add a lock-free bounded spsc interthread queue
Not entirely wait-free: allows waiting on a fd, and in general fd
notifications for poll-loop integration between threads.
Change-Id: I4f17042baf76d086ce6b20eb99402dc64c22c657
diff --git a/include/osmocom/mgcp/mgcp_threads_queue.h b/include/osmocom/mgcp/mgcp_threads_queue.h
new file mode 100644
index 0000000..bf094f5
--- /dev/null
+++ b/include/osmocom/mgcp/mgcp_threads_queue.h
@@ -0,0 +1,52 @@
+/*
+ * (C) 2021 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Eric Wild
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdatomic.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+struct spsc {
+ atomic_uint readptr;
+ atomic_uint writeptr;
+
+ int efd_r, efd_w; /* eventfds used to block/notify readers/writers */
+
+ int count;
+ int size_per_buf;
+
+ void *buf; /* buffer size count*size_per_buf */
+ uintptr_t data[0]; /* count sized array of pointers to size_per_buf chunks in buf array*/
+};
+
+struct qchan {
+ struct spsc *a;
+ struct spsc *b;
+};
+
+bool spsc_push(struct spsc *q, void *elem);
+bool spsc_pop(struct spsc *q, void *elem);
+ssize_t spsc_prep_pop(struct spsc *q);
+int spsc_get_a_rdfd(struct qchan *q);
+
+struct qchan spsc_chan_init(void *talloc_ctx, unsigned int count, unsigned int size_per_buf);
+struct qchan spsc_chan_init_ex(void *talloc_ctx, unsigned int count, unsigned int size_per_buf, bool blockr_a,
+ bool blockw_a, bool blockr_b, bool blockw_b);
+void spsc_chan_close(struct qchan *q);