parallel.c

   1 /*
   2  * Parallel processing
   3  */
   4
   5 #include <pthread.h>
   6
   7 #include "mgraph.h"
   8 #include "parallel.h"
   9
  10 typedef struct {
  11   const struct Vertices *vertices;
  12   Computation *separately;
  13   void *gendata;
  14 } ForAllThreads;
  15
  16 typedef struct {
  17   ForAllThreads *allthreads;
  18   int section;
  19   void *secdata;
  20   pthread_t thread;
  21 } PerThread;
  22
  23 #if NPROCESSORS != 1
  24 static void *routine(void *thread_v) {
  25   PerThread *t= thread_v;
  26   ForAllThreads *a= t->allthreads;
  27
  28   a->separately(a->vertices, t->section, t->secdata, a->gendata);
  29
  30   return 0;
  31 }
  32 #endif
  33
  34 void inparallel(const struct Vertices *vertices,
  35                 Computation *separately,
  36                 Computation *combine,
  37                 size_t secdatasz, void *gendata) {
  38   typedef struct { unsigned char secdata[secdatasz]; } SecData;
  39
  40   ForAllThreads allthreads;
  41   SecData secdatas[nsections];
  42
  43   allthreads.vertices= vertices;
  44   allthreads.separately= separately;
  45   allthreads.gendata= gendata;
  46
  47 #if NPROCESSORS != 1
  48   PerThread threads[nsections];
  49   int s, r;
  50
  51   for (s=0; s<nsections; s++) {
  52     threads[s].allthreads= &allthreads;
  53     threads[s].section= s;
  54     threads[s].secdata= secdatas[s].secdata;
  55     r= pthread_create(&threads[s].thread,0,routine,&threads[s]);
  56     if (r) diee("pthread_create");
  57   }
  58
  59   for (s=0; s<nsections; s++) {
  60     r= pthread_join(threads[s].thread, 0);
  61     if (r) diee("pthread_join");
  62     combine(vertices, s, threads[s].secdata, gendata);
  63   }
  64 #else
  65   separately(vertices, 0, &secdatas[0], gendata);
  66   combine(vertices, 0, &secdatas[0], gendata);
  67 #endif
  68 }