Add missing deprecation support for max threads in export

Author: ypeckstadt

data-loader/cli/src/main/java/com/scalar/db/dataloader/cli/command/dataexport/ExportCommand.java

@@ -131,6 +131,11 @@ private void validateDeprecatedOptions() {
         DEPRECATED_END_EXCLUSIVE_OPTION,
         END_INCLUSIVE_OPTION,
         END_INCLUSIVE_OPTION_SHORT);
+    validateDeprecatedOptionPair(
+        spec.commandLine(),
+        DEPRECATED_THREADS_OPTION,
+        MAX_THREADS_OPTION,
+        MAX_THREADS_OPTION_SHORT);
   }
 
   private String getScalarDbPropertiesFilePath() {

data-loader/cli/src/main/java/com/scalar/db/dataloader/cli/command/dataexport/ExportCommandOptions.java

@@ -16,6 +16,9 @@ public class ExportCommandOptions {
   public static final String END_INCLUSIVE_OPTION = "--end-inclusive";
   public static final String END_INCLUSIVE_OPTION_SHORT = "-ei";
   public static final String DEPRECATED_END_EXCLUSIVE_OPTION = "--end-exclusive";
+  public static final String MAX_THREADS_OPTION = "--max-threads";
+  public static final String MAX_THREADS_OPTION_SHORT = "-mt";
+  public static final String DEPRECATED_THREADS_OPTION = "--threads";
 
   @CommandLine.Option(
       names = {"--config", "-c"},
@@ -79,6 +82,15 @@ public class ExportCommandOptions {
           "Maximum number of threads to use for parallel processing (default: number of available processors)")
   protected Integer maxThreads;
 
+  // Deprecated option - kept for backward compatibility
+  @CommandLine.Option(
+      names = {DEPRECATED_THREADS_OPTION},
+      paramLabel = "<THREADS>",
+      description = "Deprecated: Use --max-threads instead",
+      hidden = true)
+  @Deprecated
+  protected Integer threadsDeprecated;
+
   @CommandLine.Option(
       names = {"--start-key", "-sk"},
       paramLabel = "<KEY=VALUE>",
@@ -184,5 +196,10 @@ public void applyDeprecatedOptions() {
     if (endExclusiveDeprecated != null) {
       scanEndInclusive = !endExclusiveDeprecated;
     }
+
+    // If the deprecated option is set, use its value
+    if (threadsDeprecated != null) {
+      maxThreads = threadsDeprecated;
+    }
   }
 }

data-loader/cli/src/test/java/com/scalar/db/dataloader/cli/command/dataexport/ExportCommandTest.java

@@ -191,6 +191,35 @@ void call_withOnlyDeprecatedEndExclusive_shouldApplyInvertedValue() {
     assertEquals(true, command.scanEndInclusive);
   }
 
+  @Test
+  void call_withOnlyDeprecatedThreads_shouldApplyValue() {
+    // Simulate command line parsing with only deprecated option
+    String[] args = {
+      "--config",
+      "scalardb.properties",
+      "--namespace",
+      "scalar",
+      "--table",
+      "asset",
+      "--format",
+      "JSON",
+      "--threads",
+      "12"
+    };
+    ExportCommand command = new ExportCommand();
+    CommandLine cmd = new CommandLine(command);
+    cmd.parseArgs(args);
+
+    // Verify the deprecated value was parsed
+    assertEquals(12, command.threadsDeprecated);
+
+    // Apply deprecated options (this is what the command does after validation)
+    command.applyDeprecatedOptions();
+
+    // Verify the value was applied to maxThreads
+    assertEquals(12, command.maxThreads);
+  }
+
   @Test
   void call_withMaxThreadsSpecified_shouldUseSpecifiedValue() {
     // Simulate command line parsing with --max-threads