Various small C++17 code improvements.
Replace mapbox::variant with std::variant.
Remove the bt_u64 type wrapper; instead we know have `bt_value` which
wraps a variant holding both int64_t and uint64_t, and has contructors
to send signed/unsigned integer types into the appropriate one.
lokimq::get_int checks both as appropriate during extraction.
As a side effect this means we no longer do the uint64_t -> int64_t
conversion on the wire, ever, without needing the wrapper; although this
can break older versions sending large positive integers (i.e. larger
than int64_t max) those weren't actually working completely reliably
with mapbox variant anyway, and the one place using such a value in loki
core (in a checksum) is already fully upgraded across the network
(currently using bt_u64, but always sending a positive value on the
wire).
Removes lokimq::string_view (the type alias is still provided for
backwards compat, but now is always std::string_view).
Bump version (on dev branch) to 1.2.0
This replaces the recognition of SN status to be checked per-command
invocation rather than on connection. As this breaks the API quite
substantially, though doesn't really affect the functionality, it seems
suitable to bump the minor version.
This requires a fundamental shift in how the calling application tells
LokiMQ about service nodes: rather than using a callback invoked on
connection, the application now has to call set_active_sns() (or the
more efficient update_active_sns(), if changes are readily available) to
update the list whenever it changes. LokiMQ then keeps this list
internally and uses it when determining whether to invoke.
This release also brings better request responses on errors: when a
request fails, the data argument will now be set to the failure reason,
one of:
- TIMEOUT
- UNKNOWNCOMMAND
- NOT_A_SERVICE_NODE (the remote isn't running in SN mode)
- FORBIDDEN (auth level denies the request)
- FORBIDDEN_SN (SN required and the remote doesn't see us as a SN)
Some of these (UNKNOWNCOMMAND, NOT_A_SERVICE_NODE, FORBIDDEN) were
already sent by remotes, but there was no connection to a request and so
they would log a warning, but the request would have to time out.
These errors (minus TIMEOUT, plus NO_REPLY_TAG signalling that a command
is a request but didn't include a reply tag) are also sent in response
to regular commands, but they simply result in a log warning showing the
error type and the command that caused the failure when received.
We really don't *ever* want send to block, no matter how it is called,
since the send is always in the proxy thread. This makes the actual
send call always non-blocking, and adds callbacks that we can invoke on
send failures: either on queue full errors (which might be recoverable),
or both full queue and hard failures (which are generally not
recoverable). These callbacks are both optional: they have to be passed
in using `send_option::queue_full` (if you just want queue full
notifies) or `send_option::queue_failure` (if you want queue full
notifies *and* other send exceptions).
When we try to route an internal message ("BYE", "NOT_A_SERVICE_NODE",
etc.) back to the remote from the proxy thread we can end up trying to
send to a disconnected remote, which raises an exception, but this isn't
caught in proxy code: fix this by catching and ignoring it.
This also changes the code to send these messages in "dontwait" mode so
that if we can't queue the message we get (and ignore) an exception
rather than blocking.
lokimq.cpp and lokimq.h were getting monolithic; this splits lokimq.cpp
into multiple smaller cpp files by logical purpose for better parallel
compilation ability. It also splits up the lokimq.h header slightly by
moving the ConnectionID and Message types into their own headers.
Jason Rhinelander