DSSD-dev / dssd /api.py
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DSSD demo from DSSD_demo 4a3ca5b (dssd 73b3f27)
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"""User API: load a published head set with its base model, generate with provenance.
from dssd import DSSD
m = DSSD.from_pretrained("<namespace>/DSSD-Qwen3-8B-Base")
g = m.generate("def fib(n):", max_new_tokens=256, domain="code", compare_ar=True)
g.text, g.sources, g.speedup, g.identical
Greedy decoding only; the output is identical to greedy autoregressive decoding of the same
engine (exact verification, row-invariant computation).
"""
from __future__ import annotations
import queue
import threading
import time
from collections import Counter
from dataclasses import dataclass, field
from typing import Iterator
import numpy as np
import torch
from .decode import ThresholdPolicy
from .fast import FastDecoder
from .hub import load_heads, read_config
from .layered import LayeredDecoder, use_row_invariant_blas
from .stops import make_stop
ALIASES = {"math": "gsm8k", "humaneval": "code"}
@dataclass
class Generation:
text: str
token_ids: list[int]
sources: list[str]
stats: dict
decode_tokens_per_s: float # (new_tokens - 1) / (seconds - prefill_seconds)
ar: "Generation | None" = None
speedup: float | None = None # decode_tokens_per_s / ar.decode_tokens_per_s
identical: bool | None = None # token_ids == ar.token_ids
@dataclass
class StreamEvent:
token_ids: list[int] # tokens appended by this event
sources: list[str]
text: str # text of the phase so far
done: bool
phase: str = "dssd" # "dssd" or "ar"
result: Generation | None = None # on the final event
t: float = 0.0 # seconds since the phase's first token (end of prefill), taken
# when the engine committed these tokens
class _GammaOnly:
"""Inner controller of a gamma-only cost safety: never asks for AR, no lambda."""
lam, probe, K = 0.0, False, 4
def policy(self):
return np.zeros(self.K), 0.0, False
def update(self, c):
pass
class _Cancelled(Exception):
pass
class DSSD:
MAX_ROWS = 16 # fixed engine width (row-invariant GEMMs)
def __init__(self, model, tokenizer, heads, layers, config: dict, graphs: bool | str = "auto",
max_len: int = 4096, prefill: str = "engine"):
"""No engine work here (ZeroGPU: CUDA is only emulated at module level): the engine is
built and its graphs captured on first use, or by warmup()."""
self.model, self.tokenizer, self.config = model.eval().requires_grad_(False), tokenizer, config
self.heads = [h.eval().requires_grad_(False) for h in heads]
self.layers, self.graphs, self.max_len, self.prefill = list(layers), graphs, max_len, prefill
self.domains = list(config["domains"])
eos = getattr(tokenizer, "eos_token_id", None)
self.eos_ids = frozenset() if eos is None else frozenset([eos])
self._lock = threading.Lock() # one generation at a time on the engine buffers
self._ar_step = None # seconds per AR step (cost safety), measured once
self._fast, self._ready = None, False
@property
def fast(self) -> FastDecoder:
if self._fast is None:
dev = next(self.model.parameters()).device
use_graphs = (dev.type == "cuda") if self.graphs == "auto" else bool(self.graphs)
self._fast = FastDecoder(LayeredDecoder(self.model, max_len=self.max_len), self.heads, self.layers,
max_rows=self.MAX_ROWS, use_graphs=use_graphs, prefill=self.prefill)
return self._fast
def _warmup(self) -> None:
if not self._ready:
with torch.no_grad():
self.fast.precapture([self._policy(d) for d in self.domains]
+ [ThresholdPolicy(self.heads, {k: 1.0 for k in range(len(self.heads))},
max_draft=15)])
self._ready = True
def warmup(self) -> None:
"""Build the engine and capture its graphs now (otherwise done by the first generation)."""
with self._lock:
self._warmup()
# ------------------------------------------------------------------ loading
@classmethod
def from_components(cls, model, tokenizer, heads, layers, config: dict, graphs: bool | str = "auto",
max_len: int = 4096, prefill: str = "engine") -> "DSSD":
use_row_invariant_blas() # rocBLAS on ROCm (row-invariant GEMMs); no-op elsewhere
return cls(model, tokenizer, heads, layers, config, graphs, max_len, prefill)
@classmethod
def from_pretrained(cls, repo_or_dir: str, device: str | None = None, dtype=torch.bfloat16,
graphs: bool | str = "auto", max_len: int = 4096, base_model: str | None = None,
revision: str | None = None, token: str | None = None,
prefill: str = "engine") -> "DSSD":
"""Heads from a Hub repo or directory; base model and tokenizer from the config's
base_model at its pinned revision (or `base_model`, unpinned)."""
from transformers import AutoModelForCausalLM, AutoTokenizer
device = device or ("cuda" if torch.cuda.is_available() else "cpu")
if device == "cpu":
dtype = torch.float32
conf = read_config(repo_or_dir, revision, token)
base = base_model or conf["base_model"]
base_rev = None if base_model else conf.get("base_revision")
tok = AutoTokenizer.from_pretrained(base, revision=base_rev, token=token)
model = AutoModelForCausalLM.from_pretrained(base, revision=base_rev, dtype=dtype, token=token)
model = model.to(device).eval()
heads, layers, conf = load_heads(repo_or_dir, model.config, device, dtype, revision, token)
return cls.from_components(model, tok, heads, layers, conf, graphs, max_len, prefill)
# ------------------------------------------------------------------ helpers
def _domain(self, domain: str | None) -> str:
d = ALIASES.get(domain, domain) if domain is not None else self.config.get("default_domain", self.domains[0])
if d not in self.config["domains"]:
raise ValueError(f"unknown domain {domain!r}; available: {self.domains}")
return d
def _policy(self, domain: str) -> ThresholdPolicy:
spec = self.config["domains"][domain]["policy"]
if spec.get("type") != "threshold":
raise ValueError(f"unsupported policy type {spec.get('type')!r}")
g = spec.get("cum_gamma", 0.0)
pol = ThresholdPolicy(self.heads, {int(k): float(v) for k, v in spec["thresholds"].items()},
max_draft=spec.get("max_draft", 15),
cum_gamma={int(k): float(v) for k, v in g.items()} if isinstance(g, dict) else float(g),
acc_maps=spec.get("acc_maps"))
pol.tree = spec.get("tree")
pol.star = spec.get("star")
return pol
def _ids(self, prompt) -> list[int]:
if not isinstance(prompt, str):
return list(prompt)
# as for head training and the benchmark prompts: no BOS / special tokens
return list(self.tokenizer.encode(prompt, add_special_tokens=False))
def _stop(self, domain: str, stop):
kind = self.config["domains"][domain].get("stop") if stop == "auto" else stop
return make_stop(self.tokenizer, kind)
def _check(self, ids, max_new):
if len(ids) + max_new > self.max_len - self.MAX_ROWS:
raise ValueError(f"prompt ({len(ids)} tokens) + max_new_tokens ({max_new}) exceeds "
f"max_len={self.max_len} minus {self.MAX_ROWS} draft rows")
def _result(self, out, st) -> Generation:
d = st.as_dict()
d["source_counts"] = dict(Counter(st.sources))
dec_s = st.seconds - st.prefill_seconds
return Generation(self.tokenizer.decode(out), list(out), list(st.sources), d,
(st.new_tokens - 1) / dec_s if dec_s > 0 else float("nan"))
def _ar_step_seconds(self, ids) -> float:
if self._ar_step is None:
n = min(33, self.fast.dec.max_len - self.fast.max_rows - len(ids))
_, st = self.fast.generate_ar(ids, n)
self._ar_step = st.ar_step_median
return self._ar_step
def _run_dssd(self, ids, max_new, domain, stop, no_slowdown, on_commit=None):
from .calibration import online
pol = self._policy(domain)
kw = {}
if no_slowdown: # cost safety (chantier 3b, NoSlowdown, gamma only): never slower than AR (+xi)
ctl = online.NoSlowdown(0.02, 0.02, 0.0, _GammaOnly(), gamma_min=0.0)
ctl.K, ctl.gamma_only = len(self.heads), True
kw = {"controller": ctl, "ar_step_seconds": self._ar_step_seconds(ids)}
out, st = self.fast.generate_spec(pol, ids, max_new, eos_ids=self.eos_ids, stop=self._stop(domain, stop),
pld=self.config["domains"][domain]["policy"].get("pld"),
on_commit=on_commit, **kw)
return self._result(out, st)
def _run_ar(self, ids, max_new, domain, stop, on_commit=None):
out, st = self.fast.generate_ar(ids, max_new, eos_ids=self.eos_ids, stop=self._stop(domain, stop),
on_commit=on_commit)
return self._result(out, st)
@staticmethod
def _compare(g: Generation, ar: Generation) -> Generation:
g.ar, g.identical = ar, g.token_ids == ar.token_ids
g.speedup = g.decode_tokens_per_s / ar.decode_tokens_per_s if ar.decode_tokens_per_s > 0 else None
return g
# ------------------------------------------------------------------ API
@torch.no_grad()
def generate(self, prompt, max_new_tokens: int = 256, domain: str | None = None, stop: str | None = "auto",
compare_ar: bool = False, no_slowdown: bool = False) -> Generation:
"""Greedy DSSD generation. domain: "web", "gsm8k" (alias "math") or "code" selects the
calibrated policy and, with stop="auto", the stop rule. compare_ar: also run greedy AR
on the same engine and report speedup (decoding, prefill excluded) and identity."""
d, ids = self._domain(domain), self._ids(prompt)
self._check(ids, max_new_tokens)
with self._lock:
self._warmup()
g = self._run_dssd(ids, max_new_tokens, d, stop, no_slowdown)
if compare_ar:
g = self._compare(g, self._run_ar(ids, max_new_tokens, d, stop))
return g
@torch.no_grad()
def generate_ar(self, prompt, max_new_tokens: int = 256, domain: str | None = None,
stop: str | None = "auto") -> Generation:
d, ids = self._domain(domain), self._ids(prompt)
self._check(ids, max_new_tokens)
with self._lock:
self._warmup()
return self._run_ar(ids, max_new_tokens, d, stop)
def stream(self, prompt, max_new_tokens: int = 256, domain: str | None = None, stop: str | None = "auto",
no_slowdown: bool = False, ar: bool = False) -> Iterator[StreamEvent]:
"""One event per verification cycle (DSSD), then, if ar=True, one per AR step; the
final event (done=True) carries the Generation (with .ar, speedup, identical)."""
d, ids = self._domain(domain), self._ids(prompt)
self._check(ids, max_new_tokens)
q: queue.Queue = queue.Queue()
cancel = threading.Event()
def sink(phase):
t0 = []
def cb(toks, srcs): # runs inside the timed region: enqueue only, no decoding
if cancel.is_set():
raise _Cancelled
now = time.perf_counter()
if not t0:
t0.append(now)
q.put((phase, toks, srcs, now - t0[0]))
return cb
def work():
try:
with self._lock, torch.no_grad():
self._warmup()
g = self._run_dssd(ids, max_new_tokens, d, stop, no_slowdown, sink("dssd"))
if ar:
g = self._compare(g, self._run_ar(ids, max_new_tokens, d, stop, sink("ar")))
q.put(StreamEvent([], [], g.text, True, "ar" if ar else "dssd", g))
except _Cancelled:
pass
except BaseException as e: # re-raised in the consumer
q.put(e)
th = threading.Thread(target=work, daemon=True)
th.start()
acc = {"dssd": [], "ar": []}
try:
while True:
ev = q.get()
if isinstance(ev, BaseException):
raise ev
if isinstance(ev, tuple): # (phase, tokens, sources, t) from the worker
phase, toks, srcs, t = ev
acc[phase].extend(toks)
ev = StreamEvent(toks, srcs, self.tokenizer.decode(acc[phase]), False, phase, t=t)
yield ev
if ev.done:
return
finally:
cancel.set()
th.join()