/**
* Check whether that caller can access or not ,based on current state and pre-defined policy
*
* @param throttleContext -The Context for this caller - runtime state
* @param configuration -The Configuration for this caller - data from policy
* @param currentTime - The current system time
* @return boolean -The boolean value which say access will allow or not
* @throws ThrottleException throws for invalid throttle configuration
*/
public boolean canAccess(
ThrottleContext throttleContext, CallerConfiguration configuration, long currentTime)
throws ThrottleException {
boolean canAccess;
if (configuration == null) {
if (log.isDebugEnabled()) {
log.debug("Couldn't find the configuration .");
}
return true;
}
if (configuration.getMaximumRequestPerUnitTime() < 0
|| configuration.getUnitTime() <= 0
|| configuration.getProhibitTimePeriod() < 0) {
throw new ThrottleException("Invalid Throttle Configuration");
}
// if caller access first time in his new session
if (this.firstAccessTime == 0) {
initAccess(configuration, throttleContext, currentTime);
}
// if unit time period (session time) is not over
if (this.nextTimeWindow > currentTime) {
canAccess = canAccessIfUnitTimeNotOver(configuration, throttleContext, currentTime);
} else {
canAccess = canAccessIfUnitTimeOver(configuration, throttleContext, currentTime);
}
return canAccess;
}
/**
* Init the access for a particular caller , caller will registered with context
*
* @param configuration -The Configuration for this caller
* @param throttleContext -The Throttle Context
* @param currentTime -The system current time in milliseconds
*/
private void initAccess(
CallerConfiguration configuration, ThrottleContext throttleContext, long currentTime) {
// This block should be synchronize by key as multiple threads can access this.
this.unitTime = configuration.getUnitTime();
this.firstAccessTime = currentTime;
this.nextTimeWindow = this.firstAccessTime + this.unitTime;
// Also we need to pick counter value associated with time window.
throttleContext.addCallerContext(this, this.id);
throttleContext.replicateTimeWindow(this.id);
}
/**
* To verify access if unit time has already over
*
* @param configuration -The Configuration for this caller
* @param throttleContext -The Throttle that caller having pass
* @param currentTime -The system current time
* @return boolean -The boolean value which say access will allow or not
*/
private boolean canAccessIfUnitTimeOver(
CallerConfiguration configuration, ThrottleContext throttleContext, long currentTime) {
boolean canAccess = false;
// if number of access for a unit time is less than MAX and
// if the unit time period (session time) has just over
int maxRequest = configuration.getMaximumRequestPerUnitTime();
if (maxRequest != 0) {
if ((this.globalCount.get() + this.localCount.get()) < maxRequest) {
if (this.nextTimeWindow != 0) {
// Removes and sends the current state to others (clustered env)
throttleContext.removeAndFlushCaller(this.id);
}
if (log.isDebugEnabled()) {
log.debug(
"CallerContext Checking access if unit time over next time window>> Access allowed="
+ maxRequest
+ " available="
+ (maxRequest - (this.globalCount.get() + this.localCount.get()))
+ " key="
+ this.getId()
+ " currentGlobalCount="
+ globalCount
+ " currentTime="
+ currentTime
+ " nextTimeWindow="
+ this.nextTimeWindow
+ " currentLocalCount="
+ localCount
+ " Tier="
+ configuration.getID()
+ " nextAccessTime="
+ this.nextAccessTime);
}
canAccess = true; // this is bonus access
// next time callers can access as a new one
} else {
// if number of access for a unit time has just been greater than MAX now same as a new
// session
// OR if caller in prohibit session and prohibit period has just over
if ((this.nextAccessTime == 0) || (this.nextAccessTime <= currentTime)) {
if (log.isDebugEnabled()) {
log.debug(
"CallerContext Checking access if unit time over>> Access allowed="
+ maxRequest
+ " available="
+ (maxRequest - (this.globalCount.get() + this.localCount.get()))
+ " key="
+ this.getId()
+ " currentGlobalCount="
+ globalCount
+ " currentTime="
+ currentTime
+ " nextTimeWindow="
+ this.nextTimeWindow
+ " currentLocalCount="
+ localCount
+ " Tier="
+ configuration.getID()
+ " nextAccessTime="
+ this.nextAccessTime);
}
// remove previous callercontext instance
if (this.nextTimeWindow != 0) {
throttleContext.removeCallerContext(id);
}
// reset the states so that, this is the first access
this.nextAccessTime = 0;
canAccess = true;
this.globalCount.set(0); // can access the system and this is same as first access
this.localCount.set(1);
this.firstAccessTime = currentTime;
this.nextTimeWindow = currentTime + configuration.getUnitTime();
// registers caller and send the current state to others (clustered env)
throttleContext.addAndFlushCallerContext(this, id);
throttleContext.replicateTimeWindow(this.id);
if (log.isDebugEnabled()) {
log.debug(
"Caller="
+ this.getId()
+ " has reset counters and added for replication when unit "
+ "time is over");
}
} else {
// if caller in prohibit session and prohibit period has not over
if (log.isDebugEnabled()) {
String type =
ThrottleConstants.IP_BASE == configuration.getType() ? "IP address" : "domain";
log.debug(
"Even unit time has over , CallerContext in prohibit state :"
+ type
+ " - "
+ this.id);
}
}
}
}
return canAccess;
}
/**
* To verify access if the unit time has already not over
*
* @param configuration - -The Configuration for this caller
* @param throttleContext -The Throttle Context
* @param currentTime -The system current time
* @return boolean -The boolean value which say access will allow or not
*/
private boolean canAccessIfUnitTimeNotOver(
CallerConfiguration configuration, ThrottleContext throttleContext, long currentTime) {
boolean canAccess = false;
int maxRequest = configuration.getMaximumRequestPerUnitTime();
if (maxRequest != 0) {
if ((this.globalCount.get() + this.localCount.get())
< maxRequest) { // If the globalCount is less than max request
if (log.isDebugEnabled()) {
log.debug(
"CallerContext Checking access if unit time is not over and less than max count>> Access "
+ "allowed="
+ maxRequest
+ " available="
+ (maxRequest - (this.globalCount.get() + this.localCount.get()))
+ " key="
+ this.getId()
+ " currentGlobalCount="
+ globalCount
+ " currentTime="
+ currentTime
+ " "
+ "nextTimeWindow="
+ this.nextTimeWindow
+ " currentLocalCount="
+ localCount
+ " Tier="
+ configuration.getID()
+ " nextAccessTime="
+ this.nextAccessTime);
}
canAccess = true; // can continue access
this.localCount.incrementAndGet();
// Send the current state to others (clustered env)
throttleContext.flushCallerContext(this, id);
// can complete access
} else {
// else , if caller has not already prohibit
if (this.nextAccessTime == 0) {
// and if there is no prohibit time period in configuration
long prohibitTime = configuration.getProhibitTimePeriod();
if (prohibitTime == 0) {
// prohibit access until unit time period is over
this.nextAccessTime = this.firstAccessTime + configuration.getUnitTime();
} else {
// if there is a prohibit time period in configuration ,then
// set it as prohibit period
this.nextAccessTime = currentTime + prohibitTime;
}
if (log.isDebugEnabled()) {
String type =
ThrottleConstants.IP_BASE == configuration.getType() ? "IP address" : "domain";
log.debug(
"Maximum Number of requests are reached for caller with " + type + " - " + this.id);
}
// Send the current state to others (clustered env)
throttleContext.flushCallerContext(this, id);
} else {
// else , if the caller has already prohibit and prohibit
// time period has already over
if (this.nextAccessTime <= currentTime) {
if (log.isDebugEnabled()) {
log.debug(
"CallerContext Checking access if unit time is not over before time window exceed >> "
+ "Access allowed="
+ maxRequest
+ " available="
+ (maxRequest - (this.globalCount.get() + this.localCount.get()))
+ " key="
+ this.getId()
+ " currentGlobalCount="
+ globalCount
+ " currentTime="
+ currentTime
+ " "
+ "nextTimeWindow="
+ this.nextTimeWindow
+ " currentLocalCount="
+ localCount
+ " "
+ "Tier="
+ configuration.getID()
+ " nextAccessTime="
+ this.nextAccessTime);
}
// remove previous caller context
if (this.nextTimeWindow != 0) {
throttleContext.removeCallerContext(id);
}
// reset the states so that, this is the first access
this.nextAccessTime = 0;
canAccess = true;
this.globalCount.set(0); // can access the system and this is same as first access
this.localCount.set(1);
this.firstAccessTime = currentTime;
this.nextTimeWindow = currentTime + configuration.getUnitTime();
throttleContext.addAndFlushCallerContext(this, this.id);
throttleContext.replicateTimeWindow(this.id);
if (log.isDebugEnabled()) {
log.debug(
"Caller="
+ this.getId()
+ " has reset counters and added for replication when unit "
+ "time is not over");
}
} else {
if (log.isDebugEnabled()) {
String type =
ThrottleConstants.IP_BASE == configuration.getType() ? "IP address" : "domain";
log.debug(
"Prohibit period is not yet over for caller with " + type + " - " + this.id);
}
}
}
}
}
return canAccess;
}