shmem_wait_until_all

Wait on an array of variables on the local PE until all variables meet the
specified wait condition.

Definitions

C11 Synopsis

void shmem_wait_until_all(TYPE *ivars, size_t nelems, const int *status,
                int cmp, TYPE cmp_value);

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

C/C++ Synopsis

void shmem_TYPENAME_wait_until_all(TYPE *ivars, size_t nelems, const int *status,
                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

ivars       Local address of an array of remotely accessible data objects.
            The type of ivars should match that implied in the SYNOPSIS
            section.
nelems      The number of elements in the ivars array.
status      Local address of an optional mask array of length nelems that
            indicates which elements in ivars are excluded from the wait set.
cmp         A comparison operator from Table 12 that compares elements of
            ivars with cmp_value.
cmp_value   The value to be compared with the objects pointed to by ivars.
            The type of cmp_value should match that implied in the SYNOPSIS
            section.

Description

The shmem_wait_until_all routine waits until all entries in the wait set
specified by ivars and status have satisfied the wait condition at the
calling PE. The ivars objects at the calling PE may be updated by an AMO
performed by a thread located within the calling PE or within another PE.
If nelems is 0, the wait set is empty and this routine returns immediately.
This routine compares each element of the ivars array in the wait set with
the value cmp_value according to the comparison operator cmp at the calling
PE. This routine is semantically similar to shmem_wait_until in Section
9.10.1, but adds support for point-to-point synchronization involving an
array of symmetric data objects.

The optional status is a mask array of length nelems where each element
corresponds to the respective element in ivars and indicates whether the
element is excluded from the wait set. Elements of status set to 0 will be
included in the wait set, and elements set to 1 will be ignored. If all
elements in status are set to 1 or nelems is 0, the wait set is empty and
this routine returns immediately. If status is a null pointer, it is
ignored and all elements in ivars are included in the wait set. The ivars
and status arrays must not overlap in memory.

Implementations must ensure that shmem_wait_until_all does not return before
the update of the memory indicated by ivars is fully complete.

Return Values

None.

Notes

None.

Examples

C/C++ Example

The following C11 example demonstrates the use of shmem_wait_until_all to implement a simple linear barrier synchronization.

#include <shmem.h>

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

  int *flags = shmem_calloc(npes, sizeof(int));
  int *status = NULL;

  for (int i = 0; i < npes; i++)
    shmem_atomic_set(&flags[mype], 1, i);

  shmem_wait_until_all(flags, npes, status, SHMEM_CMP_EQ, 1);

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