Throttling pattern

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throttling-pattern.png

Interface Throttler

Throttler defined a simple method used to call throttler implementaton.

public void start()

Implementaton

ThrottleTimerImpl implement Throttler used to cyclical reset service visit counter.

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new Timer(true).schedule(new TimerTask() {
      @Override
      public void run() {
        callsCount.reset();
      }
    }, 0, throttlePeriod);

Counter

CallsCount use ConcurrentHashMap to implement multi thread save counter.

private Map<String, AtomicLong> tenantCallsCount = new ConcurrentHashMap<>();

POJO

Tenant represent a kind of business.
have properties name and allowedCallsPerSecond

Service

XXXService call Throttler to start reset thread.
XXXService call counter to check whether ths visit under threshold.

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String tenantName = tenant.getName();
long count = callsCount.getCount(tenantName);
if (count >= tenant.getAllowedCallsPerSecond()) {
    // TODO throw excepton or return error code
    return ;
}
callsCount.incrementCount(tenantName);

Summary

Throttling is used to limit client visit frequency, so we need:
a overall situation counter
a daemonize thread resetor
a business represent pojo
a limited flow service