This mechanism implements a rate limiter that allows clients to monitor and control resource consumption rates.
Declared in <balb_ratelimiter.h>
class RateLimiter;The behavior of a rate limiter is determined by four properties: the sustained rate (in units/s), the sustained-rate time-window (in seconds), the peak rate (in units/s), and the peak-rate time-window (in seconds). All of these properties can be specified at construction or using the setRateLimits method.
Units can be indicated to a rate limiter as consumed by either submitting them using the submit method. Units can be marked as reserved, which effectively shorten the sustained-rate time-window and the peak-rate time-window, by using the reserve method.
Whether submitting 1 more unit would exceed the configured limits can be determined using the wouldExceedBandwidth method. The estimated amount of time to wait before 1 more unit will be allowed to be submitted can be determined using the calculateTimeToSubmit method.
The state of a rate limiter must be updated manually using the updateState method supplying the current time interval. The time intervals supplied should all refer to the same time origin.
A rate limiter keeps some statistics, including the number of submitted units, that can be accessed using the getStatistics and reset using the resetStatistics method.
This class: * is exception neutral (agnostic) * is const thread-safe For terminology see bsldoc_glossary.
| Name | Description |
|---|---|
RateLimiter [constructor] | Create a rate limiter with the specified rate limits and start time. |
~RateLimiter [destructor] | Destroy this object. |
calculateTimeToSubmit | Return the estimated wait before one more unit can be submitted. |
cancelReserved | Cancel the specified numUnits that were previously reserved. |
getStatistics | Load submitted and unused unit statistics for this rate limiter. |
lastUpdateTime | Return the time when this rate limiter was last updated. |
peakRateLimit | Return the peak rate of this rate limiter. |
peakRateWindow | Return the peak-rate time-period of this rate limiter. Note that this period is generally significantly shorter than sustainedRateWindow. |
reserve | Reserve the specified numUnits for future use by this rate limiter. |
reset | Reset the statistics counter for this rate limiter to 0, and set the lastUpdateTime of this rate limiter to the specified currentTime. |
resetStatistics | Reset the statistics collected for this rate limiter. |
setRateLimits | Set the sustained and peak rate limits for this rate limiter. |
statisticsCollectionStartTime | Return the time interval when the collection of the statistics (as returned by getStatistics) started. |
submit | Submit the specified numUnits to this rate limiter. |
submitReserved | Submit the specified numUnits that were previously reserved. |
sustainedRateLimit | Return the sustained rate of this rate limiter. |
sustainedRateWindow | Return the sustained-rate time-period of this rate limiter. Note that this period is generally significantly longer than the peakRateWindow. |
unitsReserved | Return the number of reserved units for this rate limiter. |
updateState | Set the lastUpdateTime of this rate limiter to the specified currentTime. |
wouldExceedBandwidth | Return whether submitting 1 unit at currentTime would exceed limits. |
| Name | Description |
|---|---|
supportsRateLimitsExactly | Return whether the given limits are preserved exactly by this class. |