MB-28630: Extend log info for exception in runloop

If an exception is thrown while executing stuff for a
connection it is being caught and the connection is being
shut down.

Log the entire cookie information if the exception occurs
during packet execution. For the other states include
the state name in the exception.

In addition to that catch std::bad_alloc and ignore
logging if it is being thrown while adding log entries
(to avoid crashing the server)

Change-Id: Ib7700e5b7099ccaa054dfd2f61f2784f76399815
Reviewed-on: http://review.couchbase.org/90843
Tested-by: Build Bot <[email protected]>
Reviewed-by: Tim Bradgate <[email protected]>
Reviewed-by: Dave Rigby <[email protected]>

Author: trondn

daemon/connection_mcbp.cc

@@ -972,10 +972,37 @@ void McbpConnection::runEventLoop(short which) {
     try {
         runStateMachinery();
     } catch (const std::exception& e) {
-        LOG_WARNING(
-                "{}: exception occurred in runloop - closing connection: {}",
-                getId(),
-                e.what());
+        bool logged = false;
+        if (getState() == McbpStateMachine::State::execute) {
+            try {
+                // Converting the cookie to json -> string could probably
+                // cause too much memory allcation. We don't want that to
+                // cause us to crash..
+                LOG_WARNING(
+                        "{}: exception occurred in runloop during packet "
+                        "execution. Cookie info: {} - closing connection: {}",
+                        getId(),
+                        to_string(getCookieObject().toJSON()),
+                        e.what());
+                logged = true;
+            } catch (const std::bad_alloc&) {
+                // none
+            }
+        }
+
+        if (!logged) {
+            try {
+                LOG_WARNING(
+                        "{}: exception occurred in runloop (state: \"{}\") - "
+                        "closing connection: {}",
+                        getId(),
+                        getStateName(),
+                        e.what());
+            } catch (const std::bad_alloc&) {
+                // Ditch logging.. just shut down the connection
+            }
+        }
+
         setState(McbpStateMachine::State::closing);
         /*
          * In addition to setting the state to conn_closing
@@ -986,11 +1013,15 @@ void McbpConnection::runEventLoop(short which) {
         try {
             runStateMachinery();
         } catch (const std::exception& e) {
-            LOG_WARNING(
-                    "{}: exception occurred in runloop whilst"
-                    " attempting to close connection: {}",
-                    getId(),
-                    e.what());
+            try {
+                LOG_WARNING(
+                        "{}: exception occurred in runloop whilst"
+                        " attempting to close connection: {}",
+                        getId(),
+                        e.what());
+            } catch (const std::bad_alloc&) {
+                // Drop logging
+            }
         }
     }