[GitHub] [incubator-iceberg] rdblue commented on a change in pull request #721: Add PreferredLocations support for Iceberg Spark Source

[GitBox <gi...@apache.org>]

rdblue commented on a change in pull request #721: Add PreferredLocations support for Iceberg Spark Source
URL: https://github.com/apache/incubator-iceberg/pull/721#discussion_r367011590
 
 

 ##########
 File path: spark/src/main/java/org/apache/iceberg/spark/source/Reader.java
 ##########
 @@ -308,6 +332,29 @@ private ReadTask(CombinedScanTask task, String tableSchemaString, String expecte
         encryptionManager.value(), caseSensitive);
     }
 
+    @Override
+    public String[] preferredLocations() {
+      if (!localityPreferred) {
+        return new String[0];
+      }
+
+      Configuration conf = SparkSession.active().sparkContext().hadoopConfiguration();
+      Set<String> locations = Sets.newHashSet();
+      for (FileScanTask f : task.files()) {
+        Path path = new Path(f.file().path().toString());
+        try {
+          FileSystem fs = path.getFileSystem(conf);
+          for (BlockLocation b : fs.getFileBlockLocations(path, f.start(), f.length())) {
+            locations.addAll(Arrays.asList(b.getHosts()));
+          }
+        } catch (IOException ioe) {
+          LOG.warn("Failed to get block locations for path {}", path, ioe);
 
 Review comment:
   I think I agree with the existing warn behavior. If we can't get locality info from the FS it shouldn't fail the job. It is a preference, not a requirement right?

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