Add context-aware versions of WaitUntilPos() and CatchMasterPos()

[dbnski]

WaitUntilPos() is a blocking call, so there should be a way to break out of it before it times out on its own. The patch adds new context-aware functions keeping the interface backwards compatible.

[gemini-code-assist]

Code Review

This pull request introduces context-aware versions of the wait and catch master position functions, namely WaitUntilPosContext and CatchMasterPosContext, to support cancellation and timeouts via context.Context. The feedback suggests stopping the newly created timer in WaitUntilPosContext using defer timer.Stop() to prevent resource leaks, and checking if the context is already canceled in CatchMasterPosContext before calling GetMasterPos().

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[gemini-code-assist]

The time.NewTimer is created but never stopped. In Go, timers should be stopped using defer timer.Stop() to release resources and prevent potential memory leaks, especially if the function returns early.

func (c *Canal) WaitUntilPosContext(ctx context.Context, pos mysql.Position, timeout time.Duration) error {
	timer := time.NewTimer(timeout)
	defer timer.Stop()
	for {

[dbnski]

Will fix that.

[gemini-code-assist]

It is a good practice to check if the context is already canceled or expired before performing a potentially expensive network operation like GetMasterPos().

Suggested change

	func (c *Canal) CatchMasterPosContext(ctx context.Context, timeout time.Duration) error {
	pos, err := c.GetMasterPos()
	func (c *Canal) CatchMasterPosContext(ctx context.Context, timeout time.Duration) error {
	if err := ctx.Err(); err != nil {
	return err
	}
	pos, err := c.GetMasterPos()