Refactoring (event loop moved to separate module)

Makefile

@@ -3,6 +3,7 @@ SRC	= \
 	airscan-array.c \
 	airscan-conf.c \
 	airscan-devcaps.c \
+	airscan-eloop.c \
 	airscan-math.c \
 	airscan-opt.c \
 	airscan-xml.c \

airscan-eloop.c

@@ -0,0 +1,145 @@
+/* AirScan (a.k.a. eSCL) backend for SANE
+ *
+ * Copyright (C) 2019 and up by Alexander Pevzner ([email protected])
+ * See LICENSE for license terms and conditions
+ *
+ * Event loop (runs in separate thread)
+ */
+
+#include "airscan.h"
+
+/* Static variables
+ */
+static GThread *eloop_thread;
+static GMainContext *eloop_glib_main_context;
+static GMainLoop *eloop_glib_main_loop;
+G_LOCK_DEFINE_STATIC(eloop_mutex);
+
+/* Forward declarations
+ */
+static gint
+glib_poll_hook (GPollFD *ufds, guint nfsd, gint timeout);
+
+/* Initialize event loop
+ */
+SANE_Status
+eloop_init (void)
+{
+    eloop_glib_main_context = g_main_context_new();
+    eloop_glib_main_loop = g_main_loop_new(eloop_glib_main_context, FALSE);
+    g_main_context_set_poll_func(eloop_glib_main_context, glib_poll_hook);
+
+    return SANE_STATUS_GOOD;
+}
+
+/* Cleanup event loop
+ */
+void
+eloop_cleanup (void)
+{
+    if (eloop_glib_main_context != NULL) {
+        g_main_loop_unref(eloop_glib_main_loop);
+        eloop_glib_main_loop = NULL;
+        g_main_context_unref(eloop_glib_main_context);
+        eloop_glib_main_context = NULL;
+    }
+}
+
+/* Poll function hook
+ */
+static gint
+glib_poll_hook (GPollFD *ufds, guint nfds, gint timeout)
+{
+    G_UNLOCK(eloop_mutex);
+    gint ret = g_poll(ufds, nfds, timeout);
+    G_LOCK(eloop_mutex);
+
+    return ret;
+}
+
+/* Event loop thread main function
+ */
+static gpointer
+eloop_thread_func (gpointer data)
+{
+    void (*callback)(gboolean) = data;
+
+    G_LOCK(eloop_mutex);
+
+    g_main_context_push_thread_default(eloop_glib_main_context);
+    callback(TRUE);
+    g_main_loop_run(eloop_glib_main_loop);
+    callback(FALSE);
+
+    G_UNLOCK(eloop_mutex);
+
+    return NULL;
+}
+
+/* Start event loop thread.
+ *
+ * Callback is called from the thread context twice:
+ *     callback(TRUE)  - when thread is started
+ *     callback(FALSE) - when thread is about to exit
+ */
+void
+eloop_thread_start (void (*callback)(gboolean))
+{
+    eloop_thread = g_thread_new("airscan", eloop_thread_func, callback);
+
+    /* Wait until thread is started. Otherwise, g_main_loop_quit()
+     * might not terminate the thread
+     */
+    gulong usec = 100;
+    while (!g_main_loop_is_running(eloop_glib_main_loop)) {
+        g_usleep(usec);
+        usec += usec;
+    }
+}
+
+/* Stop event loop thread and wait until its termination
+ */
+void
+eloop_thread_stop (void)
+{
+    if (eloop_thread != NULL) {
+        g_main_loop_quit(eloop_glib_main_loop);
+        g_thread_join(eloop_thread);
+        eloop_thread = NULL;
+    }
+}
+
+/* Acquire event loop mutex
+ */
+void
+eloop_mutex_lock (void)
+{
+    G_LOCK(eloop_mutex);
+}
+
+/* Release event loop mutex
+ */
+void
+eloop_mutex_unlock (void)
+{
+    G_UNLOCK(eloop_mutex);
+}
+
+/* Wait on conditional variable under the event loop mutex
+ */
+gboolean
+eloop_cond_wait (GCond *cond, gint64 timeout)
+{
+    return g_cond_wait_until(cond, &G_LOCK_NAME(eloop_mutex), timeout);
+}
+
+/* Create AvahiGLibPoll that runs in context of the event loop
+ */
+AvahiGLibPoll*
+eloop_new_avahi_poll (void)
+{
+    return avahi_glib_poll_new(eloop_glib_main_context, G_PRIORITY_DEFAULT);
+}
+
+/* vim:ts=8:sw=4:et
+ */