chore: import upstream snapshot with attribution

python/sglang/srt/mem_cache/events.py

@@ -0,0 +1,128 @@
+# 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 radix node.
+        # ``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)
+
+            block_hashes = []
+            logical_len = len(node.key)
+            page_index = 0
+            for start in range(0, logical_len, self.page_size):
+                end = min(start + self.page_size, logical_len)
+                if end <= start:
+                    continue
+
+                block_hashes.append(hash_str_to_int64(node.hash_value[page_index]))
+                page_index += 1
+
+            if block_hashes:
+                self.kv_event_queue.append(
+                    BlockRemoved(block_hashes=block_hashes, medium=medium)
+                )
+
+    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