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

On Mon, Apr 30, 2018 at 4:33 PM, Ashesh Vashi <ashesh.vashi@enterprisedb.com> wrote:

On Mon, Apr 30, 2018 at 8:58 PM, Anthony Emengo <aemengo@pivotal.io> wrote:

I was expecting a separate layer between the tree implementation, and aciTree adaptor.
Please find the patch for the example.
It will separate the two layers, and easy to replace with the new implementation in future. 

In general, we want defer the separation of the layers for now. Even though we might assume that this is the direction we want to go in. It's simply too early to be making such an architectural leap. For right now, we just know that we need the decoupling, but don't know what if we'd need the 2 layers as implemented. The principle we're adhering to here is the Last Responsible Moment principle, which states that you only make the changes that you feel is necessary for the given problems you're facing: https://blog.codinghorror.com/the-last-responsible-moment/

I would not like to see that changes in this patch.
I would like us to come up with the actual design about the hot pluggability before going in this direction.

In our point of view these 2 changes are not related. One thing is the internal code organization of the application, other thing is allowing third party to drop code in the application and it just work. These 2 should be talked separately, but the hot pluggability is not something that will be address by this work we are doing right now.

Neither - it should be part of this change.

It should be addressed separately, and discussed.

I agree. As long as this work doesn't make the pluggability problem worse, that problem should be considered separately.

So given Anthony's comments, are you happy with this patch?

 

-- Thanks, Ashesh 

Anthony && Joao

On Mon, Apr 30, 2018 at 11:03 AM, Ashesh Vashi <ashesh.vashi@enterprisedb.com> wrote:

On Mon, Apr 30, 2018 at 8:30 PM, Ashesh Vashi <ashesh.vashi@enterprisedb.com> wrote:

On Sat, Apr 28, 2018 at 3:55 AM, Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

Hi Hackers,
As you are aware we kept on working on the patch, so we are attaching to this email a new version of the patch.
This new version contains all the changes in the previous one plus more extractions of functions and refactoring of code.

The objective of this patch is to create a separation between pgAdmin and the ACI Tree. We are doing this because we realized that at this point in time we have the ACI Tree all over the code of pgAdmin. I found a very interesting article that really talks about this: https://medium.freecodecamp.org/code-dependencies-are-the-devil-35ed28b556d

In this patch there are some visions and ideas about the location of the code, the way to organize it and also try to pave the future for a application that is stable, easy to develop on and that can be release at a times notice.

We are investing a big chunk of our time in doing this refactoring, but while doing that we also try to respond to the patches sent to the mailing list. We would like the feedback from the community because we believe this is a changing point for the application. The idea is to change the way we develop this application, instead of only correcting a bug of developing a feature, with every commit we should correct the bug or develop a feature but leave the code a little better than we found it (Refactoring, refactoring, refactoring). This is hard work but that is what the users from pgAdmin expect from this community of developers.

======

It is a huge patch

                          86 files changed, 5492 inserts, 1840 deletions

and we would like to get your feedback as soon as possible, because we are continuing to work on it which means it is going to grow in size. 

At this point in time we still have 124 of 176 calls to the function itemData from ACITree.

What does each patch contain:

0001:

  Very simple patch, we found out that the linter was not looking into all the javascript test files, so this patch will ensure it is

Committed the patch along with the regression introduced because of this patch. 

0002:
  New Tree abstraction. This patch contains the new Tree that works as an adaptor for ACI Tree and is going to be used on all the extractions that we are doing.

I was expecting a separate layer between the tree implementation, and aciTree adaptor.

Please find the patch for the example.

It will separate the two layers, and easy to replace with the new implemenation in future. 

Oops forgot to attach the patch.

Please find the patch attached.

-- Thanks, Ashesh 

0003:

  Code that extracts, wrap with tests and replace ACI Tree invocations.

There are many small cases left in the patches.

Hence - I would like to know the TODO list created by you.

e.g. When we remove any of the object from the database server, we're not yet removing the respective node from the new implementation, and its children. 

 

  We start creating new pattern for the location of Javascript files and their structure.

I would not like to see that changes in this patch.

I would like us to come up with the actual design about the hot pluggability before going in this direction. 

  Create patterns for creation of dialogs (backup and restore)

It's better - we don't change the directory structure at the moment.

I am not against dividing the big javascript files in small chunks, but - I would like us to discuss first about the hot plugins design first.

-- Thanks, Ashesh 

 

  

Thanks

Joao

On Fri, Apr 27, 2018 at 5:34 AM Ashesh Vashi <ashesh.vashi@enterprisedb.com> wrote:

I have quite a few comments for the patch.

I will send them soon. 

On Fri, Apr 27, 2018, 14:45 Dave Page <dpage@pgadmin.org> wrote:

How is your work on this going Ashesh? Will you be committing today?

On Wed, Apr 25, 2018 at 8:52 AM, Dave Page <dpage@pgadmin.org> wrote:

Ashesh; you had agreed to work on this early this week. Please ensure you do so today.

Thanks.

On Tue, Apr 24, 2018 at 8:13 PM, Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

Hi Hackers,

Can someone review and merge this patch?

Thanks

Joao

On Wed, Apr 18, 2018 at 10:23 AM Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

Hi Hackers,

Any other comment about this patch?

Thanks

Joao

On Tue, Apr 10, 2018 at 12:00 PM Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

Hello Khushboo

On Mon, Apr 9, 2018 at 1:59 AM Khushboo Vashi <khushboo.vashi@enterprisedb.com> wrote:

Hi Joao,

I have reviewed your patch and have some suggestions.

On Sat, Apr 7, 2018 at 12:43 AM, Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

Hello Murtuza/Dave,
Yes now the extracted functions are spread into different files. The intent would be to make the files as small as possible, and also to group and name them in a way that would be easy to understand what each file is doing without the need of opening it.
As a example:
static/js/backup will contain all the backup related functionality inside of this folder we can see the file:

menu_utils.js At this moment in time we decided to group all the functions that are related to the menu, but we can split that also if we believe it is easier to see.

It's really very good to see the separated code for backup module. As we have done for backup, we would like do it for other PG utilities like restore, maintenance etc.

Considering this, we should separate the code in a way that some of the common functionalities can be used for other modules  like menu (as you have mentioned above), dialogue factory etc.

Also, I think these functionalities should be in their respective static folder instead of pgadmin/static.

About the location of the files. The move of the files to pgadmin/static/js was made on purpose in order to clearly separate Javascript from python code.

The rational behind it was

- Create a clear separation between the backend and frontend

- Having Javascript code concentrated in a single place, hopefully, will encourage to developers to look for a functionality, that is already implemented in another modules, because they are right there. (When we started this journey we realized that the 'nodes' have a big groups of code that could be shared, but because the Javascript is spread everywhere it is much harder to look for it)

There are some drawbacks of this separation:

- When creating a new module we will need to put the javascript in a separate location from the backend code  

 

 

static/js/datagrid folder contains all the datagrid related functionality

Same as backup module,  this should be in it's respective static/js folder.

Inside of the folder we can see the files:
get_panel_title.js is responsible for retrieving the name of the panel
show_data.js is responsible for showing the datagrid
show_query_tool.js is responsible for showing the query tool

Does this structure make sense?
Can you give an example of a comment that you think is missing and that could help?

As a personal note, unless the algorithm is very obscure or very complicated, I believe that if the code needs comments it is a signal that something needs to change in terms of naming, structure of the part in question. This being said, I am open to add some comments that might help people.

You are right, with the help of naming convention and structure of the code, any one can get the idea about the code. But it is very useful to understand the code 

very easily with the proper comments especially when there are multiple developers working on a single project.

I found some of the places where it would be great to have comments.

- treeMenu: new tree.Tree()  in a browser.js

- tree.js  (especially Tree class)

About the comment point I need a more clear understanding on what kind of comments you are looking for. Because when you read the function names you understand the intent, what they are doing. The parameters also explain what you need to pass into them.

If what you are looking for in these comments is the reasoning being the change itself, then that should be present in the commit message. Specially because this is going to be a very big patch with a very big number of changes.

Thanks
Joao

​

Thanks,

Khushboo 

On Fri, Apr 6, 2018 at 4:48 AM Murtuza Zabuawala <murtuza.zabuawala@enterprisedb.com> wrote:

Hi Joao,

Patch looks good and working as expected.

I also agree with Dave, Can we please add some comments in each file which can help us to understand the flow, I'm saying because now the code is segregated in so many separate files it will be hard to keep track of the flow from one file to another when debugging.

--

Regards,

Murtuza Zabuawala
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

On Thu, Apr 5, 2018 at 7:08 PM, Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

Hi Khushboo,

Attached you can find both patches rebased

Thanks

On Thu, Apr 5, 2018 at 6:31 AM Khushboo Vashi <khushboo.vashi@enterprisedb.com> wrote:

Hi Joao,

Can you please rebase the second patch?

Thanks,

Khushboo

On Tue, Apr 3, 2018 at 12:15 AM, Joao De Almeida Pereira <jdealmeidapereira@pivotal.io> wrote:

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

--

Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

--

Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

--

Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company