This PR builds up on the pass-through DB driver to a fully functioning DB driver implementation via our RPC layer.
To keep things separate from the plugin RPC API, and have the ability to move fast with changes, a separate field Driver is added to MattermostPlugin. Typically the field which is required to be compatible are the API and Helpers. It would be well-documented that Driver is purely for internal use by Mattermost plugins.
A new Driver interface was created which would have a client and server implementation. Every object (connection, statement, etc.) is created and added to a map on the server side. On the client side, the wrapper structs hold the object id, and communicate via the RPC API using this id.
When the server gets the object id, it picks up the appropriate object from its map and performs the operation, and sends back the data.
Some things that need to be handled are errors. Typical error types like pq.Error and mysql.MySQLError are registered with encoding/gob. But for error variables like sql.ErrNoRows, a special integer is encoded with the ErrorString struct. And on the cilent side, the integer is checked, and the appropriate error variable is returned.
Some pending things:
- Context support. This is tricky. Since context.Context is an interface, it's not possible to marshal it. We have to find a way to get the timeout value from the context and pass it.
- RowsColumnScanType(rowsID string, index int) reflect.Type API. Again, reflect.Type is an interface.
- Master/Replica API support.
* MM-19155 Change plugin helpers files to be golint complied
* add makefile target that checks if plugin/helpers files are golint
compliant
* MM-19155 - Change plugin helpers files to be golint complied
* added comment documentation to exported plugin/helpers methods
* changed variable names to be compliant with golint
* Address feedback
* Add SetWithOptions
* Avoid passing two structs to the functions
* Rename ExpiryInSeconds -> ExpireInSeconds
* Use t.Run for the tests
* Fix build
* Address feedback
* Update log message
* Update docs and use KVSetWithOptions in KVCompareAndSetJSON
* Improve code style
* Use struct instead of pointer to struct
* Fix minimum server versions
* Update documentation
* Address feedback
* Revert new implemention of kv helpers
* Adress feedback
* Implement KVCompareAndDelete and KVCompareAndDeleteJSON
* Add tests for KVCompareAndDelete
* Update minimum server version
* Handle nil value on CompareAndSet so that it deletes it
* Fix comments
* Tweaks from PR comments
* Go back to deleted, err
* move kv helpers to helpers_kv*.go
* change KVGetJSON return signature
Return a boolean and an error, to clearly indicate if no value was found and thus no value unmarshalled into the target interface.
Also fix an issue with CompareAndSet to allow an oldValue of nil (i.e.
expected to be unset).
* add missing license
* tweak documentation
* document KVSetWithExpiryJSON minimum version
* Add KV helper methods to Helpers interface
* Address code-review comments, add unit tests
* Update documentation for KVCompareAndSetJSON.
* Update assertions for helpers_bots_test.go
* Fix assertion not called name in test.
* Adding EnsureBot plugin helper.
* Removing unessisary GetBot call.
* Moving to own file and error handling cleanup.
* Removing patch functionaliy. Plugins should manage their own bot account updates for now.
* Adding tests and cleaning up errors.
* Modify to not shadow err.
* Moving helpers to seperate interface.
* Feedback fixes
