src/shared/barrier.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <stdbool.h>
   5 #include <stdint.h>
   6 #include <sys/types.h>
   7
   8 #include "macro.h"
   9
  10 /* See source file for an API description. */
  11
  12 typedef struct Barrier Barrier;
  13
  14 enum {
  15         BARRIER_SINGLE                  = 1LL,
  16         BARRIER_ABORTION                = INT64_MAX,
  17
  18         /* bias values to store state; keep @WE < @THEY < @I */
  19         BARRIER_BIAS                    = INT64_MIN,
  20         BARRIER_WE_ABORTED              = BARRIER_BIAS + 1LL,
  21         BARRIER_THEY_ABORTED            = BARRIER_BIAS + 2LL,
  22         BARRIER_I_ABORTED               = BARRIER_BIAS + 3LL,
  23 };
  24
  25 enum {
  26         BARRIER_PARENT,
  27         BARRIER_CHILD,
  28 };
  29
  30 struct Barrier {
  31         int me;
  32         int them;
  33         int pipe[2];
  34         int64_t barriers;
  35 };
  36
  37 #define BARRIER_NULL {-EBADF, -EBADF, {-EBADF, -EBADF}, 0}
  38
  39 int barrier_create(Barrier *obj);
  40 Barrier* barrier_destroy(Barrier *b);
  41
  42 DEFINE_TRIVIAL_CLEANUP_FUNC(Barrier*, barrier_destroy);
  43
  44 void barrier_set_role(Barrier *b, unsigned role);
  45
  46 bool barrier_place(Barrier *b);
  47 bool barrier_abort(Barrier *b);
  48
  49 bool barrier_wait_next(Barrier *b);
  50 bool barrier_wait_abortion(Barrier *b);
  51 bool barrier_sync_next(Barrier *b);
  52 bool barrier_sync(Barrier *b);
  53
  54 static inline bool barrier_i_aborted(Barrier *b) {
  55         return IN_SET(b->barriers, BARRIER_I_ABORTED, BARRIER_WE_ABORTED);
  56 }
  57
  58 static inline bool barrier_they_aborted(Barrier *b) {
  59         return IN_SET(b->barriers, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
  60 }
  61
  62 static inline bool barrier_we_aborted(Barrier *b) {
  63         return b->barriers == BARRIER_WE_ABORTED;
  64 }
  65
  66 static inline bool barrier_is_aborted(Barrier *b) {
  67         return IN_SET(b->barriers,
  68                       BARRIER_I_ABORTED, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
  69 }
  70
  71 static inline bool barrier_place_and_sync(Barrier *b) {
  72         (void) barrier_place(b);
  73         return barrier_sync(b);
  74 }