chore: improve relayer client with retries and metrics

[carneiro-cw]

No description provided.

[github-actions]

PR Reviewer Guide 🔍

⏱️ Estimated effort to review [1-5]	3
🧪 Relevant tests	No
🔒 Security concerns	No
⚡ Key issues to review	Retry Logic: The retry logic in send_to_relayer does not include a delay between retries, which might be necessary to handle transient issues effectively.
	Logging and Monitoring: While logging and metrics have been added, it's important to ensure that metrics are correctly capturing failures and retries. Consider adding metrics for retry attempts.
	Blocking Task: The send_to_relayer function is performing database operations which are I/O bound and should ideally be executed in a separate thread to avoid blocking the async executor.

[github-actions]

PR Code Suggestions ✨

Category	Suggestion	Score
Possible bug	Add specific error handling for JSON serialization to improve robustness To ensure that the block_json variable is correctly formatted and does not cause serialization issues, consider adding error handling specifically for the JSON serialization process. src/eth/relayer/external.rs [324] -let block_json = serde_json::to_value(block)?; +let block_json = serde_json::to_value(block).map_err(|e| anyhow!("Failed to serialize block: {}", e))?; Suggestion importance[1-10]: 10 Why: Adding specific error handling for JSON serialization improves robustness by ensuring that serialization issues are caught and handled appropriately, preventing potential runtime errors.	10
Performance	Use exponential backoff for retry delays to improve handling of transient failures Implement exponential backoff for retry delays to handle failures more efficiently. This approach increases the delay between retries progressively, which can be more effective in handling temporary failures that need more time to recover. src/eth/relayer/external.rs [329-338] +let mut delay = 1; while remaining_tries > 0 { if let Err(err) = sqlx::query!("INSERT INTO relayer_blocks (number, payload) VALUES ($1, $2)", block_number as _, &block_json) .execute(&self.pool) .await { remaining_tries -= 1; tracing::warn!(?err, ?remaining_tries, "failed to insert into relayer_blocks"); + tokio::time::sleep(tokio::time::Duration::from_secs(delay)).await; + delay *= 2; } else { break; } } Suggestion importance[1-10]: 9 Why: Exponential backoff is a well-known strategy for handling transient failures more efficiently. It progressively increases the delay between retries, which can be more effective in scenarios where temporary failures need more time to resolve.	9
Enhancement	Add a delay between retries to handle transient failures more effectively Consider adding a delay between retries when attempting to insert into relayer_blocks. This can help in scenarios where the failure is due to transient issues that may resolve in a short time. Using a delay can increase the likelihood of a successful retry. src/eth/relayer/external.rs [329-338] while remaining_tries > 0 { if let Err(err) = sqlx::query!("INSERT INTO relayer_blocks (number, payload) VALUES ($1, $2)", block_number as _, &block_json) .execute(&self.pool) .await { remaining_tries -= 1; tracing::warn!(?err, ?remaining_tries, "failed to insert into relayer_blocks"); + tokio::time::sleep(tokio::time::Duration::from_secs(1)).await; } else { break; } } Suggestion importance[1-10]: 8 Why: Adding a delay between retries can help handle transient issues more effectively, increasing the likelihood of a successful retry. This is a practical enhancement for robustness.	8
Best practice	Add a log statement for successful database insertions for better traceability It's a good practice to log the successful insertion into the database for better traceability and debugging. Consider adding a success log statement when the insertion is successful. src/eth/relayer/external.rs [330-338] if let Err(err) = sqlx::query!("INSERT INTO relayer_blocks (number, payload) VALUES ($1, $2)", block_number as _, &block_json) .execute(&self.pool) .await { remaining_tries -= 1; tracing::warn!(?err, ?remaining_tries, "failed to insert into relayer_blocks"); } else { + tracing::info!("Successfully inserted block number {} into relayer_blocks", block_number); break; } Suggestion importance[1-10]: 7 Why: Adding a log statement for successful insertions improves traceability and debugging, which is beneficial for monitoring and maintaining the system.	7