[Store] add version checking between client and server

[stmatengss]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @stmatengss, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a critical version compatibility mechanism between the Mooncake client and server. It ensures that clients only connect to servers running a compatible version by performing an explicit version check during the connection establishment phase. This enhancement prevents potential runtime errors and unexpected behavior that could arise from mismatched client and server versions.

Highlights

• Version Definition: A new header file, version.h, has been introduced to centrally define the Mooncake system's version string (initially "1.0.0") and provide a utility function to retrieve it.
• RPC Service Modification: The ServiceReady RPC method in WrappedMasterService has been updated to return a std::string representing the server's version, instead of void.
• Client-Server Version Checking: The MasterClient::Connect method now performs a version check. It retrieves the server's version via the ServiceReady RPC and compares it against the client's own version. If a mismatch is detected, the connection is rejected with an INVALID_VERSION error.

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[gemini-code-assist]

Code Review

This pull request introduces version checking between the client and server, which is a crucial feature for maintaining compatibility and stability. The implementation is straightforward, with the server exposing its version via an RPC endpoint that the client checks upon connection. My feedback includes a suggestion to improve the version checking logic for better flexibility in future releases and a minor performance optimization to avoid unnecessary string copies.

[gemini-code-assist]

This version check implementation can be improved in two ways:

1. Performance: result.value() and GetMooncakeVersion() both return references to strings, but they are being copied into server_version and client_version. You can avoid these unnecessary copies by using const std::string&.

2. Flexibility: The current strict string comparison means any version change (even a patch for a bug fix) will be a breaking change, forcing all clients to upgrade. Consider implementing a more flexible check, like comparing only the major version number. This would allow for non-breaking updates on the server.

Here is a suggested implementation that addresses both points:

Suggested change

	std::string server_version = result.value();
	std::string client_version = GetMooncakeVersion();
	if (server_version != client_version) {
	LOG(ERROR) << "Version mismatch: server=" << server_version
	<< " client=" << client_version;
	timer.LogResponse("error_code=", ErrorCode::INVALID_VERSION);
	return ErrorCode::INVALID_VERSION;
	}
	const std::string& server_version_str = result.value();
	const std::string& client_version_str = GetMooncakeVersion();
	// A simple way to check for major version compatibility.
	// For a more robust solution, consider a dedicated version parsing utility.
	auto get_major = [](const std::string& v_str) {
	return v_str.substr(0, v_str.find('.'));
	};
	if (get_major(server_version_str) != get_major(client_version_str)) {
	LOG(ERROR) << "Version mismatch: server=" << server_version_str
	<< " client=" << client_version_str;
	timer.LogResponse("error_code=", ErrorCode::INVALID_VERSION);
	return ErrorCode::INVALID_VERSION;
	}

[ykwd]

Thanks for the PR! I have two suggestions regarding the versioning logic:

1. Consider extracting the version-related logic from CMakeLists.txt into a separate .cmake file.
   We will likely need to bump the version frequently, and keeping this logic in its own file would help keep the CMakeLists.txt history cleaner and easier to review.

2. It would be helpful to add comments or documentation explaining when the version should be bumped.
   This will make the versioning policy clearer for future contributors and avoid inconsistent updates.

[ykwd]

Thanks for the PR! I have two suggestions regarding the versioning logic:

1. Consider extracting the version-related logic from CMakeLists.txt into a separate .cmake file.
   We will likely need to bump the version frequently, and keeping this logic in its own file would help keep the CMakeLists.txt history cleaner and easier to review.

2. It would be helpful to add comments or documentation explaining when the version should be bumped.
   This will make the versioning policy clearer for future contributors and avoid inconsistent updates.