Struct Bitfield 

pub struct Bitfield { /* private fields */ }

A memory-efficient bitfield using 1 bit per element.

Memory Efficiency

For a torrent with 10,000 pieces:

• Vec<bool>: 10,000 bytes
• Bitfield: 1,250 bytes (8x reduction)

Examples

use aria2_protocol::bittorrent::piece::bitfield::Bitfield;

let mut bf = Bitfield::new(100);
bf.set(5).unwrap();
assert!(bf.test(5));
assert!(!bf.test(6));
assert_eq!(bf.count_set(), 1);

Implementations

impl Bitfield

pub fn new(num_bits: usize) -> Bitfield

Create a new bitfield with all bits unset (false).

Arguments

• num_bits - Number of bits to store

Examples

use aria2_protocol::bittorrent::piece::bitfield::Bitfield;

let bf = Bitfield::new(100);
assert_eq!(bf.len(), 100);
assert!(bf.is_all_clear());

pub fn all_set(num_bits: usize) -> Bitfield

Create a bitfield with all bits set (true).

Examples

use aria2_protocol::bittorrent::piece::bitfield::Bitfield;

let bf = Bitfield::all_set(50);
assert!(bf.is_all_set());
assert_eq!(bf.count_set(), 50);

pub fn from_bytes(data: &[u8], num_bits: usize) -> Bitfield

Create a bitfield from raw bytes (e.g., from a peer’s bitfield message).

Arguments

• data - Raw byte data
• num_bits - Number of valid bits

Examples

use aria2_protocol::bittorrent::piece::bitfield::Bitfield;

// Bitfield with bits 0 and 7 set: 0b10000001 = 0x81
let bf = Bitfield::from_bytes(&[0x81], 8);
assert!(bf.test(0));
assert!(bf.test(7));

pub fn as_bytes(&self) -> &[u8]

Get the raw byte representation.

This is useful for sending bitfield messages to peers.

pub fn len(&self) -> usize

Get the total number of bits.

pub fn is_empty(&self) -> bool

Check if the bitfield is empty.

pub fn set(&mut self, index: usize) -> Option<()>

Set a bit to true.

Errors

Returns None if index is out of bounds.

Examples

use aria2_protocol::bittorrent::piece::bitfield::Bitfield;

let mut bf = Bitfield::new(10);
assert!(bf.set(5).is_some());
assert!(bf.set(100).is_none()); // Out of bounds

pub fn clear(&mut self, index: usize) -> Option<()>

Clear a bit (set to false).

Errors

Returns None if index is out of bounds.

pub fn test(&self, index: usize) -> bool

Test if a bit is set.

Returns false for out-of-bounds indices.

Examples

use aria2_protocol::bittorrent::piece::bitfield::Bitfield;

let mut bf = Bitfield::new(10);
bf.set(3).unwrap();
assert!(bf.test(3));
assert!(!bf.test(4));
assert!(!bf.test(100)); // Out of bounds returns false

pub fn count_set(&self) -> usize

Count the number of set bits.

Performance

Uses count_ones() intrinsic for fast bit counting.

pub fn count_clear(&self) -> usize

Count the number of clear bits.

pub fn is_all_set(&self) -> bool

Check if all bits are set.

pub fn is_all_clear(&self) -> bool

Check if all bits are clear.

pub fn find_first_set(&self) -> Option<usize>

Find the first set bit.

Returns None if no bits are set.

pub fn find_first_clear(&self) -> Option<usize>

Find the first clear bit.

Returns None if all bits are set.

pub fn find_next_set(&self, after: usize) -> Option<usize>

Find the next set bit after the given index.

Returns None if no more set bits exist.

pub fn iter_set(&self) -> SetBitIter<'_>

Get an iterator over all set bit indices.

pub fn iter_clear(&self) -> ClearBitIter<'_>

Get an iterator over all clear bit indices.

pub fn memory_usage(&self) -> usize

Calculate memory usage in bytes.

This is the actual storage size, not including struct overhead.

pub fn vec_bool_memory_usage(&self) -> usize

Calculate memory usage if using Vec<bool> for the same number of bits.

This is useful for comparing memory savings.

pub fn memory_savings_ratio(&self) -> f64

Calculate memory savings ratio compared to Vec<bool>.

Returns the ratio of Vec<bool> memory to Bitfield memory. A value of 8.0 means Bitfield uses 8x less memory.

pub fn set_all(&mut self)

Set all bits to true.

pub fn clear_all(&mut self)

Clear all bits.

pub fn bitand_assign(&mut self, other: &Bitfield)

Perform a bitwise AND with another bitfield.

Both bitfields must have the same length.

pub fn bitor_assign(&mut self, other: &Bitfield)

Perform a bitwise OR with another bitfield.

Both bitfields must have the same length.

pub fn bitxor_assign(&mut self, other: &Bitfield)

Perform a bitwise XOR with another bitfield.

Both bitfields must have the same length.

Trait Implementations

impl Clone for Bitfield

fn clone(&self) -> Bitfield

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Bitfield

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Eq for Bitfield

impl PartialEq for Bitfield

fn eq(&self, other: &Bitfield) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Bitfield