Concurrent Data Access with Memory Ordering in Rust

Understanding memory ordering is crucial for writing correct and efficient concurrent Rust programs. This challenge asks you to implement a simple producer-consumer scenario demonstrating the use of Rust's memory ordering primitives to ensure data consistency across threads. Successfully completing this challenge will solidify your understanding of how to control visibility and synchronization in a multi-threaded environment.

Problem Description

You are tasked with implementing a producer-consumer pattern using Rust's Arc (Atomic Reference Counted) and Mutex to share a buffer between two threads: a producer and a consumer. The producer will generate data and add it to the buffer, while the consumer will read data from the buffer. The key requirement is to use appropriate memory ordering primitives (Ordering) to ensure that the consumer always sees the latest data written by the producer, even when multiple producer and consumer threads are involved.

Specifically, you need to:

1. Create a shared buffer (a Vec<i32>) protected by an Arc<Mutex<Vec<i32>>>.
2. Implement a producer thread that adds data to the buffer. The producer should generate a sequence of numbers (e.g., 1, 2, 3, ...).
3. Implement a consumer thread that reads data from the buffer. The consumer should continuously attempt to read data from the buffer until the producer signals that it's finished.
4. Use AtomicBool to signal the consumer when the producer has finished producing data.
5. Crucially, use appropriate Ordering hints when accessing the shared buffer and the AtomicBool to ensure correct memory synchronization. You should use Release for writes and Acquire for reads. The AtomicBool should use SeqCst for both reads and writes to ensure all threads see the same state.

The expected behavior is that the consumer will read the data produced by the producer in the correct order, and the program will terminate gracefully when the producer finishes. The consumer should not read uninitialized or incomplete data.

Examples

Example 1:

Input: Producer produces 5 numbers (1, 2, 3, 4, 5). Consumer reads continuously.
Output: Consumer prints: 1, 2, 3, 4, 5
Explanation: The consumer reads the numbers in the order they were produced.

Example 2:

Input: Producer produces 10 numbers. Consumer reads 3 numbers, then the producer finishes.
Output: Consumer prints: 1, 2, 3
Explanation: The consumer reads the first three numbers before the producer signals completion.

Example 3: (Edge Case - Multiple Producers)

Input: Two producers concurrently produce numbers. Producer 1 produces [1, 3, 5] and Producer 2 produces [2, 4, 6].
Output: Consumer prints a sequence containing 1, 2, 3, 4, 5, 6 (order may vary slightly but all numbers must be present).
Explanation:  The memory ordering ensures that the consumer sees all produced data, even with concurrent producers.

Constraints

• The buffer size should be dynamically allocated based on the number of items to produce (e.g., 10).
• The producer should produce at least 10 items.
• The consumer should read all items produced by the producer.
• The program should terminate gracefully when the producer finishes.
• The solution must compile and run without panics.
• The solution should demonstrate correct use of Ordering hints. Incorrect or missing ordering hints will be considered incorrect.

Notes

• Consider using std::sync::Arc for shared ownership and std::sync::Mutex for mutual exclusion.
• std::sync::atomic::AtomicBool is useful for signaling completion.
• Think carefully about which Ordering hints are appropriate for each operation (read, write, acquire, release, seq_cst). Incorrect ordering can lead to data races and unexpected behavior.
• The order in which the consumer reads the numbers from multiple producers might not be strictly sequential, but all produced numbers must be present in the consumer's output.
• Focus on demonstrating the correct use of memory ordering primitives; performance optimization is not the primary goal.
• Use println! for output to easily verify the results.