Add api documentation and changes related to PR comments

Author: prakhar10

docs/gateway-api.md

@@ -91,3 +91,16 @@ Will return a JSON array of active Trino cluster backends:
 curl -X POST http://localhost:8080/gateway/backend/activate/trino-2
 ```
 
+## Update Routing Rules
+
+This API can be used to programmatically update the Routing Rules.
+Rule will be updated based on the rule name.
+```shell
+curl -X POST http://localhost:8080/webapp/updateRoutingRules \
+ -d '{  "name": "trino-rule",
+        "description": "updated rule description",
+        "priority": 0,
+        "actions": ["updated action"],
+        "condition": "updated condition"
+    }'
+```

gateway-ha/src/main/java/io/trino/gateway/ha/domain/RoutingRules.java

@@ -13,7 +13,6 @@
  */
 package io.trino.gateway.ha.domain;
 
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
 import java.util.List;
@@ -27,7 +26,6 @@
  * @param actions actions of the routing rule
  * @param condition condition of the routing rule
  */
-@JsonIgnoreProperties(ignoreUnknown = true)
 public record RoutingRules(
         @JsonProperty("name") String name,
         @JsonProperty("description") String description,

gateway-ha/src/main/java/io/trino/gateway/ha/resource/GatewayWebAppResource.java

@@ -13,11 +13,13 @@
  */
 package io.trino.gateway.ha.resource;
 
+import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
 import com.fasterxml.jackson.dataformat.yaml.YAMLParser;
 import com.google.common.base.Strings;
 import com.google.inject.Inject;
+import com.google.inject.Singleton;
 import io.trino.gateway.ha.clustermonitor.ClusterStats;
 import io.trino.gateway.ha.config.HaGatewayConfiguration;
 import io.trino.gateway.ha.config.ProxyBackendConfiguration;
@@ -69,6 +71,7 @@
 import static java.util.Objects.requireNonNullElse;
 
 @Path("/webapp")
+@Singleton
 public class GatewayWebAppResource
 {
     private static final LocalDateTime START_TIME = LocalDateTime.now();
@@ -443,17 +446,14 @@ public Response readExactMatchSourceSelector()
     @Path("/getRoutingRules")
     public Response getRoutingRules()
     {
-        String content = null;
         try {
             String rulesConfigPath = configuration.getRoutingRules().getRulesConfigPath();
-            content = new String(Files.readAllBytes(Paths.get(rulesConfigPath)));
-            ObjectMapper yamlReader = new ObjectMapper(new YAMLFactory());
-            YAMLParser parser = new YAMLFactory().createParser(content);
-            List<RoutingRules> routingRulesList = new ArrayList<>();
-            while (parser.nextToken() != null) {
-                RoutingRules routingRules = yamlReader.readValue(parser, RoutingRules.class);
-                routingRulesList.add(routingRules);
-            }
+            YAMLFactory yamlFactory = new YAMLFactory();
+            ObjectMapper yamlReader = new ObjectMapper(yamlFactory);
+            YAMLParser yamlParser = yamlFactory.createParser(new String(Files.readAllBytes(Paths.get(rulesConfigPath))));
+            List<RoutingRules> routingRulesList = yamlReader
+                    .readValues(yamlParser, new TypeReference<RoutingRules>() {})
+                    .readAll();
             return Response.ok(Result.ok(routingRulesList)).build();
         }
         catch (IOException e) {
@@ -466,19 +466,17 @@ public Response getRoutingRules()
     @Consumes(MediaType.APPLICATION_JSON)
     @Produces(MediaType.APPLICATION_JSON)
     @Path("/updateRoutingRules")
-    public Response updateRoutingRules(RoutingRules routingRules)
+    public synchronized Response updateRoutingRules(RoutingRules routingRules)
     {
         String rulesConfigPath = configuration.getRoutingRules().getRulesConfigPath();
         ObjectMapper yamlReader = new ObjectMapper(new YAMLFactory());
         List<RoutingRules> routingRulesList = new ArrayList<>();
-
+        YAMLFactory yamlFactory = new YAMLFactory();
         try {
-            String content = new String(Files.readAllBytes(Paths.get(rulesConfigPath)));
-            YAMLParser parser = new YAMLFactory().createParser(content);
-            while (parser.nextToken() != null) {
-                RoutingRules routingRule = yamlReader.readValue(parser, RoutingRules.class);
-                routingRulesList.add(routingRule);
-            }
+            YAMLParser yamlParser = yamlFactory.createParser(new String(Files.readAllBytes(Paths.get(rulesConfigPath))));
+            routingRulesList = yamlReader
+                    .readValues(yamlParser, new TypeReference<RoutingRules>() {})
+                    .readAll();
 
             for (int i = 0; i < routingRulesList.size(); i++) {
                 if (routingRulesList.get(i).name().equals(routingRules.name())) {