File size: 6,111 Bytes
8ede856 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 | from ..message import Message
class ContextTruncator:
"""Context truncator."""
def _has_tool_calls(self, message: Message) -> bool:
"""Check if a message contains tool calls."""
return (
message.role == "assistant"
and message.tool_calls is not None
and len(message.tool_calls) > 0
)
def fix_messages(self, messages: list[Message]) -> list[Message]:
"""修复消息列表，确保 tool call 和 tool response 的配对关系有效。
此方法确保：
1. 每个 `tool` 消息前面都有一个包含 tool_calls 的 `assistant` 消息
2. 每个包含 tool_calls 的 `assistant` 消息后面都有对应的 `tool` 响应
这是 OpenAI Chat Completions API 规范的要求（Gemini 对此执行严格检查）。
"""
if not messages:
return messages
fixed_messages: list[Message] = []
pending_assistant: Message | None = None
pending_tools: list[Message] = []
def flush_pending_if_valid() -> None:
nonlocal pending_assistant, pending_tools
if pending_assistant is not None and pending_tools:
fixed_messages.append(pending_assistant)
fixed_messages.extend(pending_tools)
pending_assistant = None
pending_tools = []
for msg in messages:
if msg.role == "tool":
# 只有在有挂起的 assistant(tool_calls) 时才记录 tool 响应
if pending_assistant is not None:
pending_tools.append(msg)
# else: 孤立的 tool 消息，直接忽略
continue
if self._has_tool_calls(msg):
# 遇到新的 assistant(tool_calls) 前，先处理旧的 pending 链
flush_pending_if_valid()
pending_assistant = msg
continue
# 非 tool，且不含 tool_calls 的消息
# 先结束任何 pending 链，再正常追加
flush_pending_if_valid()
fixed_messages.append(msg)
# 结束时处理最后一个 pending 链
flush_pending_if_valid()
return fixed_messages
def truncate_by_turns(
self,
messages: list[Message],
keep_most_recent_turns: int,
drop_turns: int = 1,
) -> list[Message]:
"""截断上下文列表，确保不超过最大长度。
一个 turn 包含一个 user 消息和一个 assistant 消息。
这个方法会保证截断后的上下文列表符合 OpenAI 的上下文格式。
Args:
messages: 上下文列表
keep_most_recent_turns: 保留最近的对话轮数
drop_turns: 一次性丢弃的对话轮数
Returns:
截断后的上下文列表
"""
if keep_most_recent_turns == -1:
return messages
first_non_system = 0
for i, msg in enumerate(messages):
if msg.role != "system":
first_non_system = i
break
system_messages = messages[:first_non_system]
non_system_messages = messages[first_non_system:]
if len(non_system_messages) // 2 <= keep_most_recent_turns:
return messages
num_to_keep = keep_most_recent_turns - drop_turns + 1
if num_to_keep <= 0:
truncated_contexts = []
else:
truncated_contexts = non_system_messages[-num_to_keep * 2 :]
# 找到第一个 role 为 user 的索引，确保上下文格式正确
index = next(
(i for i, item in enumerate(truncated_contexts) if item.role == "user"),
None,
)
if index is not None and index > 0:
truncated_contexts = truncated_contexts[index:]
result = system_messages + truncated_contexts
return self.fix_messages(result)
def truncate_by_dropping_oldest_turns(
self,
messages: list[Message],
drop_turns: int = 1,
) -> list[Message]:
"""丢弃最旧的 N 个对话轮次。"""
if drop_turns <= 0:
return messages
first_non_system = 0
for i, msg in enumerate(messages):
if msg.role != "system":
first_non_system = i
break
system_messages = messages[:first_non_system]
non_system_messages = messages[first_non_system:]
if len(non_system_messages) // 2 <= drop_turns:
truncated_non_system = []
else:
truncated_non_system = non_system_messages[drop_turns * 2 :]
index = next(
(i for i, item in enumerate(truncated_non_system) if item.role == "user"),
None,
)
if index is not None:
truncated_non_system = truncated_non_system[index:]
elif truncated_non_system:
truncated_non_system = []
result = system_messages + truncated_non_system
return self.fix_messages(result)
def truncate_by_halving(
self,
messages: list[Message],
) -> list[Message]:
"""对半砍策略，删除 50% 的消息"""
if len(messages) <= 2:
return messages
first_non_system = 0
for i, msg in enumerate(messages):
if msg.role != "system":
first_non_system = i
break
system_messages = messages[:first_non_system]
non_system_messages = messages[first_non_system:]
messages_to_delete = len(non_system_messages) // 2
if messages_to_delete == 0:
return messages
truncated_non_system = non_system_messages[messages_to_delete:]
index = next(
(i for i, item in enumerate(truncated_non_system) if item.role == "user"),
None,
)
if index is not None:
truncated_non_system = truncated_non_system[index:]
result = system_messages + truncated_non_system
return self.fix_messages(result)
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