From 0e556f1db850d47bd890d144f3a48064af554b5c Mon Sep 17 00:00:00 2001
From: jyemin <jeff.yemin@mongodb.com>
Date: Thu, 3 Dec 2020 08:43:51 -0500
Subject: [PATCH] Ensure DNS errors bubble up as errors in reactive streams

Currently DNS lookups happen synchronously in the reactive streams
driver.  This isn't good, but with this change at least DNS errors
will be properly reported.

JAVA-3852
---
 .../connection/InternalStreamConnection.java  | 55 +++++++++----------
 1 file changed, 27 insertions(+), 28 deletions(-)

diff --git a/driver-core/src/main/com/mongodb/internal/connection/InternalStreamConnection.java b/driver-core/src/main/com/mongodb/internal/connection/InternalStreamConnection.java
index 63d6e05cc22..b1faa79fd6d 100644
--- a/driver-core/src/main/com/mongodb/internal/connection/InternalStreamConnection.java
+++ b/driver-core/src/main/com/mongodb/internal/connection/InternalStreamConnection.java
@@ -145,37 +145,36 @@ public void openAsync(final SingleResultCallback<Void> callback) {
         isTrue("Open already called", stream == null, callback);
         try {
             stream = streamFactory.create(serverId.getAddress());
-        } catch (Throwable t) {
-            callback.onResult(null, t);
-            return;
-        }
-        stream.openAsync(new AsyncCompletionHandler<Void>() {
-            @Override
-            public void completed(final Void aVoid) {
-                connectionInitializer.initializeAsync(InternalStreamConnection.this, new SingleResultCallback<ConnectionDescription>() {
-                    @Override
-                    public void onResult(final ConnectionDescription result, final Throwable t) {
-                        if (t != null) {
-                            close();
-                            callback.onResult(null, t);
-                        } else {
-                            description = result;
-                            opened.set(true);
-                            sendCompressor = findSendCompressor(description);
-                            if (LOGGER.isInfoEnabled()) {
-                                LOGGER.info(format("Opened connection [%s] to %s", getId(), serverId.getAddress()));
+            stream.openAsync(new AsyncCompletionHandler<Void>() {
+                @Override
+                public void completed(final Void aVoid) {
+                    connectionInitializer.initializeAsync(InternalStreamConnection.this, new SingleResultCallback<ConnectionDescription>() {
+                        @Override
+                        public void onResult(final ConnectionDescription result, final Throwable t) {
+                            if (t != null) {
+                                close();
+                                callback.onResult(null, t);
+                            } else {
+                                description = result;
+                                opened.set(true);
+                                sendCompressor = findSendCompressor(description);
+                                if (LOGGER.isInfoEnabled()) {
+                                    LOGGER.info(format("Opened connection [%s] to %s", getId(), serverId.getAddress()));
+                                }
+                                callback.onResult(null, null);
                             }
-                            callback.onResult(null, null);
                         }
-                    }
-                });
-            }
+                    });
+                }
 
-            @Override
-            public void failed(final Throwable t) {
-                callback.onResult(null, t);
-            }
-        });
+                @Override
+                public void failed(final Throwable t) {
+                    callback.onResult(null, t);
+                }
+            });
+        } catch (Throwable t) {
+            callback.onResult(null, t);
+        }
     }
 
     private Map<Byte, Compressor> createCompressorMap(final List<MongoCompressor> compressorList) {