benchmark/mpmc-queue/mpmc-queue.h

   1 #include <stdatomic.h>
   2 #include <unrelacy.h>
   3 #include <common.h>
   4
   5 #include <spec_lib.h>
   6 #include <stdlib.h>
   7 #include <cdsannotate.h>
   8 #include <specannotation.h>
   9 #include <model_memory.h>
  10 #include "common.h"
  11
  12 /**
  13         @Begin
  14         @Class_begin
  15         @End
  16 */
  17 template <typename t_element, size_t t_size>
  18 struct mpmc_boundq_1_alt
  19 {
  20 private:
  21
  22         // elements should generally be cache-line-size padded :
  23         t_element               m_array[t_size];
  24
  25         // rdwr counts the reads & writes that have started
  26         atomic<unsigned int>    m_rdwr;
  27         // "read" and "written" count the number completed
  28         atomic<unsigned int>    m_read;
  29         atomic<unsigned int>    m_written;
  30
  31 public:
  32
  33         mpmc_boundq_1_alt()
  34         {
  35         /**
  36                 @Begin
  37                         @Entry_point
  38                         @End
  39                 */
  40                 m_rdwr = 0;
  41                 m_read = 0;
  42                 m_written = 0;
  43         }
  44
  45
  46         /**
  47                 @Begin
  48                 @Options:
  49                         LANG = CPP;
  50                         CLASS = mpmc_boundq_1_alt;
  51                 @Global_define:
  52                 @DeclareVar:
  53                         id_tag_t *tag;
  54                 @InitVar:
  55                         tag = NULL;
  56         @Happens_before:
  57                 Publish -> Fetch
  58         @End
  59         */
  60
  61         //-----------------------------------------------------
  62
  63         /**
  64                 @Begin
  65                 @Interface: Fetch
  66                 @Commit_point_set: Fetch_Succ_Point | Fetch_Fail_Point
  67                 @ID: (call_id_t) __RET__
  68                 @End
  69         */
  70         t_element * read_fetch() {
  71                 unsigned int rdwr = m_rdwr.load(mo_acquire);
  72                 /**
  73                         @Begin
  74                         @Potential_commit_point_define: true
  75                         @Label: Fetch_Potential_Point
  76                         @End
  77                 */
  78                 unsigned int rd,wr;
  79                 for(;;) {
  80                         rd = (rdwr>>16) & 0xFFFF;
  81                         wr = rdwr & 0xFFFF;
  82
  83                         if ( wr == rd ) { // empty
  84                                 /**
  85                                         @Begin
  86                                         @Commit_point_define: true
  87                                         @Potential_commit_point_label: Fetch_Potential_Point
  88                                         @Label: Fetch_Fail_Point
  89                                         @End
  90                                 */
  91                                 return false;
  92                         }
  93
  94                         bool succ = m_rdwr.compare_exchange_weak(rdwr,rdwr+(1<<16),mo_acq_rel);
  95
  96                         if (succ)
  97                                 break;
  98                         else
  99                                 thrd_yield();
 100                 }
 101
 102                 // (*1)
 103                 rl::backoff bo;
 104
 105                 while ( true ) {
 106                         if ((m_written.load(mo_acquire) & 0xFFFF) == wr) {
 107                                 /**
 108                                         @Begin
 109                                         @Commit_point_define_check: true
 110                                         @Label: Fetch_Succ_Point
 111                                         @End
 112                                 */
 113                                 break;
 114                         }
 115                         thrd_yield();
 116                 }
 117
 118                 t_element * p = & ( m_array[ rd % t_size ] );
 119
 120                 return p;
 121         }
 122
 123         void read_consume() {
 124                 m_read.fetch_add(1,mo_release);
 125         }
 126
 127         //-----------------------------------------------------
 128
 129         t_element * write_prepare() {
 130                 unsigned int rdwr = m_rdwr.load(mo_acquire);
 131                 unsigned int rd,wr;
 132                 for(;;) {
 133                         rd = (rdwr>>16) & 0xFFFF;
 134                         wr = rdwr & 0xFFFF;
 135
 136                         if ( wr == ((rd + t_size)&0xFFFF) ) { // full
 137                                 return NULL;
 138                         }
 139
 140                         bool succ = m_rdwr.compare_exchange_weak(rdwr,(rd<<16) |
 141                                 ((wr+1)&0xFFFF),mo_acq_rel);
 142                         if (succ)
 143                                 break;
 144                         else
 145                                 thrd_yield();
 146                 }
 147
 148                 // (*1)
 149                 rl::backoff bo;
 150                 while ( (m_read.load(mo_acquire) & 0xFFFF) != rd ) {
 151                         thrd_yield();
 152                 }
 153
 154                 t_element * p = & ( m_array[ wr % t_size ] );
 155
 156                 return p;
 157         }
 158
 159         /**
 160                 @Begin
 161                 @Interface: Publish
 162                 @Commit_point_set: Publish_Point
 163                 @ID: (uint64_t) elem
 164                 @End
 165         */
 166         void write_publish(t_element *elem)
 167         {
 168                 m_written.fetch_add(1,mo_release);
 169                 /**
 170                         @Begin
 171                         @Commit_point_define_check: true
 172                         @Label: Publish_Point
 173                         @End
 174                 */
 175         }
 176
 177         //-----------------------------------------------------
 178
 179
 180 };
 181 /**
 182         @Begin
 183         @Class_end
 184         @End
 185 */