Locking subsystem: Just a global BIRD lock to begin with.

1 files changed, 102 insertions, 0 deletions

diff --git a/sysdep/unix/coroutine.c b/sysdep/unix/coroutine.c
new file mode 100644
index 00000000..05f101fb
--- /dev/null
+++ b/sysdep/unix/coroutine.c
@@ -0,0 +1,102 @@
+/*
+ *	BIRD Coroutines
+ *
+ *	(c) 2017 Martin Mares <mj@ucw.cz>
+ *	(c) 2020 Maria Matejka <mq@jmq.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#undef LOCAL_DEBUG
+
+#undef DEBUG_LOCKING
+
+#include "lib/birdlib.h"
+#include "lib/locking.h"
+#include "lib/resource.h"
+
+/*
+ *	Implementation of coroutines based on POSIX threads
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <stdatomic.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/*
+ *	Locking subsystem
+ */
+
+#define ASSERT_NO_LOCK	ASSERT_DIE(last_locked == NULL)
+
+struct domain_generic {
+  pthread_mutex_t mutex;
+  struct domain_generic **prev;
+  struct lock_order *locked_by;
+  const char *name;
+};
+
+#define DOMAIN_INIT(_name) { .mutex = PTHREAD_MUTEX_INITIALIZER, .name = _name }
+
+static struct domain_generic the_bird_domain_gen = DOMAIN_INIT("The BIRD");
+
+DOMAIN(the_bird) the_bird_domain = { .the_bird = &the_bird_domain_gen };
+
+struct domain_generic *
+domain_new(const char *name)
+{
+  struct domain_generic *dg = xmalloc(sizeof(struct domain_generic));
+  *dg = (struct domain_generic) DOMAIN_INIT(name);
+  return dg;
+}
+
+void
+domain_free(struct domain_generic *dg)
+{
+  pthread_mutex_destroy(&dg->mutex);
+  xfree(dg);
+}
+
+_Thread_local struct lock_order locking_stack = {};
+_Thread_local struct domain_generic **last_locked = NULL;
+
+void do_lock(struct domain_generic *dg, struct domain_generic **lsp)
+{
+  if (lsp <= last_locked)
+    bug("Trying to lock in a bad order");
+  if (*lsp)
+    bug("Inconsistent locking stack state on lock");
+
+  pthread_mutex_lock(&dg->mutex);
+
+  if (dg->prev || dg->locked_by)
+    bug("Previous unlock not finished correctly");
+  dg->prev = last_locked;
+  *lsp = dg;
+  last_locked = lsp;
+  dg->locked_by = &locking_stack;
+}
+
+void do_unlock(struct domain_generic *dg, struct domain_generic **lsp)
+{
+  if (dg->locked_by != &locking_stack)
+    bug("Inconsistent domain state on unlock");
+  if ((last_locked != lsp) || (*lsp != dg))
+    bug("Inconsistent locking stack state on unlock");
+  dg->locked_by = NULL;
+  last_locked = dg->prev;
+  *lsp = NULL;
+  dg->prev = NULL;
+  pthread_mutex_unlock(&dg->mutex);
+}
+