btcwire definition of a network.
The category for a received coinbase output should be "generate" for a
mature coinbase (one that has reached btcchain.CoinbaseMaturity
confirmations), or "immature" if the required number of confirmations
has not been reached yet. New Confirmed and Confirmations methods
have been added to the transaction store's TxRecord type to check if
the required number of confirmations have been met for coinbase
outputs.
While here, update the main package to use the new TxRecord methods,
rather than duplicating the confirmation checking code in two places.
The last transaction store was a great example of how not to write
scalable software. For a variety of reasons, it was very slow at
processing transaction inserts. Among them:
1) Every single transaction record being saved in a linked list
(container/list), and inserting into this list would be an O(n)
operation so that records could be ordered by receive date.
2) Every single transaction in the above mentioned list was iterated
over in order to find double spends which must be removed. It is
silly to do this check for mined transactions, which already have
been checked for this by btcd. Worse yet, if double spends were
found, the list would be iterated a second (or third, or fourth)
time for each removed transaction.
3) All spend tracking for signed-by-wallet transactions was found on
each transaction insert, even if the now spent previous transaction
outputs were known by the caller.
This list could keep going on, but you get the idea. It was bad.
To resolve these issues a new transaction store had to be implemented.
The new implementation:
1) Tracks mined and unmined transactions in different data structures.
Mined transactions are cheap to track because the required double
spend checks have already been performed by the chain server, and
double spend checks are only required to be performed on
newly-inserted mined transactions which may conflict with previous
unmined transactions.
2) Saves mined transactions grouped by block first, and then by their
transaction index. Lookup keys for mined transactions are simply
the block height (in the best chain, that's all we save) and index
of the transaction in the block. This makes looking up any
arbitrary transaction almost an O(1) operation (almost, because
block height and block indexes are mapped to their slice indexes
with a Go map).
3) Saves records in each transaction for whether the outputs are
wallet credits (spendable by wallet) and for whether inputs debit
from previous credits. Both structures point back to the source
or spender (credits point to the transaction that spends them, or
nil for unspent credits, and debits include keys to lookup the
transaction credits they spent. While complicated to keep track
of, this greatly simplifies the spent tracking for transactions
across rollbacks and transaction removals.
4) Implements double spend checking as an almost O(1) operation. A
Go map is used to map each previous outpoint for all unconfirmed
transactions to the unconfirmed tx record itself. Checking for
double spends on confirmed transaction inserts only involves
looking up each previous outpoint of the inserted tx in this map.
If a double spend is found, removal is simplified by only
removing the transaction and its spend chain from store maps,
rather than iterating a linked list several times over to remove
each dead transaction in the spend chain.
5) Allows the caller to specify the previous credits which are spent
by a debiting transaction. When a transaction is created by
wallet, the previous outputs are already known, and by passing
their record types to the AddDebits method, lookups for each
previously unspent credit are omitted.
6) Bookkeeps all blocks with transactions with unspent credits, and
bookkeeps the transaction indexes of all transactions with unspent
outputs for a single block. For the case where the caller adding a
debit record does not know what credits a transaction debits from,
these bookkeeping structures allow the store to only consider known
unspent transactions, rather than searching through both spent and
unspents.
7) Saves amount deltas for the entire balance as a result of each
block, due to transactions within that block. This improves the
performance of calculating the full balance by not needing to
iterate over every transaction, and then every credit, to determine
if a credit is spent or unspent. When transactions are moved from
unconfirmed to a block structure, the amount deltas are incremented
by the amount of all transaction credits (both spent and unspent)
and debited by the total amount the transaction spends from
previous wallet credits. For the common case of calculating a
balance with just one confirmation, the only involves iterating
over each block structure and adding the (possibly negative)
amount delta. Coinbase rewards are saved similarly, but with a
different amount variable so they can be seperatly included or
excluded.
Due to all of the changes in how the store internally works, the
serialization format has changed. To simplify the serialization
logic, support for reading the last store file version has been
removed. Past this change, a rescan (run automatically) will be
required to rebuild the transaction history.
- Instead of returning a special constructed type whenever queries for an
address. Return the internal object with an immutable external
interface.
- Make the private key gettable from PubKeyAddress to prevent having to look up
multiple times to get information from the same structure
- Enforce addresses always have public keys.
Shortly we will add new types of address, so make AddressInfo an
interface, with concrete types providing address-specific information.
Adapt existing code to this new status quo.
This change replaces the old transaction store file format and
implementation. The most important change is how the full backing
transactions for any received or sent transaction are now saved,
rather than simply saving parsed-out details of the tx (tx shas, block
height/hash, pkScripts, etc.).
To support the change, notifications for received transaction outputs
and txs spending watched outpoints have been updated to use the new
redeemingtx and recvtx notifications as these contain the full tx,
which is deserializead and inserted into the store.
The old transaction store serialization code is completely removed, as
updating to the new format automatically cannot be done. Old wallets
first running past this change will error reading the file and start a
full rescan to rebuild the data. Unlike previous rescan code,
transactions spending outpoint managed by wallet are also included.
This results in recovering not just received history, but history for
sent transactions as well.
Use the new confirmed function to test whether unspent transaction
outputs are confirmed enough to be used as a possible transaction
inputs instead of the old check (which was incorrect and required an
extra confirmation).
Modified the test to require one confirmation instead of none so the
confirmed enough check actually occurs.
Previous to this commit, all change addresses were indistinguishable
from manually requested addresses. This adds a new function to return
the new address, setting a new change flag to true, and return the
change status with the AddressInfo.
This is needed as part of resolving #41 (getrawchangeaddress).
This change removes the three separate mutexes which used to lock an
account's wallet, tx store, and utxo store. Accounts no longer
contain any locking mechanism and rely on go's other synchronization
constructs (goroutines and channels) for correct access.
All accounts are now managed as a collection through the new
AccountManager, rather than the old AccountStore. AccountManager runs
as its own goroutine to provide access to accounts.
RPC requests are now queued for handling, being denied if the queue
buffer is exhausted. Notifications are also queued (instead of being
sent from their own goroutine after being received, in which order is
undefined), however, notifications are never dropped and will
potentially grow a queue of infinite size if unhandled.
Boolean options cannot be unset from a default true value on the
command line, so invert the allowfree option, renaming it
disallowfree, so attaching fees may always be forced by specifying
disallowfree = true in the configuration file, or --disallowfree on
the command line.
It may be desirable to never allow free transactions, even if the
calculated priority is high enough that a fee would not be required,
so this change adds a global configuration option to remove this check
and always attach a fee.
