From 8004c10f3960e189d0dd67c8788172e625788f06 Mon Sep 17 00:00:00 2001 From: std-any-emplace Date: Sun, 19 Jan 2020 09:54:11 +0100 Subject: [PATCH] Documentation fix regarding thread-safety of zmq_poll/zmq_poller.txt. See https://github.com/zeromq/libzmq/issues/3778. --- doc/zmq_poll.txt | 10 ++++++++++ doc/zmq_poller.txt | 11 +++++++++-- 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/doc/zmq_poll.txt b/doc/zmq_poll.txt index a55941f7..726064e1 100644 --- a/doc/zmq_poll.txt +++ b/doc/zmq_poll.txt @@ -80,6 +80,16 @@ NOTE: The _zmq_poll()_ function may be implemented or emulated using operating system interfaces other than _poll()_, and as such may be subject to the limits of those interfaces in ways not defined in this documentation. +THREAD SAFETY +------------- +The *zmq_pollitem_t* array must only be used by the thread which +will/is calling _zmq_poll_. + +If a socket is contained in multiple *zmq_pollitem_t* arrays, each owned by a +different thread, the socket itself needs to be thead-safe (Server, Client, ...). +Otherwise, behaviour is undefined. + + RETURN VALUE ------------ Upon successful completion, the _zmq_poll()_ function shall return the number diff --git a/doc/zmq_poller.txt b/doc/zmq_poller.txt index 00ee2624..070862db 100644 --- a/doc/zmq_poller.txt +++ b/doc/zmq_poller.txt @@ -56,8 +56,11 @@ In addition, _user_data_ may be specified, which is not used by the poller, but passed back to the caller when an event was signalled in a call to _zmq_poller_wait_ or _zmq_poller_wait_all_. _user_data_ may be NULL. If it is not NULL, it must be a valid pointer. Otherwise, behaviour is undefined. -_zmq_poller_add_ may not be called multiple times for the same socket -(unless _zmq_poller_remove_ has been called for that socket). +You must only add a socket to a single poller instance once (unless +_zmq_poller_remove_ has been called for that socket before). You may +add a socket to multiple poller instances, if the socket itself +is explicitly thread-safe (Server, Client, ...). If the socket is not, +you may invoke undefined behavior. _zmq_poller_modify_ modifies the subscribed events for a socket. It is legal to specify no events (i.e. 0) to disable events temporarily, and @@ -183,6 +186,10 @@ THREAD SAFETY Like most other 0MQ objects, a poller is not thread-safe. All operations must be called from the same thread. Otherwise, behaviour is undefined. +In addition to that, if you want to add a socket to multiple existing poller +instances, the socket itself needs to be thread-safe (Server, Client, ...). +Otherwise, behaviour is undefined. + RETURN VALUE ------------ _zmq_poller_new_ returns a valid pointer to a poller, or NULL in case of a failure.