Shared Ownership with Rust Arc: Exploring Atomic Reference Counting

Introduction

In this lab, we explore the usage of Arc (Atomically Reference Counted) in Rust, which is employed when shared ownership between threads is required.

Note: If the lab does not specify a file name, you can use any file name you want. For example, you can use main.rs, compile and run it with rustc main.rs && ./main.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL rust(("`Rust`")) -.-> rust/BasicConceptsGroup(["`Basic Concepts`"]) rust(("`Rust`")) -.-> rust/DataTypesGroup(["`Data Types`"]) rust(("`Rust`")) -.-> rust/ControlStructuresGroup(["`Control Structures`"]) rust(("`Rust`")) -.-> rust/FunctionsandClosuresGroup(["`Functions and Closures`"]) rust(("`Rust`")) -.-> rust/MemorySafetyandManagementGroup(["`Memory Safety and Management`"]) rust(("`Rust`")) -.-> rust/DataStructuresandEnumsGroup(["`Data Structures and Enums`"]) rust/BasicConceptsGroup -.-> rust/variable_declarations("`Variable Declarations`") rust/DataTypesGroup -.-> rust/type_casting("`Type Conversion and Casting`") rust/ControlStructuresGroup -.-> rust/for_loop("`for Loop`") rust/FunctionsandClosuresGroup -.-> rust/function_syntax("`Function Syntax`") rust/FunctionsandClosuresGroup -.-> rust/expressions_statements("`Expressions and Statements`") rust/MemorySafetyandManagementGroup -.-> rust/lifetime_specifiers("`Lifetime Specifiers`") rust/DataStructuresandEnumsGroup -.-> rust/method_syntax("`Method Syntax`") subgraph Lab Skills rust/variable_declarations -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} rust/type_casting -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} rust/for_loop -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} rust/function_syntax -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} rust/expressions_statements -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} rust/lifetime_specifiers -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} rust/method_syntax -.-> lab-99264{{"`Shared Ownership with Rust Arc`"}} end

Arc

When shared ownership between threads is needed, Arc(Atomically Reference Counted) can be used. This struct, via the Clone implementation can create a reference pointer for the location of a value in the memory heap while increasing the reference counter. As it shares ownership between threads, when the last reference pointer to a value is out of scope, the variable is dropped.

use std::time::Duration;
use std::sync::Arc;
use std::thread;

fn main() {
    // This variable declaration is where its value is specified.
    let apple = Arc::new("the same apple");

    for _ in 0..10 {
        // Here there is no value specification as it is a pointer to a
        // reference in the memory heap.
        let apple = Arc::clone(&apple);

        thread::spawn(move || {
            // As Arc was used, threads can be spawned using the value allocated
            // in the Arc variable pointer's location.
            println!("{:?}", apple);
        });
    }

    // Make sure all Arc instances are printed from spawned threads.
    thread::sleep(Duration::from_secs(1));
}

Summary

Congratulations! You have completed the Arc lab. You can practice more labs in LabEx to improve your skills.

Shared Ownership with Rust Arc

Introduction

Skills Graph

Arc

Summary

Other Rust Tutorials you may like