tracing capture interface

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/log/capture/mod.rs

@@ -0,0 +1,50 @@
+pub mod data;
+mod guard;
+pub mod layer;
+pub mod state;
+pub mod util;
+
+use std::sync::{Arc, Mutex};
+
+pub use data::Data;
+use guard::Guard;
+pub use layer::{Layer, Value};
+pub use state::State;
+pub use util::to_html;
+
+pub type Filter = dyn Fn(Data<'_>) -> bool + Send + Sync + 'static;
+pub type Closure = dyn FnMut(Data<'_>) + Send + Sync + 'static;
+
+/// Capture instance state.
+pub struct Capture {
+	state: Arc<State>,
+	filter: Option<Box<Filter>>,
+	closure: Mutex<Box<Closure>>,
+}
+
+impl Capture {
+	/// Construct a new capture instance. Capture does not start until the Guard
+	/// is in scope.
+	#[must_use]
+	pub fn new<F, C>(state: &Arc<State>, filter: Option<F>, closure: C) -> Arc<Self>
+	where
+		F: Fn(Data<'_>) -> bool + Send + Sync + 'static,
+		C: FnMut(Data<'_>) + Send + Sync + 'static,
+	{
+		Arc::new(Self {
+			state: state.clone(),
+			filter: filter.map(|p| -> Box<Filter> { Box::new(p) }),
+			closure: Mutex::new(Box::new(closure)),
+		})
+	}
+
+	#[must_use]
+	pub fn start(self: &Arc<Self>) -> Guard {
+		self.state.add(self);
+		Guard {
+			capture: self.clone(),
+		}
+	}
+
+	pub fn stop(self: &Arc<Self>) { self.state.del(self); }
+}