com.aerospike.client.policy

Class Policy

java.lang.Object

com.aerospike.client.policy.Policy

Direct Known Subclasses:

BatchPolicy, QueryPolicy, ScanPolicy, WritePolicy

public class Policy
extends Object

Transaction policy attributes used in all database commands.

Field Summary

Fields

Modifier and Type	Field and Description
ConsistencyLevel	consistencyLevel How replicas should be consulted in a read operation to provide the desired consistency guarantee.
boolean	linearizeRead Force reads to be linearized for server namespaces that support strong consistency mode.
int	maxRetries Maximum number of retries before aborting the current transaction.
Priority	priority Priority of request relative to other transactions.
Replica	replica Replica algorithm used to determine the target node for a single record command.
boolean	sendKey Send user defined key in addition to hash digest on both reads and writes.
int	sleepBetweenRetries Milliseconds to sleep between retries.
int	socketTimeout Socket idle timeout in milliseconds when processing a database command.
int	timeoutDelay Delay milliseconds after transaction timeout before closing socket in async mode only.
int	totalTimeout Total transaction timeout in milliseconds.

Constructor Summary

Constructors

Constructor and Description
Policy() Default constructor.
Policy(Policy other) Copy policy from another policy.

Method Summary

Modifier and Type	Method and Description
void	setTimeout(int timeout) Create a single timeout by setting socketTimeout and totalTimeout to the same value.
void	setTimeouts(int socketTimeout, int totalTimeout) Set socketTimeout and totalTimeout.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

priority

public Priority priority

Priority of request relative to other transactions. Currently, only used for scans.

consistencyLevel

public ConsistencyLevel consistencyLevel

How replicas should be consulted in a read operation to provide the desired consistency guarantee.

Default: ConsistencyLevel.CONSISTENCY_ONE

replica

public Replica replica

Replica algorithm used to determine the target node for a single record command. Batch, scan and query are not affected by replica algorithms.

Default: Replica.SEQUENCE

socketTimeout

public int socketTimeout

Socket idle timeout in milliseconds when processing a database command.

If socketTimeout is zero and totalTimeout is non-zero, then socketTimeout will be set to totalTimeout. If both socketTimeout and totalTimeout are non-zero and socketTimeout > totalTimeout, then socketTimeout will be set to totalTimeout. If both socketTimeout and totalTimeout are zero, then there will be no socket idle limit.

If socketTimeout is non-zero and the socket has been idle for at least socketTimeout, both maxRetries and totalTimeout are checked. If maxRetries and totalTimeout are not exceeded, the transaction is retried.

For synchronous methods, socketTimeout is the socket timeout (SO_TIMEOUT). For asynchronous methods, the socketTimeout is implemented using a HashedWheelTimer.

Default for everything but scan/query: 0 (no socket idle time limit)

Default for scan/query: 30000ms

totalTimeout

public int totalTimeout

Total transaction timeout in milliseconds.

The totalTimeout is tracked on the client and sent to the server along with the transaction in the wire protocol. The client will most likely timeout first, but the server also has the capability to timeout the transaction.

If totalTimeout is not zero and totalTimeout is reached before the transaction completes, the transaction will abort with AerospikeException.Timeout.

If totalTimeout is zero, there will be no total time limit.

Default: 0 (no time limit)

timeoutDelay

public int timeoutDelay

Delay milliseconds after transaction timeout before closing socket in async mode only. When a transaction is stopped prematurely, the socket must be closed and not placed back on the pool. This is done to prevent unread socket data from corrupting the next transaction that would use that socket.

This field delays the closing of the socket to give the transaction more time to complete in the hope that the socket can be reused. This is helpful when timeouts are aggressive and a certain percentage of timeouts is expected.

The user is still notified of the timeout in async mode at the original timeout value. The transaction's async timer is then reset to this delay and the transaction is allowed to continue. If the transactions succeeds within the delay, then the socket is placed back on the pool and the transaction response is discarded. Otherwise, the socket must be closed.

This field is ignored in sync mode because control must be returned back to user on timeout and there is no currently available thread pool to process the delay.

Default: 0 (no delay, connection closed on timeout)

maxRetries

public int maxRetries

Maximum number of retries before aborting the current transaction. The initial attempt is not counted as a retry.

If maxRetries is exceeded, the transaction will abort with AerospikeException.Timeout.

WARNING: Database writes that are not idempotent (such as add()) should not be retried because the write operation may be performed multiple times if the client timed out previous transaction attempts. It's important to use a distinct WritePolicy for non-idempotent writes which sets maxRetries = 0;

Default for read: 2 (initial attempt + 2 retries = 3 attempts)

Default for write/query/scan: 0 (no retries)

sleepBetweenRetries

public int sleepBetweenRetries

Milliseconds to sleep between retries. Enter zero to skip sleep. This field is ignored when maxRetries is zero. This field is also ignored in async mode.

The sleep only occurs on connection errors and server timeouts which suggest a node is down and the cluster is reforming. The sleep does not occur when the client's socketTimeout expires.

Reads do not have to sleep when a node goes down because the cluster does not shut out reads during cluster reformation. The default for reads is zero.

The default for writes is also zero because writes are not retried by default. Writes need to wait for the cluster to reform when a node goes down. Immediate write retries on node failure have been shown to consistently result in errors. If maxRetries is greater than zero on a write, then sleepBetweenRetries should be set high enough to allow the cluster to reform (>= 500ms).

Default: 0 (do not sleep between retries)

sendKey

public boolean sendKey

Send user defined key in addition to hash digest on both reads and writes. If the key is sent on a write, the key will be stored with the record on the server.

Default: false (do not send the user defined key)

linearizeRead

public boolean linearizeRead

Force reads to be linearized for server namespaces that support strong consistency mode.

Default: false

Constructor Detail

Policy

public Policy(Policy other)

Copy policy from another policy.

Policy

public Policy()

Default constructor.

Method Detail

setTimeout

public final void setTimeout(int timeout)

Create a single timeout by setting socketTimeout and totalTimeout to the same value.

setTimeouts

public final void setTimeouts(int socketTimeout,
                              int totalTimeout)

Set socketTimeout and totalTimeout. If totalTimeout defined and socketTimeout greater than totalTimeout, set socketTimeout to totalTimeout.