Housekeeping

Intervall and Time Budget

Housekeeping interval and time budget is configured by setting up a StorageHousekeepingController.

Available properties are:

Property Description

housekeeping-interval

Interval the housekeeping is triggered in milliseconds, default once per every second

housekeeping-time-budget

Time budget for housekeeping in nanoseconds, default is 0.01 seconds

housekeeping-adaptive

Usage of an adaptive housekeeping controller, which will increase the time budgets on demand, if the garbage collector needs more time to reach the sweeping phase.

housekeeping-increase-threshold

The threshold of the adaption cycle to calculate new budgets for the housekeeping process. Default is 5 seconds.

housekeeping-increase-amount

The amount the housekeeping budgets will be increased each cycle. Default is 50 ms.

housekeeping-maximum-time-budget

The upper limit of the housekeeping time budgets. Default is 0.5 seconds.

 
// New foundation
final EmbeddedStorageFoundation<?> foundation = EmbeddedStorage.Foundation();

// Housekeeping controller with fixed time budget
final StorageHousekeepingController fixedController = Storage.HousekeepingController(
	1000, // interval in ms
	10_000_000 // time budget in ns
);

// Wrap in adaptive controller
final StorageHousekeepingController adaptiveController = StorageHousekeepingController
	.AdaptiveBuilder(fixedController)
	.increaseThresholdMs(100)
	.increaseAmountNs(Duration.ofMillis(1).toNanos())
	.maximumTimeBudgetNs(Duration.ofMillis(100).toNanos())
	.buildFor(foundation)
;

// Use controller in foundation
foundation.setConfiguration(Storage.ConfigurationBuilder()
	.setHousekeepingController(adaptiveController)
	.createConfiguration()
);

// Start storage
final EmbeddedStorageManager storage = foundation.start();

File Sizes and Payload

The desired file min and max sizes and payload ratio is configured by the StorageDataFileEvaluator:

available properties are:

Property Description

data-file-minimum-size

Files smaller then minimum file size will be merged with other files if possible, default is 1 MB.

data-file-maximum-size

Files larger then maximum file size will be split in smaller ones, default is 8 MB.

data-file-minimum-use-ratio

Ratio of non-gap data contained in a storage file to prevent the file from being dissolved, default is 0.75 (75%).

 
EmbeddedStorageManager storage = EmbeddedStorage.Foundation(
	Storage.ConfigurationBuilder()
		.setDataFileEvaluator(Storage.DataFileEvaluator(1024*1024, 1024*1024*8, 0.75))
		.createConfiguration())
	.start();

Cache

The lifetime of objects in the internal entity cache can be configured by the StorageEntityCacheEvaluator:

Available properties are:

Property Description

entity-cache-threshold

Abstract threshold value, roughly comparable to size in bytes with a time component, at which a cache must be cleared of some entities. Default is 1000000000.

entity-cache-timeout

Time in milliseconds after that an entity is considered to be old if not read meanwhile. Must be greater zero, default is 86400000ms (1 day).

 
EmbeddedStorageManager storage = EmbeddedStorage.Foundation(
	Storage.ConfigurationBuilder()
		.setEntityCacheEvaluator(Storage.EntityCacheEvaluator(
			86_400_000,
			1_000_000_000))
		.createConfiguration())
	.start();
For external configuration see: Properties