This a refactor of the btcwallet main package to create a new wallet
package.
The main feature of this package is the integration of all the other
wallet components (waddrmgr, txstore, and chain) and the Wallet type is
'runnable', so it will be continuously updating itself against changes
notified by the remote btcd instance.
It also includes several methods which provide access to information
necessary to run a wallet RPC server.
Otherwise, if the websocket connection to btcd is lost and
reestablished, there is no sync to the current best block, and btcd
will not notify wallet of new relevant transactions.
This was previously using the most recently notified (by the chain
package) block, but transaction processing from this block may not be
finished yet. Using this block's height to calculate the number of
confirmations is therefore incorrect, and can result in every RPC
handler missing transactions or returning transactions from the wrong
block.
Wallet should handle these so that wallet clients don't end up
creating requests to btcd about the latest processed block, which is
not the same as wallet's most recently processed block.
By providing wallet clients with this info, we avoid a race where the
client thinks wallet has processed N blocks, but in fact is still
synced to N-1 (and perhaps currently processing transactions from
block N). This can cause unexpected results for many of the
bitcoind-compatible RPC APIs due to their reliance on number of
confirmations, rather than using absolute block heights.
This commit converts the wallet to use the new secure hierarchical
deterministic wallet address manager package as well as the walletdb
package.
The following is an overview of modified functionality:
- The wallet must now be created before starting the executable
- A new flag --create has been added to create the new wallet using wizard
style question and answer prompts
- Starting the process without an existing wallet will instruct now
display a message to run it with --create
- Providing the --create flag with an existing wallet will simply show an
error and return
In addition the snacl package has been modified to return the memory after
performing scrypt operations to the OS.
Previously a runtime.GC was being invoked which forced it to release the
memory as far as the garbage collector is concerned, but the memory was
not released back to the OS immediatley. This modification allows the
memory to be released immedately since it won't be needed again until the
next wallet unlock.
The notified chain server connection state was being passed through
the wallet and then notified to the RPC server, which prevented this
notification from ever firing if a wallet didn't exist yet. Instead,
make the RPC server register for these notifications directly from the
chain server RPC client.
I'm not happy with this notification and how it's handled in the code,
but to not break existing clients this change is being made. Fixing
the notifiation mess and modifying existing clients to use a new
notification API will need to be done sometime later.
Addresses do no have balances. In situations where a payment is
required and just a single address was provided, it is better to track
the unspent outputs themselves, rather than watching some artificial
measure of payment.
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.
