Add libwebsocket_cancel_service() to let a pending libwebsocket_service() return

Use poll() with a pipe instead of ppoll() to allow the stop polling
on all UNIX platforms.

diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index a280f8a..3cc5635 100644 (file)
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -90,16 +90,6 @@ static const char * const log_level_names[] = {
 #endif
 
 
-#ifdef LWS_HAS_PPOLL
-/*
- * set to the Thread ID that's doing the service loop just before entry to ppoll
- * indicates service thread likely idling in ppoll()
- * volatile because other threads may check it as part of processing for pollfd
- * event change.
- */
-static volatile int lws_idling_ppoll_tid;
-#endif
-
 /**
  * lws_get_library_version: get version and git hash library built from
  *
@@ -1276,6 +1266,8 @@ libwebsocket_context_destroy(struct libwebsocket_context *context)
        for (n = 0; n < context->fds_count; n++) {
                struct libwebsocket *wsi =
                                        context->lws_lookup[context->fds[n].fd];
+               if (!wsi)
+                       continue;
                libwebsocket_close_and_free_session(context,
                        wsi, LWS_CLOSE_STATUS_NOSTATUS /* no protocol close */);
                n--;
@@ -1313,6 +1305,8 @@ libwebsocket_context_destroy(struct libwebsocket_context *context)
 
 #if defined(WIN32) || defined(_WIN32)
 #else
+       close(context->dummy_pipe_fds[0]);
+       close(context->dummy_pipe_fds[1]);
        close(context->fd_random);
 #endif
 
@@ -1392,33 +1386,18 @@ libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
 {
        int n;
        int m;
-#ifdef LWS_HAS_PPOLL
-       struct timespec timeout_ts;
-       sigset_t sigmask;
-#endif
+       char buf;
 
        /* stay dead once we are dead */
 
        if (context == NULL)
                return 1;
 
-#ifdef LWS_HAS_PPOLL
-       lws_idling_ppoll_tid =  context->protocols[0].callback(context, NULL,
+       context->service_tid = context->protocols[0].callback(context, NULL,
                                     LWS_CALLBACK_GET_THREAD_ID, NULL, NULL, 0);
-
-       timeout_ts.tv_sec = timeout_ms / 1000;
-       timeout_ts.tv_nsec = timeout_ms % 1000;
-
-       sigprocmask(SIG_BLOCK, NULL, &sigmask);
-       sigdelset(&sigmask, SIGUSR2);
-
-       /* wait for something to need service */
-
-       n = ppoll(context->fds, context->fds_count, &timeout_ts, &sigmask);
-       lws_idling_ppoll_tid = 0;
-#else
        n = poll(context->fds, context->fds_count, timeout_ms);
-#endif
+       context->service_tid = 0;
+
        if (n == 0) /* poll timeout */ {
                libwebsocket_service_fd(context, NULL);
                return 0;
@@ -1436,6 +1415,13 @@ libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
        for (n = 0; n < context->fds_count; n++) {
                if (!context->fds[n].revents)
                        continue;
+#ifndef _WIN32
+               if (context->fds[n].fd == context->dummy_pipe_fds[0]) {
+                       if (read(context->fds[n].fd, &buf, 1) != 1)
+                               lwsl_err("Cannot read from dummy pipe.");
+                       continue;
+               }
+#endif
                m = libwebsocket_service_fd(context, &context->fds[n]);
                if (m < 0)
                        return -1;
@@ -1447,6 +1433,25 @@ libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
        return 0;
 }
 
+/**
+ * libwebsocket_cancel_service() - Cancel servicing of pending websocket activity
+ * @context:   Websocket context
+ *
+ *     This function let a call to libwebsocket_service() waiting for a timeout
+ *     immediately return.
+ *
+ *     At the moment this functionality cannot be used on Windows.
+ */
+LWS_VISIBLE void
+libwebsocket_cancel_service(struct libwebsocket_context *context)
+{
+#ifndef _WIN32
+       char buf = 0;
+       if (write(context->dummy_pipe_fds[1], &buf, sizeof(buf)) != 1)
+               lwsl_err("Cannot write to dummy pipe.");
+#endif
+}
+
 #ifndef LWS_NO_EXTENSIONS
 int
 lws_any_extension_handled(struct libwebsocket_context *context,
@@ -1498,10 +1503,8 @@ lws_change_pollfd(struct libwebsocket *wsi, int _and, int _or)
 {
        struct libwebsocket_context *context = wsi->protocol->owning_server;
        int events;
-#ifdef LWS_HAS_PPOLL
        int tid;
-       int sampled_ppoll_tid;
-#endif
+       int sampled_tid;
        struct libwebsocket_pollargs pa;
 
        pa.fd = wsi->sock;
@@ -1518,26 +1521,22 @@ lws_change_pollfd(struct libwebsocket *wsi, int _and, int _or)
                        LWS_CALLBACK_CHANGE_MODE_POLL_FD,
                        wsi->user_space, (void *) &pa, 0);
 
-
-#ifdef LWS_HAS_PPOLL
        /*
         * if we changed something in this pollfd...
         *   ... and we're running in a different thread context
         *     than the service thread...
-        *       ... and the service thread is waiting in ppoll()...
-        *          then fire a SIGUSR2 at the service thread to force it to
-        *             restart the ppoll() with our changed events
+        *       ... and the service thread is waiting ...
+        *         then cancel it to force a restart with our changed events
         */
        if (events != context->fds[wsi->position_in_fds_table].events) {
-               sampled_ppoll_tid = lws_idling_ppoll_tid;
-               if (sampled_ppoll_tid) {
+               sampled_tid = context->service_tid;
+               if (sampled_tid) {
                        tid = context->protocols[0].callback(context, NULL,
                                     LWS_CALLBACK_GET_THREAD_ID, NULL, NULL, 0);
-                       if (tid != sampled_ppoll_tid)
-                               kill(sampled_ppoll_tid, SIGUSR2);
+                       if (tid != sampled_tid)
+                               libwebsocket_cancel_service(context);
                }
        }
-#endif
 
        context->protocols[0].callback(context, wsi,
                LWS_CALLBACK_UNLOCK_POLL,
@@ -2049,7 +2048,24 @@ libwebsocket_create_context(struct lws_context_creation_info *info)
        memset(context->lws_lookup, 0, sizeof(struct libwebsocket *) *
                                                        context->max_fds);
 
+#ifdef _WIN32
        context->fds_count = 0;
+#else
+       if (pipe(context->dummy_pipe_fds)) {
+               lwsl_err("Unable to create pipe\n");
+               free(context->lws_lookup);
+               free(context->fds);
+               free(context);
+               return NULL;
+       }
+
+       /* use the read end of pipe as first item */
+       context->fds[0].fd = context->dummy_pipe_fds[0];
+       context->fds[0].events = POLLIN;
+       context->fds[0].revents = 0;
+       context->fds_count = 1;
+#endif
+
 #ifndef LWS_NO_EXTENSIONS
        context->extensions = info->extensions;
 #endif

diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index 64db7a0..18da97d 100644 (file)
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -69,10 +69,6 @@ typedef SSIZE_T ssize_t;
 
 #else // NOT WIN32
 
-/* to get ppoll() */
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
 #include <poll.h>
 #include <unistd.h>
 
@@ -969,6 +965,9 @@ libwebsocket_context_destroy(struct libwebsocket_context *context);
 LWS_VISIBLE LWS_EXTERN int
 libwebsocket_service(struct libwebsocket_context *context, int timeout_ms);
 
+LWS_VISIBLE LWS_EXTERN void
+libwebsocket_cancel_service(struct libwebsocket_context *context);
+
 LWS_VISIBLE LWS_EXTERN int
 libwebsocket_service_fd(struct libwebsocket_context *context,
                                                         struct pollfd *pollfd);

diff --git a/lib/private-libwebsockets.h b/lib/private-libwebsockets.h
index 4c340a1..af5a026 100644 (file)
--- a/lib/private-libwebsockets.h
+++ b/lib/private-libwebsockets.h
@@ -91,9 +91,6 @@
 #include <netinet/in.h>
 #include <netinet/tcp.h>
 #include <arpa/inet.h>
-
-/* to get ppoll() */
-#define __USE_GNU
 #include <poll.h>
 #include <sys/mman.h>
 #include <sys/time.h>
@@ -296,6 +293,17 @@ struct libwebsocket_context {
        int listen_service_fd;
        int listen_service_extraseen;
 
+       /*
+        * set to the Thread ID that's doing the service loop just before entry
+        * to poll indicates service thread likely idling in poll()
+        * volatile because other threads may check it as part of processing
+        * for pollfd event change.
+        */
+       volatile int service_tid;
+#ifndef _WIN32
+       int dummy_pipe_fds[2];
+#endif
+
        int ka_time;
        int ka_probes;
        int ka_interval;

diff --git a/test-server/test-server.c b/test-server/test-server.c
index 1e86146..4259f9d 100644 (file)
--- a/test-server/test-server.c
+++ b/test-server/test-server.c
@@ -59,6 +59,7 @@ struct pollfd *pollfds;
 int *fd_lookup;
 int count_pollfds;
 static volatile int force_exit = 0;
+static struct libwebsocket_context *context;
 
 /*
  * This demo server shows how to use libwebsockets for one or more
@@ -476,8 +477,7 @@ bail:
                 * if you will call "libwebsocket_callback_on_writable"
                 * from a different thread, return the caller thread ID
                 * here so lws can use this information to work out if it
-                * should signal the ppoll() loop to exit and restart early
-                * (only applies if the library has LWS_HAS_PPOLL
+                * should signal the poll() loop to exit and restart early
                 */
 
                /* return pthread_getthreadid_np(); */
@@ -732,6 +732,7 @@ static struct libwebsocket_protocols protocols[] = {
 void sighandler(int sig)
 {
        force_exit = 1;
+       libwebsocket_cancel_service(context);
 }
 
 static struct option options[] = {
@@ -755,7 +756,6 @@ int main(int argc, char **argv)
        char key_path[1024];
        int n = 0;
        int use_ssl = 0;
-       struct libwebsocket_context *context;
        int opts = 0;
        char interface_name[128] = "";
        const char *iface = NULL;