package com.bazaarvoice.ostrich.pool;
import java.util.concurrent.TimeUnit;
import static com.bazaarvoice.ostrich.pool.ServiceCachingPolicy.ExhaustionAction;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
public class ServiceCachingPolicyBuilder {
public static final ServiceCachingPolicy NO_CACHING = new ServiceCachingPolicyBuilder()
.withMaxNumServiceInstances(0)
.withMaxNumServiceInstancesPerEndPoint(0)
.withCacheExhaustionAction(ExhaustionAction.GROW)
.build();
private int _maxNumServiceInstances = -1;
private int _maxNumServiceInstancesPerEndPoint = -1;
private long _maxServiceInstanceIdleTimeNanos;
private ExhaustionAction _cacheExhaustionAction = ExhaustionAction.GROW;
/**
* Set the maximum number of cached service instances for the built policy. If never called, the policy will allow
* unbounded growth by default.
*
* @param maxNumServiceInstances The total maximum number of service instances in the cache.
* @return this
*/
public ServiceCachingPolicyBuilder withMaxNumServiceInstances(int maxNumServiceInstances) {
checkState(maxNumServiceInstances >= 0);
_maxNumServiceInstances = maxNumServiceInstances;
return this;
}
/**
* Set the maximum number of cached services instances for a single end point in the built policy. If never called,
* the policy will allow growth bounded only by the {@link #withMaxNumServiceInstances maxNumServiceInstances}.
* <p/>
* NOTE: The per end point maximum must be less than or equal to the total maximum, unless either is unbounded.
*
* @param maxNumServiceInstancesPerEndPoint The maximum number of service instances for one end point in the cache.
* @return this
*/
public ServiceCachingPolicyBuilder withMaxNumServiceInstancesPerEndPoint(int maxNumServiceInstancesPerEndPoint) {
checkState(maxNumServiceInstancesPerEndPoint >= 0);
_maxNumServiceInstancesPerEndPoint = maxNumServiceInstancesPerEndPoint;
return this;
}
/**
* Set the amount of time a cached instance is allowed to sit idle in the cache before being eligible for
* expiration. If never called, cached instances will not expire solely due to idle time.
*
* @param maxServiceInstanceIdleTime The time an instance may be idle before allowed to expire.
* @param unit The unit of time the {@code maxServiceInstanceIdleTime} is in.
* @return this
*/
public ServiceCachingPolicyBuilder withMaxServiceInstanceIdleTime(int maxServiceInstanceIdleTime, TimeUnit unit) {
checkState(maxServiceInstanceIdleTime > 0);
checkNotNull(unit);
_maxServiceInstanceIdleTimeNanos = unit.toNanos(maxServiceInstanceIdleTime);
return this;
}
/**
* Set the {@code ExhaustionAction} for the built caching policy. If never called, will default to
* {@code ExhaustionAction.GROW}.
*
* @param action The action to take when the cache is exhausted, either completely or for a requested end point.
* @return this
*/
public ServiceCachingPolicyBuilder withCacheExhaustionAction(ExhaustionAction action) {
checkNotNull(action);
_cacheExhaustionAction = action;
return this;
}
/**
* Build the {@code ServiceCachingPolicy} specified by this builder.
*
* @return The {@code ServiceCachingPolicy} that was constructed.
*/
public ServiceCachingPolicy build() {
checkState(_maxNumServiceInstances == -1 || _maxNumServiceInstancesPerEndPoint <= _maxNumServiceInstances);
final int maxNumServiceInstances = _maxNumServiceInstances;
final int maxNumServiceInstancesPerEndPoint = _maxNumServiceInstancesPerEndPoint;
final long maxServiceInstanceIdleTimeNanos = _maxServiceInstanceIdleTimeNanos;
final ExhaustionAction cacheExhaustionAction = _cacheExhaustionAction;
return new ServiceCachingPolicy() {
@Override
public int getMaxNumServiceInstances() {
return maxNumServiceInstances;
}
@Override
public int getMaxNumServiceInstancesPerEndPoint() {
return maxNumServiceInstancesPerEndPoint;
}
@Override
public long getMaxServiceInstanceIdleTime(TimeUnit unit) {
return unit.convert(maxServiceInstanceIdleTimeNanos, TimeUnit.NANOSECONDS);
}
@Override
public ExhaustionAction getCacheExhaustionAction() {
return cacheExhaustionAction;
}
};
}
}