Refactor exchange rate caching #370
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Actionable comments posted: 1
🧹 Outside diff range and nitpick comments (1)
src/currency/fiat.rs (1)
11-17: Consider usingonce_cellinstead oflazy_staticfor lazy initializationWhile
lazy_staticprovides lazy initialization, theonce_cellcrate offers a more modern and flexible approach withOnceCellandLazy. Since yourrust-versionis "1.61.0", you can use the externalonce_cellcrate, which provides similar functionality without macros and can improve readability.To refactor using
once_cell, first add it to your dependencies inCargo.toml:+ once_cell = "1.18.0"Then, update your imports and replace the
lazy_static!block:-use lazy_static::lazy_static; +use once_cell::sync::Lazy; -lazy_static! { - static ref EXCHANGE_RATE_PROVIDER: Mutex<ExchangeRateProvider<blockchain_info_consumer::ApiConsumer>> = - Mutex::new(ExchangeRateProvider { - data_source: blockchain_info_consumer::ApiConsumer, - data: None, - }); -} +static EXCHANGE_RATE_PROVIDER: Lazy<Mutex<ExchangeRateProvider<blockchain_info_consumer::ApiConsumer>>> = Lazy::new(|| { + Mutex::new(ExchangeRateProvider { + data_source: blockchain_info_consumer::ApiConsumer, + data: None, + }) +});This approach eliminates the need for a macro and aligns with modern Rust practices.
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Cargo.toml(1 hunks)src/currency/fiat.rs(3 hunks)
🔇 Additional comments (2)
src/currency/fiat.rs (1)
1-2: Appropriate imports added for thread-safe synchronization
The imports of Mutex and lazy_static are necessary for implementing thread-safe access to shared resources and lazy initialization.
Cargo.toml (1)
30-30:
Verify the version of lazy_static dependency
The specified version 1.5.0 for lazy_static may not exist. As of October 2023, the latest version available on crates.io is 1.4.0. Using a non-existent version will cause dependency resolution errors.
Please verify and update the version accordingly. You can check the latest version with the following command:
Alternatively, consider replacing lazy_static with once_cell as suggested earlier.
src/currency/fiat.rs
Outdated
| EXCHANGE_RATE_PROVIDER | ||
| .lock() | ||
| .expect("Failed to lock EXCHANGE_RATE_PROVIDER") | ||
| .btc_value(self) | ||
|
|
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🛠️ Refactor suggestion
Handle potential mutex poisoning to prevent unexpected panics
Using .expect("Failed to lock EXCHANGE_RATE_PROVIDER") will cause the program to panic if the mutex is poisoned (e.g., if another thread panicked while holding the lock). In a production environment, it's better to handle this case gracefully.
Consider handling the PoisonError by recovering or propagating an appropriate error:
- EXCHANGE_RATE_PROVIDER
- .lock()
- .expect("Failed to lock EXCHANGE_RATE_PROVIDER")
- .btc_value(self)
+ match EXCHANGE_RATE_PROVIDER.lock() {
+ Ok(provider) => provider.btc_value(self),
+ Err(poisoned) => {
+ // Handle the poisoned mutex, possibly by recovering the data
+ // or logging the error and returning a default value
+ eprintln!("Mutex poisoned: {}", poisoned);
+ // Example: Continue using the poisoned mutex
+ poisoned.into_inner().btc_value(self)
+ }
+ }Alternatively, you might consider using RwLock if read operations are more frequent than writes, which can improve concurrency performance.
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| EXCHANGE_RATE_PROVIDER | |
| .lock() | |
| .expect("Failed to lock EXCHANGE_RATE_PROVIDER") | |
| .btc_value(self) | |
| match EXCHANGE_RATE_PROVIDER.lock() { | |
| Ok(provider) => provider.btc_value(self), | |
| Err(poisoned) => { | |
| // Handle the poisoned mutex, possibly by recovering the data | |
| // or logging the error and returning a default value | |
| eprintln!("Mutex poisoned: {}", poisoned); | |
| // Example: Continue using the poisoned mutex | |
| poisoned.into_inner().btc_value(self) | |
| } | |
| } |
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Actionable comments posted: 0
🧹 Outside diff range and nitpick comments (2)
src/currency/fiat.rs (2)
11-17: Add documentation for thread-safety guaranteesWhile the implementation using
lazy_static!andMutexis correct, it would be beneficial to document the thread-safety guarantees and usage patterns.Consider adding documentation like this:
// Static to have an easy way of caching the exchange rates. +// Thread-safe singleton implementation using Mutex to ensure +// safe concurrent access to exchange rates across multiple threads. +// The lazy_static ensures one-time initialization when first accessed. lazy_static! { static ref EXCHANGE_RATE_PROVIDER: Mutex<ExchangeRateProvider<blockchain_info_consumer::ApiConsumer>> =
Line range hint
87-102: Add concurrent access testsThe current test only verifies caching behavior but not thread-safety. Given this refactoring focuses on thread-safe access, consider adding concurrent tests.
Example test to add:
#[test] fn test_concurrent_access() { use std::thread; let handles: Vec<_> = (0..10) .map(|_| { thread::spawn(|| { // Access from multiple threads let btc_value = Fiat::USD.btc_value(); assert!(btc_value > 0.0); }) }) .collect(); // Ensure all threads complete successfully handles.into_iter().for_each(|h| h.join().unwrap()); }
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- Cargo.toml
🔇 Additional comments (2)
src/currency/fiat.rs (2)
2-2: LGTM! Appropriate imports added for thread-safe implementation
The new imports for lazy_static and Mutex are correctly added and follow Rust's import conventions.
Also applies to: 4-4
54-57:
Improve error handling for mutex lock operations
The current implementation using expect() could cause panics in production. This issue was previously raised and remains valid.
As mentioned in the previous review, consider handling potential mutex poisoning:
- EXCHANGE_RATE_PROVIDER
- .lock()
- .expect("Failed to lock EXCHANGE_RATE_PROVIDER")
- .btc_value(self)
+ match EXCHANGE_RATE_PROVIDER.lock() {
+ Ok(provider) => provider.btc_value(self),
+ Err(poisoned) => {
+ // Log the error and recover the inner value
+ log::error!("Exchange rate provider mutex poisoned: {}", poisoned);
+ poisoned.into_inner().btc_value(self)
+ }
+ }Additionally, consider adding error propagation to allow callers to handle failures:
fn btc_value(&self) -> Result<f64, Box<dyn std::error::Error>> {
let provider = EXCHANGE_RATE_PROVIDER.lock()
.map_err(|e| format!("Failed to acquire exchange rate lock: {}", e))?;
Ok(provider.btc_value(self))
}
Summary by CodeRabbit
New Features
Bug Fixes
These updates ensure a more reliable and secure experience when accessing exchange rates.