|
| 1 | +""" |
| 2 | +Global request context management for trace_id and request-scoped data. |
| 3 | +
|
| 4 | +This module provides optional trace_id functionality that can be enabled |
| 5 | +when using the API components. It uses ContextVar to ensure thread safety |
| 6 | +and request isolation. |
| 7 | +""" |
| 8 | + |
| 9 | +import uuid |
| 10 | + |
| 11 | +from collections.abc import Callable |
| 12 | +from contextvars import ContextVar |
| 13 | +from typing import Any |
| 14 | + |
| 15 | + |
| 16 | +# Global context variable for request-scoped data |
| 17 | +_request_context: ContextVar[dict[str, Any] | None] = ContextVar("request_context", default=None) |
| 18 | + |
| 19 | + |
| 20 | +class RequestContext: |
| 21 | + """ |
| 22 | + Request-scoped context object that holds trace_id and other request data. |
| 23 | +
|
| 24 | + This provides a Flask g-like object for FastAPI applications. |
| 25 | + """ |
| 26 | + |
| 27 | + def __init__(self, trace_id: str | None = None): |
| 28 | + self.trace_id = trace_id or str(uuid.uuid4()) |
| 29 | + self._data: dict[str, Any] = {} |
| 30 | + |
| 31 | + def set(self, key: str, value: Any) -> None: |
| 32 | + """Set a value in the context.""" |
| 33 | + self._data[key] = value |
| 34 | + |
| 35 | + def get(self, key: str, default: Any | None = None) -> Any: |
| 36 | + """Get a value from the context.""" |
| 37 | + return self._data.get(key, default) |
| 38 | + |
| 39 | + def __setattr__(self, name: str, value: Any) -> None: |
| 40 | + if name.startswith("_") or name == "trace_id": |
| 41 | + super().__setattr__(name, value) |
| 42 | + else: |
| 43 | + if not hasattr(self, "_data"): |
| 44 | + super().__setattr__(name, value) |
| 45 | + else: |
| 46 | + self._data[name] = value |
| 47 | + |
| 48 | + def __getattr__(self, name: str) -> Any: |
| 49 | + if hasattr(self, "_data") and name in self._data: |
| 50 | + return self._data[name] |
| 51 | + raise AttributeError(f"'{self.__class__.__name__}' object has no attribute '{name}'") |
| 52 | + |
| 53 | + def to_dict(self) -> dict[str, Any]: |
| 54 | + """Convert context to dictionary.""" |
| 55 | + return {"trace_id": self.trace_id, "data": self._data.copy()} |
| 56 | + |
| 57 | + |
| 58 | +def set_request_context(context: RequestContext) -> None: |
| 59 | + """ |
| 60 | + Set the current request context. |
| 61 | +
|
| 62 | + This is typically called by the API dependency injection system. |
| 63 | + """ |
| 64 | + _request_context.set(context.to_dict()) |
| 65 | + |
| 66 | + |
| 67 | +def get_current_trace_id() -> str | None: |
| 68 | + """ |
| 69 | + Get the current request's trace_id. |
| 70 | +
|
| 71 | + Returns: |
| 72 | + The trace_id if available, None otherwise. |
| 73 | + """ |
| 74 | + context = _request_context.get() |
| 75 | + if context: |
| 76 | + return context.get("trace_id") |
| 77 | + return None |
| 78 | + |
| 79 | + |
| 80 | +def get_current_context() -> RequestContext | None: |
| 81 | + """ |
| 82 | + Get the current request context. |
| 83 | +
|
| 84 | + Returns: |
| 85 | + The current RequestContext if available, None otherwise. |
| 86 | + """ |
| 87 | + context_dict = _request_context.get() |
| 88 | + if context_dict: |
| 89 | + ctx = RequestContext(trace_id=context_dict.get("trace_id")) |
| 90 | + ctx._data = context_dict.get("data", {}).copy() |
| 91 | + return ctx |
| 92 | + return None |
| 93 | + |
| 94 | + |
| 95 | +def require_context() -> RequestContext: |
| 96 | + """ |
| 97 | + Get the current request context, raising an error if not available. |
| 98 | +
|
| 99 | + Returns: |
| 100 | + The current RequestContext. |
| 101 | +
|
| 102 | + Raises: |
| 103 | + RuntimeError: If called outside of a request context. |
| 104 | + """ |
| 105 | + context = get_current_context() |
| 106 | + if context is None: |
| 107 | + raise RuntimeError( |
| 108 | + "No request context available. This function must be called within a request handler." |
| 109 | + ) |
| 110 | + return context |
| 111 | + |
| 112 | + |
| 113 | +# Type for trace_id getter function |
| 114 | +TraceIdGetter = Callable[[], str | None] |
| 115 | + |
| 116 | +# Global variable to hold the trace_id getter function |
| 117 | +_trace_id_getter: TraceIdGetter | None = None |
| 118 | + |
| 119 | + |
| 120 | +def set_trace_id_getter(getter: TraceIdGetter) -> None: |
| 121 | + """ |
| 122 | + Set a custom trace_id getter function. |
| 123 | +
|
| 124 | + This allows the logging system to retrieve trace_id without importing |
| 125 | + API-specific modules. |
| 126 | + """ |
| 127 | + global _trace_id_getter |
| 128 | + _trace_id_getter = getter |
| 129 | + |
| 130 | + |
| 131 | +def get_trace_id_for_logging() -> str | None: |
| 132 | + """ |
| 133 | + Get trace_id for logging purposes. |
| 134 | +
|
| 135 | + This function is used by the logging system and will use either |
| 136 | + the custom getter function or fall back to the default context. |
| 137 | + """ |
| 138 | + if _trace_id_getter: |
| 139 | + try: |
| 140 | + return _trace_id_getter() |
| 141 | + except Exception: |
| 142 | + pass |
| 143 | + return get_current_trace_id() |
| 144 | + |
| 145 | + |
| 146 | +# Initialize the default trace_id getter |
| 147 | +set_trace_id_getter(get_current_trace_id) |
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