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
  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                         @Commit_point_define_check: (rdwr>>16) & 0xFFFF == rdwr & 0xFFFF
  75                         @Label: Fetch_Succ_Point1
  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                                 return false;
  85                         }
  86
  87                         bool succ = m_rdwr.compare_exchange_weak(rdwr,rdwr+(1<<16),mo_acq_rel);
  88
  89                         if (succ)
  90                                 break;
  91                         else
  92                                 thrd_yield();
  93                 }
  94
  95                 // (*1)
  96                 rl::backoff bo;
  97                 while ( true ) {
  98                         unsigned int tmp = m_written.load(mo_acquire);
  99                         /**
 100                                 @Begin
 101                                 @Commit_point_define_check: (tmp & 0xFFFF) == wr
 102                                 @Label: Fetch_Succ_Point2
 103                                 @End
 104                         */
 105                         if ((tmp & 0xFFFF) == wr)
 106                                 break;
 107                         thrd_yield();
 108                 }
 109
 110                 t_element * p = & ( m_array[ rd % t_size ] );
 111
 112                 return p;
 113         }
 114
 115         void read_consume() {
 116                 m_read.fetch_add(1,mo_release);
 117         }
 118
 119         //-----------------------------------------------------
 120
 121         t_element * write_prepare() {
 122                 unsigned int rdwr = m_rdwr.load(mo_acquire);
 123                 unsigned int rd,wr;
 124                 for(;;) {
 125                         rd = (rdwr>>16) & 0xFFFF;
 126                         wr = rdwr & 0xFFFF;
 127
 128                         if ( wr == ((rd + t_size)&0xFFFF) ) { // full
 129                                 return NULL;
 130                         }
 131
 132                         bool succ = m_rdwr.compare_exchange_weak(rdwr,(rd<<16) |
 133                                 ((wr+1)&0xFFFF),mo_acq_rel);
 134                         if (succ)
 135                                 break;
 136                         else
 137                                 thrd_yield();
 138                 }
 139
 140                 // (*1)
 141                 rl::backoff bo;
 142                 while ( (m_read.load(mo_acquire) & 0xFFFF) != rd ) {
 143                         thrd_yield();
 144                 }
 145
 146                 t_element * p = & ( m_array[ wr % t_size ] );
 147
 148                 return p;
 149         }
 150
 151         /**
 152                 @Begin
 153                 @Interface: Publish
 154                 @Commit_point_set: Publish_Point
 155                 @ID: (uint64_t) elem
 156                 @End
 157         */
 158         void write_publish(t_element *elem)
 159         {
 160                 m_written.fetch_add(1,mo_release);
 161                 /**
 162                         @Begin
 163                         @Commit_point_define_check: true
 164                         @Label: Publish_Point
 165                         @End
 166                 */
 167         }
 168
 169         //-----------------------------------------------------
 170
 171
 172 };
 173 /**
 174         @Begin
 175         @Class_end
 176         @End
 177 */