feat: add error handling for GetLedgerMetaService

Wrap LedgerManager.readLedgerMetadata() call in try-catch-finally to
properly handle errors and ensure manager is always closed:

- BKNoSuchLedgerExistsOnMetadataServerException → 404 NOT_FOUND
- Other BK errors → 500 INTERNAL_ERROR with error message

Add testGetLedgerMetaServiceNotFound to verify non-existent ledger
returns 404 with expected error body.

Author: liudezhi2098

bookkeeper-server/src/main/java/org/apache/bookkeeper/server/http/service/GetLedgerMetaService.java

@@ -22,6 +22,8 @@
 
 import com.google.common.collect.Maps;
 import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import org.apache.bookkeeper.client.BKException;
 import org.apache.bookkeeper.client.api.LedgerMetadata;
 import org.apache.bookkeeper.common.util.JsonUtil;
 import org.apache.bookkeeper.conf.ServerConfiguration;
@@ -63,20 +65,31 @@ public HttpServiceResponse handle(HttpServiceRequest request) throws Exception {
             Long ledgerId = Long.parseLong(params.get("ledger_id"));
 
             LedgerManager manager = ledgerManagerFactory.newLedgerManager();
+            try {
+                // output <ledgerId: ledgerMetadata>
+                Map<String, Object> output = Maps.newHashMap();
+                LedgerMetadata md = manager.readLedgerMetadata(ledgerId).get().getValue();
+                output.put(ledgerId.toString(), md);
 
-            // output <ledgerId: ledgerMetadata>
-            Map<String, Object> output = Maps.newHashMap();
-            LedgerMetadata md = manager.readLedgerMetadata(ledgerId).get().getValue();
-            output.put(ledgerId.toString(), md);
-
-            manager.close();
-
-            String jsonResponse = JsonUtil.toJson(output);
-            if (LOG.isDebugEnabled()) {
-                LOG.debug("output body:" + jsonResponse);
+                String jsonResponse = JsonUtil.toJson(output);
+                if (LOG.isDebugEnabled()) {
+                    LOG.debug("output body:" + jsonResponse);
+                }
+                response.setBody(jsonResponse);
+                response.setCode(HttpServer.StatusCode.OK);
+            } catch (ExecutionException e) {
+                if (e.getCause() instanceof BKException.BKNoSuchLedgerExistsOnMetadataServerException) {
+                    LOG.debug("Ledger {} not found on metadata server", ledgerId);
+                    response.setCode(HttpServer.StatusCode.NOT_FOUND);
+                    response.setBody("Ledger " + ledgerId + " not found on metadata server");
+                } else {
+                    LOG.error("Failed to read ledger metadata for {}", ledgerId, e.getCause());
+                    response.setCode(HttpServer.StatusCode.INTERNAL_ERROR);
+                    response.setBody("Failed to read ledger metadata: " + e.getCause().getMessage());
+                }
+            } finally {
+                manager.close();
             }
-            response.setBody(jsonResponse);
-            response.setCode(HttpServer.StatusCode.OK);
             return response;
         } else {
             response.setCode(HttpServer.StatusCode.NOT_FOUND);

bookkeeper-server/src/test/java/org/apache/bookkeeper/server/http/TestHttpService.java

@@ -414,6 +414,22 @@ public void testGetLedgerMetaService() throws Exception {
         assertTrue(Maps.difference(expected, actual).areEqual());
     }
 
+    @Test
+    public void testGetLedgerMetaServiceNotFound() throws Exception {
+        baseConf.setMetadataServiceUri(zkUtil.getMetadataServiceUri());
+        HttpEndpointService getLedgerMetaService = bkHttpServiceProvider
+            .provideHttpEndpointService(HttpServer.ApiType.GET_LEDGER_META);
+
+        // query a non-existent ledger, should return NOT_FOUND
+        HashMap<String, String> params = Maps.newHashMap();
+        long nonExistentLedgerId = 99999999L;
+        params.put("ledger_id", Long.toString(nonExistentLedgerId));
+        HttpServiceRequest request = new HttpServiceRequest(null, HttpServer.Method.GET, params);
+        HttpServiceResponse response = getLedgerMetaService.handle(request);
+        assertEquals(HttpServer.StatusCode.NOT_FOUND.getValue(), response.getStatusCode());
+        assertTrue(response.getBody().contains("not found on metadata server"));
+    }
+
     @Test
     public void testReadLedgerEntryService() throws Exception {
         BookKeeper.DigestType digestType = BookKeeper.DigestType.CRC32;