ValueBuffer is now the default buffer object for storing data for
recording and processing purposes, a simple recording implementation has
been done, core.py example starts recording as soon as the core has
started then on exit it saves the output as a csv file through the
ValueBuffer export_csv method
Added timestamping to ValueDescriptor to be able to record on a
timebase, timebase uses monotonic_ns() which is a system wide timebase
that can be called by connectors written in a host of languages
Added timeout to signal descriptors, live values now return None when
they are timed out
Live values are stored in the core and their fetch is relatively cheap
as it only requires locking the core live values lock
Signal descriptors are a much heavier call as they query the connector
registry and trigger an O(n) search throughout the different endpoints,
this method is not meant to be used heavily as it requires locking
multiple locks and handling alot of data, this method is meant to be
called once to retreive a list of signal descriptors that the user can
then store and use to reference values against in their frontend code
Removed useless tests, will need to complete a more comprehensive test
suite however this is not the priority right now
Added a live value dict in the core whose values are populated by the
core's input thread
Implemented handshake in json server and handoff to endpoint
Endpoint handles connector handshake accept/decline then launches both
its IO threads alongside its heartbeat thread which contains simple
timeout logic, timeout calls connection handles to close, subsequently
killing the endpoint
Isolated the JsonServer to server.py inside protocols/json
Added specific errors for server startup timeout and server startup
failed
Refactored errors for Core to CoreError generic and refactored
StateError to CoreStateMismatchError derived from CoreError
h3cx