memvec 0.2.0

Memory-backed vector, not buffer. Designed for for mmap. Not MemMap, but MemVec!
Documentation 
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use memmap2::MmapOptions;
use memvec::{MemVec, MmapAnon};

#[derive(Copy, Clone)]
#[repr(C, packed)]
struct Record {
    id: u32,
    timestamp: u64,
    data: [u8; 16],
}

impl Record {
    fn new(id: u32) -> Self {
        Self {
            id,
            timestamp: std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .unwrap()
                .as_secs(),
            data: [0; 16],
        }
    }
}

fn main() {
    println!("MemVec with Anonymous Memory Mapping Example");

    // Create anonymous memory mapping (no file)
    let mmap = MmapAnon::with_size(0).expect("mmap failed");
    let mut vec =
        unsafe { MemVec::<Record, _>::try_from_memory(mmap) }.expect("memvec creation failed");

    println!(
        "Initial - Length: {}, Capacity: {}",
        vec.len(),
        vec.capacity()
    );

    // Add some records
    for i in 0..5 {
        vec.push(Record::new(i));
        println!(
            "Added record {}: Length: {}, Capacity: {}",
            i,
            vec.len(),
            vec.capacity()
        );
    }

    // Access records
    println!("\nRecords:");
    for (i, record) in vec.iter().enumerate() {
        let id = record.id;
        let timestamp = record.timestamp;
        println!("  [{}] id={}, timestamp={}", i, id, timestamp);
    }

    // Reserve more space
    vec.reserve(20);
    println!(
        "\nAfter reserve(20) - Length: {}, Capacity: {}",
        vec.len(),
        vec.capacity()
    );

    // Add more records
    for i in 5..10 {
        vec.push(Record::new(i));
    }

    println!(
        "Final - Length: {}, Capacity: {}",
        vec.len(),
        vec.capacity()
    );
    println!("Memory is automatically managed without any files!");

    // Example with custom options
    println!("\n--- Example with custom MmapOptions ---");
    let mut options = MmapOptions::new();
    options.len(1000);
    #[cfg(target_os = "linux")]
    options.populate(); // Pre-fault pages on Linux

    let mmap2 = MmapAnon::with_options(options).expect("mmap with options failed");
    let mut vec2 =
        unsafe { MemVec::<Record, _>::try_from_memory(mmap2) }.expect("memvec creation failed");

    for i in 0..3 {
        vec2.push(Record::new(i + 100));
    }
    println!(
        "Custom options vec - Length: {}, Capacity: {}",
        vec2.len(),
        vec2.capacity()
    );
}