Policy Headers

dmr_test_policies.h and dmr_CE_policy.h are the only headers an application includes by name besides dmr.h. They stay out of the barrel because the policies behind them are optional at build time, so what they declare depends on how DMR was compiled.

#include "dmr.h"                 /* the policy interface itself */
#include "dmr_test_policies.h"   /* round and list constructors */
#include "dmr_CE_policy.h"       /* CE constructor */

The interface these constructors return, DMRPolicy and friends, comes from the barrel and is documented under Policies.

Declarations

Header	Guard	Constructors
dmr_test_policies.h	DMR_WITH_TEST_POLICIES	DMRPolicy *dmr_get_policy_round(void); DMRPolicy *dmr_get_policy_list(void);
dmr_CE_policy.h	DMR_WITH_CE_POLICY	DMRPolicy *dmr_get_policy_ce(void);

Each declaration sits inside #if defined(<guard>), so calling a constructor whose policy was not built is a compile error naming the function, not a link error at the end of the build.

Build flags

The guards are set by CMake:

CMake flag	Default	Compile definition	Policies
DMR_BUILD_TEST_POLICIES	ON	DMR_WITH_TEST_POLICIES	round, list
DMR_BUILD_CE_POLICY	ON when DMR_USE_TALP=ON	DMR_WITH_CE_POLICY	ce

DMR_BUILD_CE_POLICY=ON requires DMR_USE_TALP=ON. CMake errors out if you ask for one without the other.

Behaviour common to all three

Every constructor returns a pointer to a static singleton, so there is nothing to free and destroy is NULL. Two consequences:

• Registering the same built-in twice with different parameters does not work. The second call overwrites the first one's state.
• Parameters are re-read from the environment on every call, so re-registering is how you re-parameterise a built-in at runtime.

setenv("DMR_DEFAULT_POLICY_MAX", "16", 1);
dmr_set_policy(dmr_get_policy_round());   /* collective, picks up the new value */

What each policy decides, and which environment variables it reads, is in Built-in Policies.