evs_join(3) Multicast a message to selected groups


#include <sys/uio.h> #include <corosync/evs.h>

int evs_mcast_groups(evs_handle_t handle, evs_guraantee_t guarantee, evs_group_t *groups, int group_entries, struct iovec *iovec, int iov_len);


The evs_mcast_groups(3) function multicasts a message to all the groups specified in the arguemnt groups. Messages are delivered to all processors in the system that are described by the current configuration.

The argument handle describes a handle created with evs_initialize(3).

The argument guarantee requests a delivery guarantee for the message to be sent. The evs_guarantee_t type is defined by:

typedef enum {
    EVS_TYPE_UNORDERED,       /* not implemented */
    EVS_TYPE_FIFO,          /* same as agreed */
    EVS_TYPE_AGREED,          /* implemented */
    EVS_TYPE_SAFE           /* not implemented */
} evs_guarantee_t;

The meanings of the evs_guarantee_t typedef are:

Messages are guaranteed to be delivered, but with no particular order. This mode is unimplemented in the EVS library.
Messages are guaranteed to be delivered in first sent first delivery order from one one. In fact, this guarantee is actually the AGREED guarantee.
All processors must agree on the order of delivery. If a message is sent from two or more processors at about the same time, the delivery will occur in the same order to all processors.
All processors must agree on the order of delivery. Further all processors must have a copy of the message before any delivery takes place. This mode is unimplemented in the EVS library.

The groups argument is of the type evs_group_t which is defined by the structure:

typedef struct {
    char key[32];
} evs_groups_t;

The group_entries argument describes the number of entries in the group argument.

The iovec argument describes the scatter/gather list which is used to transmit a message. This is a standard socket structure described by:

struct iovec
    void *iov_base;     /* Pointer to data.  */
    unsigned int iov_len;     /* Length of data.  */

The iovlen argument describes the number of entires in the iovec argument.


This call returns the EVS_OK value if successful, otherwise an error is returned.


The errors are undocumented.