Evidence-Graph-Reranker / reproduce /neural_crossencoder_only.py
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"""MS MARCO MiniLM cross-encoder, loaded from uploaded weights. CPU, offline."""
import os,unicodedata,re,time
import numpy as np
import torch
from torch import nn
from safetensors.torch import load_file
from minilm_cpu_pipeline import BertEmb,Enc,WordPiece
from neural_evidence_graph_core import ROOT
class BertCrossEncoder(nn.Module):
def __init__(self):
super().__init__();self.embeddings=BertEmb();self.encoder=Enc()
self.pooler=nn.Linear(384,384);self.classifier=nn.Linear(384,1)
def forward(self,ids,mask,types):
pos=self.embeddings.position_ids[:,:ids.shape[1]]
h=self.embeddings.LayerNorm(self.embeddings.word_embeddings(ids)+self.embeddings.position_embeddings(pos)+self.embeddings.token_type_embeddings(types))
h=self.encoder(h,mask[:,None,None,:].bool())
return self.classifier(torch.tanh(self.pooler(h[:,0,:]))).squeeze(-1)
def load_crossencoder():
torch.set_num_threads(min(4,os.cpu_count() or 4))
try:torch.set_num_interop_threads(1)
except RuntimeError:pass
m=BertCrossEncoder();raw=load_file(str(ROOT/'model.safetensors'),device='cpu');clean={}
for k,v in raw.items():
if k=='bert.embeddings.position_ids':continue
if k.startswith('bert.pooler.dense.'):k='pooler.'+k[len('bert.pooler.dense.'):]
elif k.startswith('bert.'):k=k[5:]
clean[k]=v
m.load_state_dict(clean,strict=True);m.eval()
print('Loaded original pretrained MS MARCO model, tensors',len(clean),flush=True)
return m
class PairTokenizer(WordPiece):
def __init__(self,length=256):super().__init__(str(ROOT/'vocab.txt'),length)
def tokens(self,text):
text=''.join(ch for ch in unicodedata.normalize('NFD',text.lower()) if unicodedata.category(ch)!='Mn' and (ch.isspace() or unicodedata.category(ch)[0]!='C'))
out=[]
for x in re.findall(r'[^\W_]+|_|[^\w\s]',text,flags=re.UNICODE):out.extend(self.wp(x))
return out
def pair(self,q,d):
a=self.tokens(q);b=self.tokens(d);cap=self.max_length-3
while len(a)+len(b)>cap:
if len(b)>len(a):b.pop()
else:a.pop()
ids=[101]+a+[102]+b+[102]
tt=[0]*(len(a)+2)+[1]*(len(b)+1)
return ids,tt
@torch.inference_mode()
def score_pairs(m,tok,pairs,batch=20):
out=np.empty(len(pairs),np.float32);times=[]
for start in range(0,len(pairs),batch):
p=pairs[start:start+batch];inputs=[tok.pair(q,d) for q,d in p]
L=max(len(x[0]) for x in inputs)
ids=np.zeros((len(p),L),np.int64);tt=np.zeros_like(ids);mask=np.zeros_like(ids)
for i,(u,v) in enumerate(inputs):ids[i,:len(u)]=u;tt[i,:len(v)]=v;mask[i,:len(u)]=1
t=time.perf_counter();out[start:start+len(p)]=m(torch.from_numpy(ids),torch.from_numpy(mask),torch.from_numpy(tt)).numpy();times.append(time.perf_counter()-t)
if start and start%(batch*35)==0:print('scored',start,'/',len(pairs),flush=True)
return out,{'total_forward_s':float(sum(times)),'forward_ms_per_pair':float(sum(times)*1000/max(1,len(pairs))),'batches':len(times)}