Copyright 2012 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 2012 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;

import static com.netflix.hystrix.strategy.properties.HystrixPropertiesChainedProperty.forBoolean;
import static com.netflix.hystrix.strategy.properties.HystrixPropertiesChainedProperty.forInteger;
import static com.netflix.hystrix.strategy.properties.HystrixPropertiesChainedProperty.forString;

import java.util.concurrent.Future;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.netflix.hystrix.strategy.properties.HystrixDynamicProperty;
import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
import com.netflix.hystrix.strategy.properties.HystrixProperty;
import com.netflix.hystrix.util.HystrixRollingNumber;
import com.netflix.hystrix.util.HystrixRollingPercentile;

Properties for instances of HystrixCommand. 

Default implementation of methods uses Archaius (https://github.com/Netflix/archaius)
/**
 * Properties for instances of {@link HystrixCommand}.
 * <p>
 * Default implementation of methods uses Archaius (https://github.com/Netflix/archaius)
 */
public abstract class HystrixCommandProperties {
    private static final Logger logger = LoggerFactory.getLogger(HystrixCommandProperties.class);

    /* defaults */
    /* package */ static final Integer default_metricsRollingStatisticalWindow = 10000;// default => statisticalWindow: 10000 = 10 seconds (and default of 10 buckets so each bucket is 1 second)
    private static final Integer default_metricsRollingStatisticalWindowBuckets = 10;// default => statisticalWindowBuckets: 10 = 10 buckets in a 10 second window so each bucket is 1 second
    private static final Integer default_circuitBreakerRequestVolumeThreshold = 20;// default => statisticalWindowVolumeThreshold: 20 requests in 10 seconds must occur before statistics matter
    private static final Integer default_circuitBreakerSleepWindowInMilliseconds = 5000;// default => sleepWindow: 5000 = 5 seconds that we will sleep before trying again after tripping the circuit
    private static final Integer default_circuitBreakerErrorThresholdPercentage = 50;// default => errorThresholdPercentage = 50 = if 50%+ of requests in 10 seconds are failures or latent then we will trip the circuit
    private static final Boolean default_circuitBreakerForceOpen = false;// default => forceCircuitOpen = false (we want to allow traffic)
    /* package */ static final Boolean default_circuitBreakerForceClosed = false;// default => ignoreErrors = false 
    private static final Integer default_executionTimeoutInMilliseconds = 1000; // default => executionTimeoutInMilliseconds: 1000 = 1 second
    private static final Boolean default_executionTimeoutEnabled = true;
    private static final ExecutionIsolationStrategy default_executionIsolationStrategy = ExecutionIsolationStrategy.THREAD;
    private static final Boolean default_executionIsolationThreadInterruptOnTimeout = true;
    private static final Boolean default_executionIsolationThreadInterruptOnFutureCancel = false;
    private static final Boolean default_metricsRollingPercentileEnabled = true;
    private static final Boolean default_requestCacheEnabled = true;
    private static final Integer default_fallbackIsolationSemaphoreMaxConcurrentRequests = 10;
    private static final Boolean default_fallbackEnabled = true;
    private static final Integer default_executionIsolationSemaphoreMaxConcurrentRequests = 10;
    private static final Boolean default_requestLogEnabled = true;
    private static final Boolean default_circuitBreakerEnabled = true;
    private static final Integer default_metricsRollingPercentileWindow = 60000; // default to 1 minute for RollingPercentile 
    private static final Integer default_metricsRollingPercentileWindowBuckets = 6; // default to 6 buckets (10 seconds each in 60 second window)
    private static final Integer default_metricsRollingPercentileBucketSize = 100; // default to 100 values max per bucket
    private static final Integer default_metricsHealthSnapshotIntervalInMilliseconds = 500; // default to 500ms as max frequency between allowing snapshots of health (error percentage etc)

    @SuppressWarnings("unused") private final HystrixCommandKey key;
    private final HystrixProperty<Integer> circuitBreakerRequestVolumeThreshold; // number of requests that must be made within a statisticalWindow before open/close decisions are made using stats
    private final HystrixProperty<Integer> circuitBreakerSleepWindowInMilliseconds; // milliseconds after tripping circuit before allowing retry
    private final HystrixProperty<Boolean> circuitBreakerEnabled; // Whether circuit breaker should be enabled.
    private final HystrixProperty<Integer> circuitBreakerErrorThresholdPercentage; // % of 'marks' that must be failed to trip the circuit
    private final HystrixProperty<Boolean> circuitBreakerForceOpen; // a property to allow forcing the circuit open (stopping all requests)
    private final HystrixProperty<Boolean> circuitBreakerForceClosed; // a property to allow ignoring errors and therefore never trip 'open' (ie. allow all traffic through)
    private final HystrixProperty<ExecutionIsolationStrategy> executionIsolationStrategy; // Whether a command should be executed in a separate thread or not.
    private final HystrixProperty<Integer> executionTimeoutInMilliseconds; // Timeout value in milliseconds for a command
    private final HystrixProperty<Boolean> executionTimeoutEnabled; //Whether timeout should be triggered
    private final HystrixProperty<String> executionIsolationThreadPoolKeyOverride; // What thread-pool this command should run in (if running on a separate thread).
    private final HystrixProperty<Integer> executionIsolationSemaphoreMaxConcurrentRequests; // Number of permits for execution semaphore
    private final HystrixProperty<Integer> fallbackIsolationSemaphoreMaxConcurrentRequests; // Number of permits for fallback semaphore
    private final HystrixProperty<Boolean> fallbackEnabled; // Whether fallback should be attempted.
    private final HystrixProperty<Boolean> executionIsolationThreadInterruptOnTimeout; // Whether an underlying Future/Thread (when runInSeparateThread == true) should be interrupted after a timeout
    private final HystrixProperty<Boolean> executionIsolationThreadInterruptOnFutureCancel; // Whether canceling an underlying Future/Thread (when runInSeparateThread == true) should interrupt the execution thread
    private final HystrixProperty<Integer> metricsRollingStatisticalWindowInMilliseconds; // milliseconds back that will be tracked
    private final HystrixProperty<Integer> metricsRollingStatisticalWindowBuckets; // number of buckets in the statisticalWindow
    private final HystrixProperty<Boolean> metricsRollingPercentileEnabled; // Whether monitoring should be enabled (SLA and Tracers).
    private final HystrixProperty<Integer> metricsRollingPercentileWindowInMilliseconds; // number of milliseconds that will be tracked in RollingPercentile
    private final HystrixProperty<Integer> metricsRollingPercentileWindowBuckets; // number of buckets percentileWindow will be divided into
    private final HystrixProperty<Integer> metricsRollingPercentileBucketSize; // how many values will be stored in each percentileWindowBucket
    private final HystrixProperty<Integer> metricsHealthSnapshotIntervalInMilliseconds; // time between health snapshots
    private final HystrixProperty<Boolean> requestLogEnabled; // whether command request logging is enabled.
    private final HystrixProperty<Boolean> requestCacheEnabled; // Whether request caching is enabled.

    
Isolation strategy to use when executing a HystrixCommand. 


THREAD: Execute the HystrixCommand.run() method on a separate thread and restrict concurrent executions using the thread-pool size.
SEMAPHORE: Execute the HystrixCommand.run() method on the calling thread and restrict concurrent executions using the semaphore permit count.

/**
     * Isolation strategy to use when executing a {@link HystrixCommand}.
     * <p>
     * <ul>
     * <li>THREAD: Execute the {@link HystrixCommand#run()} method on a separate thread and restrict concurrent executions using the thread-pool size.</li>
     * <li>SEMAPHORE: Execute the {@link HystrixCommand#run()} method on the calling thread and restrict concurrent executions using the semaphore permit count.</li>
     * </ul>
     */
    public static enum ExecutionIsolationStrategy {
        THREAD, SEMAPHORE
    }

    protected HystrixCommandProperties(HystrixCommandKey key) {
        this(key, new Setter(), "hystrix");
    }

    protected HystrixCommandProperties(HystrixCommandKey key, HystrixCommandProperties.Setter builder) {
        this(key, builder, "hystrix");
    }

    // known that we're using deprecated HystrixPropertiesChainedServoProperty until ChainedDynamicProperty exists in Archaius
    protected HystrixCommandProperties(HystrixCommandKey key, HystrixCommandProperties.Setter builder, String propertyPrefix) {
        this.key = key;
        this.circuitBreakerEnabled = getProperty(propertyPrefix, key, "circuitBreaker.enabled", builder.getCircuitBreakerEnabled(), default_circuitBreakerEnabled);
        this.circuitBreakerRequestVolumeThreshold = getProperty(propertyPrefix, key, "circuitBreaker.requestVolumeThreshold", builder.getCircuitBreakerRequestVolumeThreshold(), default_circuitBreakerRequestVolumeThreshold);
        this.circuitBreakerSleepWindowInMilliseconds = getProperty(propertyPrefix, key, "circuitBreaker.sleepWindowInMilliseconds", builder.getCircuitBreakerSleepWindowInMilliseconds(), default_circuitBreakerSleepWindowInMilliseconds);
        this.circuitBreakerErrorThresholdPercentage = getProperty(propertyPrefix, key, "circuitBreaker.errorThresholdPercentage", builder.getCircuitBreakerErrorThresholdPercentage(), default_circuitBreakerErrorThresholdPercentage);
        this.circuitBreakerForceOpen = getProperty(propertyPrefix, key, "circuitBreaker.forceOpen", builder.getCircuitBreakerForceOpen(), default_circuitBreakerForceOpen);
        this.circuitBreakerForceClosed = getProperty(propertyPrefix, key, "circuitBreaker.forceClosed", builder.getCircuitBreakerForceClosed(), default_circuitBreakerForceClosed);
        this.executionIsolationStrategy = getProperty(propertyPrefix, key, "execution.isolation.strategy", builder.getExecutionIsolationStrategy(), default_executionIsolationStrategy);
        //this property name is now misleading.  //TODO figure out a good way to deprecate this property name
        this.executionTimeoutInMilliseconds = getProperty(propertyPrefix, key, "execution.isolation.thread.timeoutInMilliseconds", builder.getExecutionIsolationThreadTimeoutInMilliseconds(), default_executionTimeoutInMilliseconds);
        this.executionTimeoutEnabled = getProperty(propertyPrefix, key, "execution.timeout.enabled", builder.getExecutionTimeoutEnabled(), default_executionTimeoutEnabled);
        this.executionIsolationThreadInterruptOnTimeout = getProperty(propertyPrefix, key, "execution.isolation.thread.interruptOnTimeout", builder.getExecutionIsolationThreadInterruptOnTimeout(), default_executionIsolationThreadInterruptOnTimeout);
        this.executionIsolationThreadInterruptOnFutureCancel = getProperty(propertyPrefix, key, "execution.isolation.thread.interruptOnFutureCancel", builder.getExecutionIsolationThreadInterruptOnFutureCancel(), default_executionIsolationThreadInterruptOnFutureCancel);
        this.executionIsolationSemaphoreMaxConcurrentRequests = getProperty(propertyPrefix, key, "execution.isolation.semaphore.maxConcurrentRequests", builder.getExecutionIsolationSemaphoreMaxConcurrentRequests(), default_executionIsolationSemaphoreMaxConcurrentRequests);
        this.fallbackIsolationSemaphoreMaxConcurrentRequests = getProperty(propertyPrefix, key, "fallback.isolation.semaphore.maxConcurrentRequests", builder.getFallbackIsolationSemaphoreMaxConcurrentRequests(), default_fallbackIsolationSemaphoreMaxConcurrentRequests);
        this.fallbackEnabled = getProperty(propertyPrefix, key, "fallback.enabled", builder.getFallbackEnabled(), default_fallbackEnabled);
        this.metricsRollingStatisticalWindowInMilliseconds = getProperty(propertyPrefix, key, "metrics.rollingStats.timeInMilliseconds", builder.getMetricsRollingStatisticalWindowInMilliseconds(), default_metricsRollingStatisticalWindow);
        this.metricsRollingStatisticalWindowBuckets = getProperty(propertyPrefix, key, "metrics.rollingStats.numBuckets", builder.getMetricsRollingStatisticalWindowBuckets(), default_metricsRollingStatisticalWindowBuckets);
        this.metricsRollingPercentileEnabled = getProperty(propertyPrefix, key, "metrics.rollingPercentile.enabled", builder.getMetricsRollingPercentileEnabled(), default_metricsRollingPercentileEnabled);
        this.metricsRollingPercentileWindowInMilliseconds = getProperty(propertyPrefix, key, "metrics.rollingPercentile.timeInMilliseconds", builder.getMetricsRollingPercentileWindowInMilliseconds(), default_metricsRollingPercentileWindow);
        this.metricsRollingPercentileWindowBuckets = getProperty(propertyPrefix, key, "metrics.rollingPercentile.numBuckets", builder.getMetricsRollingPercentileWindowBuckets(), default_metricsRollingPercentileWindowBuckets);
        this.metricsRollingPercentileBucketSize = getProperty(propertyPrefix, key, "metrics.rollingPercentile.bucketSize", builder.getMetricsRollingPercentileBucketSize(), default_metricsRollingPercentileBucketSize);
        this.metricsHealthSnapshotIntervalInMilliseconds = getProperty(propertyPrefix, key, "metrics.healthSnapshot.intervalInMilliseconds", builder.getMetricsHealthSnapshotIntervalInMilliseconds(), default_metricsHealthSnapshotIntervalInMilliseconds);
        this.requestCacheEnabled = getProperty(propertyPrefix, key, "requestCache.enabled", builder.getRequestCacheEnabled(), default_requestCacheEnabled);
        this.requestLogEnabled = getProperty(propertyPrefix, key, "requestLog.enabled", builder.getRequestLogEnabled(), default_requestLogEnabled);

        // threadpool doesn't have a global override, only instance level makes sense
        this.executionIsolationThreadPoolKeyOverride = forString().add(propertyPrefix + ".command." + key.name() + ".threadPoolKeyOverride", null).build();
    }

    
Whether to use a HystrixCircuitBreaker or not. If false no circuit-breaker logic will be used and all requests permitted. 
 This is similar in effect to circuitBreakerForceClosed() except that continues tracking metrics and knowing whether it should be open/closed, this property results in not even instantiating a circuit-breaker. 
Returns:
HystrixProperty<Boolean>/**
     * Whether to use a {@link HystrixCircuitBreaker} or not. If false no circuit-breaker logic will be used and all requests permitted.
     * <p>
     * This is similar in effect to {@link #circuitBreakerForceClosed()} except that continues tracking metrics and knowing whether it
     * should be open/closed, this property results in not even instantiating a circuit-breaker.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> circuitBreakerEnabled() {
        return circuitBreakerEnabled;
    }

    
Error percentage threshold (as whole number such as 50) at which point the circuit breaker will trip open and reject requests.
 It will stay tripped for the duration defined in circuitBreakerSleepWindowInMilliseconds(); 
 The error percentage this is compared against comes from HystrixCommandMetrics.getHealthCounts(). 
Returns:
HystrixProperty<Integer>/**
     * Error percentage threshold (as whole number such as 50) at which point the circuit breaker will trip open and reject requests.
     * <p>
     * It will stay tripped for the duration defined in {@link #circuitBreakerSleepWindowInMilliseconds()};
     * <p>
     * The error percentage this is compared against comes from {@link HystrixCommandMetrics#getHealthCounts()}.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> circuitBreakerErrorThresholdPercentage() {
        return circuitBreakerErrorThresholdPercentage;
    }

    
If true the HystrixCircuitBreaker.allowRequest() will always return true to allow requests regardless of the error percentage from HystrixCommandMetrics.getHealthCounts(). 
 The circuitBreakerForceOpen() property takes precedence so if it set to true this property does nothing. 
Returns:
HystrixProperty<Boolean>/**
     * If true the {@link HystrixCircuitBreaker#allowRequest()} will always return true to allow requests regardless of the error percentage from {@link HystrixCommandMetrics#getHealthCounts()}.
     * <p>
     * The {@link #circuitBreakerForceOpen()} property takes precedence so if it set to true this property does nothing.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> circuitBreakerForceClosed() {
        return circuitBreakerForceClosed;
    }

    
If true the HystrixCircuitBreaker.allowRequest() will always return false, causing the circuit to be open (tripped) and reject all requests. 
 This property takes precedence over circuitBreakerForceClosed(); 
Returns:
HystrixProperty<Boolean>/**
     * If true the {@link HystrixCircuitBreaker#allowRequest()} will always return false, causing the circuit to be open (tripped) and reject all requests.
     * <p>
     * This property takes precedence over {@link #circuitBreakerForceClosed()};
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> circuitBreakerForceOpen() {
        return circuitBreakerForceOpen;
    }

    
Minimum number of requests in the metricsRollingStatisticalWindowInMilliseconds() that must exist before the HystrixCircuitBreaker will trip. 

If below this number the circuit will not trip regardless of error percentage.
Returns:
HystrixProperty<Integer>/**
     * Minimum number of requests in the {@link #metricsRollingStatisticalWindowInMilliseconds()} that must exist before the {@link HystrixCircuitBreaker} will trip.
     * <p>
     * If below this number the circuit will not trip regardless of error percentage.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> circuitBreakerRequestVolumeThreshold() {
        return circuitBreakerRequestVolumeThreshold;
    }

    
The time in milliseconds after a HystrixCircuitBreaker trips open that it should wait before trying requests again. 
Returns:
HystrixProperty<Integer>/**
     * The time in milliseconds after a {@link HystrixCircuitBreaker} trips open that it should wait before trying requests again.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> circuitBreakerSleepWindowInMilliseconds() {
        return circuitBreakerSleepWindowInMilliseconds;
    }

    
Number of concurrent requests permitted to HystrixCommand.run(). Requests beyond the concurrent limit will be rejected. 
 Applicable only when executionIsolationStrategy() == SEMAPHORE. 
Returns:
HystrixProperty<Integer>/**
     * Number of concurrent requests permitted to {@link HystrixCommand#run()}. Requests beyond the concurrent limit will be rejected.
     * <p>
     * Applicable only when {@link #executionIsolationStrategy()} == SEMAPHORE.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> executionIsolationSemaphoreMaxConcurrentRequests() {
        return executionIsolationSemaphoreMaxConcurrentRequests;
    }

    
What isolation strategy HystrixCommand.run() will be executed with. 
 If ExecutionIsolationStrategy.THREAD then it will be executed on a separate thread and concurrent requests limited by the number of threads in the thread-pool. 
 If ExecutionIsolationStrategy.SEMAPHORE then it will be executed on the calling thread and concurrent requests limited by the semaphore count. 
Returns:
HystrixProperty<Boolean>/**
     * What isolation strategy {@link HystrixCommand#run()} will be executed with.
     * <p>
     * If {@link ExecutionIsolationStrategy#THREAD} then it will be executed on a separate thread and concurrent requests limited by the number of threads in the thread-pool.
     * <p>
     * If {@link ExecutionIsolationStrategy#SEMAPHORE} then it will be executed on the calling thread and concurrent requests limited by the semaphore count.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<ExecutionIsolationStrategy> executionIsolationStrategy() {
        return executionIsolationStrategy;
    }

    
Whether the execution thread should attempt an interrupt (using Future.cancel) when a thread times out. 
 Applicable only when executionIsolationStrategy() == THREAD. 
Returns:
HystrixProperty<Boolean>/**
     * Whether the execution thread should attempt an interrupt (using {@link Future#cancel}) when a thread times out.
     * <p>
     * Applicable only when {@link #executionIsolationStrategy()} == THREAD.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> executionIsolationThreadInterruptOnTimeout() {
        return executionIsolationThreadInterruptOnTimeout;
    }

    
Whether the execution thread should be interrupted if the execution observable is unsubscribed or the future is cancelled via Future#cancel(true)). 
 Applicable only when executionIsolationStrategy() == THREAD. 
Returns:
HystrixProperty<Boolean>/**
     * Whether the execution thread should be interrupted if the execution observable is unsubscribed or the future is cancelled via {@link Future#cancel(true)}).
     * <p>
     * Applicable only when {@link #executionIsolationStrategy()} == THREAD.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> executionIsolationThreadInterruptOnFutureCancel() {
        return executionIsolationThreadInterruptOnFutureCancel;
    }

    
Allow a dynamic override of the HystrixThreadPoolKey that will dynamically change which HystrixThreadPool a HystrixCommand executes on. 
 Typically this should return NULL which will cause it to use the HystrixThreadPoolKey injected into a HystrixCommand or derived from the HystrixCommandGroupKey. 
 When set the injected or derived values will be ignored and a new HystrixThreadPool created (if necessary) and the HystrixCommand will begin using the newly defined pool. 
Returns:
HystrixProperty<String>/**
     * Allow a dynamic override of the {@link HystrixThreadPoolKey} that will dynamically change which {@link HystrixThreadPool} a {@link HystrixCommand} executes on.
     * <p>
     * Typically this should return NULL which will cause it to use the {@link HystrixThreadPoolKey} injected into a {@link HystrixCommand} or derived from the {@link HystrixCommandGroupKey}.
     * <p>
     * When set the injected or derived values will be ignored and a new {@link HystrixThreadPool} created (if necessary) and the {@link HystrixCommand} will begin using the newly defined pool.
     * 
     * @return {@code HystrixProperty<String>}
     */
    public HystrixProperty<String> executionIsolationThreadPoolKeyOverride() {
        return executionIsolationThreadPoolKeyOverride;
    }

    
Deprecated:
 As of release 1.4.0, replaced by executionTimeoutInMilliseconds(). Timeout is no longer specific to thread-isolation commands, so the thread-specific name is misleading. Time in milliseconds at which point the command will timeout and halt execution. 
 If executionIsolationThreadInterruptOnTimeout == true and the command is thread-isolated, the executing thread will be interrupted. If the command is semaphore-isolated and a HystrixObservableCommand, that command will get unsubscribed. 
Returns:
HystrixProperty<Integer>/**
     *
     * @deprecated  As of release 1.4.0, replaced by {@link #executionTimeoutInMilliseconds()}.  Timeout is no longer specific to thread-isolation commands, so the thread-specific name is misleading.
     *
     * Time in milliseconds at which point the command will timeout and halt execution.
     * <p>
     * If {@link #executionIsolationThreadInterruptOnTimeout} == true and the command is thread-isolated, the executing thread will be interrupted.
     * If the command is semaphore-isolated and a {@link HystrixObservableCommand}, that command will get unsubscribed.
     * <p>
     *
     * @return {@code HystrixProperty<Integer>}
     */
    @Deprecated //prefer {@link #executionTimeoutInMilliseconds}
    public HystrixProperty<Integer> executionIsolationThreadTimeoutInMilliseconds() {
        return executionTimeoutInMilliseconds;
    }

    
Time in milliseconds at which point the command will timeout and halt execution.
 If executionIsolationThreadInterruptOnTimeout == true and the command is thread-isolated, the executing thread will be interrupted. If the command is semaphore-isolated and a HystrixObservableCommand, that command will get unsubscribed. 

Returns:
HystrixProperty<Integer>/**
     * Time in milliseconds at which point the command will timeout and halt execution.
     * <p>
     * If {@link #executionIsolationThreadInterruptOnTimeout} == true and the command is thread-isolated, the executing thread will be interrupted.
     * If the command is semaphore-isolated and a {@link HystrixObservableCommand}, that command will get unsubscribed.
     * <p>
     *
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> executionTimeoutInMilliseconds() {
        /**
         * Calling a deprecated method here is a temporary workaround.  We do this because {@link #executionTimeoutInMilliseconds()} is a new method (as of 1.4.0-rc.7) and an extending
         * class will not have this method.  It will have {@link #executionIsolationThreadTimeoutInMilliseconds()}, however.
         * So, to stay compatible with an extension, we perform this redirect.
         */
        return executionIsolationThreadTimeoutInMilliseconds();
    }

    
Whether the timeout mechanism is enabled for this command
Returns:
HystrixProperty<Boolean>
Since:
1.4.4/**
     * Whether the timeout mechanism is enabled for this command
     *
     * @return {@code HystrixProperty<Boolean>}
     *
     * @since 1.4.4
     */
    public HystrixProperty<Boolean> executionTimeoutEnabled() {
        return executionTimeoutEnabled;
    }

    
Number of concurrent requests permitted to HystrixCommand.getFallback(). Requests beyond the concurrent limit will fail-fast and not attempt retrieving a fallback. 
Returns:
HystrixProperty<Integer>/**
     * Number of concurrent requests permitted to {@link HystrixCommand#getFallback()}. Requests beyond the concurrent limit will fail-fast and not attempt retrieving a fallback.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> fallbackIsolationSemaphoreMaxConcurrentRequests() {
        return fallbackIsolationSemaphoreMaxConcurrentRequests;
    }

    
Whether HystrixCommand.getFallback() should be attempted when failure occurs. 
Returns:
HystrixProperty<Boolean>
Since:
1.2/**
     * Whether {@link HystrixCommand#getFallback()} should be attempted when failure occurs.
     * 
     * @return {@code HystrixProperty<Boolean>}
     * 
     * @since 1.2
     */
    public HystrixProperty<Boolean> fallbackEnabled() {
        return fallbackEnabled;
    }

    
Time in milliseconds to wait between allowing health snapshots to be taken that calculate success and error percentages and affect HystrixCircuitBreaker.isOpen() status. 

On high-volume circuits the continual calculation of error percentage can become CPU intensive thus this controls how often it is calculated.
Returns:
HystrixProperty<Integer>/**
     * Time in milliseconds to wait between allowing health snapshots to be taken that calculate success and error percentages and affect {@link HystrixCircuitBreaker#isOpen()} status.
     * <p>
     * On high-volume circuits the continual calculation of error percentage can become CPU intensive thus this controls how often it is calculated.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> metricsHealthSnapshotIntervalInMilliseconds() {
        return metricsHealthSnapshotIntervalInMilliseconds;
    }

    
Maximum number of values stored in each bucket of the rolling percentile. This is passed into HystrixRollingPercentile inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Integer>/**
     * Maximum number of values stored in each bucket of the rolling percentile. This is passed into {@link HystrixRollingPercentile} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> metricsRollingPercentileBucketSize() {
        return metricsRollingPercentileBucketSize;
    }

    
Whether percentile metrics should be captured using HystrixRollingPercentile inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Boolean>/**
     * Whether percentile metrics should be captured using {@link HystrixRollingPercentile} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> metricsRollingPercentileEnabled() {
        return metricsRollingPercentileEnabled;
    }

    
Duration of percentile rolling window in milliseconds. This is passed into HystrixRollingPercentile inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Integer>
Deprecated:
Use metricsRollingPercentileWindowInMilliseconds()/**
     * Duration of percentile rolling window in milliseconds. This is passed into {@link HystrixRollingPercentile} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Integer>}
     * @deprecated Use {@link #metricsRollingPercentileWindowInMilliseconds()}
     */
    public HystrixProperty<Integer> metricsRollingPercentileWindow() {
        return metricsRollingPercentileWindowInMilliseconds;
    }

    
Duration of percentile rolling window in milliseconds. This is passed into HystrixRollingPercentile inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Integer>/**
     * Duration of percentile rolling window in milliseconds. This is passed into {@link HystrixRollingPercentile} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> metricsRollingPercentileWindowInMilliseconds() {
        return metricsRollingPercentileWindowInMilliseconds;
    }

    
Number of buckets the rolling percentile window is broken into. This is passed into HystrixRollingPercentile inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Integer>/**
     * Number of buckets the rolling percentile window is broken into. This is passed into {@link HystrixRollingPercentile} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> metricsRollingPercentileWindowBuckets() {
        return metricsRollingPercentileWindowBuckets;
    }

    
Duration of statistical rolling window in milliseconds. This is passed into HystrixRollingNumber inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Integer>/**
     * Duration of statistical rolling window in milliseconds. This is passed into {@link HystrixRollingNumber} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> metricsRollingStatisticalWindowInMilliseconds() {
        return metricsRollingStatisticalWindowInMilliseconds;
    }

    
Number of buckets the rolling statistical window is broken into. This is passed into HystrixRollingNumber inside HystrixCommandMetrics. 
Returns:
HystrixProperty<Integer>/**
     * Number of buckets the rolling statistical window is broken into. This is passed into {@link HystrixRollingNumber} inside {@link HystrixCommandMetrics}.
     * 
     * @return {@code HystrixProperty<Integer>}
     */
    public HystrixProperty<Integer> metricsRollingStatisticalWindowBuckets() {
        return metricsRollingStatisticalWindowBuckets;
    }

    
Whether AbstractCommand.getCacheKey() should be used with HystrixRequestCache to provide de-duplication functionality via request-scoped caching. 
Returns:
HystrixProperty<Boolean>/**
     * Whether {@link HystrixCommand#getCacheKey()} should be used with {@link HystrixRequestCache} to provide de-duplication functionality via request-scoped caching.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> requestCacheEnabled() {
        return requestCacheEnabled;
    }

    
Whether HystrixCommand execution and events should be logged to HystrixRequestLog. 
Returns:
HystrixProperty<Boolean>/**
     * Whether {@link HystrixCommand} execution and events should be logged to {@link HystrixRequestLog}.
     * 
     * @return {@code HystrixProperty<Boolean>}
     */
    public HystrixProperty<Boolean> requestLogEnabled() {
        return requestLogEnabled;
    }

    private static HystrixProperty<Boolean> getProperty(String propertyPrefix, HystrixCommandKey key, String instanceProperty, Boolean builderOverrideValue, Boolean defaultValue) {
        return forBoolean()
                .add(propertyPrefix + ".command." + key.name() + "." + instanceProperty, builderOverrideValue)
                .add(propertyPrefix + ".command.default." + instanceProperty, defaultValue)
                .build();
    }

    private static HystrixProperty<Integer> getProperty(String propertyPrefix, HystrixCommandKey key, String instanceProperty, Integer builderOverrideValue, Integer defaultValue) {
        return forInteger()
                .add(propertyPrefix + ".command." + key.name() + "." + instanceProperty, builderOverrideValue)
                .add(propertyPrefix + ".command.default." + instanceProperty, defaultValue)
                .build();
    }

    @SuppressWarnings("unused")
    private static HystrixProperty<String> getProperty(String propertyPrefix, HystrixCommandKey key, String instanceProperty, String builderOverrideValue, String defaultValue) {
        return forString()
                .add(propertyPrefix + ".command." + key.name() + "." + instanceProperty, builderOverrideValue)
                .add(propertyPrefix + ".command.default." + instanceProperty, defaultValue)
                .build();
    }

    private static HystrixProperty<ExecutionIsolationStrategy> getProperty(final String propertyPrefix, final HystrixCommandKey key, final String instanceProperty, final ExecutionIsolationStrategy builderOverrideValue, final ExecutionIsolationStrategy defaultValue) {
        return new ExecutionIsolationStrategyHystrixProperty(builderOverrideValue, key, propertyPrefix, defaultValue, instanceProperty);

    }

    
HystrixProperty that converts a String to ExecutionIsolationStrategy so we remain TypeSafe.
/**
     * HystrixProperty that converts a String to ExecutionIsolationStrategy so we remain TypeSafe.
     */
    private static final class ExecutionIsolationStrategyHystrixProperty implements HystrixProperty<ExecutionIsolationStrategy> {
        private final HystrixDynamicProperty<String> property;
        private volatile ExecutionIsolationStrategy value;
        private final ExecutionIsolationStrategy defaultValue;

        private ExecutionIsolationStrategyHystrixProperty(ExecutionIsolationStrategy builderOverrideValue, HystrixCommandKey key, String propertyPrefix, ExecutionIsolationStrategy defaultValue, String instanceProperty) {
            this.defaultValue = defaultValue;
            String overrideValue = null;
            if (builderOverrideValue != null) {
                overrideValue = builderOverrideValue.name();
            }
            property = forString()
                    .add(propertyPrefix + ".command." + key.name() + "." + instanceProperty, overrideValue)
                    .add(propertyPrefix + ".command.default." + instanceProperty, defaultValue.name())
                    .build();

            // initialize the enum value from the property
            parseProperty();

            // use a callback to handle changes so we only handle the parse cost on updates rather than every fetch
            property.addCallback(new Runnable() {

                @Override
                public void run() {
                    // when the property value changes we'll update the value
                    parseProperty();
                }

            });
        }

        @Override
        public ExecutionIsolationStrategy get() {
            return value;
        }

        private void parseProperty() {
            try {
                value = ExecutionIsolationStrategy.valueOf(property.get());
            } catch (Exception e) {
                logger.error("Unable to derive ExecutionIsolationStrategy from property value: " + property.get(), e);
                // use the default value
                value = defaultValue;
            }
        }
    }

    
Factory method to retrieve the default Setter.
/**
     * Factory method to retrieve the default Setter.
     */
    public static Setter Setter() {
        return new Setter();
    }

    
Factory method to retrieve the default Setter.
Groovy has a bug (GROOVY-6286) which does not allow method names and inner classes to have the same name
This method fixes Issue #967 and allows Groovy consumers to choose this method and not trigger the bug
/**
     * Factory method to retrieve the default Setter.
     * Groovy has a bug (GROOVY-6286) which does not allow method names and inner classes to have the same name
     * This method fixes Issue #967 and allows Groovy consumers to choose this method and not trigger the bug
     */
    public static Setter defaultSetter() {
        return Setter();
    }

    
Fluent interface that allows chained setting of properties that can be passed into a HystrixCommand constructor to inject instance specific property overrides. 
 See HystrixPropertiesStrategy for more information on order of precedence. 

Example:

 
HystrixCommandProperties.Setter()
          .withExecutionTimeoutInMilliseconds(100)
          .withExecuteCommandOnSeparateThread(true);
 
@NotThreadSafe
/**
     * Fluent interface that allows chained setting of properties that can be passed into a {@link HystrixCommand} constructor to inject instance specific property overrides.
     * <p>
     * See {@link HystrixPropertiesStrategy} for more information on order of precedence.
     * <p>
     * Example:
     * <p>
     * <pre> {@code
     * HystrixCommandProperties.Setter()
     *           .withExecutionTimeoutInMilliseconds(100)
     *           .withExecuteCommandOnSeparateThread(true);
     * } </pre>
     * 
     * @NotThreadSafe
     */
    public static class Setter {

        private Boolean circuitBreakerEnabled = null;
        private Integer circuitBreakerErrorThresholdPercentage = null;
        private Boolean circuitBreakerForceClosed = null;
        private Boolean circuitBreakerForceOpen = null;
        private Integer circuitBreakerRequestVolumeThreshold = null;
        private Integer circuitBreakerSleepWindowInMilliseconds = null;
        private Integer executionIsolationSemaphoreMaxConcurrentRequests = null;
        private ExecutionIsolationStrategy executionIsolationStrategy = null;
        private Boolean executionIsolationThreadInterruptOnTimeout = null;
        private Boolean executionIsolationThreadInterruptOnFutureCancel = null;
        private Integer executionTimeoutInMilliseconds = null;
        private Boolean executionTimeoutEnabled = null;
        private Integer fallbackIsolationSemaphoreMaxConcurrentRequests = null;
        private Boolean fallbackEnabled = null;
        private Integer metricsHealthSnapshotIntervalInMilliseconds = null;
        private Integer metricsRollingPercentileBucketSize = null;
        private Boolean metricsRollingPercentileEnabled = null;
        private Integer metricsRollingPercentileWindowInMilliseconds = null;
        private Integer metricsRollingPercentileWindowBuckets = null;
        /* null means it hasn't been overridden */
        private Integer metricsRollingStatisticalWindowInMilliseconds = null;
        private Integer metricsRollingStatisticalWindowBuckets = null;
        private Boolean requestCacheEnabled = null;
        private Boolean requestLogEnabled = null;

        /* package */ Setter() {
        }

        public Boolean getCircuitBreakerEnabled() {
            return circuitBreakerEnabled;
        }

        public Integer getCircuitBreakerErrorThresholdPercentage() {
            return circuitBreakerErrorThresholdPercentage;
        }

        public Boolean getCircuitBreakerForceClosed() {
            return circuitBreakerForceClosed;
        }

        public Boolean getCircuitBreakerForceOpen() {
            return circuitBreakerForceOpen;
        }

        public Integer getCircuitBreakerRequestVolumeThreshold() {
            return circuitBreakerRequestVolumeThreshold;
        }

        public Integer getCircuitBreakerSleepWindowInMilliseconds() {
            return circuitBreakerSleepWindowInMilliseconds;
        }

        public Integer getExecutionIsolationSemaphoreMaxConcurrentRequests() {
            return executionIsolationSemaphoreMaxConcurrentRequests;
        }

        public ExecutionIsolationStrategy getExecutionIsolationStrategy() {
            return executionIsolationStrategy;
        }

        public Boolean getExecutionIsolationThreadInterruptOnTimeout() {
            return executionIsolationThreadInterruptOnTimeout;
        }

        public Boolean getExecutionIsolationThreadInterruptOnFutureCancel() {
			return executionIsolationThreadInterruptOnFutureCancel;
		}

		
Deprecated:
As of 1.4.0, use getExecutionTimeoutInMilliseconds()/**
         * @deprecated As of 1.4.0, use {@link #getExecutionTimeoutInMilliseconds()}
         */
        @Deprecated
        public Integer getExecutionIsolationThreadTimeoutInMilliseconds() {
            return executionTimeoutInMilliseconds;
        }

        public Integer getExecutionTimeoutInMilliseconds() {
            return executionTimeoutInMilliseconds;
        }

        public Boolean getExecutionTimeoutEnabled() {
            return executionTimeoutEnabled;
        }

        public Integer getFallbackIsolationSemaphoreMaxConcurrentRequests() {
            return fallbackIsolationSemaphoreMaxConcurrentRequests;
        }

        public Boolean getFallbackEnabled() {
            return fallbackEnabled;
        }

        public Integer getMetricsHealthSnapshotIntervalInMilliseconds() {
            return metricsHealthSnapshotIntervalInMilliseconds;
        }

        public Integer getMetricsRollingPercentileBucketSize() {
            return metricsRollingPercentileBucketSize;
        }

        public Boolean getMetricsRollingPercentileEnabled() {
            return metricsRollingPercentileEnabled;
        }

        public Integer getMetricsRollingPercentileWindowInMilliseconds() {
            return metricsRollingPercentileWindowInMilliseconds;
        }

        public Integer getMetricsRollingPercentileWindowBuckets() {
            return metricsRollingPercentileWindowBuckets;
        }

        public Integer getMetricsRollingStatisticalWindowInMilliseconds() {
            return metricsRollingStatisticalWindowInMilliseconds;
        }

        public Integer getMetricsRollingStatisticalWindowBuckets() {
            return metricsRollingStatisticalWindowBuckets;
        }

        public Boolean getRequestCacheEnabled() {
            return requestCacheEnabled;
        }

        public Boolean getRequestLogEnabled() {
            return requestLogEnabled;
        }

        public Setter withCircuitBreakerEnabled(boolean value) {
            this.circuitBreakerEnabled = value;
            return this;
        }

        public Setter withCircuitBreakerErrorThresholdPercentage(int value) {
            this.circuitBreakerErrorThresholdPercentage = value;
            return this;
        }

        public Setter withCircuitBreakerForceClosed(boolean value) {
            this.circuitBreakerForceClosed = value;
            return this;
        }

        public Setter withCircuitBreakerForceOpen(boolean value) {
            this.circuitBreakerForceOpen = value;
            return this;
        }

        public Setter withCircuitBreakerRequestVolumeThreshold(int value) {
            this.circuitBreakerRequestVolumeThreshold = value;
            return this;
        }

        public Setter withCircuitBreakerSleepWindowInMilliseconds(int value) {
            this.circuitBreakerSleepWindowInMilliseconds = value;
            return this;
        }

        public Setter withExecutionIsolationSemaphoreMaxConcurrentRequests(int value) {
            this.executionIsolationSemaphoreMaxConcurrentRequests = value;
            return this;
        }

        public Setter withExecutionIsolationStrategy(ExecutionIsolationStrategy value) {
            this.executionIsolationStrategy = value;
            return this;
        }

        public Setter withExecutionIsolationThreadInterruptOnTimeout(boolean value) {
            this.executionIsolationThreadInterruptOnTimeout = value;
            return this;
        }

        public Setter withExecutionIsolationThreadInterruptOnFutureCancel(boolean value) {
            this.executionIsolationThreadInterruptOnFutureCancel = value;
            return this;
        }

        
Deprecated:
As of 1.4.0, replaced with withExecutionTimeoutInMilliseconds(int). Timeouts are no longer applied only to thread-isolated commands, so a thread-specific name is misleading/**
         * @deprecated As of 1.4.0, replaced with {@link #withExecutionTimeoutInMilliseconds(int)}.  Timeouts are no longer applied only to thread-isolated commands, so a thread-specific name is misleading
         */
        @Deprecated
        public Setter withExecutionIsolationThreadTimeoutInMilliseconds(int value) {
            this.executionTimeoutInMilliseconds = value;
            return this;
        }

        public Setter withExecutionTimeoutInMilliseconds(int value) {
            this.executionTimeoutInMilliseconds = value;
            return this;
        }

        public Setter withExecutionTimeoutEnabled(boolean value) {
            this.executionTimeoutEnabled = value;
            return this;
        }

        public Setter withFallbackIsolationSemaphoreMaxConcurrentRequests(int value) {
            this.fallbackIsolationSemaphoreMaxConcurrentRequests = value;
            return this;
        }

        public Setter withFallbackEnabled(boolean value) {
            this.fallbackEnabled = value;
            return this;
        }

        public Setter withMetricsHealthSnapshotIntervalInMilliseconds(int value) {
            this.metricsHealthSnapshotIntervalInMilliseconds = value;
            return this;
        }

        public Setter withMetricsRollingPercentileBucketSize(int value) {
            this.metricsRollingPercentileBucketSize = value;
            return this;
        }

        public Setter withMetricsRollingPercentileEnabled(boolean value) {
            this.metricsRollingPercentileEnabled = value;
            return this;
        }

        public Setter withMetricsRollingPercentileWindowInMilliseconds(int value) {
            this.metricsRollingPercentileWindowInMilliseconds = value;
            return this;
        }

        public Setter withMetricsRollingPercentileWindowBuckets(int value) {
            this.metricsRollingPercentileWindowBuckets = value;
            return this;
        }

        public Setter withMetricsRollingStatisticalWindowInMilliseconds(int value) {
            this.metricsRollingStatisticalWindowInMilliseconds = value;
            return this;
        }

        public Setter withMetricsRollingStatisticalWindowBuckets(int value) {
            this.metricsRollingStatisticalWindowBuckets = value;
            return this;
        }

        public Setter withRequestCacheEnabled(boolean value) {
            this.requestCacheEnabled = value;
            return this;
        }

        public Setter withRequestLogEnabled(boolean value) {
            this.requestLogEnabled = value;
            return this;
        }
    }
}