Re: [pgadmin4][patch] Initial patch to decouple from ACI Tree - Mailing list pgadmin-hackers

Hi Hackers,

Attached you can find the patch that will start to decouple pgAdmin from ACITree library.

This patch is intended to be merged after 3.0, because we do not want to cause any entropy or delay the release, but we want to start the discussion and show some code.

This job that we started is a massive tech debt chore that will take some time to finalize and we would love the help of the community to do it.

Summary of the patch:

0001 patch: 

 - Creates a new tree that will allow us to create a separation between the application and ACI Tree

 - Creates a Fake Tree (Test double, for reference on the available test doubles: https://martinfowler.com/bliki/TestDouble.html) that can be used to inplace to replace the ACITree and also encapsulate the new tree behavior on our tests

 - Adds tests for all the tree functionalities

0002 patch:

 - Extracts, refactors, adds tests and remove dependency from ACI Tree on:

- getTreeNodeHierarchy
- on backup.js: menu_enabled, menu_enabled_server, start_backup_global_server, backup_objects
- on datagrid.js: show_data_grid, get_panel_title, show_query_tool

- Start using sprintf-js as Underscore.String is deprecating sprintf function

  

This patch represents only 10 calls to ACITree.itemData out of 176 that are spread around our code

In Depth look on the process behind the patch:

We started writing this patch with the idea that we need to decouple pgAdmin4 from ACITree, because ACITree is no longer supported, the documentation is non existent and ACITree is no longer being actively developed.

Our process:

1. We "randomly" selected a function that is part of the ACITree. From this point we decided to replace that function with our own version. The function that we choose was "itemData".

The function gives us all the "data" that a specific node of the tree find.

Given in order to replace the tree we would need to have a function that would give us the same information. We had 2 options:

  a) Create a tree with a function called itemData

Pros:

 - At first view this was the simpler solution

 - Would keep the status quo

Cons:

 - Not a OOP approach

 - Not very flexible

  b) Create a tree that would return a node given an ID and then the node would be responsible for giving it's data.

Pros: 

 - OOP Approach

 - More flexible and we do not need to bring the tree around, just a node

Cons:

 - Break the current status quo

Given these 2 options we decided to go for a more OOP approach creating a Tree and a TreeNode classes, that in the future will be renamed to ACITreeWrapper and TreeNode.

2. After we decided on the starting point we searched for occurrences of the function "itemData" and we found out that there were 303 occurrences of "itemData" in the code and roughly 176 calls to the function itself (some of the hits were variable names).

3. We selected the first file on the search and found the function that was responsible for calling the itemData function.

4. Extracted the function to a separate file

5. Wrap this function with tests

6. Refactor the function to ES6, give more declarative names to variables and break the functions into smaller chunks

7. When all the tests were passing we replaced ACITree with our Tree

8. We ensured that all tests were passing

9. Remove function from the original file and use the new function

10. Ensure everything still works

11. Find the next function and execute from step 4 until all the functions are replaced, refactored and tested.

As you can see by the process this is a pretty huge undertake, because of the number of calls to the function. This is just the first step on the direction of completely isolating the ACITree so that we can solve the problem with a large number of elements on the tree.

What is on our radar that we need to address:

 - Finish the complete decoupling of the ACITree

 - Performance of the current tree implementation

 - Tweak the naming of the Tree class to explicitly tell us this is to use only with ACITree.

Thanks

Joao