shmem_test

Test whether a variable on the local PE has changed.

Definitions

C11 Synopsis

int shmem_test(TYPE *ivar, int cmp, TYPE cmp_value);

where TYPE is one of the point-to-point synchronization types specified by Table:1

C/C++ Synopsis

int shmem_TYPENAME_test(TYPE *ivar, int cmp, TYPE cmp_value);

where TYPE is one of the point-to-point synchronization types and has a corresponding TYPENAME specified by Table:1

Datatype Reference Table

Table:1

|           TYPE          |      TYPENAME       |
|-------------------------|---------------------|
|   short                 |     short           |
|   int                   |     int             |
|   long                  |     long            |
|   long long             |     longlong        |
|   unsigned short        |     ushort          |
|   unsigned int          |     uint            |
|   unsigned long         |     ulong           |
|   unsigned long long    |     ulonglong       |
|   int32_t               |     int32           |
|   int64_t               |     int64           |
|   uint32_t              |     uint32          |
|   uint64_t              |     uint64          |
|   size_t                |     size            |
|   ptrdiff_t             |     ptrdiff         |

Arguments

ivar        A pointer to a remotely accessible data object.
cmp         The comparison operator that compares ivar with cmp_value.
cmp_value   The value against which the object pointed to by ivar will be
            compared.

Description

shmem_test tests the numeric comparison of the symmetric object pointed to
by ivar with the value cmp_value according to the comparison operator cmp.

Return Values

shmem_test returns 1 if the comparison of the symmetric object pointed to by
ivar with the value cmp_value according to the comparison operator cmp
evalutes to true; otherwise, it returns 0.

Notes

None.

Examples

C/C++ Example

The following example demonstrates the use of shmem_test to wait on an array
of symmetric objects and return the index of an element that satisfies the
specified condition.

#include <stdio.h>
#include <shmem.h>

int user_wait_any(long *ivar, int count, int cmp, long value)
{
  int idx = 0;
  while (!shmem_test(&ivar[idx], cmp, value))
    idx = (idx + 1) % count;
  return idx;
}

int main(void)
{
  shmem_init();
  const int mype = shmem_my_pe();
  const int npes = shmem_n_pes();

  long *wait_vars = shmem_calloc(npes, sizeof(long));
  if (mype == 0)
  {
    int who = user_wait_any(wait_vars, npes, SHMEM_CMP_NE, 0);
    printf("PE %d observed first update from PE %d\n", mype, who);
  }
  else
    shmem_p(&wait_vars[mype], mype, 0);

  shmem_free(wait_vars);
  shmem_finalize();
  return 0;
}