Files
ssitu-ComfyUI_restart_sampling/restart_sampling.py
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Python

from __future__ import annotations
import ast
import os
import warnings
from collections import namedtuple
import comfy
import latent_preview
import torch
from comfy.sample import prepare_noise, sample_custom
from comfy.samplers import KSAMPLER, sampler_object
from comfy.utils import ProgressBar
from tqdm.auto import trange
from .restart_schedulers import SCHEDULER_MAPPING
VERBOSE = os.environ.get("COMFYUI_VERBOSE_RESTART_SAMPLING", "").strip() == "1"
DEFAULT_SEGMENTS = "[3,2,0.06,0.30],[3,1,0.30,0.59]"
def add_restart_segment(restart_segments, n_restart, k, t_min, t_max):
if restart_segments is None:
restart_segments = []
restart_segments.append({"n": n_restart, "k": k, "t_min": t_min, "t_max": t_max})
return restart_segments
def resolve_t_value(val, ms):
if isinstance(val, (float, int)):
if val >= 0.0:
return val
if val >= -1000:
return ms.sigma(torch.FloatTensor([abs(int(val))], device="cpu")).item()
if isinstance(val, str) and val.endswith("%"):
try:
val = float(val[:-1])
if val >= 0 and val <= 100:
return ms.percent_to_sigma(1.0 - val / 100.0)
except ValueError:
pass
raise ValueError("bad t_min or t_max value")
def prepare_restart_segments(restart_info, ms, sigmas):
def get_a1111_segment():
# Emulate A1111 WebUI's restart sampler behavior.
steps = len(sigmas) - 1
if steps < 20:
# Less than 20 steps - no restarts.
return []
a1111_t_max = sigmas[int(torch.argmin(abs(sigmas - 2.0), dim=0))].item()
if steps < 36:
# Less than 36 steps - one restart with 9 steps.
return [10, 1, 0.1, a1111_t_max]
# Otherwise two restarts with steps // 4 steps.
return [(steps // 4) + 1, 2, 0.1, a1111_t_max]
restart_info = restart_info.strip().lower()
if restart_info == "":
# No restarts.
return []
restart_arrays = None
if restart_info == "default":
restart_info = DEFAULT_SEGMENTS
elif restart_info == "a1111":
restart_arrays = [get_a1111_segment()]
if restart_arrays == [[]]:
return []
if restart_arrays is None:
try:
restart_arrays = ast.literal_eval(f"[{restart_info}]")
except SyntaxError:
print("Ill-formed restart segments")
raise
temp = []
default_segments = ast.literal_eval(DEFAULT_SEGMENTS)
for idx in range(len(restart_arrays)):
item = restart_arrays[idx]
if not isinstance(item, str):
temp.append(item)
continue
preset = item.strip().lower()
if preset == "default":
temp += default_segments
elif preset == "a1111":
temp.append(get_a1111_segment())
else:
raise ValueError("Ill-formed restart segment")
restart_arrays = temp
restart_segments = []
for arr in restart_arrays:
if not isinstance(arr, (list, tuple)) or len(arr) != 4:
raise ValueError("Restart segment must be a list with 4 values")
n_restart, k, val_min, val_max = arr
n_restart, k = int(n_restart), int(k)
t_min = resolve_t_value(val_min, ms)
t_max = resolve_t_value(val_max, ms)
restart_segments = add_restart_segment(
restart_segments,
n_restart,
k,
t_min,
t_max,
)
return restart_segments
def round_restart_segments(ts, restart_segments):
"""
Map nearest timestep/sigma min to the nearest timestep/sigma to segments.
:param ts: Timesteps or sigmas of the original denoising schedule
:param restart_segments: Restart segments dict of the form {'t_min': t_min, 'n': n, 'k': k, 't_max': t_max}
:return: dict of the form {nearest_t_min: {'n': n, 'k': k, 't_max': t_max}}
"""
t_min_mapping = {}
for segment in reversed(
restart_segments,
): # Reversed to prioritize segments to the front
t_min_neighbor = min(ts, key=lambda ts: abs(ts - segment["t_min"])).item()
if t_min_neighbor == ts[0]:
warnings.warn(
f"\n[Restart Sampling] nearest neighbor of segment t_min {segment['t_min']:.4f} is equal to the first t_min in the denoise schedule {ts[0]:.4f}, ignoring segment...",
stacklevel=2,
)
continue
if t_min_neighbor > segment["t_max"]:
warnings.warn(
f"\n[Restart Sampling] t_min neighbor {t_min_neighbor:.4f} is greater than t_max {segment['t_max']:.4f}, ignoring segment...",
stacklevel=2,
)
continue
if t_min_neighbor in t_min_mapping:
warnings.warn(
f"\n[Restart Sampling] Overwriting segment {t_min_mapping[t_min_neighbor]}, nearest neighbor of {segment['t_min']:.4f} is {t_min_neighbor:.4f}",
stacklevel=2,
)
t_min_mapping[t_min_neighbor] = {
"n": segment["n"],
"k": segment["k"],
"t_max": segment["t_max"],
}
return t_min_mapping
def calc_sigmas(scheduler, n, sigma_min, sigma_max, model, device):
return SCHEDULER_MAPPING[scheduler](model, n, sigma_min, sigma_max, device)
def calc_restart_steps(restart_segments):
restart_steps = 0
for segment in restart_segments.values():
restart_steps += (segment["n"] - 1) * segment["k"]
return restart_steps
def restart_sampling(
model,
seed,
steps,
cfg,
sampler,
scheduler,
positive,
negative,
latent_image,
restart_info,
restart_scheduler,
denoise=1.0,
disable_noise=False,
step_range=None,
force_full_denoise=False,
output_only=True,
custom_noise=None,
chunked_mode=True,
sigmas=None,
):
if isinstance(sampler, str):
sampler = sampler_object(sampler)
plan = RestartPlan(
model,
steps,
scheduler,
restart_info,
restart_scheduler,
denoise=denoise,
step_range=step_range,
force_full_denoise=force_full_denoise,
sigmas=sigmas,
)
plan = plan.to(model.load_device)
### UNCOMMENT TO RUN SELF TEST
# plan.self_test(
# model,
# schedules=SCHEDULER_MAPPING.keys(),
# restart_schedules=SCHEDULER_MAPPING.keys(),
# )
sigmas = plan.sigmas()
latent = latent_image
latent_image = latent["samples"]
if disable_noise:
torch.manual_seed(
seed,
) # workaround for https://github.com/comfyanonymous/ComfyUI/issues/2833
noise = torch.zeros(
latent_image.size(),
dtype=latent_image.dtype,
layout=latent_image.layout,
device="cpu",
)
else:
batch_inds = latent.get("batch_index", None)
noise = prepare_noise(latent_image, seed, batch_inds)
noise_mask = None
if "noise_mask" in latent:
noise_mask = latent["noise_mask"]
x0_output = {}
callback = latent_preview.prepare_callback(
model,
sigmas.shape[-1] - 1,
x0_output,
)
disable_pbar = not comfy.utils.PROGRESS_BAR_ENABLED
ksampler = KSAMPLER(
lambda *args, **kwargs: plan.sample(
sampler,
*args,
restart_chunked=chunked_mode,
restart_make_noise_sampler=custom_noise,
restart_seed=seed,
**kwargs,
),
extra_options=sampler.extra_options | {},
inpaint_options=sampler.inpaint_options | {},
)
# Add the additional steps to the progress bar
pbar_update_absolute = ProgressBar.update_absolute
def pbar_update_absolute_wrapper(self, value, total=None, preview=None):
pbar_update_absolute(self, value, plan.total_steps, preview)
ProgressBar.update_absolute = pbar_update_absolute_wrapper
try:
samples = sample_custom(
model,
noise,
cfg,
ksampler,
sigmas,
positive,
negative,
latent_image,
noise_mask=noise_mask,
callback=callback,
disable_pbar=disable_pbar,
seed=seed,
)
finally:
ProgressBar.update_absolute = pbar_update_absolute
out = latent.copy()
out["samples"] = samples
if output_only:
return (out,)
if "x0" in x0_output:
out_denoised = latent.copy()
out_denoised["samples"] = model.model.process_latent_out(x0_output["x0"].cpu())
else:
out_denoised = out
return (out, out_denoised)
# PlanItem:
# sigmas: Sigmas for normal (outside of a restart segment) sampling. They start from after the previous PlanItem's steps
# if there is one or simply the beginning of sampling.
# k, s_min, s_max: This is the same as the restart segment definition. Set to 0 if there is no restart segment.
# restart_sigmas: Sigmas for the restart segment if it exists, otherwise None.
# Note: n_restart is not included as it can be calculated from the length of restart_sigmas.
class PlanItem(
namedtuple(
"PlanItem",
["sigmas", "k", "s_min", "s_max", "restart_sigmas"],
defaults=[None, 0, 0.0, 0.0, None],
),
):
__slots__ = ()
def __new__(cls, *args: list, **kwargs: dict):
threshold = 1e-06
obj = super().__new__(cls, *args, **kwargs)
if len(obj.sigmas) < 2:
raise ValueError("PlanItem: invalid normal sigmas: too short")
if obj.k < 1:
return obj
if len(obj.restart_sigmas) < 2:
raise ValueError("PlanItem: invalid restart sigmas: too short")
if obj.s_min >= obj.s_max:
raise ValueError("PlanItem: invalid min/max: min >= max")
if obj.sigmas[-1] - obj.restart_sigmas[0] > threshold:
raise ValueError(
"PlanItem: invalid sigmas: last normal sigma >= first restart sigma",
)
if obj.sigmas[-1] - obj.restart_sigmas[-1] > threshold:
errstr = (
f"PlanItem: invalid sigmas: last restart sigma {obj.restart_sigmas[-1]} < last normal sigma {obj.sigmas[-1]}",
)
raise ValueError(errstr)
t = obj.sigmas.sort(descending=True, stable=True)[0].unique_consecutive()
if not torch.equal(obj.sigmas, t):
raise ValueError(
"PlanItem: invalid normal sigmas: out of order or contains duplicates",
)
t = obj.restart_sigmas.sort(descending=True, stable=True)[
0
].unique_consecutive()
if not torch.equal(obj.restart_sigmas, t):
raise ValueError(
"PlanItem: invalid restart sigmas: out of order or contains duplicates",
)
return obj
# Execute a plan item: runs sampling on the main sigmas, handles injecting noise for restarts
# as well as sampling the restart steps.
# sample: Function used sample sigmas. It takes x, a tensor with the sigmas to sample and
# the restart index (k) or -1 for sampling that isn't within a restart segment.
# get_noise_sampler: Return the noise sampler for restart segment noise injection.
# It takes x, and sigma_min, sigma_max (basically the same arguments as ComfyUI's
# BrownianTreeNoiseSampler class init function).
@torch.no_grad()
def execute(self, x, sample, get_noise_sampler):
x = sample(x, self.sigmas, -1)
if self.k < 1 or self.restart_sigmas is None:
return x
noise_sampler = get_noise_sampler(x, self.s_min, self.s_max)
for kidx in range(self.k):
x += (
noise_sampler(self.restart_sigmas[0], self.restart_sigmas[-1])
* (self.s_max**2 - self.s_min**2) ** 0.5
)
x = sample(x, self.restart_sigmas, kidx)
return x
class RestartPlan:
def __init__(
self,
model,
steps,
scheduler,
restart_info,
restart_scheduler,
denoise=1.0,
step_range=None,
force_full_denoise=False,
sigmas=None,
):
comfy.model_management.load_models_gpu([model])
real_model = model
while hasattr(real_model, "model"):
real_model = real_model.model
effective_steps = (
steps
if step_range is not None or denoise > 0.9999
else int(steps / denoise)
)
if sigmas is None:
sigmas = calc_sigmas(
scheduler,
effective_steps,
float(real_model.model_sampling.sigma_min),
float(real_model.model_sampling.sigma_max),
real_model,
"cpu",
)
else:
sigmas = sigmas.detach().cpu().clone()
if step_range is not None:
start_step, last_step = step_range
if last_step < (len(sigmas) - 1):
sigmas = sigmas[: last_step + 1]
if force_full_denoise:
sigmas[-1] = 0
if start_step < (len(sigmas) - 1):
sigmas = sigmas[start_step:]
elif effective_steps != steps:
sigmas = sigmas[-(steps + 1) :]
self.plain_sigmas = sigmas
restart_segments = prepare_restart_segments(
restart_info,
real_model.model_sampling,
sigmas,
)
self.plan, self.total_steps = self.build_plan_items(
model.model,
restart_segments,
restart_scheduler,
sigmas,
"cpu",
)
def __repr__(self) -> str:
return f"<RestartPlan: steps={self.total_steps}, plan={self.plan}>"
def __len__(self) -> int:
return self.total_steps
# Builds a list of PlanItems and calculates the total number of steps. See the comments for PlanItem
# for more information about plans.
# Returns two values: the plan and the total steps.
@staticmethod
@torch.no_grad()
def build_plan_items(
model,
restart_segments,
restart_scheduler,
sigmas,
device,
) -> tuple[list, int]:
segments = round_restart_segments(sigmas, restart_segments)
total_steps = len(sigmas) - 1 + calc_restart_steps(segments)
plan = []
range_start = -1
for i in range(len(sigmas) - 1):
if range_start == -1:
# Starting a new plan item - main sigmas start at the current index of i.
range_start = i
s_min = sigmas[i + 1].item()
seg = segments.get(s_min)
if seg is None:
continue
s_max, k, n_restart = seg["t_max"], seg["k"], seg["n"]
if k < 1 or n_restart < 2:
continue
normal_sigmas = sigmas[range_start : i + 2]
restart_sigmas = calc_sigmas(
restart_scheduler,
n_restart,
s_min if restart_scheduler != "exponential" else max(s_min, 1e-08),
s_max,
model,
device=device,
)[:-1]
# restart_sigmas[0] = s_max
restart_sigmas[-1] = s_min
plan.append(PlanItem(normal_sigmas, k, s_min, s_max, restart_sigmas))
range_start = -1
if range_start != -1:
# Include sigmas after the last restart segments in the plan.
plan.append(PlanItem(sigmas[range_start:]))
return plan, total_steps
@classmethod
def from_sigmas(cls, sigmas, threshold=1e-06):
def get_normal_segment(sigmas):
# A normal segment ends when we either reach the end of the list or
# encounter a sigma higher than the previous.
last_sigma = sigmas[0]
for idx in range(1, len(sigmas)):
sigma = sigmas[idx]
if last_sigma - sigma < threshold:
return sigmas[:idx]
last_sigma = sigma
return sigmas
def get_restart_segment(sigmas, s_min):
# s_min here is the last sigma of the previous normal segment. A restart segment
# ends when:
# 1. We reach the end of the list, or
# 2. We hit a sigma greater or equal to the last sigma, or
# 3. We hit a sigma less than s_min
last_sigma = sigmas[0]
for idx in range(1, len(sigmas)):
sigma = sigmas[idx]
if last_sigma - sigma < -threshold:
return sigmas[:idx]
if sigma <= s_min:
return sigmas[: idx + 1]
last_sigma = sigma
raise ValueError("Unexpected end of sigmas in a restart segment")
plain_sigmas = sigmas.detach().cpu().clone()
plan = []
total_steps = 0
while len(sigmas) > 0:
# Get the normal segment - a restart segment can never be first.
normal_sigmas = get_normal_segment(sigmas)
nslen = len(normal_sigmas)
if nslen < 2:
print(sigmas)
raise ValueError(
"Encountered invalid normal segment rebuilding sigmas: too short",
)
sigmas = sigmas[nslen:]
total_steps += nslen - 1
if len(sigmas) == 0:
# No restart segments follow the normal segment so we're done.
plan.append(PlanItem(normal_sigmas))
break
# If we're here there has to be a restart segment; get it.
restart_sigmas = get_restart_segment(sigmas, normal_sigmas[-1])
rslen = len(restart_sigmas)
if rslen < 2:
raise ValueError(
"Encountered invalid normal segment rebuilding sigmas: too short",
)
sigmas = sigmas[rslen:]
k = 1
# The restart segment may be repeated multiple times. If so, count the
# repeats and trim the sigmas list.
while len(sigmas) > 0 and torch.equal(sigmas[:rslen], restart_sigmas):
k += 1
sigmas = sigmas[rslen:]
total_steps += (rslen - 1) * k
plan.append(
PlanItem(
normal_sigmas,
k,
normal_sigmas[-1],
restart_sigmas[0],
restart_sigmas,
),
)
obj = cls.__new__(cls)
obj.plan = plan
obj.total_steps = total_steps
obj.plain_sigmas = plain_sigmas
return obj
def sigmas(self) -> torch.Tensor:
def sigmas_generator():
for pi in self.plan:
yield pi.sigmas.cpu()
for _ in range(pi.k):
yield pi.restart_sigmas.cpu()
return torch.flatten(torch.cat(tuple(sigmas_generator())))
def to(self, device):
obj = self.__class__.__new__(self.__class__)
obj.plain_sigmas = self.plain_sigmas.to(device)
obj.total_steps = self.total_steps
items = obj.plan = []
for pi in self.plan:
sigmas = pi.sigmas.to(device)
if pi.k < 1:
items.append(PlanItem(sigmas))
continue
items.append(
PlanItem(
sigmas,
pi.k,
pi.s_min,
pi.s_max,
pi.restart_sigmas.to(device),
),
)
return obj
# Dumps information about the plan to the console. It uses the normal plan execute
# logic.
def explain(self, chunked=True):
def pretty_sigmas(sigmas):
return ", ".join(f"{sig:.4}" for sig in sigmas.tolist())
print(f"** Dumping restart sampling plan (total steps {self.total_steps}):")
for pi in self.plan:
print(
f"\n{pi.sigmas[-1].item():.04} .. {pi.sigmas[0].item():.04} ({len(pi.sigmas)})",
)
if pi.k > 0:
print(
f" {pi.restart_sigmas[-1].item():.04} ({pi.s_min:.04}) .. {pi.restart_sigmas[0].item():.04} ({pi.s_max:.04}): k={pi.k} ({len(pi.restart_sigmas)})",
)
step = 0
last_kidx = -1
# Instead of actually sampling, we just dump information about the steps.
# When kidx==-1 this is a normal step, otherwise kidx==0 is the first restart,
# kidx==1 is the second, etc.
def do_sample(x, sigs, kidx=-1):
nonlocal step, last_kidx
rlabel = f"R{kidx+1:>3}" if kidx > last_kidx else " "
last_kidx = kidx
if not chunked:
for i in range(len(sigs) - 1):
step += 1
print(f"[{rlabel}] Step {step:>3}: {pretty_sigmas(sigs[i:i+2])}")
return x
chunk_size = len(sigs) - 2
step += 1
print(
f"[{rlabel}] Step {step:>3}..{step+chunk_size:<3}: {pretty_sigmas(sigs)}",
)
step += chunk_size
return x
# Stub function to satisfy PlanItem.execute
def get_noise_sampler(*_args: list):
return lambda *_args: 0.0
for pi in self.plan:
pi.execute(0.0, do_sample, get_noise_sampler)
print(
"** Plan legend: [Rn] - steps for restart #n, normal sampling steps otherwise. Ranges are inclusive.",
)
# Some extra explanation for a couple of these arguments:
#
# chunked:
# When chunked is False, the sampling function is called step-by-step with only two sigmas at a time.
# When chunked is is True, the sampling function will be called with sigmas for multiple steps at a time.
# this means either the steps up to the next restart segment (or the end of sampling) or the steps within
# a restart segment.
#
# make_noise_sampler:
# If set to None, restart noise will just use torch.randn_like (gaussian) for noise generation. Otherwise
# this should contain a function that takes x, sigma_min, sigma_max, seed and returns a noise sampler
# function (which takes sigma, sigma_next) and returns a noisy tensor.
@torch.no_grad()
def sample(
self,
ksampler,
model,
x,
_sigmas,
*args: list,
restart_chunked=True,
restart_make_noise_sampler=None,
restart_seed=None,
extra_args=None,
callback=None,
disable=None,
**kwargs: dict,
):
step = 0
if restart_seed is None:
seed = (extra_args or {}).get("seed", 42)
else:
seed = restart_seed
plan = self.plan
if VERBOSE:
self.explain(restart_chunked)
def noise_sampler(*_args: list):
return torch.randn_like(x)
# Passed to the PlanItem .execute method. Most of the time, self.make_noise_sampler
# is going to be None so this is just a wrapper for torch.randn_like.
# Otherwise we call the noise sampler factory and increment seed to ensure that restarts
# don't all use the same noise.
def get_noise_sampler(x, s_min, s_max):
nonlocal seed
if not restart_make_noise_sampler:
return noise_sampler
result = restart_make_noise_sampler(x, s_min, s_max, seed)
seed += 1
return result
with trange(self.total_steps, disable=disable) as pbar:
last_cb_sigma = None
def callback_wrapper(cb_state):
nonlocal step, last_cb_sigma
curr_sigma = cb_state.get("sigma")
curr_sigma = (
curr_sigma.item()
if isinstance(curr_sigma, torch.Tensor)
else curr_sigma
)
if last_cb_sigma is not None and curr_sigma == last_cb_sigma:
# No change since last time we were called, so we won't track it as a step.
return
step += 1
pbar.update(1)
cb_state["i"] = step
last_cb_sigma = curr_sigma
if callback is not None:
callback(cb_state)
# Convenience function for code reuse.
def sampler_function(x, sigs):
return ksampler.sampler_function(
model,
x,
sigs,
*args,
extra_args=extra_args,
callback=callback_wrapper,
disable=True,
**kwargs,
)
def do_sample(x, sigs, _kidx=-1):
if isinstance(sigs, (list, tuple)):
sigs = torch.tensor(sigs, device=x.device)
if restart_chunked or len(sigs) < 3:
# If running un chunked mode or there are already 2 or less sigmas, we can just
# pass the sigmas to the sampling function.
return sampler_function(x, sigs)
# Otherwise we call the sampling function step by step on slices of 2 sigmas.
for i in range(len(sigs) - 1):
x = sampler_function(x, sigs[i : i + 2])
return x
# Execute the plan items in sequence.
for pi in plan:
x = pi.execute(x, do_sample, get_noise_sampler)
return x
@staticmethod
def self_test(
model,
schedules=None,
restart_schedules=None,
segments=None,
min_steps=2,
max_steps=100,
) -> None:
if schedules is None:
schedules = SCHEDULER_MAPPING.keys() - {"simple_test"}
if restart_schedules is None:
restart_schedules = SCHEDULER_MAPPING.keys() - {"simple_test"}
if segments is None:
segments = ("default", "a1111")
for schname in schedules:
for rschname in restart_schedules:
for tsegs in segments:
print(
f"--- Test: {min_steps}..{max_steps} steps, schedules {schname}/{rschname}, segments {tsegs}",
)
for tsteps in range(min_steps, max_steps + 1):
label = f"** {tsteps:03}: {schname}, {rschname}, {tsegs}:"
try:
p1 = RestartPlan(
model,
tsteps,
schname,
tsegs,
rschname,
1.0,
)
except ValueError as err:
print(f"{label}\n\t!! FAIL: {err}")
raise
continue
try:
p2 = RestartPlan.from_sigmas(p1.sigmas())
except ValueError:
print(label)
p1.explain(chunked=True)
raise
fail = None
if len(p1) != len(p2):
fail = "steps"
if not fail:
for idx in range(len(p1.plan)):
pi1, pi2 = p1.plan[idx], p2.plan[idx]
if not torch.equal(
torch.round(pi1.sigmas, decimals=5),
torch.round(pi2.sigmas, decimals=5),
):
fail = "normal"
break
if pi1.k != pi2.k:
fail = "k"
break
if pi1.k < 1:
continue
if not torch.equal(
torch.round(pi1.restart_sigmas, decimals=5),
torch.round(pi2.restart_sigmas, decimals=5),
):
fail = "restart"
break
if fail:
print(label)
print("!!!", fail)
p1.explain()
print("====")
p2.explain()
raise ValueError("Failed rebuilding restart plan")
print("\n|| Done test")