A cluster object describes the configuration of the Cassandra cluster and is used to construct a session instance. Unlike other DataStax drivers the cluster object does not maintain the control connection.

Functions

CassCluster *

cass_cluster_new

( )

Creates a new cluster.

Returns:
Type Details
CassCluster *

Returns a cluster that must be freed.

See Also:
void

cass_cluster_free

( cluster )

Frees a cluster instance.

Parameters:
Name Type Details
in cluster
CassError

cass_cluster_set_contact_points

( cluster, contact_points )

Sets/Appends contact points. This MUST be set. The first call sets the contact points and any subsequent calls appends additional contact points. Passing an empty string will clear the contact points. White space is striped from the contact points.

Examples: “127.0.0.1” “127.0.0.1,127.0.0.2”, “server1.domain.com”

Parameters:
Name Type Details
in cluster
in contact_points

A comma delimited list of addresses or names. An empty string will clear the contact points. The string is copied into the cluster configuration; the memory pointed to by this parameter can be freed after this call.

Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_contact_points_n

( cluster, contact_points, contact_points_length )

Same as CassCluster::cass_cluster_set_contact_points, but with lengths for string parameters.

Parameters:
Name Type Details
in cluster
in contact_points
in contact_points_length
Returns:
Type Details
CassError

same as CassCluster::cass_cluster_set_contact_points

See Also:
CassError

cass_cluster_set_port

( cluster, port )

Sets the port.

Default: 9042

Parameters:
Name Type Details
in cluster
in port
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

void

cass_cluster_set_ssl

( cluster, ssl )

Sets the SSL context and enables SSL.

Parameters:
Name Type Details
in cluster
in ssl
See Also:
CassError

cass_cluster_set_protocol_version

( cluster, protocol_version )

Sets the protocol version. This will automatically downgrade if to protocol version 1.

Default: 2

Parameters:
Name Type Details
in cluster
in protocol_version
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_num_threads_io

( cluster, num_threads )

Sets the number of IO threads. This is the number of threads that will handle query requests.

Default: 1

Parameters:
Name Type Details
in cluster
in num_threads
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_queue_size_io

( cluster, queue_size )

Sets the size of the the fixed size queue that stores pending requests.

Default: 4096

Parameters:
Name Type Details
in cluster
in queue_size
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_queue_size_event

( cluster, queue_size )

Sets the size of the the fixed size queue that stores events.

Default: 4096

Parameters:
Name Type Details
in cluster
in queue_size
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_queue_size_log

( cluster, queue_size )

Sets the size of the the fixed size queue that stores log messages.

Default: 4096

Parameters:
Name Type Details
in cluster
in queue_size
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_core_connections_per_host

( cluster, num_connections )

Sets the number of connections made to each server in each IO thread.

Default: 1

Parameters:
Name Type Details
in cluster
in num_connections
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_max_connections_per_host

( cluster, num_connections )

Sets the maximum number of connections made to each server in each IO thread.

Default: 2

Parameters:
Name Type Details
in cluster
in num_connections
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

void

cass_cluster_set_reconnect_wait_time

( cluster, wait_time )

Sets the amount of time to wait before attempting to reconnect.

Default: 2000 milliseconds

Parameters:
Name Type Details
in cluster
in wait_time
CassError

cass_cluster_set_max_concurrent_creation

( cluster, num_connections )

Sets the maximum number of connections that will be created concurrently. Connections are created when the current connections are unable to keep up with request throughput.

Default: 1

Parameters:
Name Type Details
in cluster
in num_connections
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_max_concurrent_requests_threshold

( cluster, num_requests )

Sets the threshold for the maximum number of concurrent requests in-flight on a connection before creating a new connection. The number of new connections created will not exceed max_connections_per_host.

Default: 100

Parameters:
Name Type Details
in cluster
in num_requests
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_max_requests_per_flush

( cluster, num_requests )

Sets the maximum number of requests processed by an IO worker per flush.

Default: 128

Parameters:
Name Type Details
in cluster
in num_requests
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_write_bytes_high_water_mark

( cluster, num_bytes )

Sets the high water mark for the number of bytes outstanding on a connection. Disables writes to a connection if the number of bytes queued exceed this value.

Default: 64 KB

Parameters:
Name Type Details
in cluster
in num_bytes
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_write_bytes_low_water_mark

( cluster, num_bytes )

Sets the low water mark for number of bytes outstanding on a connection. After exceeding high water mark bytes, writes will only resume once the number of bytes fall below this value.

Default: 32 KB

Parameters:
Name Type Details
in cluster
in num_bytes
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_pending_requests_high_water_mark

( cluster, num_requests )

Sets the high water mark for the number of requests queued waiting for a connection in a connection pool. Disables writes to a host on an IO worker if the number of requests queued exceed this value.

Default: 128 * max_connections_per_host

Parameters:
Name Type Details
in cluster
in num_requests
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

CassError

cass_cluster_set_pending_requests_low_water_mark

( cluster, num_requests )

Sets the low water mark for the number of requests queued waiting for a connection in a connection pool. After exceeding high water mark requests, writes to a host will only resume once the number of requests fall below this value.

Default: 64 * max_connections_per_host

Parameters:
Name Type Details
in cluster
in num_requests
Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred.

void

cass_cluster_set_connect_timeout

( cluster, timeout_ms )

Sets the timeout for connecting to a node.

Default: 5000 milliseconds

Parameters:
Name Type Details
in cluster
in timeout_ms

Connect timeout in milliseconds

void

cass_cluster_set_request_timeout

( cluster, timeout_ms )

Sets the timeout for waiting for a response from a node.

Default: 12000 milliseconds

Parameters:
Name Type Details
in cluster
in timeout_ms

Request timeout in milliseconds

void

cass_cluster_set_credentials

( cluster, username, password )

Sets credentials for plain text authentication.

Parameters:
Name Type Details
in cluster
in username
in password
void

cass_cluster_set_credentials_n

( cluster, username, username_length, password, password_length )

Same as CassCluster::cass_cluster_set_credentials, but with lengths for string parameters.

Parameters:
Name Type Details
in cluster
in username
in username_length
in password
in password_length
Returns:
Type Details
void

same as CassCluster::cass_cluster_set_credentials

See Also:
void

cass_cluster_set_load_balance_round_robin

( cluster )

Configures the cluster to use round-robin load balancing.

The driver discovers all nodes in a cluster and cycles through them per request. All are considered ‘local’.

Parameters:
Name Type Details
in cluster
CassError

cass_cluster_set_load_balance_dc_aware

( cluster, local_dc, used_hosts_per_remote_dc, allow_remote_dcs_for_local_cl )

Configures the cluster to use DC-aware load balancing. For each query, all live nodes in a primary ‘local’ DC are tried first, followed by any node from other DCs.

Note: This is the default, and does not need to be called unless switching an existing from another policy or changing settings. Without further configuration, a default local_dc is chosen from the first connected contact point, and no remote hosts are considered in query plans. If relying on this mechanism, be sure to use only contact points from the local DC.

Parameters:
Name Type Details
in cluster
in local_dc

The primary data center to try first

in used_hosts_per_remote_dc

The number of host used in each remote DC if no hosts are available in the local dc

in allow_remote_dcs_for_local_cl

Allows remote hosts to be used if no local dc hosts are available and the consistency level is LOCAL_ONE or LOCAL_QUORUM

Returns:
Type Details
CassError

CASS_OK if successful, otherwise an error occurred

CassError

cass_cluster_set_load_balance_dc_aware_n

( cluster, local_dc, local_dc_length, used_hosts_per_remote_dc, allow_remote_dcs_for_local_cl )

Same as CassCluster::cass_cluster_set_load_balance_dc_aware, but with lengths for string parameters.

Parameters:
Name Type Details
in cluster
in local_dc
in local_dc_length
in used_hosts_per_remote_dc
in allow_remote_dcs_for_local_cl
Returns:
Type Details
CassError

same as CassCluster::cass_cluster_set_load_balance_dc_aware

See Also:
void

cass_cluster_set_token_aware_routing

( cluster, enabled )

Configures the cluster to use token-aware request routing, or not.

Default is cass_true (enabled).

This routing policy composes the base routing policy, routing requests first to replicas on nodes considered ‘local’ by the base load balancing policy.

Parameters:
Name Type Details
in cluster
in enabled
void

cass_cluster_set_latency_aware_routing

( cluster, enabled )

Configures the cluster to use latency-aware request routing, or not.

Default is cass_false (disabled).

This routing policy is a top-level routing policy. It uses the base routing policy to determine locality (dc-aware) and/or placement (token-aware) before considering the latency.

Parameters:
Name Type Details
in cluster
in enabled
void

cass_cluster_set_latency_aware_routing_settings

( cluster, exclusion_threshold, scale_ms, retry_period_ms, update_rate_ms, min_measured )

Configures the settings for latency-aware request routing.

Defaults:

  • exclusion_threshold: 2.0
  • scale_ms: 100 milliseconds
  • retry_period_ms: 10,000 milliseconds (10 seconds)
  • update_rate_ms: 100 milliseconds
  • min_measured: 50
Parameters:
Name Type Details
in cluster
in exclusion_threshold

Controls how much worse the latency must be compared to the average latency of the best performing node before it penalized.

in scale_ms

Controls the weight given to older latencies when calculating the average latency of a node. A bigger scale will give more weight to older latency measurements.

in retry_period_ms

The amount of time a node is penalized by the policy before being given a second chance when the current average latency exceeds the calculated threshold (exclusion_threshold * best_average_latency).

in update_rate_ms

The rate at which the best average latency is recomputed.

in min_measured

The minimum number of measurements per-host required to be considered by the policy.

void

cass_cluster_set_tcp_nodelay

( cluster, enabled )

Enable/Disable Nagel’s algorithm on connections.

Default: cass_false (disabled).

Parameters:
Name Type Details
in cluster
in enabled
void

cass_cluster_set_tcp_keepalive

( cluster, enabled, delay_secs )

Enable/Disable TCP keep-alive

Default: cass_false (disabled).

Parameters:
Name Type Details
in cluster
in enabled
in delay_secs

The initial delay in seconds, ignored when enabled is false.