[mesos] 01/02: Fixed disconnection while sending acknowledgment to IOSwitchboard.

[al...@apache.org]

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alexr pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mesos.git

commit bfa2bd24780b5c49467b3c23260855e3d8b4c948
Author: Andrei Budnik <ab...@mesosphere.com>
AuthorDate: Fri Sep 21 14:51:24 2018 +0200

    Fixed disconnection while sending acknowledgment to IOSwitchboard.
    
    Previously, an HTTP connection to the IOSwitchboard could be garbage
    collected before the agent sent an acknowledgment to the IOSwitchboard
    via this connection. This patch fixes the issue by keeping a reference
    count to the connection in a lambda callback until disconnection
    occurs.
    
    Review: https://reviews.apache.org/r/68768/
---
 src/slave/http.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/slave/http.cpp b/src/slave/http.cpp
index bf34ef7..0011ced 100644
--- a/src/slave/http.cpp
+++ b/src/slave/http.cpp
@@ -3140,7 +3140,12 @@ Future<Response> Http::_attachContainerInput(
               // so that the IOSwitchboard process can terminate itself. This is
               // a workaround for the problem with dropping outstanding HTTP
               // responses due to a lack of graceful shutdown in libprocess.
-              acknowledgeContainerInputResponse(containerId);
+              acknowledgeContainerInputResponse(containerId)
+                .onFailed([containerId](const string& failure) {
+                  LOG(ERROR) << "Failed to send an acknowledgment to the"
+                             << " IOSwitchboard for container '"
+                             << containerId << "': " << failure;
+              });
             }));
     }));
 }
@@ -3156,6 +3161,13 @@ Future<Response> Http::acknowledgeContainerInputResponse(
       request.url.domain = "";
       request.url.path = "/acknowledge_container_input_response";
 
+      // This is a non Keep-Alive request which means the connection
+      // will be closed when the response is received. Since the
+      // 'Connection' is reference-counted, we must maintain a copy
+      // until the disconnection occurs.
+      connection.disconnected()
+        .onAny([connection]() {});
+
       return connection.send(request);
     });
 }