from typing import Dict, Iterable, List, Optional, Set from aphrodite.processing.block.common import ( CopyOnWriteTracker, RefCounter, get_all_blocks_recursively, ) from aphrodite.processing.block.interfaces import Block, BlockAllocator BlockId = int Refcount = int class NaiveBlockAllocator(BlockAllocator): """A simple block allocator that manages blocks of memory without prefix caching. Args: create_block (Block.Factory): A factory function for creating new blocks. This is used when a NaiveBlockAllocator is composed within a prefix caching allocator -- the naive block allocator must construct prefix caching blocks (but shouldn't know anything else about them). num_blocks (int): The total number of blocks to manage. block_size (int): The size of each block in tokens. block_ids (Optional[Iterable[int]], optional): An optional iterable of block IDs. If not provided, block IDs will be assigned sequentially from 0 to num_blocks - 1. """ def __init__( self, create_block: Block.Factory, num_blocks: int, block_size: int, block_ids: Optional[Iterable[int]] = None, ): if block_ids is None: block_ids = range(num_blocks) self._free_block_indices: Set[BlockId] = set(block_ids) self._all_block_indices = frozenset(block_ids) assert len(self._all_block_indices) == num_blocks self._refcounter = RefCounter( all_block_indices=self._free_block_indices) self._create_block = create_block self._block_size = block_size self._cow_tracker = CopyOnWriteTracker( refcounter=self._refcounter.as_readonly(), allocator=self, ) def allocate_immutable(self, prev_block: Optional[Block], token_ids: List[int]) -> Block: """Allocates a new immutable block with the given token IDs, linked to the previous block. Args: prev_block (Optional[Block]): The previous block in the sequence. If None, then the block to be allocated is the first block in the sequence. token_ids (List[int]): The token IDs to be stored in the new block. Returns: Block: The newly allocated immutable block. """ block = self.allocate_mutable(prev_block=prev_block) block.append_token_ids(token_ids) return block def allocate_mutable(self, prev_block: Optional[Block]) -> Block: """Allocates a new mutable block, linked to the previous block. Args: prev_block (Optional[Block]): The previous block in the sequence. If None, then the block to be allocated is the first block in the sequence. Returns: Block: The newly allocated mutable block. """ block_id = self._allocate_new_block_id() return self._create_block( prev_block=prev_block, token_ids=[], block_id=block_id, block_size=self._block_size, allocator=self, ) def free(self, block: Block) -> None: self._free_block_id(block.block_id) # Mark the block as having no allocation. block.block_id = None def fork(self, last_block: Block) -> List[Block]: """Creates a new sequence of blocks that shares the same underlying memory as the original sequence. Args: last_block (Block): The last block in the original sequence. Returns: List[Block]: The new sequence of blocks that shares the same memory as the original sequence. """ source_blocks = get_all_blocks_recursively(last_block) forked_blocks = [] prev_block = None for block in source_blocks: # Increment refcount for each block. refcount = self._refcounter.incr(block.block_id) assert refcount != 1, "can't fork free'd block" forked_blocks.append( self._create_block( prev_block=prev_block, token_ids=block.token_ids, block_id=block.block_id, block_size=self._block_size, allocator=self, )) prev_block = forked_blocks[-1] return forked_blocks def get_num_free_blocks(self) -> int: return len(self._free_block_indices) def _allocate_new_block_id(self) -> BlockId: if not self._free_block_indices: raise BlockAllocator.NoFreeBlocksError() block_id = next(iter(self._free_block_indices)) self._refcounter.incr(block_id) self._free_block_indices.remove(block_id) return block_id def _free_block_id(self, block_id: BlockId) -> None: refcount = self._refcounter.decr(block_id) if refcount == 0: self._free_block_indices.add(block_id) @property def refcounter(self): return self._refcounter @property def all_block_ids(self): return self._all_block_indices def cow_block_if_not_appendable(self, block: Block) -> Optional[BlockId]: """Performs a copy-on-write operation on the given block if it is not appendable. Args: block (Block): The block to check for copy-on-write. Returns: Optional[BlockId]: The block index of the new block if a copy-on -write operation was performed, or the original block index if no copy-on-write was necessary. """ return self._cow_tracker.cow_block_if_not_appendable(block) def clear_copy_on_writes(self) -> Dict[BlockId, List[BlockId]]: """Returns the copy-on-write source->destination mapping and clears it. Returns: Dict[BlockId, List[BlockId]]: A dictionary mapping source block indices to lists of destination block indices. """ return self._cow_tracker.clear_cows() def mark_blocks_as_computed(self) -> None: """Mark blocks as computed, used in prefix caching. Since the naive allocator does not implement prefix caching, we do nothing. """ pass def get_common_computed_block_ids( self, seq_block_ids: List[List[int]]) -> List[int]: """Determine blocks that can be skipped in prefill. Since the naive allocator does not support prefix caching, always return an empty list. """ return [] class NaiveBlock(Block): """An implementation of the Block class that does not support prefix caching. The NaiveBlock class represents a block of token IDs with a fixed size. It provides methods for appending token IDs to the block and manages copy-on -write operations when necessary. Args: prev_block (Block): The previous block in the sequence. token_ids (List[int]): The initial token IDs to be stored in the block. block_size (int): The maximum number of token IDs that can be stored in the block. allocator (BlockAllocator): The block allocator associated with this block. block_id (Optional[int], optional): The physical block index of this block. Defaults to None, which means no allocation has been made. _cow_target (Optional[Block], optional): The copy-on-write target block. If not provided, it defaults to self. """ def __init__( self, prev_block: Block, token_ids: List[int], block_size: int, allocator: BlockAllocator, block_id: Optional[int] = None, _cow_target: Optional[Block] = None, ): self._token_ids = [] self._block_size = block_size self._prev_block = prev_block self._block_id = block_id self._allocator = allocator self._cow_target = _cow_target if _cow_target is not None else self self._append_token_ids_no_cow(token_ids) def append_token_ids(self, token_ids: List[int]) -> None: """Appends the given token IDs to the block, instructing the allocator to perform a copy-on-write if necessary. Args: token_ids (List[int]): The token IDs to be appended to the block. """ self._append_token_ids_no_cow(token_ids) if self._block_id is not None: self._block_id = self._allocator.cow_block_if_not_appendable( self._cow_target) def _append_token_ids_no_cow(self, token_ids: List[int]) -> None: assert self.num_empty_slots >= len(token_ids) self._token_ids.extend(token_ids) @property def block_id(self) -> Optional[int]: return self._block_id @block_id.setter def block_id(self, value: Optional[int]) -> None: self._block_id = value @property def is_full(self) -> bool: return self.num_empty_slots == 0 @property def num_empty_slots(self) -> int: return self._block_size - len(self._token_ids) @property def token_ids(self) -> List[int]: return self._token_ids def block_size(self) -> int: return self._block_size @property def prev_block(self) -> Optional["Block"]: return self._prev_block