1 files changed, 105 insertions, 0 deletions
diff --git a/include/haproxy/port_range.h b/include/haproxy/port_range.h
new file mode 100644
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+++ b/include/haproxy/port_range.h
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+/*
+ * include/haproxy/port_range.h
+ * This file defines everything needed to manage port ranges
+ *
+ * Copyright (C) 2000-2020 Willy Tarreau - w@1wt.eu
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _HAPROXY_PORT_RANGE_H
+#define _HAPROXY_PORT_RANGE_H
+
+#include <stdlib.h>
+#include <haproxy/api.h>
+#include <haproxy/port_range-t.h>
+
+#define GET_NEXT_OFF(range, off) ((off) == (range)->size - 1 ? 0 : (off) + 1)
+
+/* return an available port from range <range>, or zero if none is left */
+static inline int port_range_alloc_port(struct port_range *range)
+{
+	int ret;
+	int get;
+	int put;
+
+	get = _HA_ATOMIC_LOAD(&range->get);
+	do {
+		/* barrier to make sure get is loaded before put */
+		__ha_barrier_atomic_load();
+		put = _HA_ATOMIC_LOAD(&range->put_t);
+		if (unlikely(put == get))
+			return 0;
+		ret = range->ports[get];
+	} while (!(_HA_ATOMIC_CAS(&range->get, &get, GET_NEXT_OFF(range, get))));
+	return ret;
+}
+
+/* release port <port> into port range <range>. Does nothing if <port> is zero
+ * nor if <range> is null. The caller is responsible for marking the port
+ * unused by either setting the port to zero or the range to NULL.
+ */
+static inline void port_range_release_port(struct port_range *range, int port)
+{
+	int put;
+
+	if (!port || !range)
+		return;
+
+	put = range->put_h;
+	/* put_h is reserved for producers, so that they can each get a
+	 * free slot, put_t is what is used by consumers to know if there's
+	 * elements available or not
+	 */
+	/* First reserve or slot, we know the ring buffer can't be full,
+	 * as we will only ever release port we allocated before
+	 */
+	while (!(_HA_ATOMIC_CAS(&range->put_h, &put, GET_NEXT_OFF(range, put))));
+	_HA_ATOMIC_STORE(&range->ports[put], port);
+	/* Barrier to make sure the new port is visible before we change put_t */
+	__ha_barrier_atomic_store();
+	/* Wait until all the threads that got a slot before us are done */
+	while ((volatile int)range->put_t != put)
+		__ha_compiler_barrier();
+	/* Let the world know we're done, and any potential consumer they
+	 * can use that port.
+	 */
+	_HA_ATOMIC_STORE(&range->put_t, GET_NEXT_OFF(range, put));
+}
+
+/* return a new initialized port range of N ports. The ports are not
+ * filled in, it's up to the caller to do it.
+ */
+static inline struct port_range *port_range_alloc_range(int n)
+{
+	struct port_range *ret;
+	ret = calloc(1, sizeof(struct port_range) +
+		     (n + 1) * sizeof(((struct port_range *)0)->ports[0]));
+	if (!ret)
+		return NULL;
+	ret->size = n + 1;
+	/* Start at the first free element */
+	ret->put_h = ret->put_t = n;
+	return ret;
+}
+
+#endif /* _HAPROXY_PORT_RANGE_H */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */