src/basic/barrier.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 /***
   5   Copyright © 2014 David Herrmann <dh.herrmann@gmail.com>
   6 ***/
   7
   8 #include <stdbool.h>
   9 #include <stdint.h>
  10 #include <sys/types.h>
  11
  12 #include "macro.h"
  13
  14 /* See source file for an API description. */
  15
  16 typedef struct Barrier Barrier;
  17
  18 enum {
  19         BARRIER_SINGLE                  = 1LL,
  20         BARRIER_ABORTION                = INT64_MAX,
  21
  22         /* bias values to store state; keep @WE < @THEY < @I */
  23         BARRIER_BIAS                    = INT64_MIN,
  24         BARRIER_WE_ABORTED              = BARRIER_BIAS + 1LL,
  25         BARRIER_THEY_ABORTED            = BARRIER_BIAS + 2LL,
  26         BARRIER_I_ABORTED               = BARRIER_BIAS + 3LL,
  27 };
  28
  29 enum {
  30         BARRIER_PARENT,
  31         BARRIER_CHILD,
  32 };
  33
  34 struct Barrier {
  35         int me;
  36         int them;
  37         int pipe[2];
  38         int64_t barriers;
  39 };
  40
  41 #define BARRIER_NULL {-1, -1, {-1, -1}, 0}
  42
  43 int barrier_create(Barrier *obj);
  44 void barrier_destroy(Barrier *b);
  45
  46 DEFINE_TRIVIAL_CLEANUP_FUNC(Barrier*, barrier_destroy);
  47
  48 void barrier_set_role(Barrier *b, unsigned int role);
  49
  50 bool barrier_place(Barrier *b);
  51 bool barrier_abort(Barrier *b);
  52
  53 bool barrier_wait_next(Barrier *b);
  54 bool barrier_wait_abortion(Barrier *b);
  55 bool barrier_sync_next(Barrier *b);
  56 bool barrier_sync(Barrier *b);
  57
  58 static inline bool barrier_i_aborted(Barrier *b) {
  59         return IN_SET(b->barriers, BARRIER_I_ABORTED, BARRIER_WE_ABORTED);
  60 }
  61
  62 static inline bool barrier_they_aborted(Barrier *b) {
  63         return IN_SET(b->barriers, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
  64 }
  65
  66 static inline bool barrier_we_aborted(Barrier *b) {
  67         return b->barriers == BARRIER_WE_ABORTED;
  68 }
  69
  70 static inline bool barrier_is_aborted(Barrier *b) {
  71         return IN_SET(b->barriers,
  72                       BARRIER_I_ABORTED, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
  73 }
  74
  75 static inline bool barrier_place_and_sync(Barrier *b) {
  76         (void) barrier_place(b);
  77         return barrier_sync(b);
  78 }