This refactors the wallet notification code to reverse the order of
how notification contexts are stored. Before, watched addresses and
outpoints were used as keys, with a special reply channel as the
value. This channel was read from and replies were marshalled and
sent to the main wallet notification chan, but the goroutine handling
this marshalling never exited because the reply channel was never
closed (and couldn't have been, because there was no way to tell it
was handling notifications for any particular wallet).
Notification contexts are now primarily mapped by wallet notification
channels, and code to send the notifications send directly to the
wallet channel, with the previous goroutine reading the reply chan
properly closing.
The RPC code is also refactored with this change as well, to separate
it more from websocket code. Websocket JSON extensions are no longer
available to RPC clients.
While here, unbreak RPC. Previously, replies were never sent back.
This broke when I merged in my websocket code, as sends for the reply
channel in jsonRead blocked before a reader for the channel was
opened. A 3 liner could have fixed this, but doing a proper fix
(changing jsonRead so it did not use the reply channel as it is
unneeded for the standard RPC API) is preferred.
This change adds additional http listeners for websocket connections
on "/wallet". Websockets are used to provide asynchronous messaging
between wallet daemons (i.e. btcwallet) and btcd as they allow an easy
way for btcd to provide instant notifications (instead of a wallet
polling for updates) and multiple replies to a single request.
Standard RPC commands sent over a websocket connection are handled
just like RPC, returning the same results, the only difference being
that the connection is async. In cases where the standard RPC
commands fall short of wallet daemons requests, and to request
notifications for addresses and events, extension JSON methods are
used.
Multiple wallets can be connected to the same btcd, and replies to
websocket requests and notifications are properly routed back to the
original requesting wallet.
Due to the nature of turning a synchronous protocol asynchronous, it
is highly recommended to use the JSON id field as a type of sequence
number, so replies from btcd can be routed back to the proper handler
in a wallet daemon.
This commit is a first pass at improving the logging. It changes a number
of things to improve the readability of the output. The biggest addition
is message summaries for each message type when using the debug logging
level.
There is sitll more to do here such as allowing the level of each
subsystem to be independently specified, syslog support, and allowing the
logging level to be changed run-time.
This commit changes the code so that all calls to .Add on waitgroups
happen before the associated goroutines are launched. Doing this after
the goroutine could technically cause a race where the goroutine started
and finished before the main goroutine has a chance to increment the
counter. In our particular case none of the goroutines exit quickly
enough for this to be an issue, but nevertheless the correct way should be
used.
