Jon Shallow 0e02d751da Add in internal epoll support to expose a monitor-able file descriptor ...

If epoll is available, use it within libcoap to speed things up, as well as
present to applications a file descriptor that can be used in a select() or
returned as an event in a epoll_wait() call.

Whenever coap_new_context() is called. set up a new epoll infrastructure with
epoll_create() and destroy it with coap_free_context().

For each new endpoint or session, add the socket fd to epoll.  When the socket
is closed, remove the socket fd from epoll.

Whenever a socket wants a write, the appropriate epoll event gets EPOLLOUT
added and when the write happens reset the event back to just EPOLLIN.

As there may be a packet retry event sometime in the future, a timerfd is
created and added to the epoll structure (done in coap_new_context) which gets
freed off in coap_free_context. If coap_run_once() determines that there is
a future retry, timerfd is informed of when the event is to occur.  When
timerfd times out, the application file descriptor will indicate a read is
available.

A new function coap_context_get_coap_fd(ctx) returns the application file
descriptor.  The only other API change is that if wait_ms is set to 1 for
coap_run_once(ctx, wait_ms), there is no waiting for a new packet to arrive.

coap_run_once() is called, whether epoll support is available or not, to
process all the underlying required i/o.

If there is no epoll support, coap_run_once() continues to use the old
select() method, otherwise it will use epoll_wait(). If there is epoll
support, a modified version of coap_read() (coap_io_do_events()) is
used instead.

Makefile.am:

Do not expose coap_epoll_ctl_mod() and coap_io_do_events() to applications.

configure.ac:

Test for the presence of sys/epoll.h and sys/timerfd.h and if so setup
COAP_EPOLL_SUPPORT to be used for #ifdef testing.
Include new man page coap_io.txt.

examples/coap-server.c:

Include support for using this new exposed file descriptor.

include/coap2/coap_io.h:

Define COAP_MAX_EPOLL_EVENTS (to limit the number of events processed at once)
and include coap_endpoint_t and coap_session_t in coap_socket_t.
Include (internal) definition for coap_epoll_ctl_mod()

include/coap2/net.h:

Add epfd and eptimerfd to coap_context_t.
Define coap_context_get_coap_fd() for applications to use.
Include (internal) definition for coap_io_do_events().
Define COAP_RUN_BLOCK and COAP_RUN_NONBLOCK.

libcoap-2.map:
libcoap-2.sym:

Include coap_context_get_coap_fd.

configure.ac:
man/Makefile.am:
man/coap.txt.in:
man/coap_io.txt.in: (New)

Include the new coap_in(3) man page that documents coap_run_once() and
coap_context_get_coap_fd().

src/coap_io.c:
src/coap_openssl.c:
src/coap_session.c:
src/net.c:

Add in the epoll support.

src/net.c:

Add in coap_context_get_coap_fd() function.

2019-08-30 11:51:15 +01:00

..

coap2

Add in internal epoll support to expose a monitor-able file descriptor

2019-08-30 11:51:15 +01:00