Copyright 2016 Netflix, 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.
/**
 * Copyright 2016 Netflix, 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.netflix.hystrix.config;

import com.netflix.config.DynamicIntProperty;
import com.netflix.config.DynamicPropertyFactory;
import com.netflix.hystrix.HystrixCollapserKey;
import com.netflix.hystrix.HystrixCollapserMetrics;
import com.netflix.hystrix.HystrixCollapserProperties;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixCommandMetrics;
import com.netflix.hystrix.HystrixCommandProperties;
import com.netflix.hystrix.HystrixThreadPoolKey;
import com.netflix.hystrix.HystrixThreadPoolMetrics;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import rx.Observable;
import rx.functions.Action0;
import rx.functions.Func1;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

This class samples current Hystrix configuration and exposes that as a stream
/**
 * This class samples current Hystrix configuration and exposes that as a stream
 */
public class HystrixConfigurationStream {

    private final int intervalInMilliseconds;
    private final Observable<HystrixConfiguration> allConfigurationStream;
    private final AtomicBoolean isSourceCurrentlySubscribed = new AtomicBoolean(false);

    private static final DynamicIntProperty dataEmissionIntervalInMs =
            DynamicPropertyFactory.getInstance().getIntProperty("hystrix.stream.config.intervalInMilliseconds", 5000);


    private static final Func1<Long, HystrixConfiguration> getAllConfig =
            new Func1<Long, HystrixConfiguration>() {
                @Override
                public HystrixConfiguration call(Long timestamp) {
                    return HystrixConfiguration.from(
                            getAllCommandConfig.call(timestamp),
                            getAllThreadPoolConfig.call(timestamp),
                            getAllCollapserConfig.call(timestamp)
                    );
                }
            };

    
Params:
intervalInMilliseconds – milliseconds between data emissions
Deprecated:
Not for public use. Please use getInstance(). This facilitates better stream-sharing/**
     * @deprecated Not for public use.  Please use {@link #getInstance()}.  This facilitates better stream-sharing
     * @param intervalInMilliseconds milliseconds between data emissions
     */
    @Deprecated //deprecated in 1.5.4.
    public HystrixConfigurationStream(final int intervalInMilliseconds) {
        this.intervalInMilliseconds = intervalInMilliseconds;
        this.allConfigurationStream = Observable.interval(intervalInMilliseconds, TimeUnit.MILLISECONDS)
                .map(getAllConfig)
                .doOnSubscribe(new Action0() {
                    @Override
                    public void call() {
                        isSourceCurrentlySubscribed.set(true);
                    }
                })
                .doOnUnsubscribe(new Action0() {
                    @Override
                    public void call() {
                        isSourceCurrentlySubscribed.set(false);
                    }
                })
                .share()
                .onBackpressureDrop();
    }

    //The data emission interval is looked up on startup only
    private static final HystrixConfigurationStream INSTANCE =
            new HystrixConfigurationStream(dataEmissionIntervalInMs.get());

    public static HystrixConfigurationStream getInstance() {
        return INSTANCE;
    }

    static HystrixConfigurationStream getNonSingletonInstanceOnlyUsedInUnitTests(int delayInMs) {
        return new HystrixConfigurationStream(delayInMs);
    }

    
Return a ref-counted stream that will only do work when at least one subscriber is present
/**
     * Return a ref-counted stream that will only do work when at least one subscriber is present
     */
    public Observable<HystrixConfiguration> observe() {
        return allConfigurationStream;
    }

    public Observable<Map<HystrixCommandKey, HystrixCommandConfiguration>> observeCommandConfiguration() {
        return allConfigurationStream.map(getOnlyCommandConfig);
    }

    public Observable<Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration>> observeThreadPoolConfiguration() {
        return allConfigurationStream.map(getOnlyThreadPoolConfig);
    }

    public Observable<Map<HystrixCollapserKey, HystrixCollapserConfiguration>> observeCollapserConfiguration() {
        return allConfigurationStream.map(getOnlyCollapserConfig);
    }

    public int getIntervalInMilliseconds() {
        return this.intervalInMilliseconds;
    }

    public boolean isSourceCurrentlySubscribed() {
        return isSourceCurrentlySubscribed.get();
    }

    private static HystrixCommandConfiguration sampleCommandConfiguration(HystrixCommandKey commandKey, HystrixThreadPoolKey threadPoolKey,
                                                                          HystrixCommandGroupKey groupKey, HystrixCommandProperties commandProperties) {
        return HystrixCommandConfiguration.sample(commandKey, threadPoolKey, groupKey, commandProperties);
    }

    private static HystrixThreadPoolConfiguration sampleThreadPoolConfiguration(HystrixThreadPoolKey threadPoolKey, HystrixThreadPoolProperties threadPoolProperties) {
        return HystrixThreadPoolConfiguration.sample(threadPoolKey, threadPoolProperties);
    }

    private static HystrixCollapserConfiguration sampleCollapserConfiguration(HystrixCollapserKey collapserKey, HystrixCollapserProperties collapserProperties) {
        return HystrixCollapserConfiguration.sample(collapserKey, collapserProperties);
    }

    private static final Func1<Long, Map<HystrixCommandKey, HystrixCommandConfiguration>> getAllCommandConfig =
            new Func1<Long, Map<HystrixCommandKey, HystrixCommandConfiguration>>() {
                @Override
                public Map<HystrixCommandKey, HystrixCommandConfiguration> call(Long timestamp) {
                    Map<HystrixCommandKey, HystrixCommandConfiguration> commandConfigPerKey = new HashMap<HystrixCommandKey, HystrixCommandConfiguration>();
                    for (HystrixCommandMetrics commandMetrics: HystrixCommandMetrics.getInstances()) {
                        HystrixCommandKey commandKey = commandMetrics.getCommandKey();
                        HystrixThreadPoolKey threadPoolKey = commandMetrics.getThreadPoolKey();
                        HystrixCommandGroupKey groupKey = commandMetrics.getCommandGroup();
                        commandConfigPerKey.put(commandKey, sampleCommandConfiguration(commandKey, threadPoolKey, groupKey, commandMetrics.getProperties()));
                    }
                    return commandConfigPerKey;
                }
            };

    private static final Func1<Long, Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration>> getAllThreadPoolConfig =
            new Func1<Long, Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration>>() {
                @Override
                public Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration> call(Long timestamp) {
                    Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration> threadPoolConfigPerKey = new HashMap<HystrixThreadPoolKey, HystrixThreadPoolConfiguration>();
                    for (HystrixThreadPoolMetrics threadPoolMetrics: HystrixThreadPoolMetrics.getInstances()) {
                        HystrixThreadPoolKey threadPoolKey = threadPoolMetrics.getThreadPoolKey();
                        threadPoolConfigPerKey.put(threadPoolKey, sampleThreadPoolConfiguration(threadPoolKey, threadPoolMetrics.getProperties()));
                    }
                    return threadPoolConfigPerKey;
                }
            };

    private static final Func1<Long, Map<HystrixCollapserKey, HystrixCollapserConfiguration>> getAllCollapserConfig =
            new Func1<Long, Map<HystrixCollapserKey, HystrixCollapserConfiguration>>() {
                @Override
                public Map<HystrixCollapserKey, HystrixCollapserConfiguration> call(Long timestamp) {
                    Map<HystrixCollapserKey, HystrixCollapserConfiguration> collapserConfigPerKey = new HashMap<HystrixCollapserKey, HystrixCollapserConfiguration>();
                    for (HystrixCollapserMetrics collapserMetrics: HystrixCollapserMetrics.getInstances()) {
                        HystrixCollapserKey collapserKey = collapserMetrics.getCollapserKey();
                        collapserConfigPerKey.put(collapserKey, sampleCollapserConfiguration(collapserKey, collapserMetrics.getProperties()));
                    }
                    return collapserConfigPerKey;
                }
            };



    private static final Func1<HystrixConfiguration, Map<HystrixCommandKey, HystrixCommandConfiguration>> getOnlyCommandConfig =
            new Func1<HystrixConfiguration, Map<HystrixCommandKey, HystrixCommandConfiguration>>() {
                @Override
                public Map<HystrixCommandKey, HystrixCommandConfiguration> call(HystrixConfiguration hystrixConfiguration) {
                    return hystrixConfiguration.getCommandConfig();
                }
            };

    private static final Func1<HystrixConfiguration, Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration>> getOnlyThreadPoolConfig =
            new Func1<HystrixConfiguration, Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration>>() {
                @Override
                public Map<HystrixThreadPoolKey, HystrixThreadPoolConfiguration> call(HystrixConfiguration hystrixConfiguration) {
                    return hystrixConfiguration.getThreadPoolConfig();
                }
            };

    private static final Func1<HystrixConfiguration, Map<HystrixCollapserKey, HystrixCollapserConfiguration>> getOnlyCollapserConfig =
            new Func1<HystrixConfiguration, Map<HystrixCollapserKey, HystrixCollapserConfiguration>>() {
                @Override
                public Map<HystrixCollapserKey, HystrixCollapserConfiguration> call(HystrixConfiguration hystrixConfiguration) {
                    return hystrixConfiguration.getCollapserConfig();
                }
            };
}