Issue ReactiveX#137: Refactored Retry so that it can be shared and used for mu… (ReactiveX#138)

* Issue ReactiveX#137: Refactored Retry so that it can be shared and used for multiple requests.

Author: RobWin

resilience4j-bulkhead/src/main/java/io/github/resilience4j/bulkhead/Bulkhead.java

@@ -35,6 +35,8 @@
 import java.util.function.Supplier;
 
 /**
+ *  A Bulkhead instance is thread-safe can be used to decorate multiple requests.
+ *
  * A {@link Bulkhead} represent an entity limiting the amount of parallel operations. It does not assume nor does it mandate usage
  * of any particular concurrency and/or io model. These details are left for the client to manage. This bulkhead, depending on the
  * underlying concurrency/io model can be used to shed load, and, where it makes sense, limit resource use (i.e. limit amount of

resilience4j-cache/src/main/java/io/github/resilience4j/cache/Cache.java

@@ -19,7 +19,7 @@
 package io.github.resilience4j.cache;
 
 import io.github.resilience4j.cache.event.CacheEvent;
-import io.github.resilience4j.cache.internal.CacheContext;
+import io.github.resilience4j.cache.internal.CacheImpl;
 import io.reactivex.Flowable;
 import io.vavr.CheckedFunction0;
 import io.vavr.CheckedFunction1;
@@ -72,7 +72,7 @@ public interface Cache<K, V>  {
      */
     static <K,V> Cache<K,V> of(javax.cache.Cache<K, V> cache){
         Objects.requireNonNull(cache, "Cache must not be null");
-        return new CacheContext<>(cache);
+        return new CacheImpl<>(cache);
     }
 
     /**

resilience4j-cache/src/main/java/io/github/resilience4j/cache/internal/CacheContext.java renamed to resilience4j-cache/src/main/java/io/github/resilience4j/cache/internal/CacheImpl.java

@@ -35,15 +35,15 @@
 import java.util.concurrent.atomic.LongAdder;
 import java.util.function.Supplier;
 
-public class CacheContext<K, V>  implements Cache<K,V> {
+public class CacheImpl<K, V>  implements Cache<K,V> {
 
-    private static final Logger LOG = LoggerFactory.getLogger(CacheContext.class);
+    private static final Logger LOG = LoggerFactory.getLogger(CacheImpl.class);
 
     private final javax.cache.Cache<K, V> cache;
     private final FlowableProcessor<CacheEvent> eventPublisher;
     private final CacheMetrics metrics;
 
-    public CacheContext(javax.cache.Cache<K, V> cache) {
+    public CacheImpl(javax.cache.Cache<K, V> cache) {
         this.cache = cache;
         PublishProcessor<CacheEvent> publisher = PublishProcessor.create();
         this.eventPublisher = publisher.toSerialized();

resilience4j-circuitbreaker/src/main/java/io/github/resilience4j/circuitbreaker/CircuitBreaker.java

@@ -35,6 +35,8 @@
 import java.util.function.Supplier;
 
 /**
+ * A CircuitBreaker instance is thread-safe can be used to decorate multiple requests.
+ *
  * A {@link CircuitBreaker} manages the state of a backend system.
  * The CircuitBreaker is implemented via a finite state machine with three states: CLOSED, OPEN and HALF_OPEN.
  * The CircuitBreaker does not know anything about the backend’s state by itself, but uses the information provided by the decorators via

resilience4j-documentation/src/docs/asciidoc/core_guides/retry.adoc

@@ -12,19 +12,19 @@ RetryConfig config = RetryConfig.custom()
     .maxAttempts(3)
     .waitDuration(Duration.ofMillis(500))
     .build();
-Retry retryContext = Retry.of("id", config);
+Retry retry = Retry.of("id", config);
 ----
 
-In order to create a custom `Retry` context, you can use the Retry context builder. You can configure the maximum number of retry attempts and the wait duration between successive attempts. Furthermore, you can configure a custom Predicate which evaluates if an exception should trigger a retry.
+In order to create a custom-configured `Retry`, you can use the RetryConfig builder. You can configure the maximum number of retry attempts and the wait duration between successive attempts. Furthermore, you can configure a custom Predicate which evaluates if an exception should trigger a retry.
 
 [source,java]
 ----
 RetryConfig config = RetryConfig.custom()
     .maxAttempts(2)
     .waitDurationInOpenState(Duration.ofMillis(100))
-    .retryOnException(throwable -> Match.of(throwable)
-        .whenType(WebServiceException.class).then(false)
-        .otherwise(true).get())
+    .retryOnException(throwable -> API.Match(throwable).of(
+            API.Case($(Predicates.instanceOf(WebServiceException.class)), true),
+            API.Case($(), false)))
     .build();
 ----
 
@@ -39,9 +39,9 @@ HelloWorldService  helloWorldService = mock(HelloWorldService.class);
 given(helloWorldService.sayHelloWorld()).willThrow(new WebServiceException("BAM!"));
 
 // Create a Retry with default configuration
-Retry retryContext = Retry.ofDefaults("id");
+Retry retry = Retry.ofDefaults("id");
 // Decorate the invocation of the HelloWorldService
-CheckedFunction0<String> retryableSupplier = Retry.decorateCheckedSupplier(retryContext, helloWorldService::sayHelloWorld);
+CheckedFunction0<String> retryableSupplier = Retry.decorateCheckedSupplier(retry, helloWorldService::sayHelloWorld);
 
 // When I invoke the function
 Try<String> result = Try.of(retryableSupplier).recover((throwable) -> "Hello world from recovery function");
@@ -69,9 +69,9 @@ The RetryContext emits a stream of RetryEvents to any Observer/Consumer who subs
 
 [source,java]
 ----
-Retry retryContext = Retry.ofDefaults("id");
+Retry retry = Retry.ofDefaults("id");
 CircularEventConsumer<RetryEvent> circularEventConsumer = new CircularEventConsumer<>(10);
-retryContext.getEventStream()
+retry.getEventStream()
     .subscribe(circularEventConsumer);
 
 List<RetryEvent> bufferedEvents = circularEventConsumer.getBufferedEvents();

resilience4j-metrics/src/main/java/io/github/resilience4j/metrics/CircuitBreakerMetrics.java

@@ -18,9 +18,6 @@
  */
 package io.github.resilience4j.metrics;
 
-import static com.codahale.metrics.MetricRegistry.name;
-import static java.util.Objects.requireNonNull;
-
 import com.codahale.metrics.Gauge;
 import com.codahale.metrics.Metric;
 import com.codahale.metrics.MetricRegistry;
@@ -31,12 +28,20 @@
 
 import java.util.Map;
 
+import static com.codahale.metrics.MetricRegistry.name;
+import static java.util.Objects.requireNonNull;
+
 /**
  * An adapter which exports {@link CircuitBreaker.Metrics} as Dropwizard Metrics Gauges.
  */
 public class CircuitBreakerMetrics implements MetricSet {
 
     private static final String DEFAULT_PREFIX = "resilience4j.circuitbreaker";
+    public static final String SUCCESSFUL = "successful";
+    public static final String FAILED = "failed";
+    public static final String NOT_PERMITTED = "not_permitted";
+    public static final String BUFFERED = "buffered";
+    public static final String BUFFERED_MAX = "buffered_max";
     private final MetricRegistry metricRegistry = new MetricRegistry();
 
     private CircuitBreakerMetrics(Iterable<CircuitBreaker> circuitBreakers) {
@@ -50,15 +55,15 @@ private CircuitBreakerMetrics(String prefix, Iterable<CircuitBreaker> circuitBre
                 String name = circuitBreaker.getName();
                 CircuitBreaker.Metrics metrics = circuitBreaker.getMetrics();
 
-                metricRegistry.register(name(prefix, name, "successful"),
+                metricRegistry.register(name(prefix, name, SUCCESSFUL),
                     (Gauge<Integer>) metrics::getNumberOfSuccessfulCalls);
-                metricRegistry.register(name(prefix, name, "failed"),
+                metricRegistry.register(name(prefix, name, FAILED),
                     (Gauge<Integer>) metrics::getNumberOfFailedCalls);
-                metricRegistry.register(name(prefix, name, "not_permitted"),
+                metricRegistry.register(name(prefix, name, NOT_PERMITTED),
                     (Gauge<Long>) metrics::getNumberOfNotPermittedCalls);
-                metricRegistry.register(name(prefix, name, "buffered"),
+                metricRegistry.register(name(prefix, name, BUFFERED),
                     (Gauge<Integer>) metrics::getNumberOfBufferedCalls);
-                metricRegistry.register(name(prefix, name, "buffered_max"),
+                metricRegistry.register(name(prefix, name, BUFFERED_MAX),
                     (Gauge<Integer>) metrics::getMaxNumberOfBufferedCalls);
             }
         );

resilience4j-metrics/src/main/java/io/github/resilience4j/metrics/RetryMetrics.java

@@ -15,6 +15,10 @@
  */
 public class RetryMetrics implements MetricSet {
 
+    public static final String SUCCESSFUL_CALLS_WITHOUT_RETRY = "successful_calls_without_retry";
+    public static final String SUCCESSFUL_CALLS_WITH_RETRY = "successful_calls_with_retry";
+    public static final String FAILED_CALLS_WITHOUT_RETRY = "failed_calls_without_retry";
+    public static final String FAILED_CALLS_WITH_RETRY = "failed_calls_with_retry";
     private final MetricRegistry metricRegistry = new MetricRegistry();
     private static final String DEFAULT_PREFIX = "resilience4j.retry";
 
@@ -29,9 +33,14 @@ private RetryMetrics(String prefix, Iterable<Retry> retries){
             String name = retry.getName();
             Retry.Metrics metrics = retry.getMetrics();
 
-            metricRegistry.register(name(prefix, name, "retry_max_ratio"),
-                    new RetryRatio(metrics.getNumAttempts(), metrics.getMaxAttempts()));
-            
+            metricRegistry.register(name(prefix, name, SUCCESSFUL_CALLS_WITHOUT_RETRY),
+                    (Gauge<Long>) metrics::getNumberOfSuccessfulCallsWithoutRetryAttempt);
+            metricRegistry.register(name(prefix, name, SUCCESSFUL_CALLS_WITH_RETRY),
+                    (Gauge<Long>) metrics::getNumberOfSuccessfulCallsWithRetryAttempt);
+            metricRegistry.register(name(prefix, name, FAILED_CALLS_WITHOUT_RETRY),
+                    (Gauge<Long>) metrics::getNumberOfFailedCallsWithoutRetryAttempt);
+            metricRegistry.register(name(prefix, name, FAILED_CALLS_WITH_RETRY),
+                    (Gauge<Long>) metrics::getNumberOfFailedCallsWithRetryAttempt);
         });
     }