ReplicatedDist

Usage

use ReplicatedDist;

class Replicated

This Replicated distribution causes a domain and its arrays to be replicated across the desired locales (all the locales by default). An array receives a distinct set of elements - a “replicand” - allocated on each locale.

In other words, a Replicated-distributed domain has an implicit additional dimension - over the locales, making it behave as if there is one copy of its indices per locale.

Consistency among the replicands is not preserved automatically. That is, changes to one replicand of an array are never propagated to the other replicands by the distribution implementation. If desired, consistency needs to be maintained by the user.

When accessing a replicated domain or array from a locale not in the set of target locales, an error is reported if bounds-checking is on; undefined behavior occurs if it is off.

Otherwise, only the replicand on the current locale is accessed when referring to the domain or array.

Example

const Dbase = {1..5};  // A default-distributed domain
const Drepl = Dbase dmapped Replicated();
var Abase: [Dbase] int;
var Arepl: [Drepl] int;

// Only the current locale's replicand is accessed
Arepl[3] = 4;

// Only the current locale's replicand is accessed
forall (b,r) in zip(Abase,Arepl) do b = r;
Abase = Arepl;

// Access other locales' replicand with the replicand(loc) method
Arepl.replicand(Locales[1]) = Arepl;

See the Replicated Distribution primer for more examples of the Replicated distribution.

Initializer Arguments

The Replicated class initializer is defined as follows:

proc Replicated.init(
  targetLocales: [] locale = Locales,
  purposeMessage: string = "used to create a Replicated")

The optional purposeMessage may be useful for debugging when the initializer encounters an error.

Limitations

• Only rectangular domains are presently supported.