small changes

Signed-off-by: Petar Dzepina <petar.dzepina@vroom.com>

Author: Petar Dzepina

src/main/kotlin/org/opensearch/indexmanagement/rollup/RollupMapperService.kt

@@ -55,20 +55,24 @@ class RollupMapperService(
 
     private val logger = LogManager.getLogger(javaClass)
 
-    // If the index already exists we need to verify it's a rollup index,
-    // confirm it does not conflict with existing jobs and is a valid job
+    /**
+     * If the index already exists we need to verify it's a rollup index,
+     * confirm it does not conflict with existing jobs and is a valid job.
+     * If
+     *
+     * @param rollup Rollup job we're currently executing
+     * @param targetIndexResolvedName concrete index name
+     * @param hasLegacyPlugin flag to indicate if we're running legacy plugin
+     * @return RollupJobValidationResult indicating success or failure with appropriate error message included.
+     */
     @Suppress("ReturnCount")
     private suspend fun validateAndAttemptToUpdateTargetIndex(
         rollup: Rollup,
         targetIndexResolvedName: String,
         hasLegacyPlugin: Boolean
     ): RollupJobValidationResult {
-        /**
-         * Target Index is valid alias if either all backing indices have this job in _meta
-         * or there isn't any rollup job present in _meta
-         */
-        val aliasValidationResult = validateTargetIndexAlias(rollup, targetIndexResolvedName)
         if (rollup.isTargetIndexAlias()) {
+            val aliasValidationResult = validateTargetIndexAlias(rollup, targetIndexResolvedName)
             if (aliasValidationResult !is RollupJobValidationResult.Valid) {
                 return aliasValidationResult
             } else if (!isRollupIndex(targetIndexResolvedName, clusterService.state())) {
@@ -84,20 +88,25 @@ class RollupMapperService(
         }
     }
 
+    /**
+     * Target Index is valid alias if either all backing indices have this job in _meta
+     * or there isn't any rollup job present in _meta
+     */
     @Suppress("ReturnCount")
     suspend fun validateTargetIndexAlias(rollup: Rollup, targetIndexResolvedName: String): RollupJobValidationResult {
 
         var errorMessage: String
 
         if (!RollupFieldValueExpressionResolver.indexAliasUtils.hasAlias(targetIndexResolvedName)) {
+            logger.error("[${rollup.targetIndex}] is not an alias!")
             return RollupJobValidationResult.Failure("[${rollup.targetIndex}] is not an alias!")
         }
 
         val rollupJobs = clusterService.state().metadata.index(targetIndexResolvedName).getRollupJobs()
         if (rollupJobs != null &&
             (rollupJobs.size > 1 || rollupJobs[0].id != rollup.id)
         ) {
-            errorMessage = "If target_index is alias, write backing index must be used only by this rollup job: [$targetIndexResolvedName]"
+            errorMessage = "More than one rollup job present on the backing index, cannot add alias for target index: [$targetIndexResolvedName]"
             logger.error(errorMessage)
             return RollupJobValidationResult.Failure(errorMessage)
         }
@@ -106,8 +115,8 @@ class RollupMapperService(
         val backingIndices = RollupFieldValueExpressionResolver.indexAliasUtils.getBackingIndicesForAlias(rollup.targetIndex)
         backingIndices?.forEach {
             if (it.index.name != targetIndexResolvedName) {
-                val rollupJobs = clusterService.state().metadata.index(it.index.name).getRollupJobs()
-                val validationResult = validateNonWriteBackingIndex(it.index.name, rollup, rollupJobs)
+                val allRollupJobs = clusterService.state().metadata.index(it.index.name).getRollupJobs()
+                val validationResult = validateNonWriteBackingIndex(it.index.name, rollup, allRollupJobs)
                 if (validationResult !is RollupJobValidationResult.Valid) {
                     return validationResult
                 }
@@ -139,7 +148,12 @@ class RollupMapperService(
     suspend fun attemptCreateRollupTargetIndex(job: Rollup, hasLegacyPlugin: Boolean): RollupJobValidationResult {
         val targetIndexResolvedName = RollupFieldValueExpressionResolver.resolve(job, job.targetIndex)
         if (indexExists(targetIndexResolvedName)) {
-            return validateAndAttemptToUpdateTargetIndex(job, targetIndexResolvedName, hasLegacyPlugin)
+            val validationResult = validateAndAttemptToUpdateTargetIndex(job, targetIndexResolvedName, hasLegacyPlugin)
+            when (validationResult) {
+                is RollupJobValidationResult.Failure -> logger.error(validationResult.message)
+                is RollupJobValidationResult.Invalid -> logger.error(validationResult.reason)
+            }
+            return validationResult
         } else {
             val errorMessage = "Failed to create target index [$targetIndexResolvedName]"
             return try {
@@ -180,10 +194,11 @@ class RollupMapperService(
         try {
             // 1. First we need to add index.plugins.rollup_index setting to index
             if (addRollupSettingToIndex(targetIndexResolvedName, hasLegacyPlugin) == false) {
+                logger.error("Failed to update rollup settings for target index: [$targetIndexResolvedName]")
                 return RollupJobValidationResult.Invalid("Failed to update rollup settings for target index: [$targetIndexResolvedName]")
             }
 
-            // 2. Put rollup mappings
+            // 2. Put rollup target_index mappings
             val putMappingRequest: PutMappingRequest =
                 PutMappingRequest(targetIndexResolvedName).source(IndexManagementIndices.rollupTargetMappings, XContentType.JSON)
             val respMappings: AcknowledgedResponse = client.admin().indices().suspendUntil {
@@ -192,7 +207,7 @@ class RollupMapperService(
             if (!respMappings.isAcknowledged) {
                 return RollupJobValidationResult.Invalid("Failed to put initial rollup mappings for target index [$targetIndexResolvedName]")
             }
-            // 3.
+            // 3. Add this rollup job to target_index's _meta
             errorMessage = "Failed to update mappings for target index [$targetIndexResolvedName]"
             updateRollupIndexMappings(rollup, targetIndexResolvedName)
         } catch (e: RemoteTransportException) {