com.alibaba.csp.sentinel.slots.system

Class SystemRuleManager

java.lang.Object

com.alibaba.csp.sentinel.slots.system.SystemRuleManager

public class SystemRuleManager
extends Object

Sentinel System Rule makes the inbound traffic and capacity meet. It takes average rt, qps, thread count of incoming requests into account. And it also provides a measurement of system's load, but only available on Linux.

rt, qps, thread count is easy to understand. If the incoming requests' rt,qps, thread count exceeds its threshold, the requests will be rejected.however, we use a different method to calculate the load.

Consider the system as a pipeline，transitions between constraints result in three different regions (traffic-limited, capacity-limited and danger area) with qualitatively different behavior. When there isn’t enough request in flight to fill the pipe, RTprop determines behavior; otherwise, the system capacity dominates. Constraint lines intersect at inflight = Capacity × RTprop. Since the pipe is full past this point, the inflight –capacity excess creates a queue, which results in the linear dependence of RTT on inflight traffic and an increase in system load.In danger area, system will stop responding.
Referring to BBR algorithm to learn more.

Note that SystemRule only effect on inbound requests, outbound traffic will not limit by SystemRule

Author:

jialiang.linjl, leyou

Constructor Summary

Constructors

Constructor and Description
SystemRuleManager()

Method Summary

Modifier and Type	Method and Description
static void	checkSystem(ResourceWrapper resourceWrapper) Apply SystemRule to the resource.
static Boolean	getCheckSystemStatus()
static double	getCpuUsageThreshold()
static double	getCurrentCpuUsage()
static double	getCurrentSystemAvgLoad()
static double	getHighestSystemLoad()
static long	getMaxRt()
static long	getMaxThread()
static double	getQps()
static List<SystemRule>	getRules() Get a copy of the rules.
static void	loadRules(List<SystemRule> rules) Load SystemRules, former rules will be replaced.
static void	loadSystemConf(SystemRule rule)
static void	register2Property(SentinelProperty<List<SystemRule>> property) Listen to the SentinelProperty for SystemRules.
static void	setHighestSystemLoad(double highestSystemLoad)
static void	setQps(double qps)

Methods inherited from class java.lang.Object

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

Constructor Detail

SystemRuleManager

public SystemRuleManager()

Method Detail

register2Property

public static void register2Property(SentinelProperty<List<SystemRule>> property)

Listen to the SentinelProperty for SystemRules. The property is the source of SystemRules. System rules can also be set by loadRules(List) directly.

Parameters:

property - the property to listen.

loadRules

public static void loadRules(List<SystemRule> rules)

Load SystemRules, former rules will be replaced.

Parameters:

rules - new rules to load.

getRules

public static List<SystemRule> getRules()

Get a copy of the rules.

Returns:

a new copy of the rules.

getQps

public static double getQps()

setQps

public static void setQps(double qps)

getMaxRt

public static long getMaxRt()

getMaxThread

public static long getMaxThread()

getCheckSystemStatus

public static Boolean getCheckSystemStatus()

getHighestSystemLoad

public static double getHighestSystemLoad()

setHighestSystemLoad

public static void setHighestSystemLoad(double highestSystemLoad)

getCpuUsageThreshold

public static double getCpuUsageThreshold()

loadSystemConf

public static void loadSystemConf(SystemRule rule)

checkSystem

public static void checkSystem(ResourceWrapper resourceWrapper)
                        throws BlockException

Apply SystemRule to the resource. Only inbound traffic will be checked.

Parameters:

resourceWrapper - the resource.

Throws:

BlockException - when any system rule's threshold is exceeded.

getCurrentSystemAvgLoad

public static double getCurrentSystemAvgLoad()

getCurrentCpuUsage

public static double getCurrentCpuUsage()