Line data    Source code

       1             : #ifndef HEADER_fd_src_waltz_mib_fd_seqlock_h
       2             : #define HEADER_fd_src_waltz_mib_fd_seqlock_h
       3             : 
       4             : #include "../../util/fd_util_base.h"
       5             : #include <stdatomic.h>
       6             : 
       7             : static inline void
       8           0 : fd_seqlock_init( atomic_ulong * lock ) {
       9           0 :   atomic_store_explicit( lock, 0UL, memory_order_release );
      10           0 : }
      11             : 
      12             : static inline void
      13          15 : fd_seqlock_write_lock( atomic_ulong * lock ) {
      14          15 :   for(;;) {
      15          15 :     ulong seq = atomic_load_explicit( lock, memory_order_relaxed );
      16          15 :     if( FD_UNLIKELY( seq & 1UL ) ) continue;
      17          15 :     if( FD_LIKELY( atomic_compare_exchange_weak_explicit( lock, &seq, seq+1UL, memory_order_acquire, memory_order_relaxed ) ) ) {
      18          15 :       return;
      19          15 :     }
      20          15 :   }
      21          15 : }
      22             : 
      23             : static inline void
      24          15 : fd_seqlock_write_unlock( atomic_ulong * lock ) {
      25          15 :   atomic_fetch_add_explicit( lock, 1UL, memory_order_release );
      26          15 : }
      27             : 
      28             : static inline ulong
      29          33 : fd_seqlock_read_try( atomic_ulong const * lock ) {
      30          33 :   for(;;) {
      31          33 :     ulong seq = atomic_load_explicit( lock, memory_order_acquire );
      32          33 :     if( FD_LIKELY( !(seq & 1UL) ) ) return seq;
      33          33 :   }
      34          33 : }
      35             : 
      36             : static inline int
      37             : fd_seqlock_read_test( atomic_ulong const * lock,
      38          33 :                       ulong                seq ) {
      39          33 :   atomic_thread_fence( memory_order_acquire );
      40          33 :   return atomic_load_explicit( lock, memory_order_acquire )==seq;
      41          33 : }
      42             : 
      43             : static inline int
      44           0 : fd_seqlock_locked_hint( atomic_ulong const * lock ) {
      45           0 :   return atomic_load_explicit( lock, memory_order_relaxed ) & 1UL;
      46           0 : }
      47             : 
      48             : #endif /* HEADER_fd_src_waltz_mib_fd_seqlock_h */