diff options
Diffstat (limited to '3rdparty/libuv/docs/src/poll.rst')
-rw-r--r-- | 3rdparty/libuv/docs/src/poll.rst | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/3rdparty/libuv/docs/src/poll.rst b/3rdparty/libuv/docs/src/poll.rst new file mode 100644 index 00000000000..6dc41839ac1 --- /dev/null +++ b/3rdparty/libuv/docs/src/poll.rst @@ -0,0 +1,103 @@ + +.. _poll: + +:c:type:`uv_poll_t` --- Poll handle +=================================== + +Poll handles are used to watch file descriptors for readability and +writability, similar to the purpose of :man:`poll(2)`. + +The purpose of poll handles is to enable integrating external libraries that +rely on the event loop to signal it about the socket status changes, like +c-ares or libssh2. Using uv_poll_t for any other purpose is not recommended; +:c:type:`uv_tcp_t`, :c:type:`uv_udp_t`, etc. provide an implementation that is faster and +more scalable than what can be achieved with :c:type:`uv_poll_t`, especially on +Windows. + +It is possible that poll handles occasionally signal that a file descriptor is +readable or writable even when it isn't. The user should therefore always +be prepared to handle EAGAIN or equivalent when it attempts to read from or +write to the fd. + +It is not okay to have multiple active poll handles for the same socket, this +can cause libuv to busyloop or otherwise malfunction. + +The user should not close a file descriptor while it is being polled by an +active poll handle. This can cause the handle to report an error, +but it might also start polling another socket. However the fd can be safely +closed immediately after a call to :c:func:`uv_poll_stop` or :c:func:`uv_close`. + +.. note:: + On windows only sockets can be polled with poll handles. On Unix any file + descriptor that would be accepted by :man:`poll(2)` can be used. + + +Data types +---------- + +.. c:type:: uv_poll_t + + Poll handle type. + +.. c:type:: void (*uv_poll_cb)(uv_poll_t* handle, int status, int events) + + Type definition for callback passed to :c:func:`uv_poll_start`. + +.. c:type:: uv_poll_event + + Poll event types + + :: + + enum uv_poll_event { + UV_READABLE = 1, + UV_WRITABLE = 2 + }; + + +Public members +^^^^^^^^^^^^^^ + +N/A + +.. seealso:: The :c:type:`uv_handle_t` members also apply. + + +API +--- + +.. c:function:: int uv_poll_init(uv_loop_t* loop, uv_poll_t* handle, int fd) + + Initialize the handle using a file descriptor. + + .. versionchanged:: 1.2.2 the file descriptor is set to non-blocking mode. + +.. c:function:: int uv_poll_init_socket(uv_loop_t* loop, uv_poll_t* handle, uv_os_sock_t socket) + + Initialize the handle using a socket descriptor. On Unix this is identical + to :c:func:`uv_poll_init`. On windows it takes a SOCKET handle. + + .. versionchanged:: 1.2.2 the socket is set to non-blocking mode. + +.. c:function:: int uv_poll_start(uv_poll_t* handle, int events, uv_poll_cb cb) + + Starts polling the file descriptor. `events` is a bitmask consisting made up + of UV_READABLE and UV_WRITABLE. As soon as an event is detected the callback + will be called with `status` set to 0, and the detected events set on the + `events` field. + + If an error happens while polling, `status` will be < 0 and corresponds + with one of the UV_E* error codes (see :ref:`errors`). The user should + not close the socket while the handle is active. If the user does that + anyway, the callback *may* be called reporting an error status, but this + is **not** guaranteed. + + .. note:: + Calling :c:func:`uv_poll_start` on a handle that is already active is fine. Doing so + will update the events mask that is being watched for. + +.. c:function:: int uv_poll_stop(uv_poll_t* poll) + + Stop polling the file descriptor, the callback will no longer be called. + +.. seealso:: The :c:type:`uv_handle_t` API functions also apply. |