castorini · lintool · Aug 19, 2025 · Aug 18, 2025 · Aug 19, 2025 · Aug 19, 2025
diff --git a/src/main/java/io/anserini/index/IndexReaderUtils.java b/src/main/java/io/anserini/index/IndexReaderUtils.java
@@ -844,24 +844,44 @@ public static Map<String, String>  getFieldInfoDescription(IndexReader reader) {
   }
 
   public static Path getIndex(String index) {
+    boolean isPrebuiltLabel = false;
     try {
       PrebuiltIndexHandler handler = new PrebuiltIndexHandler(index);
       handler.initialize();
-      handler.download();
-      String indexLocation = handler.decompressIndex();
-      return Paths.get(indexLocation);
+      isPrebuiltLabel = true;
     } catch (Exception e) {
-      // Not a prebuilt index -- continue to check local path
+      // isPrebuiltLabel remains false
     }
-
+
+    boolean localExists = Files.exists(Paths.get(index));
+
+    if (isPrebuiltLabel && localExists) {
+      throw new IllegalArgumentException(String.format(
+          "Ambiguous index reference \"%s\": both a prebuilt index label and a local path exist. " +
+          "Please disambiguate by specifying a full local path or removing/renaming the local directory.", index));
+    }
+
+    if (isPrebuiltLabel) {
+      try {
+        PrebuiltIndexHandler handler = new PrebuiltIndexHandler(index);
+        handler.initialize();
+        handler.download();
+        String indexLocation = handler.decompressIndex();
+        return Paths.get(indexLocation);
+      } catch (Exception e) {
+        //Fall through.
+      }
+    }
+
+    // Try local path
     Path indexPath = Paths.get(index);
     if (Files.exists(indexPath)) {
       return indexPath;
     }
-
+    
     // Path doesn't exist locally + it's not a prebuilt index.
     throw new IllegalArgumentException(String.format("\"%s\" does not appear to be a valid index.", index));
- }
+  }
 
   // This is needed by src/main/python/run_regression.py
 

diff --git a/src/main/java/io/anserini/rerank/GenerateRerankerRequests.java b/src/main/java/io/anserini/rerank/GenerateRerankerRequests.java
@@ -194,15 +194,32 @@ public void getTopics(String topicsFile) throws IOException {
   }
 
   public IndexReader getIndexReader(String index) {
-    if (!Files.exists(Paths.get(index))) { // get inverted index if index doesn't exist locally
+    String resolvedIndex;
+
+    boolean isPrebuiltLabel = IndexInfo.contains(index);
+    boolean localExists = Files.exists(Paths.get(index));
+
+    // If both a prebuilt label and a local path exist, fail fast with
+    // a clear error to force disambiguation.
+    if (isPrebuiltLabel && localExists) {
+      throw new IllegalArgumentException(String.format(
+          "Ambiguous index reference \"%s\": both a prebuilt index label and a local path exist. " +
+          "Please disambiguate by specifying a full local path or removing/renaming the local directory.", index));
+    }
+
+    if (isPrebuiltLabel) {
       IndexInfo currentIndex = IndexInfo.get(index);
-      index = IndexReaderUtils.getIndex(currentIndex.invertedIndex).toString();
+      resolvedIndex = IndexReaderUtils.getIndex(currentIndex.invertedIndex).toString();
+    } else {
+      // Not a known prebuilt label; resolve as prebuilt (if any) or local path.
+      resolvedIndex = IndexReaderUtils.getIndex(index).toString();
     }
-    LOG.info("Generating reranker requests with raw documents from index: " + index);
+
+    LOG.info("Generating reranker requests with raw documents from index: " + resolvedIndex);
     try {
-      return IndexReaderUtils.getReader(index);
+      return IndexReaderUtils.getReader(resolvedIndex);
     } catch (IOException e) {
-      throw new IllegalArgumentException(String.format("\"%s\" does not appear to have a valid inverted index.", index));
+      throw new IllegalArgumentException(String.format("\"%s\" does not appear to have a valid inverted index.", resolvedIndex));
     }
   }
 

diff --git a/src/test/java/io/anserini/index/IndexReaderUtilsTest.java b/src/test/java/io/anserini/index/IndexReaderUtilsTest.java
@@ -659,4 +659,33 @@ public void testFormatSize() {
     assertEquals("1.0 MB", IndexReaderUtils.formatSize(1048576));
     assertEquals("1.0 GB", IndexReaderUtils.formatSize(1073741824));
   }
+
+  private static final String PREBUILT_LABEL = "msmarco-v1-passage";
+
+  @Test
+  public void testAmbiguousPrebuiltLabelAndLocalPathThrows() throws IOException {
+    Path cwd = java.nio.file.Paths.get("");
+    Path localDir = cwd.resolve(PREBUILT_LABEL);
+
+    // Ensure clean state, create the conflicting local directory, then clean it up in finally.
+    if (java.nio.file.Files.exists(localDir)) {
+      // If it already exists for some reason, fail fast to avoid breaking other tests.
+      fail("Test setup error: unexpected existing directory " + localDir);
+    }
+
+    try {
+      java.nio.file.Files.createDirectory(localDir);
+      try {
+        IndexReaderUtils.getIndex(PREBUILT_LABEL);
+        fail("Expected IllegalArgumentException due to ambiguous index reference");
+      } catch (IllegalArgumentException e) {
+        assertTrue(e.getMessage().contains("Ambiguous index reference"));
+        assertTrue(e.getMessage().contains(PREBUILT_LABEL));
+      }
+    } finally {
+      if (java.nio.file.Files.exists(localDir)) {
+        java.nio.file.Files.delete(localDir);
+      }
+    }
+  }
 }
diff --git a/src/test/java/io/anserini/rerank/GenerateRerankerRequestsTest.java b/src/test/java/io/anserini/rerank/GenerateRerankerRequestsTest.java
@@ -163,4 +163,39 @@ public void testGenerate() throws Exception {
     assertTrue(new File("test_reranker_requests.jsonl").delete());
     restoreStderr();
   }
+
+  @Test
+  public void testAmbiguousIndexLabelAndLocalPath() throws Exception {
+    // Create a local directory that matches a known prebuilt label to force ambiguity.
+    final String prebuiltLabel = "msmarco-v1-passage";
+    File localDir = new File(prebuiltLabel);
+    if (localDir.exists()) {
+      // If it already exists, fail to avoid interfering with other tests.
+      throw new IllegalStateException("Unexpected pre-existing directory: " + localDir.getAbsolutePath());
+    }
+
+    try {
+      if (!localDir.mkdir()) {
+        throw new IllegalStateException("Failed to create test directory: " + localDir.getAbsolutePath());
+      }
+
+      GenerateRerankerRequests.Args args = new GenerateRerankerRequests.Args();
+      args.index = prebuiltLabel; // Ambiguous: label exists and local dir exists
+      args.run = "src/test/resources/sample_runs/run4";
+      args.topics = "cacm";
+      args.output = "test_reranker_requests.jsonl";
+
+      try (GenerateRerankerRequests<?> ignored = new GenerateRerankerRequests<>(args)) {
+        assertTrue("Expected IllegalArgumentException due to ambiguous index reference", false);
+      } catch (IllegalArgumentException e) {
+        assertTrue(e.getMessage().contains("Ambiguous index reference"));
+      }
+    } finally {
+      if (localDir.exists()) {
+        assertTrue(localDir.delete());
+      }
+      // Ensure we don't leave the output file around if it was accidentally created
+      new File("test_reranker_requests.jsonl").delete();
+    }
+  }
 }