This rewrites the shutdown logic to simplify the shutdown signalling.
All cleanup is now run from deferred functions in the main function and
channels are used to signal shutdown either from OS signals or from
other subsystems such as the RPC server and windows service controller.
The RPC server has been modified to use a new channel for signalling
shutdown that is exposed via the RequestedProcessShutdown function
instead of directly calling Stop on the server as it previously did.
Finally, it adds a few checks for early termination during the main
start sequence so the process can be stopped without starting all the
subsystems if desired.
This is a backport of the equivalent logic from Decred with a few slight
modifications. Credits go to @jrick.
This commit modifies btcd to run cleanly as a Windows service. btcd is
intended to be a long running process that stays synchronized with the
bitcoin block chain and provides chain services to multiple users. It
follows that a service is the best option on Windows for this
functionality.
A few key points are:
- Supports graceful shutdown via the service stop/shutdown commands
- Integrates cleanly with the Windows event log
- Adds a new /s flag that can be used to install/remove/start/stop the
service
One outstanding issue is that the application data directory is currently
user specific which means, by default, if you start btcd as a user, the
same data won't be used as when it's running as a service. This needs to
be resovled. The most likely approach will be to put all data into the
common appdata directory Windows provides, but it will require some
additional work to deal with permissions properly as user processes can't
write there by default.
Closes#42.
