com.elastisys.scale.cloudpool.commons.basepool.config.PoolFetchConfig Maven / Gradle / Ivy

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package com.elastisys.scale.cloudpool.commons.basepool.config;

import static com.google.common.base.Preconditions.checkArgument;

import java.util.concurrent.TimeUnit;

import com.elastisys.scale.cloudpool.api.CloudPool;
import com.elastisys.scale.cloudpool.api.types.MachinePool;
import com.elastisys.scale.commons.json.JsonUtils;
import com.elastisys.scale.commons.json.types.TimeInterval;
import com.google.common.base.Objects;

/**
 * Control's the {@link CloudPool}'s behavior with respect to how often to
 * attempt fetching of {@link MachinePool} and for how long to mask fetch
 * errors.
 */
public class PoolFetchConfig {

	/** Retry handling when fetching pool members from the cloud API fails. */
	private final RetriesConfig retries;
	/**
	 * How often to refresh the cloud pool's view of the {@link MachinePool}
	 * members.
	 */
	private final TimeInterval refreshInterval;
	/**
	 * How long to respond with cached {@link MachinePool} observations before
	 * responding with a cloud reachability error. In other words, for how long
	 * should failures to fetch the machine pool be masked.
	 */
	private final TimeInterval reachabilityTimeout;

	/**
	 * Creates a {@link PoolFetchConfig}.
	 *
	 * @param retries
	 *            Retry handling when fetching pool members from the cloud API
	 *            fails.
	 * @param refreshInterval
	 *            How often to refresh the cloud pool's view of the
	 *            {@link MachinePool} members.
	 * @param reachabilityTimeout
	 *            How long to respond with cached {@link MachinePool}
	 *            observations before responding with a cloud reachability
	 *            error. In other words, for how long should failures to fetch
	 *            the machine pool be masked.
	 */
	public PoolFetchConfig(RetriesConfig retries, TimeInterval refreshInterval,
			TimeInterval reachabilityTimeout) {
		this.retries = retries;
		this.refreshInterval = refreshInterval;
		this.reachabilityTimeout = reachabilityTimeout;
	}

	/**
	 * Retry handling when fetching pool members from the cloud API fails.
	 *
	 * @return
	 */
	public RetriesConfig getRetries() {
		return this.retries;
	}

	/**
	 * How often to refresh the cloud pool's view of the {@link MachinePool}
	 * members.
	 *
	 * @return
	 */
	public TimeInterval getRefreshInterval() {
		return this.refreshInterval;
	}

	/**
	 * How long to respond with cached {@link MachinePool} observations before
	 * responding with a cloud reachability error. In other words, for how long
	 * should failures to fetch the machine pool be masked.
	 *
	 * @return
	 */
	public TimeInterval getReachabilityTimeout() {
		return this.reachabilityTimeout;
	}

	@Override
	public int hashCode() {
		return Objects.hashCode(this.retries, this.refreshInterval,
				this.reachabilityTimeout);
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof PoolFetchConfig) {
			PoolFetchConfig that = (PoolFetchConfig) obj;
			return Objects.equal(this.retries, that.retries)
					&& Objects.equal(this.refreshInterval, that.refreshInterval)
					&& Objects.equal(this.reachabilityTimeout,
							that.reachabilityTimeout);

		}
		return false;
	}

	@Override
	public String toString() {
		return JsonUtils.toPrettyString(JsonUtils.toJson(this));
	}

	public void validate() throws IllegalArgumentException {
		checkArgument(this.retries != null, "poolFetch: missing retries");
		checkArgument(this.refreshInterval != null,
				"poolFetch: missing refreshInterval");
		checkArgument(this.reachabilityTimeout != null,
				"poolFetch: missing reachabilityTimeout");

		this.retries.validate();
		this.refreshInterval.validate();
		this.reachabilityTimeout.validate();

		long refreshMillis = TimeUnit.MILLISECONDS.convert(
				this.refreshInterval.getTime(), this.refreshInterval.getUnit());
		long timeoutMillis = TimeUnit.MILLISECONDS.convert(
				this.reachabilityTimeout.getTime(),
				this.reachabilityTimeout.getUnit());
		checkArgument(refreshMillis < timeoutMillis,
				"poolFetch: reachabilityTimeout cannot be shorter than refreshInterval");
	}

}