When a pipe processes a delimiter and is already not in active state but still
has an unfinished message, the message is leaked.
Solution: issue a rollback before losing the reference to the pipe.
ZMQ_ROUTER_NOTIFY doesn't have a context and doesn't play nice with protocols. with ZMQ_DISCONNECT_MSG we can set it to a protocol message, like DISCONNECT in majordomo. Router will send it when a peer is disconnected. Another advantage of ZMQ_DISCONNECT_MSG is that it also works on inproc.
Together with ZMQ_HEARTBEAT it allows to build very reliable protocols, and much simpler as well.
When using ZMQ_HEARTBEAT one still needs to implement application-level heartbeat in order to know when to send a hello message.
For example, with the majordomo protocol, the worker needs to send a READY message when connecting to a broker. If the connection to the broker drops, and the heartbeat recognizes it the worker won't know about it and won't send the READY msg.
To solve that, the majordomo worker still has to implement heartbeat. With this new option, whenever the connection drops and reconnects the hello message will be sent, greatly simplify the majordomo protocol, as now READY and HEARTBEAT can be handled by zeromq.
Solution: add API and ZMQ_EVENT_PIPES_STATS event which generates 2
values, one for the egress and one for the ingress pipes respectively.
Refactor the events code to be able to send multiple values.
Solution: initialise *hwmboost to -1 instead of 1, and use it only if
it's >= 0. The socket option code checks anyway that the
user-provided value is >= 0 so there is no risk of clashing. The
documentation also specifies that it has to be >= 0.
Solution: The Coverity Static Code Analyzer was used on libzmq code and found
many issues with uninitialized member variables, some redefinition of variables
hidding previous instances of same variable name and a couple of functions
where return values were not checked, even though all other occurrences were
checked (e.g. init_size() return).
This reduces chances of race between writer deactivation and activation.
Reader sends activation command to writer when number or messages is
multiple of LWM. In situation with high throughput (millions of messages
per second) and correspondingly large HWM (e.g. 10M) the difference
between HWM needs to be large enough - so that activation command is
received before pipe becomes full.
Of course people still "can" distributed the sources under the
LGPLv3. However we provide COPYING.LESSER with additional grants.
Solution: specify these grants in the header of each source file.
