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WebSockets: additional method for event loop integration

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Some distro repositories offer versions of libwebsockets that have not been
compiled with LWS_WITH_GLIB or LWS_WITH_EXTERNAL_POLL enabled. For such cases
a different event loop integration method is needed.

True for Ubuntu 20.04 as of Jun '21
This commit is contained in:
Luciano Iam 2021-06-13 18:21:24 +02:00
parent a5a952be2a
commit 2bea7afcd4
2 changed files with 103 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

108
libs/surfaces/websockets/server.cc
View file

@ -52,6 +52,8 @@ using namespace ArdourSurface;
WebsocketsServer::WebsocketsServer (ArdourSurface::ArdourWebsockets& surface)
: SurfaceComponent (surface)
, _lws_context (0)
, _fd_callbacks (false)
, _g_source (0)
{
/* keep references to all config for libwebsockets 2 */
lws_protocols proto;
@ -125,31 +127,47 @@ WebsocketsServer::start ()
stop ();
}
/* Event loop integration method depends on how libwebsockets is configured
* for Ardour build environment and how libwebsockets is compiled for the
* system running Ardour. */
#ifdef LWS_WITH_GLIB
void *foreign_loops[1];
foreign_loops[0] = main_loop ()->gobj ();
_lws_info.foreign_loops = foreign_loops;
_lws_info.options = LWS_SERVER_OPTION_GLIB;
#endif
_lws_context = lws_create_context (&_lws_info);
if (!_lws_context) {
PBD::error << "ArdourWebsockets: could not create the libwebsockets context" << endmsg;
return -1;
}
#ifndef LWS_WITH_GLIB
/* sometimes LWS_WITH_EXTERNAL_POLL is missing from lws_config.h
but the feature is still available, hence this runtime check */
if (_fd_ctx.empty ()) {
PBD::error << "ArdourWebsockets: check your libwebsockets was compiled"
" with LWS_WITH_GLIB or LWS_WITH_EXTERNAL_POLL enabled"
<< endmsg;
return -1;
}
#endif
if (_lws_context) {
/* LWS_WITH_GLIB was enabled for Ardour build environment libwebsockets
and also for the version the user has installed in their system */
PBD::info << "ArdourWebsockets: using event loop integration method 1" << endmsg;
} else {
/* Either Ardour build environment libwebsockets was not configured with
LWS_WITH_GLIB enabled or user installed library is missing the feature */
_fd_callbacks = true;
_lws_info.foreign_loops = 0;
_lws_info.options = 0;
_lws_context = lws_create_context (&_lws_info);
if (!_lws_context) {
PBD::error << "ArdourWebsockets: could not create the libwebsockets context" << endmsg;
return -1;
}
if (!_fd_ctx.empty ()) {
// LWS_CALLBACK_ADD_POLL_FD was called, LWS_WITH_EXTERNAL_POLL is available
PBD::info << "ArdourWebsockets: using event loop integration method 2" << endmsg;
} else {
// Neither LWS_WITH_EXTERNAL_POLL or LWS_WITH_GLIB are available
PBD::info << "ArdourWebsockets: using event loop integration method 3" << endmsg;
_g_source = g_idle_source_new();
g_source_set_callback (_g_source, WebsocketsServer::glib_idle_callback, _lws_context, 0);
g_source_attach (_g_source, g_main_loop_get_context (main_loop ()->gobj ()));
}
}
PBD::info << "ArdourWebsockets: listening on: http://"
<< lws_canonical_hostname (_lws_context)
<< ":"
@ -163,17 +181,21 @@ WebsocketsServer::start ()
int
WebsocketsServer::stop ()
{
#ifndef LWS_WITH_GLIB
for (LwsPollFdGlibSourceMap::iterator it = _fd_ctx.begin (); it != _fd_ctx.end (); ++it) {
it->second.rg_iosrc->destroy ();
if (!_fd_ctx.empty ()) { // Method 2
for (LwsPollFdGlibSourceMap::iterator it = _fd_ctx.begin (); it != _fd_ctx.end (); ++it) {
it->second.rg_iosrc->destroy ();
if (it->second.wg_iosrc) {
it->second.wg_iosrc->destroy ();
if (it->second.wg_iosrc) {
it->second.wg_iosrc->destroy ();
}
}
_fd_ctx.clear ();
}
_fd_ctx.clear ();
#endif
if (_g_source) { // Method 3
g_source_destroy (_g_source);
}
if (_lws_context) {
lws_context_destroy (_lws_context);
@ -405,19 +427,30 @@ WebsocketsServer::lws_callback (struct lws* wsi, enum lws_callback_reasons reaso
rc = server->send_availsurf_body (wsi);
break;
#ifndef LWS_WITH_GLIB
/* fd callbacks must be skipped for integration method 1 */
case LWS_CALLBACK_ADD_POLL_FD:
rc = server->add_poll_fd (static_cast<struct lws_pollargs*> (in));
if (server->fd_callbacks()) {
rc = server->add_poll_fd (static_cast<struct lws_pollargs*> (in));
} else {
rc = 0;
}
break;
case LWS_CALLBACK_CHANGE_MODE_POLL_FD:
rc = server->mod_poll_fd (static_cast<struct lws_pollargs*> (in));
if (server->fd_callbacks()) {
rc = server->mod_poll_fd (static_cast<struct lws_pollargs*> (in));
} else {
rc = 0;
}
break;
case LWS_CALLBACK_DEL_POLL_FD:
rc = server->del_poll_fd (static_cast<struct lws_pollargs*> (in));
if (server->fd_callbacks()) {
rc = server->del_poll_fd (static_cast<struct lws_pollargs*> (in));
} else {
rc = 0;
}
break;
#endif // LWS_WITH_GLIB
#if LWS_LIBRARY_VERSION_NUM >= 2001000
// lws_callback_http_dummy is not available on lws < 2.1.0
@ -453,7 +486,6 @@ WebsocketsServer::lws_callback (struct lws* wsi, enum lws_callback_reasons reaso
return rc;
}
#ifndef LWS_WITH_GLIB
int
WebsocketsServer::add_poll_fd (struct lws_pollargs* pa)
{
@ -597,4 +629,18 @@ WebsocketsServer::ioc_to_events (IOCondition ioc)
return events;
}
#endif // LWS_WITH_GLIB
void
WebsocketsServer::request_write ()
{
// cancel lws_service() in the idle callback to write pending data asap
lws_cancel_service (_lws_context);
}
gboolean
WebsocketsServer::glib_idle_callback (void *data)
{
struct lws_context *lws_ctx = static_cast<struct lws_context *>(data);
lws_service (lws_ctx, 0);
return TRUE;
}