MinAvailablePolicy.java

/**
 * Copyright 2016 Yahoo Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.yahoo.pulsar.common.policies.impl;

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

import java.util.SortedSet;

import com.google.common.base.Objects;
import com.yahoo.pulsar.common.policies.AutoFailoverPolicy;
import com.yahoo.pulsar.common.policies.data.AutoFailoverPolicyData;
import com.yahoo.pulsar.common.policies.data.AutoFailoverPolicyType;
import com.yahoo.pulsar.common.policies.data.BrokerStatus;

public class MinAvailablePolicy extends AutoFailoverPolicy {
    private static final String MIN_LIMIT_KEY = "min_limit";
    private static final String USAGE_THRESHOLD_KEY = "usage_threshold";
    private static final int MAX_USAGE_THRESHOLD = 100;

    public int min_limit;
    public int usage_threshold;

    MinAvailablePolicy(int minLimit, int usageThreshold) {
        this.min_limit = minLimit;
        this.usage_threshold = usageThreshold;
    }

    public MinAvailablePolicy(AutoFailoverPolicyData policyData) {
        checkArgument(policyData.policy_type.equals(AutoFailoverPolicyType.min_available));
        checkArgument(policyData.parameters.containsKey(MIN_LIMIT_KEY));
        checkArgument(policyData.parameters.containsKey(USAGE_THRESHOLD_KEY));
        this.min_limit = Integer.parseInt(policyData.parameters.get(MIN_LIMIT_KEY));
        this.usage_threshold = Integer.parseInt(policyData.parameters.get(USAGE_THRESHOLD_KEY));
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof MinAvailablePolicy) {
            MinAvailablePolicy other = (MinAvailablePolicy) obj;
            return Objects.equal(min_limit, other.min_limit) && Objects.equal(usage_threshold, other.usage_threshold);
        }
        return false;
    }

    @Override
    public boolean isBrokerAvailable(BrokerStatus brokerStatus) {
        return brokerStatus.isActive()
                && (usage_threshold == MAX_USAGE_THRESHOLD || brokerStatus.getLoadFactor() < usage_threshold);
    }

    @Override
    public boolean shouldFailoverToSecondary(SortedSet<BrokerStatus> primaryCandidates) {
        int numAvailablePrimaryBrokers = 0;
        for (BrokerStatus brkStatus : primaryCandidates) {
            if (isBrokerAvailable(brkStatus)) {
                numAvailablePrimaryBrokers++;
            }
        }

        return numAvailablePrimaryBrokers < this.min_limit;
    }

    @Override
    public boolean shouldFailoverToSecondary(int totalPrimaryCandidates) {
        return totalPrimaryCandidates < this.min_limit;
    }

    @Override
    public String toString() {
        return String.format("[policy_type=min_available min_limit=%s usage_threshold=%s]", min_limit, usage_threshold);
    }
}