Reworking the build system

1 files changed, 271 insertions, 0 deletions

diff --git a/kit/threads.posix.c b/kit/threads.posix.c
new file mode 100644
index 0000000..44465a3
--- /dev/null
+++ b/kit/threads.posix.c
@@ -0,0 +1,271 @@
+#include "threads.h"
+
+#ifndef KIT_DISABLE_SYSTEM_THREADS
+#  include "allocator.h"
+
+#  if !defined(_WIN32) || defined(__CYGWIN__)
+#    include <assert.h>
+#    include <errno.h>
+#    include <limits.h>
+#    include <sched.h>
+#    include <stdlib.h>
+#    include <unistd.h>
+
+#    ifndef PTHREAD_STACK_MIN
+#      define PTHREAD_STACK_MIN 16384
+#    endif
+
+/*
+Configuration macro:
+
+  EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
+    Use pthread_mutex_timedlock() for `mtx_timedlock()'
+    Otherwise use mtx_trylock() + *busy loop* emulation.
+*/
+#    if !defined(__CYGWIN__) && !defined(__APPLE__) && \
+        !defined(__NetBSD__)
+#      define EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
+#    endif
+
+/*
+Implementation limits:
+  - Conditionally emulation for "mutex with timeout"
+    (see EMULATED_THREADS_USE_NATIVE_TIMEDLOCK macro)
+*/
+typedef struct {
+  thrd_start_t func;
+  void        *arg;
+} impl_thrd_param_t;
+
+static void *impl_thrd_routine(void *p) {
+  impl_thrd_param_t pack = *((impl_thrd_param_t *) p);
+  kit_alloc_dispatch(NULL, KIT_DEALLOCATE, 0, 0, p);
+  return (void *) (intptr_t) pack.func(pack.arg);
+}
+
+void call_once(once_flag *flag, void (*func)(void)) {
+  pthread_once(flag, func);
+}
+
+int cnd_broadcast(cnd_t *cond) {
+  assert(cond != NULL);
+  return (pthread_cond_broadcast(cond) == 0) ? thrd_success
+                                             : thrd_error;
+}
+
+void cnd_destroy(cnd_t *cond) {
+  assert(cond);
+  pthread_cond_destroy(cond);
+}
+
+int cnd_init(cnd_t *cond) {
+  assert(cond != NULL);
+  return (pthread_cond_init(cond, NULL) == 0) ? thrd_success
+                                              : thrd_error;
+}
+
+int cnd_signal(cnd_t *cond) {
+  assert(cond != NULL);
+  return (pthread_cond_signal(cond) == 0) ? thrd_success : thrd_error;
+}
+
+int cnd_timedwait(cnd_t *cond, mtx_t *mtx,
+                  struct timespec const *abs_time) {
+  int rt;
+
+  assert(mtx != NULL);
+  assert(cond != NULL);
+  assert(abs_time != NULL);
+
+  rt = pthread_cond_timedwait(cond, mtx, abs_time);
+  if (rt == ETIMEDOUT)
+    return thrd_timedout;
+  return (rt == 0) ? thrd_success : thrd_error;
+}
+
+int cnd_wait(cnd_t *cond, mtx_t *mtx) {
+  assert(mtx != NULL);
+  assert(cond != NULL);
+  return (pthread_cond_wait(cond, mtx) == 0) ? thrd_success
+                                             : thrd_error;
+}
+
+void mtx_destroy(mtx_t *mtx) {
+  assert(mtx != NULL);
+  pthread_mutex_destroy(mtx);
+}
+
+/*
+ * XXX: Workaround when building with -O0 and without pthreads link.
+ *
+ * In such cases constant folding and dead code elimination won't be
+ * available, thus the compiler will always add the pthread_mutexattr*
+ * functions into the binary. As we try to link, we'll fail as the
+ * symbols are unresolved.
+ *
+ * Ideally we'll enable the optimisations locally, yet that does not
+ * seem to work.
+ *
+ * So the alternative workaround is to annotate the symbols as weak.
+ * Thus the linker will be happy and things don't clash when building
+ * with -O1 or greater.
+ */
+#    if defined(KIT_HAVE_FUNC_ATTRIBUTE_WEAK) && !defined(__CYGWIN__)
+__attribute__((weak)) int pthread_mutexattr_init(
+    pthread_mutexattr_t *attr);
+
+__attribute__((weak)) int pthread_mutexattr_settype(
+    pthread_mutexattr_t *attr, int type);
+
+__attribute__((weak)) int pthread_mutexattr_destroy(
+    pthread_mutexattr_t *attr);
+#    endif
+
+int mtx_init(mtx_t *mtx, int type) {
+#    ifdef KIT_HAVE_PTHREAD_MUTEXATTR_SETTYPE
+  pthread_mutexattr_t attr;
+#    endif
+  assert(mtx != NULL);
+  if (type != mtx_plain && type != mtx_timed &&
+      type != (mtx_plain | mtx_recursive) &&
+      type != (mtx_timed | mtx_recursive))
+    return thrd_error;
+
+  if ((type & mtx_recursive) == 0) {
+    pthread_mutex_init(mtx, NULL);
+    return thrd_success;
+  }
+
+#    ifdef KIT_HAVE_PTHREAD_MUTEXATTR_SETTYPE
+  pthread_mutexattr_init(&attr);
+  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+  pthread_mutex_init(mtx, &attr);
+  pthread_mutexattr_destroy(&attr);
+  return thrd_success;
+#    else
+  return thrd_error;
+#    endif
+}
+
+int mtx_lock(mtx_t *mtx) {
+  assert(mtx != NULL);
+  return (pthread_mutex_lock(mtx) == 0) ? thrd_success : thrd_error;
+}
+
+int mtx_timedlock(mtx_t *mtx, const struct timespec *ts) {
+  assert(mtx != NULL);
+  assert(ts != NULL);
+
+  {
+#    ifdef EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
+    int rt;
+    rt = pthread_mutex_timedlock(mtx, ts);
+    if (rt == 0)
+      return thrd_success;
+    return (rt == ETIMEDOUT) ? thrd_timedout : thrd_error;
+#    else
+    time_t expire = time(NULL);
+    expire += ts->tv_sec;
+    while (mtx_trylock(mtx) != thrd_success) {
+      time_t now = time(NULL);
+      if (expire < now)
+        return thrd_timedout;
+      // busy loop!
+      thrd_yield();
+    }
+    return thrd_success;
+#    endif
+  }
+}
+
+int mtx_trylock(mtx_t *mtx) {
+  assert(mtx != NULL);
+  return (pthread_mutex_trylock(mtx) == 0) ? thrd_success : thrd_busy;
+}
+
+int mtx_unlock(mtx_t *mtx) {
+  assert(mtx != NULL);
+  return (pthread_mutex_unlock(mtx) == 0) ? thrd_success : thrd_error;
+}
+
+int thrd_create_with_stack(thrd_t *thr, thrd_start_t func, void *arg,
+                           ptrdiff_t const require_stack_size) {
+  impl_thrd_param_t *pack;
+  assert(thr != NULL);
+  assert(require_stack_size == 0 ||
+         require_stack_size >= PTHREAD_STACK_MIN);
+  pthread_attr_t  attr;
+  pthread_attr_t *attr_p = NULL;
+  if (require_stack_size > 0) {
+    ptrdiff_t const page_size  = (ptrdiff_t) sysconf(_SC_PAGESIZE);
+    ptrdiff_t const delta      = require_stack_size % page_size;
+    ptrdiff_t const stack_size = delta == 0 ? require_stack_size
+                                            : require_stack_size +
+                                                  page_size - delta;
+    if (pthread_attr_init(&attr) != 0)
+      return thrd_nomem;
+    if (pthread_attr_setstacksize(&attr, (size_t) stack_size) != 0)
+      return thrd_wrong_stack_size;
+    attr_p = &attr;
+  }
+
+  pack = (impl_thrd_param_t *) kit_alloc_dispatch(
+      NULL, KIT_ALLOCATE, sizeof(impl_thrd_param_t), 0, NULL);
+  if (!pack) {
+    if (attr_p)
+      pthread_attr_destroy(attr_p);
+    return thrd_nomem;
+  }
+  pack->func = func;
+  pack->arg  = arg;
+  if (pthread_create(thr, attr_p, impl_thrd_routine, pack) != 0) {
+    kit_alloc_dispatch(NULL, KIT_DEALLOCATE, 0, 0, pack);
+    if (attr_p)
+      pthread_attr_destroy(attr_p);
+    return thrd_error;
+  }
+  if (attr_p)
+    pthread_attr_destroy(attr_p);
+  return thrd_success;
+}
+
+int thrd_create(thrd_t *thr, thrd_start_t func, void *arg) {
+  return thrd_create_with_stack(thr, func, arg, 0);
+}
+thrd_t thrd_current(void) {
+  return pthread_self();
+}
+
+int thrd_detach(thrd_t thr) {
+  return (pthread_detach(thr) == 0) ? thrd_success : thrd_error;
+}
+
+int thrd_equal(thrd_t thr0, thrd_t thr1) {
+  return pthread_equal(thr0, thr1);
+}
+
+_Noreturn void thrd_exit(int res) {
+  pthread_exit((void *) (intptr_t) res);
+}
+
+int thrd_join(thrd_t thr, int *res) {
+  void *code;
+  if (pthread_join(thr, &code) != 0)
+    return thrd_error;
+  if (res)
+    *res = (int) (intptr_t) code;
+  return thrd_success;
+}
+
+int thrd_sleep(const struct timespec *time_point,
+               struct timespec       *remaining) {
+  assert(time_point != NULL);
+  return nanosleep(time_point, remaining);
+}
+
+void thrd_yield(void) {
+  sched_yield();
+}
+
+#  endif
+#endif