14_mutex.c File Reference

#include <stdio.h>
#include <serene/rt/fiber/mutex.h>
#include <serene/runtime.h>

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Macros
#define	FIBER_COUNT   64
#define	ITERATIONS   100
#define	WORKER_COUNT   4

Functions
static srn_fiber_result_t	bump (srn_context_t *ctx, void *arg)
int	main (void)

Variables
static srn_fiber_mutex_t	lock
static long	counter

Macro Definition Documentation

FIBER_COUNT

#define FIBER_COUNT   64

Definition at line 39 of file 14_mutex.c.

ITERATIONS

#define ITERATIONS   100

Definition at line 40 of file 14_mutex.c.

WORKER_COUNT

#define WORKER_COUNT   4

Definition at line 41 of file 14_mutex.c.

Function Documentation

bump()

srn_fiber_result_t bump ( srn_context_t * ctx, void * arg )

static

Definition at line 49 of file 14_mutex.c.

                                                              {
  (void)ctx;
  (void)arg;
  for (int i = 0; i < ITERATIONS; i++) {
    srn_fiber_mutex_lock(&lock);
    // The read and the write must not interleave with another fiber. Two fibers
    // reading the same value would each write it back once and lose an update.
    long seen = counter;
    counter   = seen + 1;
    srn_fiber_mutex_unlock(&lock);
  }
  return nullptr;
}

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main()

int main

(

void

)

Definition at line 63 of file 14_mutex.c.

               {
  SERENE_RUNTIME_INIT_WITH_SCHED(engine, sched, nullptr);
  srn_context_t *ctx = srn_context_make(engine);
 
  srn_fiber_mutex_init(&lock);
  counter = 0;
 
  for (int i = 0; i < FIBER_COUNT; i++) {
    (void)srn_fiber_spawn(ctx, bump, nullptr);
  }
 
  long expected = (long)FIBER_COUNT * ITERATIONS;
  printf(
    "running %d fibers x %d iterations across %d workers\n", FIBER_COUNT, ITERATIONS, WORKER_COUNT
  );
  srn_sched_run(sched, WORKER_COUNT);
 
  printf(
    "counted %ld (expected %ld): %s\n", counter, expected,
    counter == expected ? "every increment landed" : "lost an update"
  );
 
  srn_context_release(ctx);
  SERENE_RUNTIME_SHUTDOWN(engine);
  return 0;
}

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Variable Documentation

counter

long counter

static

Definition at line 47 of file 14_mutex.c.

lock

srn_fiber_mutex_t lock

static

Definition at line 43 of file 14_mutex.c.