minimal: smp + foreign: libuv foreign loops

AG: various fixes and adaptation of test protocol to use ring lock
to protect global wsi list against modifications from other threads
while in use

minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/CMakeLists.txt

+project(lws-minimal-ws-server-threads-foreign-smp C)
+cmake_minimum_required(VERSION 2.8)
+find_package(libwebsockets CONFIG REQUIRED)
+list(APPEND CMAKE_MODULE_PATH ${LWS_CMAKE_DIR})
+include(CheckIncludeFile)
+include(CheckCSourceCompiles)
+include(LwsCheckRequirements)
+
+set(SAMP lws-minimal-ws-server-threads-foreign-smp)
+set(SRCS minimal-ws-server.c)
+
+set(requirements 1)
+require_pthreads(requirements)
+require_lws_config(LWS_ROLE_WS 1 requirements)
+require_lws_config(LWS_WITH_SERVER 1 requirements)
+require_lws_config(LWS_WITH_TLS 1 requirements)
+require_lws_config(LWS_WITH_LIBUV 1 requirements)
+
+CHECK_C_SOURCE_COMPILES("#include <libwebsockets.h>\nint main(void) {\n#if defined(LWS_WITH_LIBUV)\n return 0;\n#else\n fail;\n#endif\n return 0;\n}\n" LWS_WITH_LIBUV)
+
+if (NOT LWS_WITH_LIBUV)
+	set(requirements 0)
+endif()
+
+
+if (requirements)
+	add_executable(${SAMP} ${SRCS})
+	
+	find_path(LIBUV_INCLUDE_DIRS NAMES uv.h)
+	find_library(LIBUV_LIBRARIES NAMES uv)
+	message("libuv include dir: ${LIBUV_INCLUDE_DIRS}")
+	message("libuv libraries: ${LIBUV_LIBRARIES}")
+	include_directories("${LIBUV_INCLUDE_DIRS}")
+	set(extralibs ${extralibs} ${LIBUV_LIBRARIES})
+	
+	message("Extra libs: ${extralibs}")
+
+		if (websockets_shared)
+			target_link_libraries(${SAMP} websockets_shared ${extralibs} ${PTHREAD_LIB} ${LIBWEBSOCKETS_DEP_LIBS})
+			add_dependencies(${SAMP} websockets_shared)
+		else()
+			target_link_libraries(${SAMP} websockets ${extralibs} ${PTHREAD_LIB} ${LIBWEBSOCKETS_DEP_LIBS})
+		endif()
+endif()

minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/README.md

+# lws minimal ws server (threads) + SMP
+
+This demonstrates both independent threads creating content as in the
+-threads example, multiple service threads as in the http-server-smp
+example (but with ws), and using the foreign libuv loop.
+
+## build
+
+You must first build libwebsockets itself with cmake `-DLWS_MAX_SMP=8`
+or some other number greater than one, as well as `-DLWS_WITH_LIBUV=1`
+
+```
+ $ cmake . && make
+```
+
+Pthreads is required on your system.
+
+## usage
+
+```
+ $ ./lws-minimal-ws-server-threads-smp
+[2019/01/28 06:59:17:4217] USER: LWS minimal ws server + threads + smp | visit http://localhost:7681
+[2019/01/28 06:59:17:4219] NOTICE:   Service threads: 2
+[2019/01/28 06:59:17:4220] NOTICE: LWS_CALLBACK_EVENT_WAIT_CANCELLED in svc tid 0x7fec48af8700
+[2019/01/28 06:59:17:4220] NOTICE: LWS_CALLBACK_EVENT_WAIT_CANCELLED in svc tid 0x7fec48af8700
+...
+```
+
+Visit http://localhost:7681 on multiple browser windows.  You may need to open
+4 before the second service thread is used (check "svc tid" in the browser output).
+
+Two lws service threads are started.
+
+Two separate asynchronous threads generate strings and add them to a ringbuffer,
+signalling all lws service threads to send new entries to all the browser windows.
+
+This demonstrates how to safely manage asynchronously generated content
+and hook it up to the lws service threads.
+

minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/minimal-ws-server.c

+/*
+ * lws-minimal-ws-server
+ *
+ * Written in 2010-2020 by Andy Green <andy@warmcat.com>
+ *
+ * This file is made available under the Creative Commons CC0 1.0
+ * Universal Public Domain Dedication.
+ *
+ * This demonstrates a minimal ws server that can cooperate with
+ * other threads cleanly.  Two other threads are started, which fill
+ * a ringbuffer with strings at 10Hz.
+ *
+ * The actual work and thread spawning etc are done in the protocol
+ * implementation in protocol_lws_minimal.c.
+ *
+ * To keep it simple, it serves stuff in the subdirectory "./mount-origin" of
+ * the directory it was started in.
+ * You can change that by changing mount.origin.
+ */
+
+#include <libwebsockets.h>
+#include <string.h>
+#include <signal.h>
+#if defined(WIN32)
+#define HAVE_STRUCT_TIMESPEC
+#if defined(pid_t)
+#undef pid_t
+#endif
+#endif
+#include <pthread.h>
+#include <uv.h>
+
+#define COUNT_THREADS 5
+
+#define LWS_PLUGIN_STATIC
+#include "protocol_lws_minimal.c"
+
+static struct lws_protocols protocols[] = {
+	{ "http", lws_callback_http_dummy, 0, 0 },
+	LWS_PLUGIN_PROTOCOL_MINIMAL,
+	{ NULL, NULL, 0, 0 } /* terminator */
+};
+
+static struct lws_context *context;
+static int interrupted;
+static uv_loop_t loop[COUNT_THREADS];
+
+static const struct lws_http_mount mount = {
+	/* .mount_next */		NULL,		/* linked-list "next" */
+	/* .mountpoint */		"/",		/* mountpoint URL */
+	/* .origin */			"./mount-origin", /* serve from dir */
+	/* .def */			"index.html",	/* default filename */
+	/* .protocol */			NULL,
+	/* .cgienv */			NULL,
+	/* .extra_mimetypes */		NULL,
+	/* .interpret */		NULL,
+	/* .cgi_timeout */		0,
+	/* .cache_max_age */		0,
+	/* .auth_mask */		0,
+	/* .cache_reusable */		0,
+	/* .cache_revalidate */		0,
+	/* .cache_intermediaries */	0,
+	/* .origin_protocol */		LWSMPRO_FILE,	/* files in a dir */
+	/* .mountpoint_len */		1,		/* char count */
+	/* .basic_auth_login_file */	NULL,
+};
+
+/*
+ * This demonstrates how to pass a pointer into a specific protocol handler
+ * running on a specific vhost.  In this case, it's our default vhost and
+ * we pass the pvo named "config" with the value a const char * "myconfig".
+ *
+ * This is the preferred way to pass configuration into a specific vhost +
+ * protocol instance.
+ */
+
+static const struct lws_protocol_vhost_options pvo_ops = {
+	NULL,
+	NULL,
+	"config",		/* pvo name */
+	(void *)"myconfig"	/* pvo value */
+};
+
+static const struct lws_protocol_vhost_options pvo = {
+	NULL,		/* "next" pvo linked-list */
+	&pvo_ops,	/* "child" pvo linked-list */
+	"lws-minimal",	/* protocol name we belong to on this vhost */
+	""		/* ignored */
+};
+
+void *thread_service(void *threadid)
+{
+	while (lws_service_tsi(context, 0,
+			       (int)(lws_intptr_t)threadid) >= 0 &&
+	       !interrupted)
+		lwsl_notice("%s\n", __func__);
+
+	pthread_exit(NULL);
+
+	return NULL;
+}
+
+void signal_cb(uv_signal_t *watcher, int signum)
+{
+	int n;
+
+	if (interrupted)
+		return;
+
+	lwsl_notice("signal_cb: signal %d caught\n", watcher->signum);
+	interrupted = 1;
+	uv_signal_stop(watcher);
+	lws_context_destroy(context);
+	for (n = 0; n < COUNT_THREADS; n++)
+		uv_stop(&loop[n]);
+}
+
+int main(int argc, const char **argv)
+{
+	int n, logs = LLL_USER | LLL_ERR | LLL_WARN | LLL_NOTICE;
+	uv_signal_t *s, signal_outer[3 * COUNT_THREADS];
+	pthread_t pthread_service[COUNT_THREADS];
+	struct lws_context_creation_info info;
+	void *foreign_loops[COUNT_THREADS];
+	const char *p;
+	void *retval;
+
+	if ((p = lws_cmdline_option(argc, argv, "-d")))
+		logs = atoi(p);
+
+	lws_set_log_level(logs, NULL);
+	lwsl_user("LWS minimal ws server + threads + smp | visit http://localhost:7681\n");
+
+	for (n = 0; n < COUNT_THREADS; n++) {
+		int m;
+
+		uv_loop_init(&loop[n]);
+
+		for (m = 0; m < 3; m++) {
+			s = &signal_outer[n * 3 + m];
+			uv_signal_init(&loop[n], s);
+			uv_signal_start(s, signal_cb, SIGINT);
+		}
+
+		foreign_loops[n] = &loop[n];
+	}
+
+	memset(&info, 0, sizeof info); /* otherwise uninitialized garbage */
+	info.port = 7681;
+	info.mounts = &mount;
+	info.pcontext = &context;
+	info.protocols = protocols;
+	info.pvo = &pvo; /* per-vhost options */
+	info.foreign_loops = foreign_loops;
+	info.count_threads = COUNT_THREADS;
+	info.options = LWS_SERVER_OPTION_LIBUV |
+		LWS_SERVER_OPTION_HTTP_HEADERS_SECURITY_BEST_PRACTICES_ENFORCE;
+
+	context = lws_create_context(&info);
+	if (!context) {
+		lwsl_err("lws init failed\n");
+		return 1;
+	}
+
+	lwsl_notice("  Service threads: %d\n", lws_get_count_threads(context));
+
+	/* start all the service threads */
+
+	for (n = 0; n < lws_get_count_threads(context); n++)
+		if (pthread_create(&pthread_service[n], NULL, thread_service,
+				   (void *)(lws_intptr_t)n))
+			lwsl_err("Failed to start service thread\n");
+
+	/* wait for all the service threads to exit */
+
+	while ((--n) >= 0)
+		pthread_join(pthread_service[n], &retval);
+
+	lws_context_destroy(context);
+
+	return 0;
+}

minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/mount-origin/example.js

+var head = 0, tail = 0, ring = new Array();
+
+function get_appropriate_ws_url(extra_url)
+{
+	var pcol;
+	var u = document.URL;
+
+	/*
+	 * We open the websocket encrypted if this page came on an
+	 * https:// url itself, otherwise unencrypted
+	 */
+
+	if (u.substring(0, 5) === "https") {
+		pcol = "wss://";
+		u = u.substr(8);
+	} else {
+		pcol = "ws://";
+		if (u.substring(0, 4) === "http")
+			u = u.substr(7);
+	}
+
+	u = u.split("/");
+
+	/* + "/xxx" bit is for IE10 workaround */
+
+	return pcol + u[0] + "/" + extra_url;
+}
+
+function new_ws(urlpath, protocol)
+{
+	return new WebSocket(urlpath, protocol);
+}
+
+document.addEventListener("DOMContentLoaded", function() {
+
+	var ws = new_ws(get_appropriate_ws_url(""), "lws-minimal");
+	try {
+		ws.onopen = function() {
+			document.getElementById("r").disabled = 0;
+		};
+	
+		ws.onmessage =function got_packet(msg) {
+			var n, s = "";
+	
+			ring[head] = msg.data + "\n";
+			head = (head + 1) % 50;
+			if (tail === head)
+				tail = (tail + 1) % 50;
+	
+			n = tail;
+			do {
+				s = s + ring[n];
+				n = (n + 1) % 50;
+			} while (n !== head);
+	
+			document.getElementById("r").value = s; 
+			document.getElementById("r").scrollTop =
+				document.getElementById("r").scrollHeight;
+		};
+	
+		ws.onclose = function(){
+			document.getElementById("r").disabled = 1;
+		};
+	} catch(exception) {
+		alert("<p>Error " + exception);  
+	}
+
+}, false);

minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/mount-origin/index.html

+<html>
+ <head>
+  <meta charset=utf-8 http-equiv="Content-Language" content="en"/>
+  <script src="/example.js"></script>
+ </head>
+	<body>
+		<img src="libwebsockets.org-logo.svg">
+		<img src="strict-csp.svg"><br>
+
+		<b>Minimal ws server threads SMP example</b>.<br>
+		Strings generated by server threads are sent to
+		all browsers open on this page.<br>
+		The textarea show the last 50 lines received.
+		<br>
+		<br>
+		<textarea id=r readonly cols=80 rows=50></textarea><br>
+	</body>
+</html>
+

minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/mount-origin/libwebsockets.org-logo.svg

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+<metadata>
+<rdf:RDF>
+<cc:Work rdf:about="">
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+<dc:title/>
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minimal-examples/ws-server/minimal-ws-server-threads-foreign-smp/protocol_lws_minimal.c

+/*
+ * ws protocol handler plugin for "lws-minimal" demonstrating multithread
+ *
+ * Written in 2010-2019 by Andy Green <andy@warmcat.com>
+ *
+ * This file is made available under the Creative Commons CC0 1.0
+ * Universal Public Domain Dedication.
+ */
+
+#if !defined (LWS_PLUGIN_STATIC)
+#define LWS_DLL
+#define LWS_INTERNAL
+#include <libwebsockets.h>
+#endif
+
+#include <string.h>
+#include <assert.h>
+
+/* one of these created for each message in the ringbuffer */
+
+struct msg {
+	void *payload; /* is malloc'd */
+	size_t len;
+};
+
+/*
+ * One of these is created for each client connecting to us.
+ *
+ * It is ONLY read or written from the lws service thread context.
+ */
+
+struct per_session_data__minimal {
+	struct per_session_data__minimal *pss_list;
+	struct lws *wsi;
+	uint32_t tail;
+};
+
+/*
+ * One of these is created for each vhost our protocol is used with, that
+ * means it is a shared resource between the SMP threads and must be locked.
+ */
+
+struct per_vhost_data__minimal {
+	struct lws_context *context;
+	struct lws_vhost *vhost;
+	const struct lws_protocols *protocol;
+
+	struct per_session_data__minimal *pss_list; /* linked-list of live pss*/
+	pthread_t pthread_spam[2];
+
+	pthread_mutex_t lock_ring; /* serialize access to the ring buffer */
+	struct lws_ring *ring; /* {lock_ring} ringbuffer holding unsent content */
+
+	const char *config;
+	char finished;
+};
+
+#if defined(WIN32)
+static void usleep(unsigned long l) { Sleep(l / 1000); }
+#endif
+
+/*
+ * This runs under both lws service and "spam threads" contexts.
+ * Access is serialized by vhd->lock_ring.
+ */
+
+static void
+__minimal_destroy_message(void *_msg)
+{
+	struct msg *msg = _msg;
+
+	free(msg->payload);
+	msg->payload = NULL;
+	msg->len = 0;
+}
+
+/*
+ * This runs under the "spam thread" thread context only.
+ *
+ * We spawn two threads that generate messages with this.
+ *
+ */
+
+static void *
+thread_spam(void *d)
+{
+	struct per_vhost_data__minimal *vhd =
+			(struct per_vhost_data__minimal *)d;
+	struct msg amsg;
+	int len = 128, index = 1, n, whoami = 0;
+
+	for (n = 0; n < (int)LWS_ARRAY_SIZE(vhd->pthread_spam); n++)
+		if (pthread_equal(pthread_self(), vhd->pthread_spam[n]))
+			whoami = n + 1;
+
+	do {
+		pthread_mutex_lock(&vhd->lock_ring); /* --------- ring lock { */
+
+		/* don't generate output if nobody connected */
+		if (!vhd->pss_list)
+			goto wait_unlock;
+
+		/* only create if space in ringbuffer */
+		n = (int)lws_ring_get_count_free_elements(vhd->ring);
+		if (!n) {
+			// lwsl_user("dropping!\n");
+			goto wait_unlock;
+		}
+
+		amsg.payload = malloc(LWS_PRE + len);
+		if (!amsg.payload) {
+			lwsl_user("OOM: dropping\n");
+			goto wait_unlock;
+		}
+		n = lws_snprintf((char *)amsg.payload + LWS_PRE, len,
+			         "%s: spam tid: %d, msg: %d", vhd->config,
+			         whoami, index++);
+		amsg.len = n;
+		n = (int)lws_ring_insert(vhd->ring, &amsg, 1);
+		if (n != 1) {
+			__minimal_destroy_message(&amsg);
+			// lwsl_user("dropping!\n");
+		} else
+			/*
+			 * This will cause a LWS_CALLBACK_EVENT_WAIT_CANCELLED
+			 * in the lws service thread context.
+			 */
+			lws_cancel_service(vhd->context);
+
+wait_unlock:
+		pthread_mutex_unlock(&vhd->lock_ring); /* } ring lock ------- */
+
+		usleep(100000);
+
+	} while (!vhd->finished);
+
+	lwsl_notice("thread_spam %d exiting\n", whoami);
+
+	pthread_exit(NULL);
+
+	return NULL;
+}
+
+/* this runs under the lws service thread context only */
+
+static int
+callback_minimal(struct lws *wsi, enum lws_callback_reasons reason,
+			void *user, void *in, size_t len)
+{
+	struct per_session_data__minimal *pss =
+			(struct per_session_data__minimal *)user;
+	struct per_vhost_data__minimal *vhd =
+			(struct per_vhost_data__minimal *)
+			lws_protocol_vh_priv_get(lws_get_vhost(wsi),
+					lws_get_protocol(wsi));
+	const struct lws_protocol_vhost_options *pvo;
+	const struct msg *pmsg;
+	char temp[LWS_PRE + 256];
+	void *retval;
+	int n, m, r = 0;
+
+	switch (reason) {
+	case LWS_CALLBACK_PROTOCOL_INIT:
+		/* create our per-vhost struct */
+		vhd = lws_protocol_vh_priv_zalloc(lws_get_vhost(wsi),
+				lws_get_protocol(wsi),
+				sizeof(struct per_vhost_data__minimal));
+		if (!vhd)
+			return 1;
+
+		pthread_mutex_init(&vhd->lock_ring, NULL);
+
+		/* recover the pointer to the globals struct */
+		pvo = lws_pvo_search(
+			(const struct lws_protocol_vhost_options *)in,
+			"config");
+		if (!pvo || !pvo->value) {
+			lwsl_err("%s: Can't find \"config\" pvo\n", __func__);
+			return 1;
+		}
+		vhd->config = pvo->value;
+
+		vhd->context = lws_get_context(wsi);
+		vhd->protocol = lws_get_protocol(wsi);
+		vhd->vhost = lws_get_vhost(wsi);
+
+		vhd->ring = lws_ring_create(sizeof(struct msg), 8,
+					    __minimal_destroy_message);
+		if (!vhd->ring) {
+			lwsl_err("%s: failed to create ring\n", __func__);
+			return 1;
+		}
+
+		/* start the content-creating threads */
+
+		for (n = 0; n < (int)LWS_ARRAY_SIZE(vhd->pthread_spam); n++)
+			if (pthread_create(&vhd->pthread_spam[n], NULL,
+					   thread_spam, vhd)) {
+				lwsl_err("thread creation failed\n");
+				r = 1;
+				goto init_fail;
+			}
+		break;
+
+	case LWS_CALLBACK_PROTOCOL_DESTROY:
+init_fail:
+		vhd->finished = 1;
+		for (n = 0; n < (int)LWS_ARRAY_SIZE(vhd->pthread_spam); n++)
+			pthread_join(vhd->pthread_spam[n], &retval);
+
+		if (vhd->ring)
+			lws_ring_destroy(vhd->ring);
+
+		pthread_mutex_destroy(&vhd->lock_ring);
+		break;
+
+	case LWS_CALLBACK_ESTABLISHED:
+		/* add ourselves to the list of live pss held in the vhd */
+		pthread_mutex_lock(&vhd->lock_ring);
+		lws_ll_fwd_insert(pss, pss_list, vhd->pss_list);
+		pss->tail = lws_ring_get_oldest_tail(vhd->ring);
+		pss->wsi = wsi;
+		pthread_mutex_unlock(&vhd->lock_ring);
+		break;
+
+	case LWS_CALLBACK_CLOSED:
+		/* doesn't reference ring */
+		pthread_mutex_lock(&vhd->lock_ring);
+		/* remove our closing pss from the list of live pss */
+		lws_ll_fwd_remove(struct per_session_data__minimal, pss_list,
+				  pss, vhd->pss_list);
+		pthread_mutex_unlock(&vhd->lock_ring);
+		break;
+
+	case LWS_CALLBACK_SERVER_WRITEABLE:
+		pthread_mutex_lock(&vhd->lock_ring); /* --------- ring lock { */
+
+		pmsg = lws_ring_get_element(vhd->ring, &pss->tail);
+		if (!pmsg) {
+			pthread_mutex_unlock(&vhd->lock_ring); /* } ring lock ------- */
+
+			break;
+		}
+
+		assert(pmsg->payload);
+
+		n = lws_snprintf(temp + LWS_PRE, sizeof(temp) - LWS_PRE,
+			      "svc, %s",
+			      (char *)pmsg->payload + LWS_PRE);
+
+		/* notice we allowed for LWS_PRE in the payload already */
+		m = lws_write(wsi, (unsigned char *)temp + LWS_PRE, n,
+			      LWS_WRITE_TEXT);
+		if (m < n) {
+			pthread_mutex_unlock(&vhd->lock_ring); /* } ring lock ------- */
+
+			lwsl_err("ERROR %d writing to ws socket\n", m);
+			return -1;
+		}
+
+		lws_ring_consume_and_update_oldest_tail(
+			vhd->ring,	/* lws_ring object */
+			struct per_session_data__minimal, /* type of objects with tails */
+			&pss->tail,	/* tail of guy doing the consuming */
+			1,		/* number of payload objects being consumed */
+			vhd->pss_list, /* head of list of objects with tails */
+			tail,		/* member name of tail in objects with tails */
+			pss_list	/* member name of next object in objects with tails */
+		);
+
+		/* more to do? */
+		if (lws_ring_get_element(vhd->ring, &pss->tail))
+			/* come back as soon as we can write more */
+			lws_callback_on_writable(pss->wsi);
+
+		pthread_mutex_unlock(&vhd->lock_ring); /* } ring lock ------- */
+
+		break;
+
+	case LWS_CALLBACK_RECEIVE:
+		break;
+
+	case LWS_CALLBACK_EVENT_WAIT_CANCELLED:
+		// lwsl_notice("EVENT_WAIT_CANCELLED tsi %d\n", lws_wsi_tsi(wsi));
+		if (!vhd)
+			break;
+		/*
+		 * When the "spam" threads add a message to the ringbuffer,
+		 * they create this event in the lws service thread context
+		 * using lws_cancel_service().
+		 *
+		 * We respond by scheduling a writable callback for all
+		 * connected clients.
+		 */
+
+		pthread_mutex_lock(&vhd->lock_ring); /* --------- ring lock { */
+
+		lws_start_foreach_llp(struct per_session_data__minimal **,
+				      ppss, vhd->pss_list) {
+			if (lws_wsi_tsi((*ppss)->wsi) == lws_wsi_tsi(wsi))
+				lws_callback_on_writable((*ppss)->wsi);
+		} lws_end_foreach_llp(ppss, pss_list);
+
+		pthread_mutex_unlock(&vhd->lock_ring); /* } ring lock ------- */
+		break;
+
+	default:
+		break;
+	}
+
+	return r;
+}
+
+#define LWS_PLUGIN_PROTOCOL_MINIMAL \
+	{ \
+		"lws-minimal", \
+		callback_minimal, \
+		sizeof(struct per_session_data__minimal), \
+		128, \
+		0, NULL, 0 \
+	}