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Erik JohnstonandClaude Fable 5
c3dfbfc6ef
The "current logcontext" slot moves from a Python threading.local into the Rust extension, together with a native port of LoggingContext. A Python thread-local is invisible to Rust: each tokio worker thread would see its own slot, permanently at the sentinel, so logging emitted from Rust could not be attributed to the request that caused it. This lays the storage groundwork; a follow-up change gives tokio tasks a task-scoped capture (see the module-doc TODO). Design notes, for review: - The slot is typed: Option<Py<LoggingContext>>, with None representing the sentinel. The _Sentinel class and SENTINEL_CONTEXT singleton stay pure Python, unchanged; thin wrappers on current_context and set_current_context in synapse.logging.context convert between the singleton and None at the boundary, so no Rust code ever sees or produces the sentinel object. pyo3's extraction enforces the type: anything that is not a LoggingContext (or subclass) or None raises TypeError. - The accounting policy is native too: set_current_context reads the thread rusage once via libc (no per-switch struct_rusage allocation) and runs the stop/start bookkeeping inline for base LoggingContexts, only dispatching through Python for subclasses (BackgroundProcessLoggingContext) so their overrides run. start()/stop() now take an Optional[tuple[float, float]] instead of a struct_rusage, the get_thread_resource_usage/is_thread_resource_usage_supported/ get_thread_id module helpers are gone, LoggingContext.previous_context is now Optional[LoggingContext] (None where it used to hold SENTINEL_CONTEXT), and the nominally-private _resource_usage attribute is no longer exposed (nothing read it; use get_resource_usage()) — worth an upgrade note when this is released, as out-of-tree code may rely on the old shapes. - The switch path avoids per-operation allocation and Python round-trips: names are stored as Py<PyString> (LoggingContextFilter reads server_name and str(context) per log record process-wide, now INCREF-only), error messages materialise the context name only in the cold branches, and the thread id is read via PyThread_get_thread_ident (the exact value threading.get_ident() returns) rather than by calling into Python. - The attribute surface, method set and error-message wording are a compatibility contract, pinned by the characterization tests (which now exercise the tuple-based start/stop API). - The opt-in synapse.logging.context.debug switch traces are emitted from Rust via pyo3-log, whose level cache only refreshes on reset_logging_config(); docs/log_contexts.md documents the manhole procedure. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01JFbRtswu7rsHrttJFauUUb