Use a per-queue dispatcher, not a global one

Using a single dispatcher never works with decorated functions and
context capturing: each time a new connection appears, it overwrites
the worker_ping method in the dispatcher.

The idea behind the original code was based on a momentary
misunderstanding of how Python’s decorators and scoping works.
It was supposed to have added a single entry point into the JSON RPC
dispatcher, which would capture the queue context from the enclosing
function, handle it and then call the actual worker_ping handler.

Unfortunately, that’s not how 1) decorators, 2) nested functions or 3)
scope capturing works in Python. The decorator just takes the function,
wraps in and returns it back (under the original name), with the context
already enclosed. However, .add_method decorators *also* adds the newly
created function into the global state of dispatcher, overwriting the
previously configured handler for worker_ping, resulting in all ping
messages going to the handler created while handling the last
connection.

The proper solution is, of course, to use a dispatcher per connection.
Signed-off-by: Andrej Shadura's avatarAndrej Shadura <andrew.shadura@collabora.co.uk>
parent 12dd5ae0
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