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//! The handle callers hold: submits a job, owns the worker thread, and
//! reports what the worker has done.
use std::sync::atomic::Ordering;
use std::sync::mpsc::{self, Sender};
use std::sync::Arc;
use std::thread::{self, JoinHandle};
use ferrox_models::tokenizer::StopTokens;
use ferrox_models::Decoder;
use crate::budget::ContextCeiling;
use crate::generate::{
paged_hold_positions, paged_window_policy, DecodeError, FinishReason, GenerationParams,
PagedKvConfig, Usage,
};
use crate::policy::anchor::WindowPolicy;
use super::block_budget::BlockBudget;
use super::config::{BatcherConfig, BatcherEvent, DecodeFn};
use super::counters::{BatcherStats, Counters};
use super::queue::{AbortInbox, QueueGate};
use super::row::Job;
use super::worker::worker_loop;
/// Owns a dedicated worker thread that batches decode steps. Cheap to
/// clone (`Sender` only); the worker stays alive as long as any clone
/// (or the original) exists.
#[derive(Clone)]
pub struct ContinuousBatcher {
tx: Sender<Job>,
counters: Arc<Counters>,
queue: Arc<QueueGate>,
budget: Arc<BlockBudget>,
aborts: Arc<AbortInbox>,
/// The window a paged row slides by, when the store is paged and
/// every layer of this model slides by the same window.
///
/// Held here so the block budget prices a request at what it will
/// actually hold. Without it the budget would keep pricing a
/// windowed request at its whole context and refuse admissions the
/// paged store would happily serve -- two components disagreeing
/// about the same server.
paged_window: Option<WindowPolicy>,
}
pub(super) struct WorkerGuard {
pub(super) _join: JoinHandle<()>,
}
impl ContinuousBatcher {
/// Spawns the worker. Holds `decoder` and a detokenize callback for
/// the worker's lifetime. Returns the shareable handle; the worker
/// exits when the last `ContinuousBatcher` clone is dropped.
/// Spawns the worker with the scheduler knobs passed in rather than
/// read from the environment, building the ceiling from
/// `config.max_context` and the decoder's own shape.
///
/// Tests use this: two tests setting `FERROX_CB_*` in one process
/// would race each other. Production goes through
/// [`Self::spawn_with_ceiling`], so the ceiling the batched path
/// enforces is the same *object* the private path enforces rather
/// than a second copy of the same arithmetic.
#[cfg(test)]
pub fn spawn_with_config(
decoder: Arc<Decoder>,
decode: DecodeFn,
config: BatcherConfig,
) -> Self {
Self::spawn_with_config_paged(decoder, decode, config, None)
}
/// `spawn_with_config` with a paged store, for the tests that check
/// batching and paging compose.
#[cfg(test)]
pub fn spawn_with_config_paged(
decoder: Arc<Decoder>,
decode: DecodeFn,
config: BatcherConfig,
paged: Option<PagedKvConfig>,
) -> Self {
let ceiling = Arc::new(ContextCeiling::new(
config.max_context,
// Prefill runs one token at a time here, so a sliding layer
// needs `window + 1 - 1` positions live: chunk = 1.
ferrox_models::KvShape::from_config(&decoder.config, ferrox_models::KvElem::F32),
));
Self::spawn_with_ceiling(decoder, decode, config, ceiling, paged)
}
/// `spawn_with_config` with the per-request context ceiling handed
/// in rather than rebuilt from `config.max_context`.
///
/// This is the production entry point. The point of passing the
/// `Arc` is that `crate::main` builds exactly one `ContextCeiling`
/// for the loaded model and gives it to both the batcher and the
/// private `generate` path: a request refused by one is refused by
/// the other, priced identically, counted once.
pub fn spawn_with_ceiling(
decoder: Arc<Decoder>,
decode: DecodeFn,
config: BatcherConfig,
ceiling: Arc<ContextCeiling>,
paged: Option<PagedKvConfig>,
) -> Self {
let (tx, rx) = mpsc::channel::<Job>();
let counters = Arc::new(Counters::default());
let queue = Arc::new(QueueGate::new(config.max_queue));
let budget = Arc::new(BlockBudget::new(
config.kv_block_size,
config.kv_blocks,
ceiling,
));
let aborts = Arc::new(AbortInbox::default());
let paged_window = paged
.as_ref()
.and_then(|p| paged_window_policy(&decoder, p));
let worker_counters = Arc::clone(&counters);
let worker_queue = Arc::clone(&queue);
let worker_budget = Arc::clone(&budget);
let worker_aborts = Arc::clone(&aborts);
let worker_paged = paged.clone();
let _join = thread::Builder::new()
.name("ferrox-continuous-batch".into())
.spawn(move || {
worker_loop(
decoder,
decode,
rx,
config,
worker_counters,
worker_queue,
worker_budget,
worker_aborts,
worker_paged,
)
})
.expect("spawn continuous-batch worker");
// Detach join handle intentionally: dropping the last Sender
// closes `rx` and ends the loop. Keep a process-lifetime leak
// of the JoinHandle via Box::leak so dropping batcher clones
// does not join (callers may still be mid-generate).
let _guard: &'static WorkerGuard = Box::leak(Box::new(WorkerGuard { _join }));
ContinuousBatcher {
tx,
counters,
queue,
budget,
aborts,
paged_window,
}
}
/// Live scheduler counters. Cheap (a handful of relaxed atomic
/// loads) and safe to call from any thread while the worker runs.
pub fn stats(&self) -> BatcherStats {
BatcherStats {
prefill_chunks: self.counters.prefill_chunks.load(Ordering::Relaxed),
prefill_tokens: self.counters.prefill_tokens.load(Ordering::Relaxed),
decode_steps: self.counters.decode_steps.load(Ordering::Relaxed),
queue_depth: self.queue.depth(),
queue_rejected: self.queue.rejected(),
kv_blocks_total: self.budget.total.unwrap_or(0),
kv_blocks_free: self.budget.free(),
kv_block_size: self.budget.block_size,
kv_rejected_too_large: self.budget.rejected_too_large.load(Ordering::Relaxed),
kv_rejected_context_length: self.budget.ceiling.refused(),
kv_blocks_peak: self.counters.peak_blocks.load(Ordering::Relaxed),
aborted: self.aborts.aborted(),
}
}
/// Submit one generation job and block until it finishes. Safe to
/// call from many `spawn_blocking` tasks concurrently -- they
/// serialize only on the shared decode worker, which is the point.
pub fn generate(
&self,
prompt_tokens: Vec<usize>,
params: GenerationParams,
stop_tokens: StopTokens,
) -> Result<(FinishReason, Vec<usize>, String, Usage), DecodeError> {
self.generate_streaming(prompt_tokens, params, stop_tokens, None::<fn(&str)>)
}
/// Like [`Self::generate`], but invokes `on_chunk` on the worker
/// thread for each detokenized piece as it becomes visible.
pub fn generate_streaming(
&self,
prompt_tokens: Vec<usize>,
params: GenerationParams,
stop_tokens: StopTokens,
mut on_chunk: Option<impl FnMut(&str)>,
) -> Result<(FinishReason, Vec<usize>, String, Usage), DecodeError> {
// A request that could never fit is refused first, and refused
// with the ceiling named: queueing it would only make it wait
// for capacity that will never be enough. This is the
// immovable half of the rejection split -- 400, not 503.
let max_seq_len = prompt_tokens.len().saturating_add(params.max_tokens);
// What this request will HOLD, which is its whole length unless
// a sliding window gives the tail back as it goes. The ceiling
// is still checked against the full length below: a window
// bounds the memory, not what the request asked for, and a
// deployment that caps context at 8k means 8k either way.
let positions = paged_hold_positions(
max_seq_len,
prompt_tokens.len(),
self.budget.block_size,
self.paged_window.as_ref(),
);
let blocks = self.budget.blocks_for(positions);
if let Some(refusal) = self.budget.immovable_refusal(max_seq_len, positions) {
return Err(refusal);
}
// Refuse before allocating a queue slot for the prompt, so a
// retry storm costs a rejection rather than memory.
self.queue
.try_reserve()
.map_err(|queued| DecodeError::QueueFull {
queued,
cap: self.queue.cap,
})?;
let (reply_tx, reply_rx) = mpsc::channel::<BatcherEvent>();
let abort = self.aborts.next_id();
let cancel = params.cancel.clone();
if self
.tx
.send(Job {
prompt_tokens,
params,
stop_tokens,
reply: reply_tx,
abort,
blocks,
})
.is_err()
{
// The worker is gone, so nothing will ever dequeue this
// reservation: release it here or the gate leaks a slot.
self.queue.release();
return Err(DecodeError::KvPoolExhausted);
}
// Registered after the send, so an id only ever reaches the
// inbox for a job the worker will actually see. `on_cancel`
// fires immediately if the token is already cancelled, so the
// window between the send and this line loses nothing.
if let Some(token) = cancel {
let inbox = Arc::clone(&self.aborts);
token.on_cancel(move || inbox.enqueue(abort));
}
loop {
match reply_rx.recv() {
Ok(BatcherEvent::Chunk(chunk)) => {
if let Some(ref mut f) = on_chunk {
f(&chunk);
}
}
Ok(BatcherEvent::Finished(result)) => return *result,
Err(_) => return Err(DecodeError::KvPoolExhausted),
}
}
}
}