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sglang/python/sglang/srt/mem_cache/events.py
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# Copyright 2025 SGLang Team
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""KV cache placement event emission mixin.
The mixin produces the ``BlockStored`` / ``BlockRemoved`` / ``AllBlocksCleared``
events consumed by KV-aware routers (e.g. dynamo).
"""
from typing import Any
from sglang.srt.disaggregation.kv_events import (
AllBlocksCleared,
BlockRemoved,
BlockStored,
StorageMedium,
)
from sglang.srt.mem_cache.utils import (
compute_node_hash_values,
hash_str_to_int64,
)
class KVCacheEventMixin:
def _record_store_event(self, node: Any, medium=None):
# One BlockStored per ``page_size`` chunk.
# ``medium`` defaults to StorageMedium.GPU but callers may override
# for lower-tier insertions (e.g. StorageMedium.CPU for host/L2 cache).
if self.enable_kv_cache_events:
if medium is None:
medium = StorageMedium.GPU
# Compute hash_value lazily if not already set
if node.hash_value is None:
node.hash_value = compute_node_hash_values(node, self.page_size)
# Get parent's last hash value for first page
parent_block_hash = None
if node.parent is not None and node.parent != self.root_node:
if (
node.parent.hash_value is not None
and len(node.parent.hash_value) > 0
):
parent_block_hash = hash_str_to_int64(node.parent.hash_value[-1])
page_index = 0
logical_len = len(node.key)
is_bigram = node.key.is_bigram
raw = node.key.token_ids
for start in range(0, logical_len, self.page_size):
end = min(start + self.page_size, logical_len)
if end <= start:
continue
# Preserve historical event payload: bigram pages expose tuples.
if is_bigram:
page_tokens = [(raw[j], raw[j + 1]) for j in range(start, end)]
else:
page_tokens = list(raw[start:end])
block_hash = hash_str_to_int64(node.hash_value[page_index])
self.kv_event_queue.append(
BlockStored(
block_hashes=[block_hash],
parent_block_hash=parent_block_hash,
token_ids=page_tokens,
block_size=len(page_tokens),
lora_id=None,
medium=medium,
)
)
parent_block_hash = block_hash
page_index += 1
def _record_remove_event(self, node: Any, medium=None):
# One BlockRemoved per chunk.
# ``medium`` defaults to StorageMedium.GPU but callers may override for
# lower-tier removals (e.g. StorageMedium.CPU when evicting from host).
if self.enable_kv_cache_events:
if medium is None:
medium = StorageMedium.GPU
# Compute hash_value lazily if not already set (must match what was stored)
if node.hash_value is None:
node.hash_value = compute_node_hash_values(node, self.page_size)
page_index = 0
logical_len = len(node.key)
for start in range(0, logical_len, self.page_size):
end = min(start + self.page_size, logical_len)
if end <= start:
continue
block_hash = hash_str_to_int64(node.hash_value[page_index])
self.kv_event_queue.append(
BlockRemoved(block_hashes=[block_hash], medium=medium)
)
page_index += 1
def _record_all_cleared_event(self):
if self.enable_kv_cache_events:
self.kv_event_queue.append(AllBlocksCleared())
def take_events(self):
"""Atomically takes all events and clears the queue.
Returns:
A list of KV cache events.
"""
if not self.enable_kv_cache_events:
return []
events = self.kv_event_queue
self.kv_event_queue = []
return events