[Backport 2.13] Fix: change max chunk limit exception

CHANGELOG.md

@@ -20,6 +20,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Removed map of subquery to subquery index in favor of storing index as part of disi wrapper to improve hybrid query latencies by 20% ([#711](https://github.com/opensearch-project/neural-search/pull/711))
 ### Bug Fixes
 - Add support for request_cache flag in hybrid query ([#663](https://github.com/opensearch-project/neural-search/pull/663))
+- Avoid change max_chunk_limit exceed exception in text chunking processor ([#717](https://github.com/opensearch-project/neural-search/pull/717))
 ### Infrastructure
 ### Documentation
 ### Maintenance

src/main/java/org/opensearch/neuralsearch/processor/TextChunkingProcessor.java

@@ -12,6 +12,7 @@
 import java.util.List;
 import java.util.Objects;
 
+import org.apache.commons.lang3.StringUtils;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.env.Environment;
 import org.opensearch.index.IndexService;
@@ -30,6 +31,7 @@
 import static org.opensearch.neuralsearch.processor.chunker.Chunker.MAX_CHUNK_LIMIT_FIELD;
 import static org.opensearch.neuralsearch.processor.chunker.Chunker.DEFAULT_MAX_CHUNK_LIMIT;
 import static org.opensearch.neuralsearch.processor.chunker.Chunker.DISABLED_MAX_CHUNK_LIMIT;
+import static org.opensearch.neuralsearch.processor.chunker.Chunker.CHUNK_STRING_COUNT_FIELD;
 import static org.opensearch.neuralsearch.processor.chunker.ChunkerParameterParser.parseIntegerParameter;
 
 /**
@@ -170,9 +172,11 @@ public IngestDocument execute(final IngestDocument ingestDocument) {
         // fixed token length algorithm needs runtime parameter max_token_count for tokenization
         Map<String, Object> runtimeParameters = new HashMap<>();
         int maxTokenCount = getMaxTokenCount(sourceAndMetadataMap);
+        int chunkStringCount = getChunkStringCountFromMap(sourceAndMetadataMap, fieldMap);
         runtimeParameters.put(FixedTokenLengthChunker.MAX_TOKEN_COUNT_FIELD, maxTokenCount);
         runtimeParameters.put(MAX_CHUNK_LIMIT_FIELD, maxChunkLimit);
-        chunkMapType(sourceAndMetadataMap, fieldMap, runtimeParameters, 0);
+        runtimeParameters.put(CHUNK_STRING_COUNT_FIELD, chunkStringCount);
+        chunkMapType(sourceAndMetadataMap, fieldMap, runtimeParameters);
         return ingestDocument;
     }
 
@@ -230,13 +234,51 @@ private void validateListTypeValue(final String sourceKey, final Object sourceVa
     }
 
     @SuppressWarnings("unchecked")
-    private int chunkMapType(
+    private int getChunkStringCountFromMap(Map<String, Object> sourceAndMetadataMap, final Map<String, Object> fieldMap) {
+        int chunkStringCount = 0;
+        for (Map.Entry<String, Object> fieldMapEntry : fieldMap.entrySet()) {
+            String originalKey = fieldMapEntry.getKey();
+            Object targetKey = fieldMapEntry.getValue();
+            if (targetKey instanceof Map) {
+                // call this method recursively when target key is a map
+                Object sourceObject = sourceAndMetadataMap.get(originalKey);
+                if (sourceObject instanceof List) {
+                    List<Object> sourceObjectList = (List<Object>) sourceObject;
+                    for (Object source : sourceObjectList) {
+                        if (source instanceof Map) {
+                            chunkStringCount += getChunkStringCountFromMap((Map<String, Object>) source, (Map<String, Object>) targetKey);
+                        }
+                    }
+                } else if (sourceObject instanceof Map) {
+                    chunkStringCount += getChunkStringCountFromMap((Map<String, Object>) sourceObject, (Map<String, Object>) targetKey);
+                }
+            } else {
+                // chunk the object when target key is of leaf type (null, string and list of string)
+                Object chunkObject = sourceAndMetadataMap.get(originalKey);
+                chunkStringCount += getChunkStringCountFromLeafType(chunkObject);
+            }
+        }
+        return chunkStringCount;
+    }
+
+    @SuppressWarnings("unchecked")
+    private int getChunkStringCountFromLeafType(final Object value) {
+        // leaf type means null, String or List<String>
+        // the result should be an empty list when the input is null
+        if (value instanceof String) {
+            return StringUtils.isEmpty((String) value) ? 0 : 1;
+        } else if (isListOfString(value)) {
+            return (int) ((List<String>) value).stream().filter(s -> !StringUtils.isEmpty(s)).count();
+        }
+        return 0;
+    }
+
+    @SuppressWarnings("unchecked")
+    private void chunkMapType(
         Map<String, Object> sourceAndMetadataMap,
         final Map<String, Object> fieldMap,
-        final Map<String, Object> runtimeParameters,
-        final int chunkCount
+        final Map<String, Object> runtimeParameters
     ) {
-        int updatedChunkCount = chunkCount;
         for (Map.Entry<String, Object> fieldMapEntry : fieldMap.entrySet()) {
             String originalKey = fieldMapEntry.getKey();
             Object targetKey = fieldMapEntry.getValue();
@@ -247,21 +289,11 @@ private int chunkMapType(
                     List<Object> sourceObjectList = (List<Object>) sourceObject;
                     for (Object source : sourceObjectList) {
                         if (source instanceof Map) {
-                            updatedChunkCount = chunkMapType(
-                                (Map<String, Object>) source,
-                                (Map<String, Object>) targetKey,
-                                runtimeParameters,
-                                updatedChunkCount
-                            );
+                            chunkMapType((Map<String, Object>) source, (Map<String, Object>) targetKey, runtimeParameters);
                         }
                     }
                 } else if (sourceObject instanceof Map) {
-                    updatedChunkCount = chunkMapType(
-                        (Map<String, Object>) sourceObject,
-                        (Map<String, Object>) targetKey,
-                        runtimeParameters,
-                        updatedChunkCount
-                    );
+                    chunkMapType((Map<String, Object>) sourceObject, (Map<String, Object>) targetKey, runtimeParameters);
                 }
             } else {
                 // chunk the object when target key is of leaf type (null, string and list of string)
@@ -270,15 +302,21 @@ private int chunkMapType(
                 sourceAndMetadataMap.put(String.valueOf(targetKey), chunkedResult);
             }
         }
-        return updatedChunkCount;
     }
 
     /**
      * Chunk the content, update the runtime max_chunk_limit and return the result
      */
     private List<String> chunkString(final String content, final Map<String, Object> runTimeParameters) {
-        // update runtime max_chunk_limit if not disabled
+        // return an empty list for empty string
+        if (StringUtils.isEmpty(content)) {
+            return List.of();
+        }
         List<String> contentResult = chunker.chunk(content, runTimeParameters);
+        // update chunk_string_count for each string
+        int chunkStringCount = parseIntegerParameter(runTimeParameters, CHUNK_STRING_COUNT_FIELD, 1);
+        runTimeParameters.put(CHUNK_STRING_COUNT_FIELD, chunkStringCount - 1);
+        // update runtime max_chunk_limit if not disabled
         int runtimeMaxChunkLimit = parseIntegerParameter(runTimeParameters, MAX_CHUNK_LIMIT_FIELD, maxChunkLimit);
         if (runtimeMaxChunkLimit != DISABLED_MAX_CHUNK_LIMIT) {
             runTimeParameters.put(MAX_CHUNK_LIMIT_FIELD, runtimeMaxChunkLimit - contentResult.size());

src/main/java/org/opensearch/neuralsearch/processor/chunker/Chunker.java

@@ -14,6 +14,7 @@
 public interface Chunker {
 
     String MAX_CHUNK_LIMIT_FIELD = "max_chunk_limit";
+    String CHUNK_STRING_COUNT_FIELD = "chunk_string_count";
     int DEFAULT_MAX_CHUNK_LIMIT = 100;
     int DISABLED_MAX_CHUNK_LIMIT = -1;
 
@@ -33,4 +34,16 @@ public interface Chunker {
      * @return chunked passages
      */
     List<String> chunk(String content, Map<String, Object> runtimeParameters);
+
+    /**
+     * Checks whether the chunking results would exceed the max chunk limit after adding a passage
+     * If exceeds, then return true
+     *
+     * @param chunkResultSize the size of chunking result
+     * @param runtimeMaxChunkLimit runtime max_chunk_limit, used to check with chunkResultSize
+     * @param chunkStringCount runtime chunk_string_count, used to check with chunkResultSize
+     */
+    static boolean checkRunTimeMaxChunkLimit(int chunkResultSize, int runtimeMaxChunkLimit, int chunkStringCount) {
+        return runtimeMaxChunkLimit != DISABLED_MAX_CHUNK_LIMIT && chunkResultSize + chunkStringCount >= runtimeMaxChunkLimit;
+    }
 }

src/main/java/org/opensearch/neuralsearch/processor/chunker/DelimiterChunker.java

@@ -49,25 +49,29 @@ public void parseParameters(Map<String, Object> parameters) {
      * @param content input string
      * @param runtimeParameters a map for runtime parameters, containing the following runtime parameters:
      * 1. max_chunk_limit field level max chunk limit
+     * 2. chunk_string_count number of non-empty strings (including itself) which need to be chunked later
      */
     @Override
     public List<String> chunk(final String content, final Map<String, Object> runtimeParameters) {
         int runtimeMaxChunkLimit = parseIntegerParameter(runtimeParameters, MAX_CHUNK_LIMIT_FIELD, maxChunkLimit);
+        int chunkStringCount = parseIntegerParameter(runtimeParameters, CHUNK_STRING_COUNT_FIELD, 1);
 
         List<String> chunkResult = new ArrayList<>();
         int start = 0, end;
         int nextDelimiterPosition = content.indexOf(delimiter);
 
         while (nextDelimiterPosition != -1) {
-            ChunkerUtil.checkRunTimeMaxChunkLimit(chunkResult.size(), runtimeMaxChunkLimit, maxChunkLimit);
+            if (Chunker.checkRunTimeMaxChunkLimit(chunkResult.size(), runtimeMaxChunkLimit, chunkStringCount)) {
+                break;
+            }
             end = nextDelimiterPosition + delimiter.length();
             chunkResult.add(content.substring(start, end));
             start = end;
             nextDelimiterPosition = content.indexOf(delimiter, start);
         }
 
+        // add the rest content into the chunk result
         if (start < content.length()) {
-            ChunkerUtil.checkRunTimeMaxChunkLimit(chunkResult.size(), runtimeMaxChunkLimit, maxChunkLimit);
             chunkResult.add(content.substring(start));
         }
 

src/main/java/org/opensearch/neuralsearch/processor/chunker/FixedTokenLengthChunker.java

@@ -117,11 +117,13 @@ public void parseParameters(Map<String, Object> parameters) {
      * @param runtimeParameters a map for runtime parameters, containing the following runtime parameters:
      * 1. max_token_count the max token limit for the tokenizer
      * 2. max_chunk_limit field level max chunk limit
+     * 3. chunk_string_count number of non-empty strings (including itself) which need to be chunked later
      */
     @Override
     public List<String> chunk(final String content, final Map<String, Object> runtimeParameters) {
         int maxTokenCount = parsePositiveIntegerParameter(runtimeParameters, MAX_TOKEN_COUNT_FIELD, DEFAULT_MAX_TOKEN_COUNT);
         int runtimeMaxChunkLimit = parseIntegerParameter(runtimeParameters, MAX_CHUNK_LIMIT_FIELD, this.maxChunkLimit);
+        int chunkStringCount = parseIntegerParameter(runtimeParameters, CHUNK_STRING_COUNT_FIELD, 1);
 
         List<AnalyzeToken> tokens = tokenize(content, tokenizer, maxTokenCount);
         List<String> chunkResult = new ArrayList<>();
@@ -131,13 +133,17 @@ public List<String> chunk(final String content, final Map<String, Object> runtim
         int overlapTokenNumber = (int) Math.floor(tokenLimit * overlapRate);
 
         while (startTokenIndex < tokens.size()) {
-            ChunkerUtil.checkRunTimeMaxChunkLimit(chunkResult.size(), runtimeMaxChunkLimit, maxChunkLimit);
             if (startTokenIndex == 0) {
                 // include all characters till the start if no previous passage
                 startContentPosition = 0;
             } else {
                 startContentPosition = tokens.get(startTokenIndex).getStartOffset();
             }
+            if (Chunker.checkRunTimeMaxChunkLimit(chunkResult.size(), runtimeMaxChunkLimit, chunkStringCount)) {
+                // include all characters till the end if exceeds max chunk limit
+                chunkResult.add(content.substring(startContentPosition));
+                break;
+            }
             if (startTokenIndex + tokenLimit >= tokens.size()) {
                 // include all characters till the end if no next passage
                 endContentPosition = content.length();