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//! Safe wrapper around `llama_batch`.
use crate::token::LlamaToken;
use llama_cpp_sys_4::{llama_batch, llama_batch_free, llama_batch_init, llama_pos, llama_seq_id};
/// A safe wrapper around `llama_batch`.
#[derive(Debug)]
#[allow(clippy::struct_field_names)]
pub struct LlamaBatch {
/// The number of tokens the batch was allocated with. they are safe to write to - but not necessarily read from as they are not necessarily initialized
allocated: usize,
/// The logits that are initialized. Used by [`LlamaContext`] to ensure that only initialized logits are accessed.
pub(crate) initialized_logits: Vec<i32>,
/// The `llama_cpp` batch. always initialize by `llama_cpp_sys_4::llama_batch_init(allocated, <unknown>, <unknown>)`
pub(crate) llama_batch: llama_batch,
}
/// Errors that can occur when adding a token to a batch.
#[derive(thiserror::Error, Debug, PartialEq, Eq)]
pub enum BatchAddError {
/// There was not enough space in the batch to add the token.
#[error("Insufficient Space of {0}")]
InsufficientSpace(usize),
}
impl LlamaBatch {
/// Clear the batch. This does not free the memory associated with the batch, but it does reset
/// the number of tokens to 0.
pub fn clear(&mut self) {
self.llama_batch.n_tokens = 0;
self.initialized_logits.clear();
}
/// add a token to the batch for sequences `seq_ids` at position `pos`. If `logits` is true, the
/// token will be initialized and can be read from after the next decode.
///
/// # Panics
///
/// - `self.llama_batch.n_tokens` does not fit into a usize
/// - `seq_ids.len()` does not fit into a [`llama_seq_id`]
///
/// # Errors
///
/// returns a error if there is insufficient space in the buffer
pub fn add(
&mut self,
LlamaToken(id): LlamaToken,
pos: llama_pos,
seq_ids: &[i32],
logits: bool,
) -> Result<(), BatchAddError> {
if self.allocated
< usize::try_from(self.n_tokens() + 1).expect("cannot fit n_tokens into a usize")
{
return Err(BatchAddError::InsufficientSpace(self.allocated));
}
let offset = self.llama_batch.n_tokens;
let offset_usize = usize::try_from(offset).expect("cannot fit n_tokens into a usize");
unsafe {
// batch.token [batch.n_tokens] = id;
self.llama_batch.token.add(offset_usize).write(id);
// batch.pos [batch.n_tokens] = pos,
self.llama_batch.pos.add(offset_usize).write(pos);
// batch.n_seq_id[batch.n_tokens] = seq_ids.size();
self.llama_batch.n_seq_id.add(offset_usize).write(
llama_seq_id::try_from(seq_ids.len())
.expect("cannot fit seq_ids.len() into a llama_seq_id"),
);
// for (size_t i = 0; i < seq_ids.size(); ++i) {
// batch.seq_id[batch.n_tokens][i] = seq_ids[i];
// }
for (i, seq_id) in seq_ids.iter().enumerate() {
let tmp = *self.llama_batch.seq_id.add(offset_usize);
tmp.add(i).write(*seq_id);
}
// batch.logits [batch.n_tokens] = logits;
self.llama_batch
.logits
.add(offset_usize)
.write(i8::from(logits));
}
if logits {
self.initialized_logits.push(offset);
} else {
self.initialized_logits.retain(|l| l != &offset);
}
// batch.n_tokens++;
self.llama_batch.n_tokens += 1;
Ok(())
}
/// Add a sequence of tokens to the batch for the given sequence id. If `logits_all` is true, the
/// tokens will be initialized and can be read from after the next decode.
///
/// Either way the last token in the sequence will have its logits set to `true`.
///
/// # Errors
///
/// Returns an error if there is insufficient space in the buffer
///
/// # Panics
///
/// - `self.llama_batch.n_tokens` does not fit into a [`usize`]
/// - [`n_tokens - 1`] does not fit into a [`llama_pos`]
pub fn add_sequence(
&mut self,
tokens: &[LlamaToken],
seq_id: i32,
logits_all: bool,
) -> Result<(), BatchAddError> {
let n_tokens_0 =
usize::try_from(self.llama_batch.n_tokens).expect("cannot fit n_tokens into a usize");
let n_tokens = tokens.len();
if self.allocated < n_tokens_0 + n_tokens {
return Err(BatchAddError::InsufficientSpace(self.allocated));
}
let last_index = llama_pos::try_from(n_tokens.saturating_sub(1))
.expect("cannot fit n_tokens into a llama_pos");
for (i, token) in (0..).zip(tokens.iter()) {
self.add(*token, i, &[seq_id], logits_all || i == last_index)?;
}
Ok(())
}
/// Create a new `LlamaBatch` that can contain up to `n_tokens` tokens.
///
/// # Arguments
///
/// - `n_tokens`: the maximum number of tokens that can be added to the batch
/// - `n_seq_max`: the maximum number of sequences that can be added to the batch (generally 1 unless you know what you are doing)
///
/// # Panics
///
/// Panics if `n_tokens` is greater than `i32::MAX`.
#[must_use]
pub fn new(n_tokens: usize, n_seq_max: i32) -> Self {
let n_tokens_i32 = i32::try_from(n_tokens).expect("cannot fit n_tokens into a i32");
let batch = unsafe { llama_batch_init(n_tokens_i32, 0, n_seq_max) };
LlamaBatch {
allocated: n_tokens,
initialized_logits: vec![],
llama_batch: batch,
}
}
/// Returns the number of tokens in the batch.
#[must_use]
pub fn n_tokens(&self) -> i32 {
self.llama_batch.n_tokens
}
/// Create a batch from a slice of tokens for simple one-shot decoding.
///
/// The returned batch uses the provided token buffer directly and does not own the memory.
/// All tokens are assigned to sequence 0 and logits are enabled for the last token only.
///
/// **Note:** The returned batch does NOT free memory on drop — it borrows from the input
/// slice. The caller must ensure `tokens` outlives the returned batch.
///
/// # Panics
///
/// Panics if `tokens.len()` does not fit into an `i32`.
#[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
#[must_use]
pub fn get_one(tokens: &mut [LlamaToken]) -> llama_batch {
unsafe {
llama_cpp_sys_4::llama_batch_get_one(
tokens.as_mut_ptr().cast(),
tokens.len() as i32,
)
}
}
}
impl Drop for LlamaBatch {
/// Drops the `LlamaBatch`.
///
/// ```
/// # use llama_cpp_4::llama_batch::LlamaBatch;
/// # use std::error::Error;
/// # fn main() -> Result<(), Box<dyn Error>> {
/// let batch = LlamaBatch::new(512, 1);
/// // frees the memory associated with the batch. (allocated by llama.cpp)
/// drop(batch);
/// # Ok(())
/// # }
fn drop(&mut self) {
unsafe {
llama_batch_free(self.llama_batch);
}
}
}