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-rw-r--r--src/shared/barrier.h74
1 files changed, 74 insertions, 0 deletions
diff --git a/src/shared/barrier.h b/src/shared/barrier.h
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index 0000000..0eb3d27
--- /dev/null
+++ b/src/shared/barrier.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+#include "macro.h"
+
+/* See source file for an API description. */
+
+typedef struct Barrier Barrier;
+
+enum {
+ BARRIER_SINGLE = 1LL,
+ BARRIER_ABORTION = INT64_MAX,
+
+ /* bias values to store state; keep @WE < @THEY < @I */
+ BARRIER_BIAS = INT64_MIN,
+ BARRIER_WE_ABORTED = BARRIER_BIAS + 1LL,
+ BARRIER_THEY_ABORTED = BARRIER_BIAS + 2LL,
+ BARRIER_I_ABORTED = BARRIER_BIAS + 3LL,
+};
+
+enum {
+ BARRIER_PARENT,
+ BARRIER_CHILD,
+};
+
+struct Barrier {
+ int me;
+ int them;
+ int pipe[2];
+ int64_t barriers;
+};
+
+#define BARRIER_NULL {-1, -1, {-1, -1}, 0}
+
+int barrier_create(Barrier *obj);
+void barrier_destroy(Barrier *b);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Barrier*, barrier_destroy);
+
+void barrier_set_role(Barrier *b, unsigned role);
+
+bool barrier_place(Barrier *b);
+bool barrier_abort(Barrier *b);
+
+bool barrier_wait_next(Barrier *b);
+bool barrier_wait_abortion(Barrier *b);
+bool barrier_sync_next(Barrier *b);
+bool barrier_sync(Barrier *b);
+
+static inline bool barrier_i_aborted(Barrier *b) {
+ return IN_SET(b->barriers, BARRIER_I_ABORTED, BARRIER_WE_ABORTED);
+}
+
+static inline bool barrier_they_aborted(Barrier *b) {
+ return IN_SET(b->barriers, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
+}
+
+static inline bool barrier_we_aborted(Barrier *b) {
+ return b->barriers == BARRIER_WE_ABORTED;
+}
+
+static inline bool barrier_is_aborted(Barrier *b) {
+ return IN_SET(b->barriers,
+ BARRIER_I_ABORTED, BARRIER_THEY_ABORTED, BARRIER_WE_ABORTED);
+}
+
+static inline bool barrier_place_and_sync(Barrier *b) {
+ (void) barrier_place(b);
+ return barrier_sync(b);
+}