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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:11:38 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:12:43 +0000 |
commit | cf94bdc0742c13e2a0cac864c478b8626b266e1b (patch) | |
tree | 044670aa50cc5e2b4229aa0b6b3df6676730c0a6 /vendor/tracing-subscriber-0.3.3/src/reload.rs | |
parent | Adding debian version 1.65.0+dfsg1-2. (diff) | |
download | rustc-cf94bdc0742c13e2a0cac864c478b8626b266e1b.tar.xz rustc-cf94bdc0742c13e2a0cac864c478b8626b266e1b.zip |
Merging upstream version 1.66.0+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/tracing-subscriber-0.3.3/src/reload.rs')
-rw-r--r-- | vendor/tracing-subscriber-0.3.3/src/reload.rs | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/vendor/tracing-subscriber-0.3.3/src/reload.rs b/vendor/tracing-subscriber-0.3.3/src/reload.rs new file mode 100644 index 000000000..b8ec67dfa --- /dev/null +++ b/vendor/tracing-subscriber-0.3.3/src/reload.rs @@ -0,0 +1,237 @@ +//! Wrapper for a `Layer` to allow it to be dynamically reloaded. +//! +//! This module provides a [`Layer` type] which wraps another type implementing +//! the [`Layer` trait], allowing the wrapped type to be replaced with another +//! instance of that type at runtime. +//! +//! This can be used in cases where a subset of `Subscriber` functionality +//! should be dynamically reconfigured, such as when filtering directives may +//! change at runtime. Note that this layer introduces a (relatively small) +//! amount of overhead, and should thus only be used as needed. +//! +//! [`Layer` type]: struct.Layer.html +//! [`Layer` trait]: ../layer/trait.Layer.html +use crate::layer; +use crate::sync::RwLock; + +use std::{ + error, fmt, + marker::PhantomData, + sync::{Arc, Weak}, +}; +use tracing_core::{ + callsite, span, + subscriber::{Interest, Subscriber}, + Event, Metadata, +}; + +/// Wraps a `Layer`, allowing it to be reloaded dynamically at runtime. +#[derive(Debug)] +pub struct Layer<L, S> { + // TODO(eliza): this once used a `crossbeam_util::ShardedRwLock`. We may + // eventually wish to replace it with a sharded lock implementation on top + // of our internal `RwLock` wrapper type. If possible, we should profile + // this first to determine if it's necessary. + inner: Arc<RwLock<L>>, + _s: PhantomData<fn(S)>, +} + +/// Allows reloading the state of an associated `Layer`. +#[derive(Debug)] +pub struct Handle<L, S> { + inner: Weak<RwLock<L>>, + _s: PhantomData<fn(S)>, +} + +/// Indicates that an error occurred when reloading a layer. +#[derive(Debug)] +pub struct Error { + kind: ErrorKind, +} + +#[derive(Debug)] +enum ErrorKind { + SubscriberGone, + Poisoned, +} + +// ===== impl Layer ===== + +impl<L, S> crate::Layer<S> for Layer<L, S> +where + L: crate::Layer<S> + 'static, + S: Subscriber, +{ + fn on_layer(&mut self, subscriber: &mut S) { + try_lock!(self.inner.write(), else return).on_layer(subscriber); + } + + #[inline] + fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest { + try_lock!(self.inner.read(), else return Interest::sometimes()).register_callsite(metadata) + } + + #[inline] + fn enabled(&self, metadata: &Metadata<'_>, ctx: layer::Context<'_, S>) -> bool { + try_lock!(self.inner.read(), else return false).enabled(metadata, ctx) + } + + #[inline] + fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_new_span(attrs, id, ctx) + } + + #[inline] + fn on_record(&self, span: &span::Id, values: &span::Record<'_>, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_record(span, values, ctx) + } + + #[inline] + fn on_follows_from(&self, span: &span::Id, follows: &span::Id, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_follows_from(span, follows, ctx) + } + + #[inline] + fn on_event(&self, event: &Event<'_>, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_event(event, ctx) + } + + #[inline] + fn on_enter(&self, id: &span::Id, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_enter(id, ctx) + } + + #[inline] + fn on_exit(&self, id: &span::Id, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_exit(id, ctx) + } + + #[inline] + fn on_close(&self, id: span::Id, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_close(id, ctx) + } + + #[inline] + fn on_id_change(&self, old: &span::Id, new: &span::Id, ctx: layer::Context<'_, S>) { + try_lock!(self.inner.read()).on_id_change(old, new, ctx) + } +} + +impl<L, S> Layer<L, S> +where + L: crate::Layer<S> + 'static, + S: Subscriber, +{ + /// Wraps the given `Layer`, returning a `Layer` and a `Handle` that allows + /// the inner type to be modified at runtime. + pub fn new(inner: L) -> (Self, Handle<L, S>) { + let this = Self { + inner: Arc::new(RwLock::new(inner)), + _s: PhantomData, + }; + let handle = this.handle(); + (this, handle) + } + + /// Returns a `Handle` that can be used to reload the wrapped `Layer`. + pub fn handle(&self) -> Handle<L, S> { + Handle { + inner: Arc::downgrade(&self.inner), + _s: PhantomData, + } + } +} + +// ===== impl Handle ===== + +impl<L, S> Handle<L, S> +where + L: crate::Layer<S> + 'static, + S: Subscriber, +{ + /// Replace the current layer with the provided `new_layer`. + pub fn reload(&self, new_layer: impl Into<L>) -> Result<(), Error> { + self.modify(|layer| { + *layer = new_layer.into(); + }) + } + + /// Invokes a closure with a mutable reference to the current layer, + /// allowing it to be modified in place. + pub fn modify(&self, f: impl FnOnce(&mut L)) -> Result<(), Error> { + let inner = self.inner.upgrade().ok_or(Error { + kind: ErrorKind::SubscriberGone, + })?; + + let mut lock = try_lock!(inner.write(), else return Err(Error::poisoned())); + f(&mut *lock); + // Release the lock before rebuilding the interest cache, as that + // function will lock the new layer. + drop(lock); + + callsite::rebuild_interest_cache(); + Ok(()) + } + + /// Returns a clone of the layer's current value if it still exists. + /// Otherwise, if the subscriber has been dropped, returns `None`. + pub fn clone_current(&self) -> Option<L> + where + L: Clone, + { + self.with_current(L::clone).ok() + } + + /// Invokes a closure with a borrowed reference to the current layer, + /// returning the result (or an error if the subscriber no longer exists). + pub fn with_current<T>(&self, f: impl FnOnce(&L) -> T) -> Result<T, Error> { + let inner = self.inner.upgrade().ok_or(Error { + kind: ErrorKind::SubscriberGone, + })?; + let inner = try_lock!(inner.read(), else return Err(Error::poisoned())); + Ok(f(&*inner)) + } +} + +impl<L, S> Clone for Handle<L, S> { + fn clone(&self) -> Self { + Handle { + inner: self.inner.clone(), + _s: PhantomData, + } + } +} + +// ===== impl Error ===== + +impl Error { + fn poisoned() -> Self { + Self { + kind: ErrorKind::Poisoned, + } + } + + /// Returns `true` if this error occurred because the layer was poisoned by + /// a panic on another thread. + pub fn is_poisoned(&self) -> bool { + matches!(self.kind, ErrorKind::Poisoned) + } + + /// Returns `true` if this error occurred because the `Subscriber` + /// containing the reloadable layer was dropped. + pub fn is_dropped(&self) -> bool { + matches!(self.kind, ErrorKind::SubscriberGone) + } +} + +impl fmt::Display for Error { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let msg = match self.kind { + ErrorKind::SubscriberGone => "subscriber no longer exists", + ErrorKind::Poisoned => "lock poisoned", + }; + f.pad(msg) + } +} + +impl error::Error for Error {} |