src/basic/barrier.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 /***
   5   This file is part of systemd.
   6
   7   Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
   8 ***/
   9
  10 #include <stdbool.h>
  11 #include <stdint.h>
  12 #include <sys/types.h>
  13
  14 #include "macro.h"
  15
  16 /* See source file for an API description. */
  17
  18 typedef struct Barrier Barrier;
  19
  20 enum {
  21         BARRIER_SINGLE                  = 1LL,
  22         BARRIER_ABORTION                = INT64_MAX,
  23
  24         /* bias values to store state; keep @WE < @THEY < @I */
  25         BARRIER_BIAS                    = INT64_MIN,
  26         BARRIER_WE_ABORTED              = BARRIER_BIAS + 1LL,
  27         BARRIER_THEY_ABORTED            = BARRIER_BIAS + 2LL,
  28         BARRIER_I_ABORTED               = BARRIER_BIAS + 3LL,
  29 };
  30
  31 enum {
  32         BARRIER_PARENT,
  33         BARRIER_CHILD,
  34 };
  35
  36 struct Barrier {
  37         int me;
  38         int them;
  39         int pipe[2];
  40         int64_t barriers;
  41 };
  42
  43 #define BARRIER_NULL {-1, -1, {-1, -1}, 0}
  44
  45 int barrier_create(Barrier *obj);
  46 void barrier_destroy(Barrier *b);
  47
  48 DEFINE_TRIVIAL_CLEANUP_FUNC(Barrier*, barrier_destroy);
  49
  50 void barrier_set_role(Barrier *b, unsigned int role);
  51
  52 bool barrier_place(Barrier *b);
  53 bool barrier_abort(Barrier *b);
  54
  55 bool barrier_wait_next(Barrier *b);
  56 bool barrier_wait_abortion(Barrier *b);
  57 bool barrier_sync_next(Barrier *b);
  58 bool barrier_sync(Barrier *b);
  59
  60 static inline bool barrier_i_aborted(Barrier *b) {
  61         return IN_SET(b->barriers, BARRIER_I_ABORTED, BARRIER_WE_ABORTED);
  62 }
  63
  64 static inline bool barrier_they_aborted(Barrier *b) {
  65         return IN_SET(b->barriers, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
  66 }
  67
  68 static inline bool barrier_we_aborted(Barrier *b) {
  69         return b->barriers == BARRIER_WE_ABORTED;
  70 }
  71
  72 static inline bool barrier_is_aborted(Barrier *b) {
  73         return IN_SET(b->barriers,
  74                       BARRIER_I_ABORTED, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
  75 }
  76
  77 static inline bool barrier_place_and_sync(Barrier *b) {
  78         (void) barrier_place(b);
  79         return barrier_sync(b);
  80 }