This allows making any message handler async in lnpeer.
Note: `process_message` is only called from `_message_loop`.
There are(would be) basically three types of message handlers:
1. "traditional blocking msg handlers". non-async ones. When these handlers are called, `process_message` naturally blocks until the handler returns, which means `_message_loop` also blocks until the message is fully processed before starting the next iteration.
2. "async blocking msg handlers". async ones where we want the previous property, i.e. we want the `_message_loop` to wait until the handler finishes. We await the handler inside `process_message`, and `_message_loop` awaits `process_message`.
3. "async non-blocking msg handlers". async message handlers that can be spawned e.g. onto `Peer.taskgroup` and the loop is free to start processing subsequent messages. e.g. msg handlers that start a negotiation, such as `on_shutdown` and `on_open_channel`.
Any non-async message handler (`def on_...`) automatically goes into category 1.
An async message handler, by default, goes into category 2, "blocking";
to go into category 3 ("non-blocking"), we use the `runs_in_taskgroup` function decorator.
Previously, generally, in case of any error, commands would raise a generic "Exception()" and the CLI/RPC would convert that and return it as `str(e)`.
With this change, we now distinguish "user-facing exceptions" (e.g. "Password required" or "wallet not loaded") and "internal errors" (e.g. bugs).
- for "user-facing exceptions", the behaviour is unchanged
- for "internal errors", we now pass around the traceback (e.g. from daemon server to rpc client) and show it to the user (previously, assuming there was a daemon running, the user could only retrieve the exception from the log of that daemon). These errors use a new jsonrpc error code int (code 2).
As the logic only changes for "internal errors", I deem this change not to be compatibility-breaking.
----------
Examples follow.
Consider the following two commands:
```
@command('')
async def errorgood(self):
from electrum.util import UserFacingException
raise UserFacingException("heyheyhey")
@command('')
async def errorbad(self):
raise Exception("heyheyhey")
```
----------
(before change)
CLI with daemon:
```
$ ./run_electrum --testnet daemon -d
starting daemon (PID 9221)
$ ./run_electrum --testnet errorgood
heyheyhey
$ ./run_electrum --testnet errorbad
heyheyhey
$ ./run_electrum --testnet stop
Daemon stopped
```
CLI without daemon:
```
$ ./run_electrum --testnet -o errorgood
heyheyhey
$ ./run_electrum --testnet -o errorbad
heyheyhey
```
RPC:
```
$ curl --data-binary '{"id":"curltext","jsonrpc":"2.0","method":"errorgood","params":[]}' http://user:pass@127.0.0.1:7777
{"id": "curltext", "jsonrpc": "2.0", "error": {"code": 1, "message": "heyheyhey"}}
$ curl --data-binary '{"id":"curltext","jsonrpc":"2.0","method":"errorbad","params":[]}' http://user:pass@127.0.0.1:7777
{"id": "curltext", "jsonrpc": "2.0", "error": {"code": 1, "message": "heyheyhey"}}
```
----------
(after change)
CLI with daemon:
```
$ ./run_electrum --testnet daemon -d
starting daemon (PID 9254)
$ ./run_electrum --testnet errorgood
heyheyhey
$ ./run_electrum --testnet errorbad
(inside daemon): Traceback (most recent call last):
File "/home/user/wspace/electrum/electrum/daemon.py", line 254, in handle
response['result'] = await f(*params)
File "/home/user/wspace/electrum/electrum/daemon.py", line 361, in run_cmdline
result = await func(*args, **kwargs)
File "/home/user/wspace/electrum/electrum/commands.py", line 163, in func_wrapper
return await func(*args, **kwargs)
File "/home/user/wspace/electrum/electrum/commands.py", line 217, in errorbad
raise Exception("heyheyhey")
Exception: heyheyhey
internal error while executing RPC
$ ./run_electrum --testnet stop
Daemon stopped
```
CLI without daemon:
```
$ ./run_electrum --testnet -o errorgood
heyheyhey
$ ./run_electrum --testnet -o errorbad
0.78 | E | __main__ | error running command (without daemon)
Traceback (most recent call last):
File "/home/user/wspace/electrum/./run_electrum", line 534, in handle_cmd
result = fut.result()
File "/usr/lib/python3.10/concurrent/futures/_base.py", line 458, in result
return self.__get_result()
File "/usr/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
raise self._exception
File "/home/user/wspace/electrum/./run_electrum", line 255, in run_offline_command
result = await func(*args, **kwargs)
File "/home/user/wspace/electrum/electrum/commands.py", line 163, in func_wrapper
return await func(*args, **kwargs)
File "/home/user/wspace/electrum/electrum/commands.py", line 217, in errorbad
raise Exception("heyheyhey")
Exception: heyheyhey
```
RPC:
```
$ curl --data-binary '{"id":"curltext","jsonrpc":"2.0","method":"errorgood","params":[]}' http://user:pass@127.0.0.1:7777
{"id": "curltext", "jsonrpc": "2.0", "error": {"code": 1, "message": "heyheyhey"}}
$ curl --data-binary '{"id":"curltext","jsonrpc":"2.0","method":"errorbad","params":[]}' http://user:pass@127.0.0.1:7777
{"id": "curltext", "jsonrpc": "2.0", "error": {"code": 2, "message": "internal error while executing RPC", "data": {"exception": "Exception('heyheyhey')", "traceback": "Traceback (most recent call last):\n File \"/home/user/wspace/electrum/electrum/daemon.py\", line 254, in handle\n response['result'] = await f(*params)\n File \"/home/user/wspace/electrum/electrum/commands.py\", line 163, in func_wrapper\n return await func(*args, **kwargs)\n File \"/home/user/wspace/electrum/electrum/commands.py\", line 217, in errorbad\n raise Exception(\"heyheyhey\")\nException: heyheyhey\n"}}}
```
- scenario:
- reuse same seed between two devices, LN enabled on both
- open channel using device1, import chan backup on device2
- local-force-close channel using device1
- tx1 (ctx) gets into mempool (or even mined), tx2 (sweep tx for to_local) is a local (future) tx
- history tab on device1 shows tx1 and tx2
- history tab on device2 was showing only tx2, and no info about tx1
- device2 knows about tx1, it was just not showing it previously.
With this commit, tx1 is now shown in the history.
- note: tx1 might linger in the mempool for an indeterminate amount of time, or even become local.
During that time, it is confusing on device2 not to show any feedback. Also,
if tx1 becomes local, it is useful to be able to rebroadcast it.
was getting log spam when running the pycharm debugger in certain cases:
```
3.29 | E | concurrent.futures | exception calling callback for <Future at 0x1d4987bcc70 state=cancelled>
Traceback (most recent call last):
File "...\Python310\lib\concurrent\futures\_base.py", line 342, in _invoke_callbacks
callback(self)
File "...\electrum\electrum\util.py", line 1785, in on_done
if exc := fut_.exception():
File "...\Python310\lib\concurrent\futures\_base.py", line 485, in exception
raise CancelledError()
concurrent.futures._base.CancelledError
```
```
$ ./electrum/scripts/quick_start.py
Traceback (most recent call last):
File "/home/user/wspace/electrum/./electrum/scripts/quick_start.py", line 32, in <module>
wallet.start_network(network)
File "/home/user/wspace/electrum/electrum/wallet.py", line 620, in start_network
assert self.network is None, "already started"
AssertionError: already started
```
just the sanity check added in 6ac3f84095
user complained:
> when you want to sweep an address. it's very unclear to me as a noob who is getting the money
> might want a little picture with an arrow to show which direction the funds are going
ghost43
Sander van Grieken