BewareMyPower opened a new pull request, #317: URL: https://github.com/apache/pulsar-client-cpp/pull/317
### Motivation We observed server null `ClientConnection` accesses in test environment. See the `this=0x0` outputs in the following two typical stacks. ``` #8 bytesWritten (this=0xb8, size=371) at lib/SharedBuffer.h:166 #9 pulsar::ClientConnection::handleRead (this=0x0, err=..., bytesTransferred=371, minReadSize=4) at lib/ClientConnection.cc:609 ``` ``` #12 0x00007f33202933d2 in unique_lock (__m=..., this=0x7f3311c82800) at /opt/rh/devtoolset-7/root/usr/include/c++/7/bits/std_mutex.h:197 #13 pulsar::ClientConnection::sendPendingCommands (this=0x0) at lib/ClientConnection.cc:1071 #14 0x00007f3320293d2d in pulsar::ClientConnection::handleSendPair (this=0x0, err=...) at lib/ClientConnection.cc:1066 ``` Though `shared_from_this()` is always passed to the `std::bind` function, when the method of `ClientConnection` is called, the pointer is still `null`. ### Modifications First, replace all `std::bind` calls with the lambda expression that catches `std::weak_ptr<ClientConnection>` and perform null checks explicitly on the value returned by the `lock()` method. Since now all asio callbacks don't hold a `shared_ptr`, the owner of the `ClientConnection` object should be `ConnectionPool`, i.e. the pool maintains some connections, while all asio callbacks use `weak_ptr` to test if the connection is present. Second, make `ClientConnection::getConnection` return `shared_ptr` rather than `weak_ptr` so that the caller side does not need to check if `lock()` returns null in the callback of this future. We cannot make `ConnectionPool::getConnectionAsync` return `shared_ptr` because it could return the future of `connectPromise_`, which is hold by `ClientConnection` itself. We should avoid holding a `shared_ptr` of `ClientConnection` because its owner is `ConnectionPool`. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
