pd.if.org Git - liblfds/blob - liblfds/liblfds7.0.0/liblfds700/src/lfds700_ringbuffer/lfds700_ringbuffer_write.c

   1 /***** includes *****/
   2 #include "lfds700_ringbuffer_internal.h"
   3
   4
   5
   6
   7
   8 /****************************************************************************/
   9 void lfds700_ringbuffer_write( struct lfds700_ringbuffer_state *rs,
  10                                void *key,
  11                                void *value,
  12                                enum lfds700_misc_flag *overwrite_occurred_flag,
  13                                void **overwritten_key,
  14                                void **overwritten_value,
  15                                struct lfds700_misc_prng_state *ps )
  16 {
  17   int
  18     rv = 0;
  19
  20   struct lfds700_freelist_element
  21     *fe;
  22
  23   struct lfds700_queue_element
  24     *qe;
  25
  26   struct lfds700_ringbuffer_element
  27     *re = NULL;
  28
  29   LFDS700_PAL_ASSERT( rs != NULL );
  30   // TRD : key can be NULL
  31   // TRD : value can be NULL
  32   // TRD : overwrite_occurred_flag can be NULL
  33   // TRD : overwritten_key can be NULL
  34   // TRD : overwritten_value can be NULL
  35   LFDS700_PAL_ASSERT( ps != NULL );
  36
  37   if( overwrite_occurred_flag != NULL )
  38     *overwrite_occurred_flag = LFDS700_MISC_FLAG_LOWERED;
  39
  40   do
  41   {
  42     rv = lfds700_freelist_pop( &rs->fs, &fe, ps );
  43
  44     if( rv == 1 )
  45       re = LFDS700_FREELIST_GET_VALUE_FROM_ELEMENT( *fe );
  46
  47     if( rv == 0 )
  48     {
  49       // TRD : the queue can return empty as well - remember, we're lock-free; anything could have happened since the previous instruction
  50       rv = lfds700_queue_dequeue( &rs->qs, &qe, ps );
  51
  52       if( rv == 1 )
  53       {
  54         re = LFDS700_QUEUE_GET_VALUE_FROM_ELEMENT( *qe );
  55         re->qe_use = (struct lfds700_queue_element *) qe;
  56
  57         if( overwrite_occurred_flag != NULL )
  58           *overwrite_occurred_flag = LFDS700_MISC_FLAG_RAISED;
  59
  60         if( overwritten_key != NULL )
  61           *overwritten_key = re->key;
  62
  63         if( overwritten_value != NULL )
  64           *overwritten_value = re->value;
  65       }
  66     }
  67   }
  68   while( rv == 0 );
  69
  70   re->key = key;
  71   re->value = value;
  72
  73   LFDS700_QUEUE_SET_VALUE_IN_ELEMENT( *re->qe_use, re );
  74   lfds700_queue_enqueue( &rs->qs, re->qe_use, ps );
  75
  76   return;
  77 }
  78