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ce4f5a29fb
Co-authored-by: ElizaWszola <eliza@neuralmagic.com> Co-authored-by: Michael Goin <michael@neuralmagic.com>
85 lines
2.3 KiB
Python
85 lines
2.3 KiB
Python
"""Token blocks."""
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from typing import List
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from vllm.utils import Device
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_BLANK_TOKEN_ID = -1
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DEFAULT_LAST_ACCESSED_TIME = -1
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class LogicalTokenBlock:
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"""A block that stores a contiguous chunk of tokens from left to right.
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Logical blocks are used to represent the states of the corresponding
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physical blocks in the KV cache.
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"""
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def __init__(
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self,
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block_number: int,
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block_size: int,
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) -> None:
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self.block_number = block_number
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self.block_size = block_size
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self.token_ids = [_BLANK_TOKEN_ID] * block_size
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self.num_tokens = 0
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def is_empty(self) -> bool:
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return self.num_tokens == 0
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def get_num_empty_slots(self) -> int:
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return self.block_size - self.num_tokens
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def is_full(self) -> bool:
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return self.num_tokens == self.block_size
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def append_tokens(self, token_ids: List[int]) -> None:
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assert len(token_ids) <= self.get_num_empty_slots()
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curr_idx = self.num_tokens
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self.token_ids[curr_idx:curr_idx + len(token_ids)] = token_ids
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self.num_tokens += len(token_ids)
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def get_token_ids(self) -> List[int]:
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return self.token_ids[:self.num_tokens]
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def get_last_token_id(self) -> int:
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assert self.num_tokens > 0
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return self.token_ids[self.num_tokens - 1]
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class PhysicalTokenBlock:
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"""Represents the state of a block in the KV cache."""
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def __init__(
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self,
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device: Device,
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block_number: int,
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block_size: int,
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block_hash: int,
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num_hashed_tokens: int,
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) -> None:
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self.device = device
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self.block_number = block_number
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self.block_size = block_size
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self.block_hash = block_hash
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self.num_hashed_tokens = num_hashed_tokens
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self.ref_count = 0
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self.last_accessed = DEFAULT_LAST_ACCESSED_TIME
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self.computed = False
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def __repr__(self) -> str:
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return (f'PhysicalTokenBlock(device={self.device}, '
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f'block_number={self.block_number}, '
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f'num_hashed_tokens={self.num_hashed_tokens}, '
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f'ref_count={self.ref_count}, '
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f'last_accessed={self.last_accessed}, '
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f'computed={self.computed})')
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# Mapping: logical block number -> physical block.
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BlockTable = List[PhysicalTokenBlock]
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