Implement yielding spin lock type

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_ */

src/common/util/thread.h

@@ -37,8 +37,20 @@ Thread thread_delete_handle(Thread th);
  * Waits for a thread to exit
  * @param th the thread to join
  * @param result_ptr pointer to store the exit result or NULL
- * @return bool on success, false on failure (errno may be set)
+ * @return true on success, false on failure (errno may be set)
  */
 bool thread_join(Thread th, ThreadResult *result_ptr);
 
+/**
+ * Terminates current thread
+ * @param result exit result to return via thread_join
+ */
+void thread_exit(ThreadResult result) __attribute__((noreturn));
+
+/**
+ * Hints the OS to release CPU used by this thread
+ * @return true on success, false on failure (errno may be set)
+ */
+bool thread_yield();
+
 #endif /* end of include guard: COMMON_UTIL_THREAD_H_ */

src/common/util/thread.posix.c

@@ -1,6 +1,7 @@
 #include "thread.h"
 
 #include <pthread.h>
+#include <sched.h>
 #include <errno.h>
 #include <assert.h>
 
@@ -114,3 +115,15 @@ thread_join(Thread th, ThreadResult *result_ptr)
 	}
 	return true;
 }
+
+void
+thread_exit(ThreadResult result)
+{
+	pthread_exit(result.pointer);
+}
+
+bool
+thread_yield()
+{
+	return !sched_yield();
+}

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)