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本文主要研究一下HystrixPropertiesStrategy
HystrixPropertiesStrategy
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/strategy/properties/HystrixPropertiesStrategy.java
/**
* Abstract class with default implementations of factory methods for properties used by various components of Hystrix.
* <p>
* See {@link HystrixPlugins} or the Hystrix GitHub Wiki for information on configuring plugins: <a
* href="https://github.com/Netflix/Hystrix/wiki/Plugins">https://github.com/Netflix/Hystrix/wiki/Plugins</a>.
*/
public abstract class HystrixPropertiesStrategy {
/**
* Construct an implementation of {@link HystrixCommandProperties} for {@link HystrixCommand} instances with {@link HystrixCommandKey}.
* <p>
* <b>Default Implementation</b>
* <p>
* Constructs instance of {@link HystrixPropertiesCommandDefault}.
*
* @param commandKey
* {@link HystrixCommandKey} representing the name or type of {@link HystrixCommand}
* @param builder
* {@link com.netflix.hystrix.HystrixCommandProperties.Setter} with default overrides as injected from the {@link HystrixCommand} implementation.
* <p>
* The builder will return NULL for each value if no override was provided.
* @return Implementation of {@link HystrixCommandProperties}
*/
public HystrixCommandProperties getCommandProperties(HystrixCommandKey commandKey, HystrixCommandProperties.Setter builder) {
return new HystrixPropertiesCommandDefault(commandKey, builder);
}
/**
* Cache key used for caching the retrieval of {@link HystrixCommandProperties} implementations.
* <p>
* Typically this would return <code>HystrixCommandKey.name()</code> but can be done differently if required.
* <p>
* For example, null can be returned which would cause it to not cache and invoke {@link #getCommandProperties} for each {@link HystrixCommand} instantiation (not recommended).
* <p>
* <b>Default Implementation</b>
* <p>
* Returns {@link HystrixCommandKey#name()}
*
* @param commandKey command key used in determining command's cache key
* @param builder builder for {@link HystrixCommandProperties} used in determining command's cache key
* @return String value to be used as the cache key of a {@link HystrixCommandProperties} implementation.
*/
public String getCommandPropertiesCacheKey(HystrixCommandKey commandKey, HystrixCommandProperties.Setter builder) {
return commandKey.name();
}
/**
* Construct an implementation of {@link HystrixThreadPoolProperties} for {@link HystrixThreadPool} instances with {@link HystrixThreadPoolKey}.
* <p>
* <b>Default Implementation</b>
* <p>
* Constructs instance of {@link HystrixPropertiesThreadPoolDefault}.
*
* @param threadPoolKey
* {@link HystrixThreadPoolKey} representing the name or type of {@link HystrixThreadPool}
* @param builder
* {@link com.netflix.hystrix.HystrixThreadPoolProperties.Setter} with default overrides as injected via {@link HystrixCommand} to the {@link HystrixThreadPool} implementation.
* <p>
* The builder will return NULL for each value if no override was provided.
*
* @return Implementation of {@link HystrixThreadPoolProperties}
*/
public HystrixThreadPoolProperties getThreadPoolProperties(HystrixThreadPoolKey threadPoolKey, HystrixThreadPoolProperties.Setter builder) {
return new HystrixPropertiesThreadPoolDefault(threadPoolKey, builder);
}
/**
* Cache key used for caching the retrieval of {@link HystrixThreadPoolProperties} implementations.
* <p>
* Typically this would return <code>HystrixThreadPoolKey.name()</code> but can be done differently if required.
* <p>
* For example, null can be returned which would cause it to not cache and invoke {@link #getThreadPoolProperties} for each {@link HystrixThreadPool} instantiation (not recommended).
* <p>
* <b>Default Implementation</b>
* <p>
* Returns {@link HystrixThreadPoolKey#name()}
*
* @param threadPoolKey thread pool key used in determining thread pool's cache key
* @param builder builder for {@link HystrixThreadPoolProperties} used in determining thread pool's cache key
* @return String value to be used as the cache key of a {@link HystrixThreadPoolProperties} implementation.
*/
public String getThreadPoolPropertiesCacheKey(HystrixThreadPoolKey threadPoolKey, HystrixThreadPoolProperties.Setter builder) {
return threadPoolKey.name();
}
/**
* Construct an implementation of {@link HystrixCollapserProperties} for {@link HystrixCollapser} instances with {@link HystrixCollapserKey}.
* <p>
* <b>Default Implementation</b>
* <p>
* Constructs instance of {@link HystrixPropertiesCollapserDefault}.
*
* @param collapserKey
* {@link HystrixCollapserKey} representing the name or type of {@link HystrixCollapser}
* @param builder
* {@link com.netflix.hystrix.HystrixCollapserProperties.Setter} with default overrides as injected to the {@link HystrixCollapser} implementation.
* <p>
* The builder will return NULL for each value if no override was provided.
*
* @return Implementation of {@link HystrixCollapserProperties}
*/
public HystrixCollapserProperties getCollapserProperties(HystrixCollapserKey collapserKey, HystrixCollapserProperties.Setter builder) {
return new HystrixPropertiesCollapserDefault(collapserKey, builder);
}
/**
* Cache key used for caching the retrieval of {@link HystrixCollapserProperties} implementations.
* <p>
* Typically this would return <code>HystrixCollapserKey.name()</code> but can be done differently if required.
* <p>
* For example, null can be returned which would cause it to not cache and invoke {@link #getCollapserProperties} for each {@link HystrixCollapser} instantiation (not recommended).
* <p>
* <b>Default Implementation</b>
* <p>
* Returns {@link HystrixCollapserKey#name()}
*
* @param collapserKey collapser key used in determining collapser's cache key
* @param builder builder for {@link HystrixCollapserProperties} used in determining collapser's cache key
* @return String value to be used as the cache key of a {@link HystrixCollapserProperties} implementation.
*/
public String getCollapserPropertiesCacheKey(HystrixCollapserKey collapserKey, HystrixCollapserProperties.Setter builder) {
return collapserKey.name();
}
/**
* Construct an implementation of {@link com.netflix.hystrix.HystrixTimerThreadPoolProperties} for configuration of the timer thread pool
* that handles timeouts and collapser logic.
* <p>
* Constructs instance of {@link HystrixPropertiesTimerThreadPoolDefault}.
*
*
* @return Implementation of {@link com.netflix.hystrix.HystrixTimerThreadPoolProperties}
*/
public HystrixTimerThreadPoolProperties getTimerThreadPoolProperties() {
return new HystrixPropertiesTimerThreadPoolDefault();
}
}
提供获取HystrixCommandProperties、HystrixThreadPoolProperties、HystrixCollapserProperties、HystrixTimerThreadPoolProperties的方法
HystrixCommandProperties
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/HystrixCommandProperties.java
/**
* 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)
//......
}
提供了hystrix command的相关参数计默认值
HystrixThreadPoolProperties
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/HystrixThreadPoolProperties.java
/**
* Properties for instances of {@link HystrixThreadPool}.
* <p>
* Default implementation of methods uses Archaius (https://github.com/Netflix/archaius)
*
* Note a change in behavior in 1.5.7. Prior to that version, the configuration for 'coreSize' was used to control
* both coreSize and maximumSize. This is a fixed-size threadpool that can never give up an unused thread. In 1.5.7+,
* the values can diverge, and if you set coreSize < maximumSize, threads can be given up (subject to the keep-alive
* time)
*
* It is OK to leave maximumSize unset using any version of Hystrix. If you do, then maximum size will default to
* core size and you'll have a fixed-size threadpool.
*
* If you accidentally set maximumSize < coreSize, then maximum will be raised to coreSize
* (this prioritizes keeping extra threads around rather than inducing threadpool rejections)
*/
public abstract class HystrixThreadPoolProperties {
/* defaults */
static int default_coreSize = 10; // core size of thread pool
static int default_maximumSize = 10; // maximum size of thread pool
static int default_keepAliveTimeMinutes = 1; // minutes to keep a thread alive
static int default_maxQueueSize = -1; // size of queue (this can't be dynamically changed so we use 'queueSizeRejectionThreshold' to artificially limit and reject)
// -1 turns it off and makes us use SynchronousQueue
static boolean default_allow_maximum_size_to_diverge_from_core_size = false; //should the maximumSize config value get read and used in configuring the threadPool
//turning this on should be a conscious decision by the user, so we default it to false
static int default_queueSizeRejectionThreshold = 5; // number of items in queue
static int default_threadPoolRollingNumberStatisticalWindow = 10000; // milliseconds for rolling number
static int default_threadPoolRollingNumberStatisticalWindowBuckets = 10; // number of buckets in rolling number (10 1-second buckets)
private final HystrixProperty<Integer> corePoolSize;
private final HystrixProperty<Integer> maximumPoolSize;
private final HystrixProperty<Integer> keepAliveTime;
private final HystrixProperty<Integer> maxQueueSize;
private final HystrixProperty<Integer> queueSizeRejectionThreshold;
private final HystrixProperty<Boolean> allowMaximumSizeToDivergeFromCoreSize;
private final HystrixProperty<Integer> threadPoolRollingNumberStatisticalWindowInMilliseconds;
private final HystrixProperty<Integer> threadPoolRollingNumberStatisticalWindowBuckets;
//......
}
提供了hystrix thread pool的相关参数计默认值
HystrixCollapserProperties
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/HystrixCollapserProperties.java
/**
* Properties for instances of {@link HystrixCollapser}.
* <p>
* Default implementation of methods uses Archaius (https://github.com/Netflix/archaius)
*/
public abstract class HystrixCollapserProperties {
/* defaults */
private static final Integer default_maxRequestsInBatch = Integer.MAX_VALUE;
private static final Integer default_timerDelayInMilliseconds = 10;
private static final Boolean default_requestCacheEnabled = true;
/* 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 Boolean default_metricsRollingPercentileEnabled = 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 final HystrixProperty<Integer> maxRequestsInBatch;
private final HystrixProperty<Integer> timerDelayInMilliseconds;
private final HystrixProperty<Boolean> requestCacheEnabled;
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
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
//......
}
提供了hystrix collapser相关参数计默认值
HystrixTimerThreadPoolProperties
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/HystrixTimerThreadPoolProperties.java
/**
* Properties for Hystrix timer thread pool.
* <p>
* Default implementation of methods uses Archaius (https://github.com/Netflix/archaius)
*/
public abstract class HystrixTimerThreadPoolProperties {
private final HystrixProperty<Integer> corePoolSize;
protected HystrixTimerThreadPoolProperties() {
this(new Setter().withCoreSize(Runtime.getRuntime().availableProcessors()));
}
//......
}
提供了hystrix timer threadpool相关参数，主要是corePoolSize，默认是Runtime.getRuntime().availableProcessors()
HystrixPropertiesChainedProperty
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/strategy/properties/HystrixPropertiesChainedProperty.java
public static abstract class ChainBuilder<T> {
private ChainBuilder() {
super();
}
private List<HystrixDynamicProperty<T>> properties =
new ArrayList<HystrixDynamicProperty<T>>();
public ChainBuilder<T> add(HystrixDynamicProperty<T> property) {
properties.add(property);
return this;
}
public ChainBuilder<T> add(String name, T defaultValue) {
properties.add(getDynamicProperty(name, defaultValue, getType()));
return this;
}
public HystrixDynamicProperty<T> build() {
if (properties.size() < 1) throw new IllegalArgumentException();
if (properties.size() == 1) return properties.get(0);
List<HystrixDynamicProperty<T>> reversed =
new ArrayList<HystrixDynamicProperty<T>>(properties);
Collections.reverse(reversed);
ChainProperty<T> current = null;
for (HystrixDynamicProperty<T> p : reversed) {
if (current == null) {
current = new ChainProperty<T>(p);
}
else {
current = new ChainProperty<T>(p, current);
}
}
return new ChainHystrixProperty<T>(current);
}
protected abstract Class<T> getType();
}
这里build返回的是HystrixDynamicProperty的实现ChainHystrixProperty，具体是由HystrixDynamicProperties来获取
HystrixDynamicProperties
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/strategy/properties/HystrixDynamicProperties.java
/**
* A hystrix plugin (SPI) for resolving dynamic configuration properties. This
* SPI allows for varying configuration sources.
*
* The HystrixPlugin singleton will load only one implementation of this SPI
* throught the {@link ServiceLoader} mechanism.
*
* @author agentgt
*
*/
public interface HystrixDynamicProperties {
/**
* Requests a property that may or may not actually exist.
* @param name property name, never <code>null</code>
* @param fallback default value, maybe <code>null</code>
* @return never <code>null</code>
*/
public HystrixDynamicProperty<String> getString(String name, String fallback);
/**
* Requests a property that may or may not actually exist.
* @param name property name, never <code>null</code>
* @param fallback default value, maybe <code>null</code>
* @return never <code>null</code>
*/
public HystrixDynamicProperty<Integer> getInteger(String name, Integer fallback);
/**
* Requests a property that may or may not actually exist.
* @param name property name, never <code>null</code>
* @param fallback default value, maybe <code>null</code>
* @return never <code>null</code>
*/
public HystrixDynamicProperty<Long> getLong(String name, Long fallback);
/**
* Requests a property that may or may not actually exist.
* @param name property name
* @param fallback default value
* @return never <code>null</code>
*/
public HystrixDynamicProperty<Boolean> getBoolean(String name, Boolean fallback);
/**
* @ExcludeFromJavadoc
*/
public static class Util {
/**
* A convenience method to get a property by type (Class).
* @param properties never <code>null</code>
* @param name never <code>null</code>
* @param fallback maybe <code>null</code>
* @param type never <code>null</code>
* @return a dynamic property with type T.
*/
@SuppressWarnings("unchecked")
public static <T> HystrixDynamicProperty<T> getProperty(
HystrixDynamicProperties properties, String name, T fallback, Class<T> type) {
return (HystrixDynamicProperty<T>) doProperty(properties, name, fallback, type);
}
private static HystrixDynamicProperty<?> doProperty(
HystrixDynamicProperties delegate,
String name, Object fallback, Class<?> type) {
if(type == String.class) {
return delegate.getString(name, (String) fallback);
}
else if (type == Integer.class) {
return delegate.getInteger(name, (Integer) fallback);
}
else if (type == Long.class) {
return delegate.getLong(name, (Long) fallback);
}
else if (type == Boolean.class) {
return delegate.getBoolean(name, (Boolean) fallback);
}
throw new IllegalStateException();
}
}
}
这个接口只是规范了获取动态参数的一些方法
HystrixPlugins.resolveDynamicProperties
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/strategy/HystrixPlugins.java
private static HystrixDynamicProperties resolveDynamicProperties(ClassLoader classLoader, LoggerSupplier logSupplier) {
HystrixDynamicProperties hp = getPluginImplementationViaProperties(HystrixDynamicProperties.class,
HystrixDynamicPropertiesSystemProperties.getInstance());
if (hp != null) {
logSupplier.getLogger().debug(
"Created HystrixDynamicProperties instance from System property named "
+ "\"hystrix.plugin.HystrixDynamicProperties.implementation\". Using class: {}",
hp.getClass().getCanonicalName());
return hp;
}
hp = findService(HystrixDynamicProperties.class, classLoader);
if (hp != null) {
logSupplier.getLogger()
.debug("Created HystrixDynamicProperties instance by loading from ServiceLoader. Using class: {}",
hp.getClass().getCanonicalName());
return hp;
}
hp = HystrixArchaiusHelper.createArchaiusDynamicProperties();
if (hp != null) {
logSupplier.getLogger().debug("Created HystrixDynamicProperties. Using class : {}",
hp.getClass().getCanonicalName());
return hp;
}
hp = HystrixDynamicPropertiesSystemProperties.getInstance();
logSupplier.getLogger().info("Using System Properties for HystrixDynamicProperties! Using class: {}",
hp.getClass().getCanonicalName());
return hp;
}
这个方法去决定使用哪个HystrixDynamicProperties的实现类，优先级如下：
- hystrix.plugin.HystrixDynamicProperties.implementation指定的实现类
- 通过ServiceLoader找到的HystrixDynamicProperties的实现类
- 使用com.netflix.hystrix.strategy.properties.archaius.HystrixDynamicPropertiesArchaius实现
- 使用系统变量HystrixDynamicPropertiesSystemProperties
小结
HystrixPropertiesStrategy提供给开发者去自定义hystrix各个组件的配置，没有找到任何实现的话，则使用代码里头默认的参数值。目前这个版本的代码默认寻找到的HystrixDynamicProperties实现是HystrixDynamicPropertiesArchaius。
