feat: add guard in execute tx

[hsxyl]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces a guard mechanism to prevent concurrent transaction execution by tracking executing pools.

• Adds an ExecuteTxGuard struct in utils.rs with a Drop implementation for cleanup.
• Extends state.rs with an executing_pools field to maintain a set of active pools.
• Uses the guard in canister.rs to enforce transactional exclusivity.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
ree-cookie-canister/src/utils.rs	Introduces ExecuteTxGuard with a new guard and Drop pattern.
ree-cookie-canister/src/state.rs	Adds an executing_pools field to track active executor pools.
ree-cookie-canister/src/canister.rs	Applies ExecuteTxGuard in execute_tx() to prevent duplicate execution.

Comments suppressed due to low confidence (1)

ree-cookie-canister/src/canister.rs:295

• [nitpick] The error message 'Pool {0} Executing' could be made more descriptive (e.g., 'Transaction already executing for pool {0}') to improve clarity for API consumers.

    .ok_or(format!("Pool {0} Executing", pool_address).to_string())?;

[Copilot]

[nitpick] The explicit type annotation in 'return None::' may be redundant; consider simplifying the return statement to 'None' for clarity.

Suggested change

	return None::<ExecuteTxGuard>;
	return None;