105 lines
2.9 KiB
Rust
105 lines
2.9 KiB
Rust
pub fn calculate_xor_parity(data_stripes: &[Vec<u8>]) -> Vec<u8> {
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if data_stripes.is_empty() {
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return Vec::new();
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}
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let stripe_size = data_stripes[0].len();
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let mut parity = vec![0u8; stripe_size];
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for stripe in data_stripes {
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if stripe.len() != stripe_size {
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panic!("All stripes must have same size for parity calculation");
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}
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for i in 0..stripe_size {
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parity[i] ^= stripe[i];
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}
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}
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parity
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}
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pub fn reconstruct_missing_data(
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available_data: &[Vec<u8>],
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parity: &[u8],
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_missing_index: usize,
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) -> Vec<u8> {
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if available_data.is_empty() || parity.is_empty() {
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return Vec::new();
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}
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let stripe_size = available_data[0].len();
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let mut reconstructed = parity.to_vec();
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for data in available_data.iter() {
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if data.len() != stripe_size {
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panic!("All data must have same size for reconstruction");
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}
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for i in 0..stripe_size {
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reconstructed[i] ^= data[i];
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}
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}
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reconstructed
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}
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pub fn calculate_new_parity(
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old_parity: &[u8],
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old_data: &[u8],
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new_data: &[u8],
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) -> Vec<u8> {
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if old_parity.len() != old_data.len() || old_data.len() != new_data.len() {
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panic!("Parity and data must have same size");
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}
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let stripe_size = old_parity.len();
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let mut new_parity = vec![0u8; stripe_size];
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for i in 0..stripe_size {
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new_parity[i] = old_parity[i] ^ old_data[i] ^ new_data[i];
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}
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new_parity
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_xor_parity_basic() {
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let d1 = vec![1u8, 2, 3, 4];
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let d2 = vec![5u8, 6, 7, 8];
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let d3 = vec![9u8, 10, 11, 12];
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let parity = calculate_xor_parity(&[d1.clone(), d2.clone(), d3.clone()]);
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assert_eq!(parity, vec![1^5^9, 2^6^10, 3^7^11, 4^8^12]);
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}
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#[test]
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fn test_reconstruct_single_disk_failure() {
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let d1 = vec![1u8, 2, 3, 4];
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let d2 = vec![5u8, 6, 7, 8];
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let d3 = vec![9u8, 10, 11, 12];
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let parity = calculate_xor_parity(&[d1.clone(), d2.clone(), d3.clone()]);
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let reconstructed_d2 = reconstruct_missing_data(&[d1.clone(), d3.clone()], &parity, 1);
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assert_eq!(reconstructed_d2, d2);
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}
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#[test]
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fn test_update_parity() {
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let old_data = vec![1u8, 2, 3, 4];
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let new_data = vec![10u8, 20, 30, 40];
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let d2 = vec![5u8, 6, 7, 8];
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let d3 = vec![9u8, 10, 11, 12];
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let old_parity = calculate_xor_parity(&[old_data.clone(), d2.clone(), d3.clone()]);
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let new_parity = calculate_new_parity(&old_parity, &old_data, &new_data);
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let expected_parity = calculate_xor_parity(&[new_data.clone(), d2.clone(), d3.clone()]);
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assert_eq!(new_parity, expected_parity);
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}
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} |