[automatic failover] Implement add/remove endpoints (#4200)

* - weighted cluster seleciton
- Healtstatus manager with initial listener and registration logic
- pluggable health checker strategy  introduced,  these are draft NoOpStrategy, EchoStrategy, LagAwareStrategy,
- fix failing tests impacted from weighted clusters

* - add builder for ClusterConfig
- add echo ot CommandObjects and UnifiedJEdis
- improve StrategySupplier by accepting jedisclientconfig
- adapt EchoStrategy to StrategySupplier. Now it handles the creation of connection by accepting endpoint and JedisClientConfig
- make healthchecks disabled by default
- drop noOpStrategy
-  add unit&integration tests for health check

* - fix naming

* clean up and mark override methods

* fix link in javadoc

* fix formatting

* - fix double registered listeners in healtstatusmgr
- clear redundant catch
- replace failover options and drop failoveroptions class
- remove forced_unhealthy from healthstatus
- fix failback check
- add disabled flag to cluster
- update/fix related tests

* Update src/main/java/redis/clients/jedis/mcf/EchoStrategy.java

Co-authored-by: Copilot <[email protected]>

* - add remove endpoints

* - replace cluster disabled with failbackCandidate
- replace failback enabled with failbacksupported in client
- fix formatting
- set defaults

* - remove failback candidate
- fix failing tests

* - fix remove logic
- fix failing tests

---------

Co-authored-by: Copilot <[email protected]>

Author: atakavci

src/main/java/redis/clients/jedis/MultiClusterClientConfig.java

@@ -147,10 +147,10 @@ public static interface StrategySupplier {
     //////////// Failover Config ////////////
 
     /** Whether to retry failed commands during failover */
-    private boolean retryOnFailover = false;
+    private boolean retryOnFailover;
 
-    /** Whether failback is enabled */
-    private boolean failback = false;
+    /** Whether failback is supported by client */
+    private boolean isFailbackSupported;
 
     public MultiClusterClientConfig(ClusterConfig[] clusterConfigs) {
         this.clusterConfigs = clusterConfigs;
@@ -220,8 +220,13 @@ public boolean isRetryOnFailover() {
         return retryOnFailover;
     }
 
-    public boolean isFailback() {
-        return failback;
+    /** Whether failback is supported by client */
+    public boolean isFailbackSupported() {
+        return isFailbackSupported;
+    }
+
+    public static Builder builder(ClusterConfig[] clusterConfigs) {
+        return new Builder(clusterConfigs);
     }
 
     public static class ClusterConfig {
@@ -284,7 +289,6 @@ public static class Builder {
 
             private float weight = 1.0f;
             private StrategySupplier healthCheckStrategySupplier = EchoStrategy.DEFAULT;
-            private boolean healthCheckEnabled = true;
 
             public Builder(HostAndPort hostAndPort, JedisClientConfig clientConfig) {
                 this.hostAndPort = hostAndPort;
@@ -318,7 +322,6 @@ public Builder healthCheckStrategy(HealthCheckStrategy healthCheckStrategy) {
             }
 
             public Builder healthCheckEnabled(boolean healthCheckEnabled) {
-                this.healthCheckEnabled = healthCheckEnabled;
                 if (!healthCheckEnabled) {
                     this.healthCheckStrategySupplier = null;
                 } else if (healthCheckStrategySupplier == null) {
@@ -354,7 +357,7 @@ public static class Builder {
         private List<Class<? extends Throwable>> fallbackExceptionList = FALLBACK_EXCEPTIONS_DEFAULT;
 
         private boolean retryOnFailover = false;
-        private boolean failback = false;
+        private boolean isFailbackSupported = true;
 
         public Builder(ClusterConfig[] clusterConfigs) {
 
@@ -453,8 +456,8 @@ public Builder retryOnFailover(boolean retryOnFailover) {
             return this;
         }
 
-        public Builder failback(boolean failback) {
-            this.failback = failback;
+        public Builder failbackSupported(boolean supported) {
+            this.isFailbackSupported = supported;
             return this;
         }
 
@@ -484,7 +487,7 @@ public MultiClusterClientConfig build() {
             config.fallbackExceptionList = this.fallbackExceptionList;
 
             config.retryOnFailover = this.retryOnFailover;
-            config.failback = this.failback;
+            config.isFailbackSupported = this.isFailbackSupported;
 
             return config;
         }