Class NoSQLRateLimiter

Cloud Service or Cloud Simulator only. Default rate limiter used by the SDK.

Inheritance

Object

NoSQLRateLimiter

Implements

IRateLimiter

Namespace: Oracle.NoSQL.SDK

Assembly: Oracle.NoSQL.SDK.dll

Syntax

public class NoSQLRateLimiter : Object, IRateLimiter

Remarks

This class implements default rate limiting algorithm used by the SDK. The driver will use it if rate limiting is enabled and you did not specify RateLimiterCreator delegate. You do not need to create or use instances of this class, the following is presented for information only.

Two rate limiter instances are used per each table in use, one for reads and another for writes (see IRateLimiter).

This implementation uses a token bucket based algorithm, although the state is kept in terms of time instead of tokens. It is assumed that the units refill at constant rate being equivalent to the set limit of units per second. The state is kept in terms of next, which is the time when the next operation can proceed without waiting, meaning the limiter is at its limit. All operations issued before next will have to wait accordingly. Based on the value of next and the current time, the appropriate wait time may be computed before the wait begins. If current time is greater than or equal to next, no wait is needed.

Note that when ConsumeUnitsAsync(Int32, TimeSpan, Boolean, CancellationToken) is called, the entered units will only affect the wait time of subsequent operations and not the current operation, which will use the value of next as it currently is to determine the wait time. This is done to avoid needless wait time when the operations come in rarely.

Because every time when ConsumeUnitsAsync(Int32, TimeSpan, Boolean, CancellationToken) is called with positive number of units, next is pushed forward, the operations will be effectively staggered in time according to the order of their arrival with no preferential treatment given to any operation, thus avoiding starvation.

This rate limiter uses burst mode, allowing a set maximum number of stored units that has not been used to be consumed immediately without waiting. This value is expressed as duration, which is effectively a maximum number of seconds worth of unused stored units. The minimum duration is internally bound such that at least one unused unit may be consumed without waiting. The default value of duration is 30 seconds.

Constructors

Name	Description
NoSQLRateLimiter()	Initializes new instance of NoSQLRateLimiter with a default duration of 30 seconds.
NoSQLRateLimiter(TimeSpan)	Initializes new instance of NoSQLRateLimiter with given a given duration.

Methods

Name	Description
ConsumeUnitsAsync(Int32, TimeSpan, Boolean, CancellationToken)	Consumes the specified number of units and blocks (sleeps) asynchronously if required before an operation can proceed.
HandleThrottlingException(RetryableException)	Defines the behavior of the rate limiter when throttling exception occurs.
SetLimit(Double)	Configures rate limiter by setting its limit in units per second.