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from collections import deque
import numpy as np
import xxhash
from flashcosyvoice.engine.sequence import Sequence
class Block:
def __init__(self, block_id):
self.block_id = block_id
self.ref_count = 0
self.hash = -1
self.token_ids = []
def update(self, hash: int, token_ids: list[int]):
self.hash = hash
self.token_ids = token_ids
def reset(self):
self.ref_count = 1
self.hash = -1
self.token_ids = []
class BlockManager:
def __init__(self, num_blocks: int, block_size: int):
assert num_blocks > 0
self.block_size = block_size
self.blocks: list[Block] = [Block(i) for i in range(num_blocks)]
self.hash_to_block_id: dict[int, int] = dict()
self.free_block_ids: deque[int] = deque(range(num_blocks))
self.used_block_ids: set[int] = set()
@classmethod
def compute_hash(cls, token_ids: list[int], prefix: int = -1):
h = xxhash.xxh64()
if prefix != -1:
h.update(prefix.to_bytes(8, "little"))
h.update(np.array(token_ids).tobytes())
return h.intdigest()
def _allocate_block(self, block_id: int) -> Block:
block = self.blocks[block_id]
assert block.ref_count == 0
block.reset()
self.free_block_ids.remove(block_id)
self.used_block_ids.add(block_id)
return self.blocks[block_id]
def _deallocate_block(self, block_id: int) -> Block:
assert self.blocks[block_id].ref_count == 0
self.used_block_ids.remove(block_id)
self.free_block_ids.append(block_id)
def can_allocate(self, seq: Sequence) -> bool:
return len(self.free_block_ids) >= seq.num_blocks
def allocate(self, seq: Sequence):
assert not seq.block_table
h = -1
cache_miss = False
for i in range(seq.num_blocks):
token_ids = seq.block(i)
h = self.compute_hash(token_ids, h) if len(token_ids) == self.block_size else -1
block_id = self.hash_to_block_id.get(h, -1)
if block_id == -1 or self.blocks[block_id].token_ids != token_ids:
cache_miss = True
if cache_miss:
block_id = self.free_block_ids[0]
block = self._allocate_block(block_id)
else:
seq.num_cached_tokens += self.block_size
if block_id in self.used_block_ids:
block = self.blocks[block_id]
block.ref_count += 1
else:
block = self._allocate_block(block_id)
if h != -1:
block.update(h, token_ids)
self.hash_to_block_id[h] = block_id
seq.block_table.append(block_id)
def deallocate(self, seq: Sequence):
for block_id in reversed(seq.block_table):
block = self.blocks[block_id]
block.ref_count -= 1
if block.ref_count == 0:
self._deallocate_block(block_id)
seq.num_cached_tokens = 0
seq.block_table.clear()
def can_append(self, seq: Sequence) -> bool:
return len(self.free_block_ids) >= (len(seq) % self.block_size == 1)
def may_append(self, seq: Sequence):
block_table = seq.block_table
last_block = self.blocks[block_table[-1]]
if len(seq) % self.block_size == 1:
assert last_block.hash != -1
block_id = self.free_block_ids[0]
self._allocate_block(block_id)
block_table.append(block_id)
elif len(seq) % self.block_size == 0:
assert last_block.hash == -1
token_ids = seq.block(seq.num_blocks - 1)
prefix = self.blocks[block_table[-2]].hash if len(block_table) > 1 else -1
h = self.compute_hash(token_ids, prefix)
last_block.update(h, token_ids)
self.hash_to_block_id[h] = last_block.block_id
else:
assert last_block.hash == -1