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475from __future__ import annotations
import dataclasses
from abc import ABC, abstractmethod
from collections.abc import Mapping
from typing import Any, Generic, TypeAlias, TypeVar, overload
from configs import dify_config
from core.file.models import File
from core.variables.segments import (
ArrayFileSegment,
ArraySegment,
BooleanSegment,
FileSegment,
FloatSegment,
IntegerSegment,
NoneSegment,
ObjectSegment,
Segment,
StringSegment,
)
from core.variables.utils import dumps_with_segments
from core.workflow.nodes.variable_assigner.common.helpers import UpdatedVariable
_MAX_DEPTH = 100
class _QAKeys:
"""dict keys for _QAStructure"""
QA_CHUNKS = "qa_chunks"
QUESTION = "question"
ANSWER = "answer"
class _PCKeys:
"""dict keys for _ParentChildStructure"""
PARENT_MODE = "parent_mode"
PARENT_CHILD_CHUNKS = "parent_child_chunks"
PARENT_CONTENT = "parent_content"
CHILD_CONTENTS = "child_contents"
_T = TypeVar("_T")
@dataclasses.dataclass(frozen=True)
class _PartResult(Generic[_T]):
value: _T
value_size: int
truncated: bool
class MaxDepthExceededError(Exception):
pass
class UnknownTypeError(Exception):
pass
JSONTypes: TypeAlias = int | float | str | list[object] | dict[str, object] | None | bool
@dataclasses.dataclass(frozen=True)
class TruncationResult:
result: Segment
truncated: bool
class BaseTruncator(ABC):
@abstractmethod
def truncate(self, segment: Segment) -> TruncationResult:
pass
@abstractmethod
def truncate_variable_mapping(self, v: Mapping[str, Any]) -> tuple[Mapping[str, Any], bool]:
pass
class VariableTruncator(BaseTruncator):
"""
Handles variable truncation with structure-preserving strategies.
This class implements intelligent truncation that prioritizes maintaining data structure
integrity while ensuring the final size doesn't exceed specified limits.
Uses recursive size calculation to avoid repeated JSON serialization.
"""
def __init__(
self,
string_length_limit=5000,
array_element_limit: int = 20,
max_size_bytes: int = 1024_000, # 1000 KiB
):
if string_length_limit <= 3:
raise ValueError("string_length_limit should be greater than 3.")
self._string_length_limit = string_length_limit
if array_element_limit <= 0:
raise ValueError("array_element_limit should be greater than 0.")
self._array_element_limit = array_element_limit
if max_size_bytes <= 0:
raise ValueError("max_size_bytes should be greater than 0.")
self._max_size_bytes = max_size_bytes
@classmethod
def default(cls) -> VariableTruncator:
return VariableTruncator(
max_size_bytes=dify_config.WORKFLOW_VARIABLE_TRUNCATION_MAX_SIZE,
array_element_limit=dify_config.WORKFLOW_VARIABLE_TRUNCATION_ARRAY_LENGTH,
string_length_limit=dify_config.WORKFLOW_VARIABLE_TRUNCATION_STRING_LENGTH,
)
def truncate_variable_mapping(self, v: Mapping[str, Any]) -> tuple[Mapping[str, Any], bool]:
"""
`truncate_variable_mapping` is responsible for truncating variable mappings
generated during workflow execution, such as `inputs`, `process_data`, or `outputs`
of a WorkflowNodeExecution record. This ensures the mappings remain within the
specified size limits while preserving their structure.
"""
budget = self._max_size_bytes
is_truncated = False
truncated_mapping: dict[str, Any] = {}
length = len(v.items())
used_size = 0
for key, value in v.items():
used_size += self.calculate_json_size(key)
if used_size > budget:
truncated_mapping[key] = "..."
continue
value_budget = (budget - used_size) // (length - len(truncated_mapping))
if isinstance(value, Segment):
part_result = self._truncate_segment(value, value_budget)
else:
part_result = self._truncate_json_primitives(value, value_budget)
is_truncated = is_truncated or part_result.truncated
truncated_mapping[key] = part_result.value
used_size += part_result.value_size
return truncated_mapping, is_truncated
@staticmethod
def _segment_need_truncation(segment: Segment) -> bool:
if isinstance(
segment,
(NoneSegment, FloatSegment, IntegerSegment, FileSegment, BooleanSegment, ArrayFileSegment),
):
return False
return True
@staticmethod
def _json_value_needs_truncation(value: Any) -> bool:
if value is None:
return False
if isinstance(value, (bool, int, float)):
return False
return True
def truncate(self, segment: Segment) -> TruncationResult:
if isinstance(segment, StringSegment):
result = self._truncate_segment(segment, self._string_length_limit)
else:
result = self._truncate_segment(segment, self._max_size_bytes)
if result.value_size > self._max_size_bytes:
if isinstance(result.value, str):
result = self._truncate_string(result.value, self._max_size_bytes)
return TruncationResult(StringSegment(value=result.value), True)
# Apply final fallback - convert to JSON string and truncate
json_str = dumps_with_segments(result.value, ensure_ascii=False)
if len(json_str) > self._max_size_bytes:
json_str = json_str[: self._max_size_bytes] + "..."
return TruncationResult(result=StringSegment(value=json_str), truncated=True)
return TruncationResult(
result=segment.model_copy(update={"value": result.value.value}), truncated=result.truncated
)
def _truncate_segment(self, segment: Segment, target_size: int) -> _PartResult[Segment]:
"""
Apply smart truncation to a variable value.
Args:
value: The value to truncate (can be Segment or raw value)
Returns:
TruncationResult with truncated data and truncation status
"""
if not VariableTruncator._segment_need_truncation(segment):
return _PartResult(segment, self.calculate_json_size(segment.value), False)
result: _PartResult[Any]
# Apply type-specific truncation with target size
if isinstance(segment, ArraySegment):
result = self._truncate_array(segment.value, target_size)
elif isinstance(segment, StringSegment):
result = self._truncate_string(segment.value, target_size)
elif isinstance(segment, ObjectSegment):
result = self._truncate_object(segment.value, target_size)
else:
raise AssertionError("this should be unreachable.")
return _PartResult(
value=segment.model_copy(update={"value": result.value}),
value_size=result.value_size,
truncated=result.truncated,
)
@staticmethod
def calculate_json_size(value: Any, depth=0) -> int:
"""Recursively calculate JSON size without serialization."""
if isinstance(value, Segment):
return VariableTruncator.calculate_json_size(value.value)
if isinstance(value, UpdatedVariable):
# TODO(Workflow): migrate UpdatedVariable serialization upstream and drop this fallback.
return VariableTruncator.calculate_json_size(value.model_dump(), depth=depth + 1)
if depth > _MAX_DEPTH:
raise MaxDepthExceededError()
if isinstance(value, str):
# Ideally, the size of strings should be calculated based on their utf-8 encoded length.
# However, this adds complexity as we would need to compute encoded sizes consistently
# throughout the code. Therefore, we approximate the size using the string's length.
# Rough estimate: number of characters, plus 2 for quotes
return len(value) + 2
elif isinstance(value, (int, float)):
return len(str(value))
elif isinstance(value, bool):
return 4 if value else 5 # "true" or "false"
elif value is None:
return 4 # "null"
elif isinstance(value, list):
# Size = sum of elements + separators + brackets
total = 2 # "[]"
for i, item in enumerate(value):
if i > 0:
total += 1 # ","
total += VariableTruncator.calculate_json_size(item, depth=depth + 1)
return total
elif isinstance(value, dict):
# Size = sum of keys + values + separators + brackets
total = 2 # "{}"
for index, key in enumerate(value.keys()):
if index > 0:
total += 1 # ","
total += VariableTruncator.calculate_json_size(str(key), depth=depth + 1) # Key as string
total += 1 # ":"
total += VariableTruncator.calculate_json_size(value[key], depth=depth + 1)
return total
elif isinstance(value, File):
return VariableTruncator.calculate_json_size(value.model_dump(), depth=depth + 1)
else:
raise UnknownTypeError(f"got unknown type {type(value)}")
def _truncate_string(self, value: str, target_size: int) -> _PartResult[str]:
if (size := self.calculate_json_size(value)) < target_size:
return _PartResult(value, size, False)
if target_size < 5:
return _PartResult("...", 5, True)
truncated_size = min(self._string_length_limit, target_size - 5)
truncated_value = value[:truncated_size] + "..."
return _PartResult(truncated_value, self.calculate_json_size(truncated_value), True)
def _truncate_array(self, value: list[object], target_size: int) -> _PartResult[list[object]]:
"""
Truncate array with correct strategy:
1. First limit to 20 items
2. If still too large, truncate individual items
"""
truncated_value: list[object] = []
truncated = False
used_size = self.calculate_json_size([])
target_length = self._array_element_limit
for i, item in enumerate(value):
# Dirty fix:
# The output of `Start` node may contain list of `File` elements,
# causing `AssertionError` while invoking `_truncate_json_primitives`.
#
# This check ensures that `list[File]` are handled separately
if isinstance(item, File):
truncated_value.append(item)
continue
if i >= target_length:
return _PartResult(truncated_value, used_size, True)
if i > 0:
used_size += 1 # Account for comma
if used_size > target_size:
break
remaining_budget = target_size - used_size
if item is None or isinstance(item, (str, list, dict, bool, int, float, UpdatedVariable)):
part_result = self._truncate_json_primitives(item, remaining_budget)
else:
raise UnknownTypeError(f"got unknown type {type(item)} in array truncation")
truncated_value.append(part_result.value)
used_size += part_result.value_size
truncated = part_result.truncated
return _PartResult(truncated_value, used_size, truncated)
@classmethod
def _maybe_qa_structure(cls, m: Mapping[str, Any]) -> bool:
qa_chunks = m.get(_QAKeys.QA_CHUNKS)
if qa_chunks is None:
return False
if not isinstance(qa_chunks, list):
return False
return True
@classmethod
def _maybe_parent_child_structure(cls, m: Mapping[str, Any]) -> bool:
parent_mode = m.get(_PCKeys.PARENT_MODE)
if parent_mode is None:
return False
if not isinstance(parent_mode, str):
return False
parent_child_chunks = m.get(_PCKeys.PARENT_CHILD_CHUNKS)
if parent_child_chunks is None:
return False
if not isinstance(parent_child_chunks, list):
return False
return True
def _truncate_object(self, mapping: Mapping[str, Any], target_size: int) -> _PartResult[Mapping[str, Any]]:
"""
Truncate object with key preservation priority.
Strategy:
1. Keep all keys, truncate values to fit within budget
2. If still too large, drop keys starting from the end
"""
if not mapping:
return _PartResult(mapping, self.calculate_json_size(mapping), False)
truncated_obj = {}
truncated = False
used_size = self.calculate_json_size({})
# Sort keys to ensure deterministic behavior
sorted_keys = sorted(mapping.keys())
for i, key in enumerate(sorted_keys):
if used_size > target_size:
# No more room for additional key-value pairs
truncated = True
break
pair_size = 0
if i > 0:
pair_size += 1 # Account for comma
# Calculate budget for this key-value pair
# do not try to truncate keys, as we want to keep the structure of
# object.
key_size = self.calculate_json_size(key) + 1 # +1 for ":"
pair_size += key_size
remaining_pairs = len(sorted_keys) - i
value_budget = max(0, (target_size - pair_size - used_size) // remaining_pairs)
if value_budget <= 0:
truncated = True
break
# Truncate the value to fit within budget
value = mapping[key]
if isinstance(value, Segment):
value_result = self._truncate_segment(value, value_budget)
else:
value_result = self._truncate_json_primitives(mapping[key], value_budget)
truncated_obj[key] = value_result.value
pair_size += value_result.value_size
used_size += pair_size
if value_result.truncated:
truncated = True
return _PartResult(truncated_obj, used_size, truncated)
@overload
def _truncate_json_primitives(
self, val: UpdatedVariable, target_size: int
) -> _PartResult[Mapping[str, object]]: ...
@overload
def _truncate_json_primitives(self, val: str, target_size: int) -> _PartResult[str]: ...
@overload
def _truncate_json_primitives(self, val: list[object], target_size: int) -> _PartResult[list[object]]: ...
@overload
def _truncate_json_primitives(self, val: dict[str, object], target_size: int) -> _PartResult[dict[str, object]]: ...
@overload
def _truncate_json_primitives(self, val: bool, target_size: int) -> _PartResult[bool]: ... # type: ignore
@overload
def _truncate_json_primitives(self, val: int, target_size: int) -> _PartResult[int]: ...
@overload
def _truncate_json_primitives(self, val: float, target_size: int) -> _PartResult[float]: ...
@overload
def _truncate_json_primitives(self, val: None, target_size: int) -> _PartResult[None]: ...
@overload
def _truncate_json_primitives(self, val: File, target_size: int) -> _PartResult[File]: ...
def _truncate_json_primitives(
self,
val: UpdatedVariable | File | str | list[object] | dict[str, object] | bool | int | float | None,
target_size: int,
) -> _PartResult[Any]:
"""Truncate a value within an object to fit within budget."""
if isinstance(val, UpdatedVariable):
# TODO(Workflow): push UpdatedVariable normalization closer to its producer.
return self._truncate_object(val.model_dump(), target_size)
elif isinstance(val, str):
return self._truncate_string(val, target_size)
elif isinstance(val, list):
return self._truncate_array(val, target_size)
elif isinstance(val, dict):
return self._truncate_object(val, target_size)
elif isinstance(val, File):
# File objects should not be truncated, return as-is
return _PartResult(val, self.calculate_json_size(val), False)
elif val is None or isinstance(val, (bool, int, float)):
return _PartResult(val, self.calculate_json_size(val), False)
else:
raise AssertionError("this statement should be unreachable.")
class DummyVariableTruncator(BaseTruncator):
"""
A no-op variable truncator that doesn't truncate any data.
This is used for Service API calls where truncation should be disabled
to maintain backward compatibility and provide complete data.
"""
def truncate_variable_mapping(self, v: Mapping[str, Any]) -> tuple[Mapping[str, Any], bool]:
"""
Return original mapping without truncation.
Args:
v: The variable mapping to process
Returns:
Tuple of (original_mapping, False) where False indicates no truncation occurred
"""
return v, False
def truncate(self, segment: Segment) -> TruncationResult:
"""
Return original segment without truncation.
Args:
segment: The segment to process
Returns:
The original segment unchanged
"""
# For Service API, we want to preserve the original segment
# without any truncation, so just return it as-is
return TruncationResult(result=segment, truncated=False)