flux_attr_get(3)

SYNOPSIS

#include <flux/core.h>

const char *flux_attr_get (flux_t *h, const char *name);

int flux_attr_set (flux_t *h, const char *name, const char *val);

int flux_attr_set_ex (flux_t *h,
                      const char *name,
                      const char *val,
                      bool force,
                      flux_error_t *error);

Link with -lflux-core.

DESCRIPTION

Flux broker attributes are both a simple, general-purpose key-value store with scope limited to the local broker rank, and a method for the broker to export information needed by Flux services and utilities.

flux_attr_get() retrieves the value of the attribute name.

Attributes that have the broker tags as immutable are cached automatically in the flux_t handle. For example, the "rank" attribute is a frequently accessed attribute whose value never changes. It will be cached on the first access and thereafter does not require an RPC to the broker to access.

flux_attr_set() updates the value of attribute name to val. If name is not currently a valid attribute, it is created. If val is NULL, the attribute is unset.

flux_attr_set_ex() is the same as above with extra arguments. If force is set, protections against runtime updates of the attribute are bypassed. If error is non-NULL, it is filled with a human readable error message on failure.

RETURN VALUE

flux_attr_get() returns the requested value on success. On error, NULL is returned and errno is set appropriately.

flux_attr_set() and flux_attr_set_ex() return zero on success. On error, -1 is returned and errno is set appropriately.

ERRORS

ENOENT: The requested attribute is invalid or has a NULL value on the broker.
EINVAL: Some arguments were invalid.
EPERM: Set was attempted on an attribute that is not writable with the user's credentials.

RESOURCES

Flux: http://flux-framework.org

Flux RFC: https://flux-framework.readthedocs.io/projects/flux-rfc

Issue Tracker: https://github.com/flux-framework/flux-core/issues