hystrix(4) properties配置

這一節我們來講hystrix的properties配置體系，properties配置也是各個功能模塊的基礎功能。hystrix將配置分成三個部分：

　　1.HystrixCommandProperties用於HystrixCommand配置，一個HystrixCommandKey對應一個HystrixCommandProperties實例。

　　2.HystrixThreadPoolProperties用於HystrixThreadPool配置，一個HystrixThreadPoolKey對應一個HystrixThreadPoolProperties實例。

　　3.HystrixCollapserProperties用於HystrixCollapserCommand配置，一個HystrixCollapserKey對應一個HystrixCollapserProperties實例。

類別	配置項	默認值	說明
HystrixCommandProperties	hystrix.threadpool.[commandkey].circuitBreaker.enabled	true
	hystrix.threadpool.[commandkey].circuitBreaker.requestVolumeThreshold	20
	hystrix.threadpool.[commandkey].circuitBreaker.sleepWindowInMilliseconds	5000
	hystrix.threadpool.[commandkey].circuitBreaker.errorThresholdPercentage	50
	hystrix.threadpool.[commandkey].circuitBreaker.forceOpen	false
	hystrix.threadpool.[commandkey].circuitBreaker.forceClosed	false
	hystrix.threadpool.[commandkey].execution.isolation.strategy	Thread
	hystrix.threadpool.[commandkey].execution.isolation.thread.timeoutInMilliseconds	1000
	hystrix.threadpool.[commandkey].execution.timeout.enabled	true
	hystrix.threadpool.[commandkey].execution.isolation.thread.interruptOnTimeout	true
	hystrix.threadpool.[commandkey].execution.isolation.thread.interruptOnFutureCancel	false
	hystrix.threadpool.[commandkey].execution.isolation.semaphore.maxConcurrentRequests	10
	hystrix.threadpool.[commandkey].fallback.isolation.semaphore.maxConcurrentRequests	10
	hystrix.threadpool.[commandkey].fallback.enabled	true
	hystrix.threadpool.[commandkey].metrics.rollingStats.timeInMilliseconds	10000
	hystrix.threadpool.[commandkey].metrics.rollingStats.numBuckets	10
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.enabled	true
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.timeInMilliseconds	60000
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.numBuckets	6
	hystrix.threadpool.[commandkey].metrics.rollingPercentile.bucketSize	100
	hystrix.threadpool.[commandkey].metrics.healthSnapshot.intervalInMilliseconds	500
	hystrix.threadpool.[commandkey].requestCache.enabled	true
	hystrix.threadpool.[commandkey].requestLog.enabled	true
	hystrix.threadpool.[commandkey].threadPoolKeyOverride
HystrixThreadPoolProperties	hystrix.threadpool.[threadPoolkey].coreSize	10
	hystrix.threadpool.[threadPoolkey].allowMaximumSizeToDivergeFromCoreSize	false
	hystrix.threadpool.[threadPoolkey].maximumSize	10
	hystrix.threadpool.[threadPoolkey].keepAliveTimeMinutes	1
	hystrix.threadpool.[threadPoolkey].maxQueueSize	-1
	hystrix.threadpool.[threadPoolkey].queueSizeRejectionThreshold	5
	hystrix.threadpool.[threadPoolkey].metrics.rollingStats.timeInMilliseconds	10000
	hystrix.threadpool.[threadPoolkey].metrics.rollingStats.numBuckets	10
HystrixCollapserProperties	hystrix.collapser.[collapserCommandkey].maxRequestsInBatch	Integer.MAX_VALUE
	hystrix.collapser.[collapserCommandkey].timerDelayInMilliseconds	10
	hystrix.collapser.[collapserCommandkey].requestCache.enabled	true
	hystrix.collapser.[collapserCommandkey].metrics.rollingStats.timeInMilliseconds	10000
	hystrix.collapser.[collapserCommandkey].metrics.rollingStats.numBuckets	10
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.enabled	true
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.timeInMilliseconds	60000
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.numBuckets	6
	hystrix.collapser.[collapserCommandkey].metrics.rollingPercentile.bucketSize	100

　　內部每個屬性由一個ChainHystrixProperty表示，ChainHystrixProperty是一個串聯的HystrixDynamicProperty，持續獲取串中的屬性值，直到獲得不為null值為止。ChainHystrixProperty串聯的HystrixDynamicProperty默認通過插件獲取的HystrixDynamicProperties獲取（最后我們會講到插件）。

　　HystrixDynamicProperty表示動態配置數據，如果配置源發送變化，通過該對象獲取配置也會相應變化。hystrix中有種實現類：

　　　　1.通過archaius實現獲取配置項，通過HystrixDynamicPropertiesArchaius創建該類HystrixDynamicProperty。

　　　　2.通過system實現獲取配置項，通過HystrixDynamicPropertiesSystemProperties創建該類HystrixDynamicProperty。