1 files changed, 179 insertions, 0 deletions
diff --git a/sysdep/unix/coroutine.c b/sysdep/unix/coroutine.c
new file mode 100644
index 00000000..2eba142c
--- /dev/null
+++ b/sysdep/unix/coroutine.c
@@ -0,0 +1,179 @@
+/*
+ *	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/coro.h"
+#include "lib/resource.h"
+#include "lib/timer.h"
+
+/* Using a rather big stack for coroutines to allow for stack-local allocations.
+ * In real world, the kernel doesn't alloc this memory until it is used.
+ * */
+#define CORO_STACK_SIZE	1048576
+
+/*
+ *	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
+ */
+
+_Thread_local struct lock_order locking_stack = {};
+_Thread_local struct domain_generic **last_locked = NULL;
+
+#define ASSERT_NO_LOCK	ASSERT_DIE(last_locked == NULL)
+
+struct domain_generic {
+  pthread_mutex_t mutex;
+  uint order;
+  struct domain_generic **prev;
+  struct lock_order *locked_by;
+  const char *name;
+};
+
+#define DOMAIN_INIT(_name, _order) { .mutex = PTHREAD_MUTEX_INITIALIZER, .name = _name, .order = _order }
+
+static struct domain_generic the_bird_domain_gen = DOMAIN_INIT("The BIRD", OFFSETOF(struct lock_order, the_bird));
+
+DOMAIN(the_bird) the_bird_domain = { .the_bird = &the_bird_domain_gen };
+
+struct domain_generic *
+domain_new(const char *name, uint order)
+{
+  ASSERT_DIE(order < sizeof(struct lock_order));
+  struct domain_generic *dg = xmalloc(sizeof(struct domain_generic));
+  *dg = (struct domain_generic) DOMAIN_INIT(name, order);
+  return dg;
+}
+
+void
+domain_free(struct domain_generic *dg)
+{
+  pthread_mutex_destroy(&dg->mutex);
+  xfree(dg);
+}
+
+void do_lock(struct domain_generic *dg, struct domain_generic **lsp)
+{
+  if ((char *) lsp - (char *) &locking_stack != dg->order)
+    bug("Trying to lock on bad position: order=%u, lsp=%p, base=%p", dg->order, lsp, &locking_stack);
+
+  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 ((char *) lsp - (char *) &locking_stack != dg->order)
+    bug("Trying to unlock on bad position: order=%u, lsp=%p, base=%p", dg->order, lsp, &locking_stack);
+
+  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);
+}
+
+/* Coroutines */
+struct coroutine {
+  resource r;
+  pthread_t id;
+  pthread_attr_t attr;
+  void (*entry)(void *);
+  void *data;
+};
+
+static _Thread_local _Bool coro_cleaned_up = 0;
+
+static void coro_free(resource *r)
+{
+  struct coroutine *c = (void *) r;
+  ASSERT_DIE(pthread_equal(pthread_self(), c->id));
+  pthread_attr_destroy(&c->attr);
+  coro_cleaned_up = 1;
+}
+
+static struct resclass coro_class = {
+  .name = "Coroutine",
+  .size = sizeof(struct coroutine),
+  .free = coro_free,
+};
+
+static void *coro_entry(void *p)
+{
+  struct coroutine *c = p;
+  ASSERT_DIE(c->entry);
+
+  c->entry(c->data);
+  ASSERT_DIE(coro_cleaned_up);
+
+  return NULL;
+}
+
+struct coroutine *coro_run(pool *p, void (*entry)(void *), void *data)
+{
+  ASSERT_DIE(entry);
+  ASSERT_DIE(p);
+
+  struct coroutine *c = ralloc(p, &coro_class);
+
+  c->entry = entry;
+  c->data = data;
+
+  int e = 0;
+
+  if (e = pthread_attr_init(&c->attr))
+    die("pthread_attr_init() failed: %M", e);
+
+  if (e = pthread_attr_setstacksize(&c->attr, CORO_STACK_SIZE))
+    die("pthread_attr_setstacksize(%u) failed: %M", CORO_STACK_SIZE, e);
+
+  if (e = pthread_attr_setdetachstate(&c->attr, PTHREAD_CREATE_DETACHED))
+    die("pthread_attr_setdetachstate(PTHREAD_CREATE_DETACHED) failed: %M", e);
+
+  if (e = pthread_create(&c->id, &c->attr, coro_entry, c))
+    die("pthread_create() failed: %M", e);
+
+  return c;
+}