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.
When we fail to send to a SN but can retry (e.g. because we had an
incoming connection which no longer works, but can retry an outgoing
connection) we were recursing, but this was resulting in a double-free
of the request callback (since we'd try to take ownership of the
incoming serialized pointer twice).
Rewrite the code to use a loop with single ownership instead.
This also changes the request callback behaviour to fire a failure
callback immediately if we can't send a request; previously you'd have
to wait for a timeout, but that is pointless if we couldn't get the
request out.
For example:
lmq.request(conn, "some.method", callback, lokimq::request_timeout{5s});
will result in the callback being called with a failure if the response
doesn't arrive within 5s. (If it still arrives, but after the failure
callback, it gets dropped).
The previous 1s default seems on the long side; this reduces it to
250ms. It also makes it a public member so that it can be configured
(which is mainly needed for the test suite, but might be useful for
lokimq-calling code that needs faster or slower connection cleanups).
Having this as a vector seems to cause armhf/gcc-6 to segfault. On
closer inspection there's no good reason this should be a vector in the
first place: it only gets used during new connection handshaking and
isn't in any hot loop, plus the elements are fairly large tuples where
shifting elements is going to be relatively expensive. Thus switching
it to a list everywhere (rather than just on old gcc arm) seems fine.
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.
This removes two superfluous erases that occur during connection closing
(the proxy_close_connection just above them already removes the element
from `peers`), and also short-circuits the incoming message loop if our
pollitems becomes stale so that we don't try to use a closed connection.
It also fixes a bug in the outgoing connection index that was
decrementing the wrong connection indices, leading to failures when
trying to send on an existing connection after a disconnect.
Also adds a test case (which fails before the changes in this commit) to
test this.
This makes it much more convenience to use them with a run-time
condition; this simplifies:
if (should_be_optional)
lmq.send(..., send_option::optional{});
else
lmq.send(...);
to:
lmq.send(..., send_option::optional{should_be_optional});
This allows storing a ConnectionID received in a message callback and
using it later to send another message along the connection without
worrying about a routing id: the ConnectionID will have it if it is
required. Previously you would have had to store the ConnectionID *and*
the routing prefix, and then specified the route as a
send_option::route{}, which was annoying and cumbersome.
This adds a separate category (and reserve count) for "reply jobs",
which are jobs triggered by receiving a reply to a request, or after a
successful connect or unsuccessful timeout. Previously these were
scheduled as regular batch jobs; this schedules them as a new "reply
jobs" category with its own reserved threads count.
This also changes the defaults for batch jobs and reply jobs to be based
on the specified general workers count rather than directly on hardware
concurrency, so that if you are on a 16-thread CPU but override general
workers from its default of 16 to 4 and don't change batch workers you
now get reserved batch workers set to 2 rather than 8 which constrains
the typical parallel batch jobs to 4 (i.e. the general worker limit)
rather than exceeding it with the batch job limit.
Similarly for reply jobs, which is now ceil(general/8) by default.
The existing code was largely set up for SN-to-SN or client-to-SN
communications, where messages can always get to the right place because
we can always send by pubkey.
This doesn't work when we want general communications with a random
remote address.
This commit overhauls the way loki-mq handles communication in a few
important ways:
- Listening instances no longer pass bind addresses into the
constructor; instead they call `listen_curve()` or `listen_plain()`
before invoking `start()`.
- `listen_curve()` is equivalent to the existing bind support: it
listens on a socket and accepts encrypted handshaked connections from
anyone who already knows the server's public key.
- `listen_plain()` is all new: it sets up a plain text listening socket
over which random clients can connect and talk. End-points aren't
verified, and it isn't encrypted, but if you don't know who you are
talking to then encryption isn't doing anything anyway.
- Connecting to a remote now connections in CURVE encryption or NULL
(plain-text) encryption based on whether you provide a remote_pubkey.
For CURVE, the connection will fail if the pubkey does not match.
- `ConnectionID` objects are now returned when connecting to a remote
address; this object is then passed in to send/request/etc. to direct
the message. For SN communication, ConnectionID's can be created
implicitly from SN pubkey strings, so the existing interface of
`lmq.send(pubkey, ...)` will still work in most cases.
- A ConnectionID is now passed to the ConnectSuccess and ConnectFailure
callbacks. This can be used to uniquely identify which connection
succeeded or failed, and can determine whether the remote is a service
node (`.sn()`) and/or the pubkey (`.pubkey()`). (Obviously the service
node status is only available when the client can do service node
lookups, and the pubkey() is only non-empty for encrypted connections).
string_view isn't supposed to be implicitly convertible to std::string
and code would break compiling under c++17 (when our local string_view
is simply a std::string_view typedef).
Pre-C++17 char_traits::compare isn't constexpr so we can't constexpr the
find/rfind methods that use it.
begin() etc, however, can be constexpr (and need to be for some of the
other constexpr methods here that use them).
This was meant to be an optimization but doesn't actually work because
we don't do a ZAP request at all when connecting inproc sockets, so the
metadata we need never gets set.
Remove it so a SN can still connect to itself.
Fix bug from quorumnet transition; quorumnet set the user id to
something like "S:abc..." or "C:abc..." to indicate SN or non-SN, but
now that gets carried in a separate message property but the +2 on the
copying position was still erroneously being used.
Jason Rhinelander