Скачать или смотреть How to Share Arc Mutex T in Rust

Discover how to effectively share `Arc Mutex T ` in Rust and resolve common issues with moving data in shared references.
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This video is based on the question https://stackoverflow.com/q/64768601/ asked by the user 'sergeda' ( https://stackoverflow.com/u/2975535/ ) and on the answer https://stackoverflow.com/a/64768785/ provided by the user 'Aplet123' ( https://stackoverflow.com/u/5923139/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Share Arc<Mutex<T>> in Rust: A Guide for Beginners

Sharing data safely and efficiently is a crucial skill when programming in Rust, especially when dealing with multi-threading scenarios. One common situation developers encounter is trying to share an Arc<Mutex<T>> among functions. In this guide, we will explore the problem and provide a step-by-step guide on how to properly share an Arc<Mutex<T>> in your Rust applications.

Understanding the Problem

Imagine you have an instance of Arc<Mutex<T>>, and you want to pass it to another function. The typical approach might lead to errors if you attempt to move the Arc from one place to another directly. For instance, consider the following code snippet that aims to create a connection pool using Arc<Mutex<PostgresDb>>:

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The Error Encountered

When running the above code, you might encounter the error:

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This error occurs because you cannot move out of a shared reference (&Arc<Mutex<PostgresDb>>).

The Solution

The solution involves cloning the Arc instead of trying to move it. Arc is designed to be cloned, allowing multiple owners of the same data. Let’s break it down:

Step 1: Modify the Pool Struct

First, ensure that your Pool struct can accept a cloned Arc<Mutex<PostgresDb>> in its constructor:

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Step 2: Clone the Arc<Mutex<PostgresDb>>

In your main function, instead of passing a reference to postgres, clone it when calling the setup function:

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Step 3: Update the setup Function

Finally, update the setup function to accept an Arc<Mutex<PostgresDb>> directly, rather than a reference:

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Complete Working Example

Combining all the steps, here is a complete example that works without errors:

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Conclusion

Sharing an Arc<Mutex<T>> is straightforward once you understand the cloning mechanism that Rust provides. By adjusting your function parameters and using Arc::clone, you can avoid common pitfalls and ensure your data is shared safely and efficiently across your application.

Happy coding with Rust!