Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Improve Initializable readability using intermediate variables #4576

Merged
merged 4 commits into from
Sep 5, 2023
Merged

Improve Initializable readability using intermediate variables #4576

Show file tree
Hide file tree
Changes from 3 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
b7de50c
Improve Initializable readability using intermediate variables
Amxx Sep 5, 2023
9249a0b
Update lazy-rice-joke.md
frangio Sep 5, 2023
329dc22
Update contracts/proxy/utils/Initializable.sol
Amxx Sep 5, 2023
175b1e9
Update contracts/proxy/utils/Initializable.sol
Amxx Sep 5, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions .changeset/lazy-rice-joke.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'openzeppelin-solidity': minor
---

`Initializable`: Use intermediate variables to improve readability.
12 changes: 11 additions & 1 deletion contracts/proxy/utils/Initializable.sol
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -104,9 +104,19 @@ abstract contract Initializable {
// solhint-disable-next-line var-name-mixedcase
InitializableStorage storage $ = _getInitializableStorage();

// Cache values to avoid duplicated sloads
bool isTopLevelCall = !$._initializing;
uint64 initialized = $._initialized;
if (!(isTopLevelCall && initialized < 1) && !(address(this).code.length == 0 && initialized == 1)) {

// Allowed calls:
// - initialSetup: the contract is not in the initializing state and no previous version was
// initialized
// - construction: the contract is initialized at version 1 (no reininitialization) and the
// current contract is just being deployed
bool initialSetup = initialized == 0 && isTopLevelCall;
bool construction = initialized == 1 && address(this).code.length == 0;

if (!firstCall && !construction) {
Amxx marked this conversation as resolved.
Show resolved Hide resolved
revert AlreadyInitialized();
}
$._initialized = 1;
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more. 

$._initialized = 1;
$._initializing = isTopLevelCall;

May be cheaper here, removing redundant SLOAD operation in case of !isTopLevelCall

Copy link
Collaborator Author

@Amxx Amxx Sep 5, 2023 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm not sure I understand your proposal. Before doing _;, we want to make sure the initializing is true, this would possibly invert it to false.

Also I'm not sure where the duplicated sload is.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Also I'm not sure where the duplicated sload is.

Since $ is a struct with two fields packed in one storage slot, compiler need to load this slot if you change only one field. If you write all the fields of the structure at once, the compiler does not need to read this slot before SSTORE

Copy link
Contributor

@0xVolosnikov 0xVolosnikov Sep 5, 2023 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

So it could (in theory) save around 100 gas here

openzeppelin-contracts/contracts/proxy/utils/Initializable.sol

Lines 122 to 125 in 175b1e9

$._initialized = 1;
if (isTopLevelCall) {
$._initializing = true;
}

If do it like

$._initialized = 1;
$._initializing = isTopLevelCall;

Copy link
Contributor

@0xVolosnikov 0xVolosnikov Sep 5, 2023 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

this would possibly invert it to false

Upd: yes, in this case my proposal should be rather:

  $._initialized = 1;
  $._initializing = true;

And here:

$._initialized = 1;
$._initializing = false;

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Writing it that way requires proving that the _; part doesn't change the value of $._initialized.

I think it is true, because $._initializing = true prevents that value from changing in the rest of the contract, but it's more difficult to see.

I think I prefer to keep the current code at this stage (audit fixes) and come back to this for a future release. @vladyan18 can you open an issue?

Expand Down