fix(libwaterlinked): harden TCP command handling

[Kurtuveys]

Summary

This PR improves reliability of the Water Linked TCP client and callback handling.

The TCP command path had several reliability risks:

• pending_requests_ was accessed from multiple threads without locking.
• A fast DVL response could arrive before the promise was registered.
• Pending command requests could remain unresolved when the DVL did not respond.
• Pending requests were not failed explicitly when the TCP connection was lost.
• The socket could leak if connection setup failed after socket() succeeded.
• Report callback vectors could be modified while the polling thread was iterating over them.

Changes

• Protect pending_requests_ with request_mutex_.
• Register the pending promise before sending the command.
• Add command response timeout handling.
• Fail all pending commands on connection loss.
• Close the socket on constructor connection failure paths.
• Protect report callback registration and callback iteration with a mutex.

Validation

Tested with:

colcon build --packages-up-to waterlinked_dvl_driver
colcon test --packages-select libwaterlinked --event-handlers console_direct+
colcon test-result --verbose

[Copilot]

Pull request overview

This PR hardens the libwaterlinked TCP client’s command/response and callback handling to improve reliability under concurrency, fast responses, timeouts, and connection-loss scenarios, and updates the ROS driver wiring to pass the new timeout configuration.

Changes:

• Extend WaterLinkedClient to support a configurable command-response timeout and track pending requests with deadlines.
• Add mutex protection around pending command requests and around callback registration/iteration.
• Update the driver to pass the timeout for both connection setup and command responses, and clarify the parameter description.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
waterlinked_dvl_driver/src/waterlinked_dvl_driver.cpp	Passes the timeout into the updated WaterLinkedClient constructor (connection + command).
waterlinked_dvl_driver/src/waterlinked_dvl_driver_parameters.yaml	Clarifies that the timeout applies to both connection and command responses.
libwaterlinked/src/client.cpp	Implements pending-request locking, deadline-based timeouts, connection-loss failure, and callback locking.
libwaterlinked/include/libwaterlinked/client.hpp	Updates the public API and internal pending-request tracking structures to support command timeouts and locking.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[wltry]

Thank you for the pull request - and sorry for taking so long to review it. In general it looks sane, with protecting requests and handling of socket connection. It seems that the locking of request_mutex_ when calling the blocking send() could be avoided, and rather use a send_mutex to protect writing to the socket. Nothing that can't be fixed after merge, but I'll keep it open for a little while longer.

[wltry]

Thanks for the PR. Fixes issue #30 and improves TCP socket handling.