From aaa595dbb7cea13cc38344c08b4822a59ced3b7c Mon Sep 17 00:00:00 2001
From: Vftdan <vftdan@gmail.com>
Date: Fri, 25 Oct 2024 01:32:21 +0200
Subject: [PATCH] Implement yielding spin lock type

---
 src/common/util/spin_lock.h | 35 +++++++++++++++++++++++++++++++++++
 src/server/main.c           |  1 +
 2 files changed, 36 insertions(+)
 create mode 100644 src/common/util/spin_lock.h

diff --git a/src/common/util/spin_lock.h b/src/common/util/spin_lock.h
new file mode 100644
index 0000000..3b16d5c
--- /dev/null
+++ b/src/common/util/spin_lock.h
@@ -0,0 +1,35 @@
+#ifndef COMMON_UTIL_SPIN_LOCK_H_
+#define COMMON_UTIL_SPIN_LOCK_H_
+
+#include "common/util/thread.h"
+
+#include <stdatomic.h>
+#include <errno.h>
+
+typedef struct {
+	volatile atomic_flag flag;
+} SpinLock;
+
+HEADER_FN bool
+spin_lock_try_acquire(SpinLock *lock)
+{
+	return !atomic_flag_test_and_set(&lock->flag);
+}
+
+HEADER_FN void
+spin_lock_acquire(SpinLock *lock)
+{
+	int save_errno = errno;
+	while (!spin_lock_try_acquire(lock)) {
+		thread_yield();
+	}
+	errno = save_errno;
+}
+
+HEADER_FN void
+spin_lock_release(SpinLock *lock)
+{
+	atomic_flag_clear(&lock->flag);
+}
+
+#endif /* end of include guard: COMMON_UTIL_SPIN_LOCK_H_ */
diff --git a/src/server/main.c b/src/server/main.c
index 4daadc4..2b7f76a 100644
--- a/src/server/main.c
+++ b/src/server/main.c
@@ -4,6 +4,7 @@
 #include "common/util/hash_table.h"
 #include "common/util/byte_serdes.h"
 #include "common/util/thread.h"
+#include "common/util/spin_lock.h"
 
 int
 main(int argc, char **argv)