feat(gofeatureflag): Add support of flag change cache removal

providers/go-feature-flag/pom.xml

@@ -68,6 +68,12 @@
             <version>2.0.13</version>
         </dependency>
 
+        <dependency>
+            <groupId>io.reactivex.rxjava3</groupId>
+            <artifactId>rxjava</artifactId>
+            <version>3.1.8</version>
+        </dependency>
+
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>
             <artifactId>log4j-slf4j2-impl</artifactId>

providers/go-feature-flag/src/main/java/dev/openfeature/contrib/providers/gofeatureflag/EvaluationResponse.java

@@ -13,5 +13,5 @@
 @Getter
 public class EvaluationResponse<T> {
     private ProviderEvaluation<T> providerEvaluation;
-    private Boolean cachable;
+    private Boolean cacheable;
 }

providers/go-feature-flag/src/main/java/dev/openfeature/contrib/providers/gofeatureflag/GoFeatureFlagProviderOptions.java

@@ -50,7 +50,11 @@ public class GoFeatureFlagProviderOptions {
     /**
      * (optional) If cache custom configuration is wanted, you should provide
      * a cache builder.
-     * Default: null
+     * Default:
+     * CACHE_TTL_MS: 5min
+     * CACHE_CONCURRENCY_LEVEL: 1
+     * CACHE_INITIAL_CAPACITY: 100
+     * CACHE_MAXIMUM_SIZE: 100000
      */
     private CacheBuilder<String, ProviderEvaluation<?>> cacheBuilder;
 
@@ -70,8 +74,23 @@ public class GoFeatureFlagProviderOptions {
 
     /**
      * (optional) max pending events aggregated before publishing for collection data to the proxy.
-     * When event is added while events collection is full, event is omitted.
+     * When an event is added while an events collection is full, the event is omitted.
      * default: 10000
      */
     private Integer maxPendingEvents;
+
+    /**
+     * (optional) interval time we poll the proxy to check if the configuration has changed.
+     * If the cache is enabled, we will poll the relay-proxy every X milliseconds
+     * to check if the configuration has changed.
+     * default: 120000
+     */
+    private Long flagChangePollingIntervalMs;
+
+    /**
+     * (optional) disableDataCollection set to true if you don't want to collect the usage of
+     * flags retrieved in the cache.
+     * default: false
+     */
+    private boolean disableDataCollection;
 }

providers/go-feature-flag/src/main/java/dev/openfeature/contrib/providers/gofeatureflag/bean/BeanUtils.java

@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import dev.openfeature.sdk.EvaluationContext;
 import lombok.AccessLevel;
 import lombok.NoArgsConstructor;
 
@@ -13,7 +14,7 @@ public class BeanUtils {
 
     private static final ObjectMapper objectMapper = new ObjectMapper();
 
-    public static String buildKey(GoFeatureFlagUser goFeatureFlagUser) throws JsonProcessingException {
-        return objectMapper.writeValueAsString(goFeatureFlagUser);
+    public static String buildKey(EvaluationContext evaluationContext) throws JsonProcessingException {
+        return objectMapper.writeValueAsString(evaluationContext);
     }
 }

providers/go-feature-flag/src/main/java/dev/openfeature/contrib/providers/gofeatureflag/bean/ConfigurationChange.java

@@ -0,0 +1,10 @@
+package dev.openfeature.contrib.providers.gofeatureflag.bean;
+
+/**
+ * ConfigurationChange is an enum to represent the change of the configuration.
+ */
+public enum ConfigurationChange {
+    FLAG_CONFIGURATION_INITIALIZED,
+    FLAG_CONFIGURATION_UPDATED,
+    FLAG_CONFIGURATION_NOT_CHANGED
+}

providers/go-feature-flag/src/main/java/dev/openfeature/contrib/providers/gofeatureflag/controller/CacheController.java

@@ -0,0 +1,57 @@
+package dev.openfeature.contrib.providers.gofeatureflag.controller;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+import dev.openfeature.contrib.providers.gofeatureflag.GoFeatureFlagProviderOptions;
+import dev.openfeature.contrib.providers.gofeatureflag.bean.BeanUtils;
+import dev.openfeature.sdk.EvaluationContext;
+import dev.openfeature.sdk.ProviderEvaluation;
+import lombok.Builder;
+
+import java.time.Duration;
+
+/**
+ * CacheController is a controller to manage the cache of the provider.
+ */
+public class CacheController {
+    public static final long DEFAULT_CACHE_TTL_MS = 5L * 60L * 1000L;
+    public static final int DEFAULT_CACHE_CONCURRENCY_LEVEL = 1;
+    public static final int DEFAULT_CACHE_INITIAL_CAPACITY = 100;
+    public static final int DEFAULT_CACHE_MAXIMUM_SIZE = 100000;
+    private final Cache<String, ProviderEvaluation<?>> cache;
+
+    @Builder
+    public CacheController(GoFeatureFlagProviderOptions options) {
+        this.cache = options.getCacheBuilder() != null ? options.getCacheBuilder().build() : buildDefaultCache();
+    }
+
+    private Cache<String, ProviderEvaluation<?>> buildDefaultCache() {
+        return CacheBuilder.newBuilder()
+                .concurrencyLevel(DEFAULT_CACHE_CONCURRENCY_LEVEL)
+                .initialCapacity(DEFAULT_CACHE_INITIAL_CAPACITY)
+                .maximumSize(DEFAULT_CACHE_MAXIMUM_SIZE)
+                .expireAfterWrite(Duration.ofMillis(DEFAULT_CACHE_TTL_MS))
+                .build();
+    }
+
+    public void put(final String key, final EvaluationContext evaluationContext,
+                    final ProviderEvaluation<?> providerEvaluation) throws JsonProcessingException {
+        this.cache.put(buildCacheKey(key, evaluationContext), providerEvaluation);
+    }
+
+    public ProviderEvaluation<?> getIfPresent(final String key, final EvaluationContext evaluationContext)
+            throws JsonProcessingException {
+        return this.cache.getIfPresent(buildCacheKey(key, evaluationContext));
+    }
+
+    public void invalidateAll() {
+        this.cache.invalidateAll();
+    }
+
+    private String buildCacheKey(String key, EvaluationContext evaluationContext) throws JsonProcessingException {
+        String originalKey = key + "," + BeanUtils.buildKey(evaluationContext);
+        int hash = originalKey.hashCode();
+        return String.valueOf(hash);
+    }
+}