Files
LEANN/packages/leann-backend-diskann/leann_backend_diskann/diskann_backend.py
2025-07-06 01:54:46 +00:00

224 lines
8.3 KiB
Python

import numpy as np
import os
import json
import struct
from pathlib import Path
from typing import Dict
import contextlib
import threading
import time
import atexit
import socket
import subprocess
import sys
from leann.embedding_server_manager import EmbeddingServerManager
from leann.registry import register_backend
from leann.interface import (
LeannBackendFactoryInterface,
LeannBackendBuilderInterface,
LeannBackendSearcherInterface
)
from . import _diskannpy as diskannpy
METRIC_MAP = {
"mips": diskannpy.Metric.INNER_PRODUCT,
"l2": diskannpy.Metric.L2,
"cosine": diskannpy.Metric.COSINE,
}
@contextlib.contextmanager
def chdir(path):
original_dir = os.getcwd()
os.chdir(path)
try:
yield
finally:
os.chdir(original_dir)
def _write_vectors_to_bin(data: np.ndarray, file_path: str):
num_vectors, dim = data.shape
with open(file_path, 'wb') as f:
f.write(struct.pack('I', num_vectors))
f.write(struct.pack('I', dim))
f.write(data.tobytes())
@register_backend("diskann")
class DiskannBackend(LeannBackendFactoryInterface):
@staticmethod
def builder(**kwargs) -> LeannBackendBuilderInterface:
return DiskannBuilder(**kwargs)
@staticmethod
def searcher(index_path: str, **kwargs) -> LeannBackendSearcherInterface:
path = Path(index_path)
meta_path = path.parent / f"{path.name}.meta.json"
if not meta_path.exists():
raise FileNotFoundError(f"Leann metadata file not found at {meta_path}.")
with open(meta_path, 'r') as f:
meta = json.load(f)
# Pass essential metadata to the searcher
kwargs['meta'] = meta
return DiskannSearcher(index_path, **kwargs)
class DiskannBuilder(LeannBackendBuilderInterface):
def __init__(self, **kwargs):
self.build_params = kwargs
def build(self, data: np.ndarray, index_path: str, **kwargs):
path = Path(index_path)
index_dir = path.parent
index_prefix = path.stem
index_dir.mkdir(parents=True, exist_ok=True)
if data.dtype != np.float32:
data = data.astype(np.float32)
if not data.flags['C_CONTIGUOUS']:
data = np.ascontiguousarray(data)
data_filename = f"{index_prefix}_data.bin"
_write_vectors_to_bin(data, index_dir / data_filename)
build_kwargs = {**self.build_params, **kwargs}
metric_str = build_kwargs.get("distance_metric", "mips").lower()
metric_enum = METRIC_MAP.get(metric_str)
if metric_enum is None:
raise ValueError(f"Unsupported distance_metric '{metric_str}'.")
complexity = build_kwargs.get("complexity", 64)
graph_degree = build_kwargs.get("graph_degree", 32)
final_index_ram_limit = build_kwargs.get("search_memory_maximum", 4.0)
indexing_ram_budget = build_kwargs.get("build_memory_maximum", 8.0)
num_threads = build_kwargs.get("num_threads", 8)
pq_disk_bytes = build_kwargs.get("pq_disk_bytes", 0)
codebook_prefix = ""
print(f"INFO: Building DiskANN index for {data.shape[0]} vectors with metric {metric_enum}...")
try:
with chdir(index_dir):
diskannpy.build_disk_float_index(
metric_enum,
data_filename,
index_prefix,
complexity,
graph_degree,
final_index_ram_limit,
indexing_ram_budget,
num_threads,
pq_disk_bytes,
codebook_prefix
)
print(f"✅ DiskANN index built successfully at '{index_dir / index_prefix}'")
except Exception as e:
print(f"💥 ERROR: DiskANN index build failed. Exception: {e}")
raise
finally:
temp_data_file = index_dir / data_filename
if temp_data_file.exists():
os.remove(temp_data_file)
class DiskannSearcher(LeannBackendSearcherInterface):
def __init__(self, index_path: str, **kwargs):
self.meta = kwargs.get("meta", {})
if not self.meta:
raise ValueError("DiskannSearcher requires metadata from .meta.json.")
dimensions = self.meta.get("dimensions")
if not dimensions:
raise ValueError("Dimensions not found in Leann metadata.")
self.distance_metric = self.meta.get("distance_metric", "mips").lower()
metric_enum = METRIC_MAP.get(self.distance_metric)
if metric_enum is None:
raise ValueError(f"Unsupported distance_metric '{self.distance_metric}'.")
self.embedding_model = self.meta.get("embedding_model")
if not self.embedding_model:
print("WARNING: embedding_model not found in meta.json. Recompute will fail if attempted.")
path = Path(index_path)
index_dir = path.parent
index_prefix = path.stem
num_threads = kwargs.get("num_threads", 8)
num_nodes_to_cache = kwargs.get("num_nodes_to_cache", 0)
try:
full_index_prefix = str(index_dir / index_prefix)
self._index = diskannpy.StaticDiskFloatIndex(
metric_enum, full_index_prefix, num_threads, num_nodes_to_cache, 1, "", ""
)
self.num_threads = num_threads
self.embedding_server_manager = EmbeddingServerManager(
backend_module_name="leann_backend_diskann.embedding_server"
)
print("✅ DiskANN index loaded successfully.")
except Exception as e:
print(f"💥 ERROR: Failed to load DiskANN index. Exception: {e}")
raise
def search(self, query: np.ndarray, top_k: int, **kwargs) -> Dict[str, any]:
complexity = kwargs.get("complexity", 256)
beam_width = kwargs.get("beam_width", 4)
USE_DEFERRED_FETCH = kwargs.get("USE_DEFERRED_FETCH", False)
skip_search_reorder = kwargs.get("skip_search_reorder", False)
recompute_beighbor_embeddings = kwargs.get("recompute_beighbor_embeddings", False)
dedup_node_dis = kwargs.get("dedup_node_dis", False)
prune_ratio = kwargs.get("prune_ratio", 0.0)
batch_recompute = kwargs.get("batch_recompute", False)
global_pruning = kwargs.get("global_pruning", False)
if recompute_beighbor_embeddings:
print(f"INFO: DiskANN ZMQ mode enabled - ensuring embedding server is running")
if not self.embedding_model:
raise ValueError("Cannot use recompute_beighbor_embeddings without 'embedding_model' in meta.json.")
zmq_port = kwargs.get("zmq_port", 6666)
server_started = self.embedding_server_manager.start_server(
port=zmq_port,
model_name=self.embedding_model,
distance_metric=self.distance_metric
)
if not server_started:
print(f"WARNING: Failed to start embedding server, falling back to PQ computation")
recompute_beighbor_embeddings = False
if query.dtype != np.float32:
query = query.astype(np.float32)
if query.ndim == 1:
query = np.expand_dims(query, axis=0)
try:
labels, distances = self._index.batch_search(
query,
query.shape[0],
top_k,
complexity,
beam_width,
self.num_threads,
USE_DEFERRED_FETCH,
skip_search_reorder,
recompute_beighbor_embeddings,
dedup_node_dis,
prune_ratio,
batch_recompute,
global_pruning
)
return {"labels": labels, "distances": distances}
except Exception as e:
print(f"💥 ERROR: DiskANN search failed. Exception: {e}")
batch_size = query.shape[0]
return {"labels": np.full((batch_size, top_k), -1, dtype=np.int64),
"distances": np.full((batch_size, top_k), float('inf'), dtype=np.float32)}
def __del__(self):
if hasattr(self, 'embedding_server_manager'):
self.embedding_server_manager.stop_server()