Cluster Information

Detailed Description

These functions return status information about the handle, the current connection, and the number of nodes found within the cluster.

See also

lcb_cntl() for more functions to retrieve status info

Function Documentation

lcb_get_node()

const char * lcb_get_node	(	lcb_INSTANCE *	instance,
		lcb_GETNODETYPE	type,
		unsigned	index )

Return a string of host:port for a node of the given type.

Parameters

instance	the instance from which to retrieve the node
type	the type of node to return
index	the node number if index is out of bounds it will be wrapped around, thus there is never an invalid value for this parameter

Returns

a string in the form of host:port. If LCB_NODE_NEVERNULL was specified as an option in type then the string constant LCB_GETNODE_UNAVAILABLE is returned. Otherwise NULL is returned if the type is unrecognized or the LCB_NODE_CONNECTED option was specified and no connected node could be found or a memory allocation failed.

Note

The index parameter is ignored if type is LCB_NODE_HTCONFIG|LCB_NODE_CONNECTED as there will always be only a single HTTP bootstrap node.

const char *viewnode = lcb_get_node(instance, LCB_NODE_VIEWS, 0);
// Get the connected REST endpoint:
const char *restnode = lcb_get_node(instance, LCB_NODE_HTCONFIG|LCB_NODE_CONNECTED, 0);
if (!restnode) {
  printf("Instance not connected via HTTP!\n");
}

Iterate over all the data nodes:

unsigned ii;
for (ii = 0; ii < lcb_get_num_servers(instance); ii++) {
  const char *kvnode = lcb_get_node(instance, LCB_NODE_DATA, ii);
  if (kvnode) {
    printf("KV node %s exists at index %u\n", kvnode, ii);
  } else {
    printf("No node for index %u\n", ii);
  }
}

Stability

Committed

lcb_get_keynode()

const char * lcb_get_keynode	(	lcb_INSTANCE *	instance,
		const void *	key,
		size_t	nkey )

Get the target server for a given key.

Stability

Committed

This is a convenience function wrapping around the vBucket API which allows you to retrieve the target node (the node which will be contacted) when performing KV operations involving the key.

Parameters

instance	the instance
key	the key to use
nkey	the length of the key

Returns

a string containing the hostname, or NULL on error.

Since this is a convenience function, error details are not contained here in favor of brevity. Use the full vBucket API for more powerful functions.

lcb_get_num_replicas()

lcb_S32 lcb_get_num_replicas

(

lcb_INSTANCE *

instance

)

Get the number of the replicas in the cluster.

Parameters

instance

The handle to lcb

Returns

-1 if the cluster wasn't configured yet, and number of replicas otherwise. This may be 0 if there are no replicas.

Stability

Committed

lcb_get_num_nodes()

lcb_S32 lcb_get_num_nodes

(

lcb_INSTANCE *

instance

)

Get the number of the nodes in the cluster.

Parameters

instance

The handle to lcb

Returns

-1 if the cluster wasn't configured yet, and number of nodes otherwise.

Stability

Committed

lcb_get_server_list()

const char *const * lcb_get_server_list

(

lcb_INSTANCE *

instance

)

Get a list of nodes in the cluster.

Returns

a NULL-terminated list of 0-terminated strings consisting of node hostnames:admin_ports for the entire cluster. The storage duration of this list is only valid until the next call to a libcouchbase function and/or when returning control to libcouchbase' event loop.

const char * const * curp = lcb_get_server_list(instance);
for (; *curp; curp++) {
  printf("Have node %s\n", *curp);
}

Stability

Committed

Enumeration Type Documentation

lcb_GETNODETYPE

enum lcb_GETNODETYPE

Type of node to retrieve for the lcb_get_node() function.

Enumerator
LCB_NODE_HTCONFIG	Get an HTTP configuration (Rest API) node.
LCB_NODE_DATA	Get a data (memcached) node.
LCB_NODE_VIEWS	Get a view (CAPI) node.
LCB_NODE_CONNECTED	Only return a node which is connected, or a node which is known to be up.
LCB_NODE_NEVERNULL	Specifying this flag adds additional semantics which instruct the library to search additional resources to return a host, and finally, if no host can be found, return the string constant LCB_GETNODE_UNAVAILABLE.
LCB_NODE_HTCONFIG_CONNECTED	Equivalent to LCB_NODE_HTCONFIG|LCB_NODE_CONNECTED
LCB_NODE_HTCONFIG_ANY	Equivalent to LCB_NODE_HTCONFIG|LCB_NODE_NEVERNULL. When this is passed, some additional attempts may be made by the library to return any kind of host, including searching the initial list of hosts passed to the lcb_create() function.