Add tracing-trace

tracing-trace/src/bin/trace-to-firefox.rs

@@ -0,0 +1,18 @@
+use std::ffi::OsString;
+use std::io::Write;
+
+fn main() {
+    let input_file = std::env::args_os().nth(1).expect("missing <INPUT> file");
+    let input =
+        std::io::BufReader::new(std::fs::File::open(&input_file).expect("could not open <INPUT>"));
+    let trace = tracing_trace::TraceReader::new(input);
+    let profile =
+        tracing_trace::processor::firefox_profiler::to_firefox_profile(trace, "Meilisearch")
+            .unwrap();
+    let mut output_file = OsString::new();
+    output_file.push("firefox-");
+    output_file.push(input_file);
+    let mut output_file = std::io::BufWriter::new(std::fs::File::create(output_file).unwrap());
+    serde_json::to_writer(&mut output_file, &profile).unwrap();
+    output_file.flush().unwrap();
+}

tracing-trace/src/entry.rs

@@ -0,0 +1,96 @@
+use std::borrow::Cow;
+
+use serde::{Deserialize, Serialize};
+use tracing::span::Id as TracingId;
+
+#[derive(Debug, Serialize, Deserialize)]
+pub enum Entry {
+    /// A code location was accessed for the first time
+    NewCallsite(NewCallsite),
+
+    /// A new thread was accessed
+    NewThread(NewThread),
+
+    /// A new call started
+    NewSpan(NewSpan),
+
+    /// An already in-flight call started doing work.
+    ///
+    /// For synchronous functions, open should always be followed immediately by enter, exit and close,
+    /// but for asynchronous functions, work can suspend (exiting the span without closing it), and then
+    /// later resume (entering the span again without opening it).
+    ///
+    /// The timer for a span only starts when the span is entered.
+    SpanEnter(SpanEnter),
+
+    /// An in-flight call suspended and paused work.
+    ///
+    /// For synchronous functions, exit should always be followed immediately by close,
+    /// but for asynchronous functions, work can suspend and then later resume.
+    ///
+    /// The timer for a span pauses when the span is exited.
+    SpanExit(SpanExit),
+
+    /// A call ended
+    SpanClose(SpanClose),
+}
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, Hash)]
+pub struct SpanId(u64);
+
+impl From<&TracingId> for SpanId {
+    fn from(value: &TracingId) -> Self {
+        Self(value.into_u64())
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct NewCallsite {
+    pub call_id: ResourceId,
+    pub name: Cow<'static, str>,
+    pub module_path: Option<Cow<'static, str>>,
+    pub file: Option<Cow<'static, str>>,
+    pub line: Option<u32>,
+    pub target: Cow<'static, str>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct NewThread {
+    pub thread_id: ResourceId,
+    pub name: Option<String>,
+}
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+pub struct SpanEnter {
+    pub id: SpanId,
+    pub time: std::time::Duration,
+}
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+pub struct SpanExit {
+    pub id: SpanId,
+    pub time: std::time::Duration,
+}
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+pub struct NewSpan {
+    pub id: SpanId,
+    pub call_id: ResourceId,
+    pub parent_id: Option<SpanId>,
+    pub thread_id: ResourceId,
+}
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+pub struct SpanClose {
+    pub id: SpanId,
+    pub time: std::time::Duration,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, Hash)]
+pub struct ResourceId(pub(crate) usize);
+
+impl ResourceId {
+    pub fn to_usize(self) -> usize {
+        self.0
+    }
+}

tracing-trace/src/error.rs

@@ -0,0 +1,19 @@
+#[derive(Debug)]
+pub enum Error {
+    Json(serde_json::Error),
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("error de/serializing trace entry:")?;
+        match self {
+            Error::Json(error) => std::fmt::Display::fmt(&error, f),
+        }
+    }
+}
+
+impl From<serde_json::Error> for Error {
+    fn from(value: serde_json::Error) -> Self {
+        Self::Json(value)
+    }
+}

tracing-trace/src/layer.rs

@@ -0,0 +1,152 @@
+use std::borrow::Cow;
+use std::collections::HashMap;
+use std::io::Write;
+use std::ops::ControlFlow;
+use std::sync::RwLock;
+
+use tracing::span::{Attributes, Id as TracingId};
+use tracing::{Metadata, Subscriber};
+use tracing_subscriber::layer::Context;
+use tracing_subscriber::Layer;
+
+use crate::entry::{
+    Entry, NewCallsite, NewSpan, NewThread, ResourceId, SpanClose, SpanEnter, SpanExit, SpanId,
+};
+use crate::{Error, Trace};
+
+/// Layer that measures the time spent in spans.
+pub struct TraceLayer {
+    sender: std::sync::mpsc::Sender<Entry>,
+    callsites: RwLock<HashMap<OpaqueIdentifier, ResourceId>>,
+    start_time: std::time::Instant,
+    // TODO: kero add handle to allocator stats here
+}
+
+impl<W: Write> Trace<W> {
+    pub fn new(writer: W) -> (Self, TraceLayer) {
+        let (sender, receiver) = std::sync::mpsc::channel();
+        let trace = Trace { writer, receiver };
+        let layer = TraceLayer {
+            sender,
+            callsites: Default::default(),
+            start_time: std::time::Instant::now(),
+        };
+        (trace, layer)
+    }
+
+    pub fn receive(&mut self) -> Result<ControlFlow<(), ()>, Error> {
+        let Ok(entry) = self.receiver.recv() else {
+            return Ok(ControlFlow::Break(()));
+        };
+        self.write(entry)?;
+        Ok(ControlFlow::Continue(()))
+    }
+
+    pub fn write(&mut self, entry: Entry) -> Result<(), Error> {
+        Ok(serde_json::ser::to_writer(&mut self.writer, &entry)?)
+    }
+
+    pub fn try_receive(&mut self) -> Result<ControlFlow<(), ()>, Error> {
+        let Ok(entry) = self.receiver.try_recv() else {
+            return Ok(ControlFlow::Break(()));
+        };
+        self.write(entry)?;
+        Ok(ControlFlow::Continue(()))
+    }
+
+    pub fn flush(&mut self) -> Result<(), std::io::Error> {
+        self.writer.flush()
+    }
+}
+
+#[derive(PartialEq, Eq, Hash)]
+enum OpaqueIdentifier {
+    Thread(std::thread::ThreadId),
+    Call(tracing::callsite::Identifier),
+}
+
+impl TraceLayer {
+    fn resource_id(&self, opaque: OpaqueIdentifier) -> Option<ResourceId> {
+        self.callsites.read().unwrap().get(&opaque).copied()
+    }
+
+    fn register_resource_id(&self, opaque: OpaqueIdentifier) -> ResourceId {
+        let mut map = self.callsites.write().unwrap();
+        let len = map.len();
+        *map.entry(opaque).or_insert(ResourceId(len))
+    }
+
+    fn elapsed(&self) -> std::time::Duration {
+        self.start_time.elapsed()
+    }
+
+    fn send(&self, entry: Entry) {
+        // we never care that the other end hanged on us
+        let _ = self.sender.send(entry);
+    }
+
+    fn register_callsite(&self, metadata: &'static Metadata<'static>) -> ResourceId {
+        let call_id = self.register_resource_id(OpaqueIdentifier::Call(metadata.callsite()));
+
+        let module_path = metadata.module_path();
+        let file = metadata.file();
+        let line = metadata.line();
+        let name = metadata.name();
+        let target = metadata.target();
+
+        self.send(Entry::NewCallsite(NewCallsite {
+            call_id,
+            module_path: module_path.map(Cow::Borrowed),
+            file: file.map(Cow::Borrowed),
+            line,
+            name: Cow::Borrowed(name),
+            target: Cow::Borrowed(target),
+        }));
+        call_id
+    }
+
+    fn register_thread(&self) -> ResourceId {
+        let thread_id = std::thread::current().id();
+        let name = std::thread::current().name().map(ToOwned::to_owned);
+        let thread_id = self.register_resource_id(OpaqueIdentifier::Thread(thread_id));
+        self.send(Entry::NewThread(NewThread { thread_id, name }));
+        thread_id
+    }
+}
+
+impl<S> Layer<S> for TraceLayer
+where
+    S: Subscriber,
+{
+    fn on_new_span(&self, attrs: &Attributes<'_>, id: &TracingId, _ctx: Context<'_, S>) {
+        let call_id = self
+            .resource_id(OpaqueIdentifier::Call(attrs.metadata().callsite()))
+            .unwrap_or_else(|| self.register_callsite(attrs.metadata()));
+
+        let thread_id = self
+            .resource_id(OpaqueIdentifier::Thread(std::thread::current().id()))
+            .unwrap_or_else(|| self.register_thread());
+
+        let parent_id = attrs
+            .parent()
+            .cloned()
+            .or_else(|| tracing::Span::current().id())
+            .map(|id| SpanId::from(&id));
+
+        self.send(Entry::NewSpan(NewSpan { id: id.into(), call_id, parent_id, thread_id }));
+    }
+
+    fn on_enter(&self, id: &TracingId, _ctx: Context<'_, S>) {
+        // TODO kero: add memory here
+        self.send(Entry::SpanEnter(SpanEnter { id: id.into(), time: self.elapsed() }))
+    }
+
+    fn on_exit(&self, id: &TracingId, _ctx: Context<'_, S>) {
+        // TODO kero: add memory here
+        self.send(Entry::SpanExit(SpanExit { id: id.into(), time: self.elapsed() }))
+    }
+
+    fn on_close(&self, id: TracingId, _ctx: Context<'_, S>) {
+        self.send(Entry::SpanClose(SpanClose { id: Into::into(&id), time: self.elapsed() }))
+    }
+}

tracing-trace/src/lib.rs

@@ -0,0 +1,40 @@
+use std::io::{Read, Write};
+
+use entry::Entry;
+
+pub mod entry;
+mod error;
+pub mod layer;
+pub mod processor;
+
+pub use error::Error;
+
+pub struct Trace<W: Write> {
+    writer: W,
+    receiver: std::sync::mpsc::Receiver<Entry>,
+}
+
+pub struct TraceReader<R: Read> {
+    reader: R,
+}
+
+impl<R: Read> TraceReader<R> {
+    pub fn new(reader: R) -> Self {
+        Self { reader }
+    }
+
+    fn read(&mut self) -> Option<Result<Entry, Error>> {
+        serde_json::Deserializer::from_reader(&mut self.reader)
+            .into_iter()
+            .next()
+            .map(|res| res.map_err(Into::into))
+    }
+}
+
+impl<R: Read> Iterator for TraceReader<R> {
+    type Item = Result<Entry, Error>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.read()
+    }
+}

tracing-trace/src/main.rs

@@ -0,0 +1,133 @@
+use tracing::{instrument, Span};
+use tracing_error::{ErrorLayer, InstrumentResult, SpanTrace, TracedError};
+
+#[instrument(level = "trace", target = "profile::indexing")]
+fn foo() -> Result<(), TracedError<Error>> {
+    let _ = bar(40, 2);
+    bar(40, 2)
+}
+
+#[derive(Debug)]
+pub enum Error {
+    XTooBig,
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("x too big")
+    }
+}
+
+impl std::error::Error for Error {}
+
+#[instrument(level = "trace", target = "profile::indexing")]
+fn bar(x: u32, y: u32) -> Result<(), TracedError<Error>> {
+    let handle_ok = spawn_in_current_scope(move || baz(y));
+    let handle = spawn_in_current_scope(move || baz(x + y));
+    handle_ok.join().unwrap().and(handle.join().unwrap())
+}
+
+pub fn spawn_in_current_scope<F, T>(f: F) -> std::thread::JoinHandle<T>
+where
+    F: FnOnce() -> T + Send + 'static,
+    T: Send + 'static,
+{
+    let current = Span::current();
+    std::thread::spawn(move || {
+        let span = tracing::trace_span!(parent: &current, "thread_spawn", id = ?std::thread::current().id(), name = tracing::field::Empty);
+        if let Some(name) = std::thread::current().name() {
+            span.record("name", name);
+        }
+        span.in_scope(f)
+    })
+}
+
+#[instrument(level = "trace", target = "profile::indexing")]
+fn baz(x: u32) -> Result<(), TracedError<Error>> {
+    if x > 10 {
+        fibo_recursive(10);
+        return Err(Error::XTooBig).in_current_span();
+    }
+    Ok(())
+}
+
+#[instrument(level = "trace", target = "profile::indexing")]
+fn fibo_recursive(n: u32) -> u32 {
+    if n == 0 {
+        return 1;
+    }
+    if n == 1 {
+        return 2;
+    }
+    return fibo_recursive(n - 1) - fibo_recursive(n - 2);
+}
+
+use tracing_error::ExtractSpanTrace as _;
+use tracing_subscriber::layer::SubscriberExt as _;
+use tracing_trace::processor;
+
+fn on_panic(info: &std::panic::PanicInfo) {
+    let info = info.to_string();
+    let trace = SpanTrace::capture();
+    tracing::error!(%info, %trace);
+}
+
+fn main() {
+    let (mut trace, profiling_layer) =
+        tracing_trace::Trace::new(std::fs::File::create("trace.json").unwrap());
+
+    let subscriber = tracing_subscriber::registry()
+        // any number of other subscriber layers may be added before or
+        // after the `ErrorLayer`...
+        .with(ErrorLayer::default())
+        .with(profiling_layer)
+        /*.with(
+            tracing_subscriber::fmt::layer()
+                .with_line_number(true)
+                .with_span_events(FmtSpan::FULL), /*.with_filter(
+                                                      tracing_subscriber::filter::LevelFilter::from_level(tracing::Level::TRACE).and(
+                                                          tracing_subscriber::filter::Targets::new()
+                                                              .with_target("profile", tracing::Level::TRACE)
+                                                              .not(),
+                                                      ),
+                                                  )*/
+        )*/;
+
+    // set the subscriber as the default for the application
+    tracing::subscriber::set_global_default(subscriber).unwrap();
+
+    std::panic::set_hook(Box::new(on_panic));
+
+    let res = foo();
+
+    if let Err(error) = res {
+        print_extracted_spantraces(&error)
+    }
+
+    while trace.try_receive().unwrap().is_continue() {}
+
+    trace.flush().unwrap();
+
+    let trace = tracing_trace::TraceReader::new(std::fs::File::open("trace.json").unwrap());
+
+    let profile = processor::firefox_profiler::to_firefox_profile(trace, "test").unwrap();
+    serde_json::to_writer(std::fs::File::create("processed.json").unwrap(), &profile).unwrap();
+}
+
+fn print_extracted_spantraces(error: &(dyn std::error::Error + 'static)) {
+    let mut error = Some(error);
+    let mut ind = 0;
+
+    eprintln!("Error:");
+
+    while let Some(err) = error {
+        if let Some(spantrace) = err.span_trace() {
+            eprintln!("found a spantrace:\n{}", color_spantrace::colorize(spantrace));
+        } else {
+            eprintln!("{:>4}: {}", ind, err);
+        }
+
+        error = err.source();
+        ind += 1;
+    }
+}

tracing-trace/src/processor/firefox_profiler.rs

@@ -0,0 +1,255 @@
+use std::collections::HashMap;
+
+use fxprof_processed_profile::{
+    CategoryPairHandle, CpuDelta, Frame, FrameFlags, FrameInfo, MarkerDynamicField,
+    MarkerFieldFormat, MarkerLocation, MarkerSchema, MarkerSchemaField, Profile, ProfilerMarker,
+    ReferenceTimestamp, SamplingInterval, StringHandle, Timestamp,
+};
+use serde_json::json;
+
+use crate::entry::{
+    Entry, NewCallsite, NewSpan, ResourceId, SpanClose, SpanEnter, SpanExit, SpanId,
+};
+use crate::{Error, TraceReader};
+
+pub fn to_firefox_profile<R: std::io::Read>(
+    trace: TraceReader<R>,
+    app: &str,
+) -> Result<Profile, Error> {
+    let mut profile = Profile::new(
+        app,
+        ReferenceTimestamp::from_millis_since_unix_epoch(0.0),
+        SamplingInterval::from_nanos(15),
+    );
+
+    let mut last_timestamp = Timestamp::from_nanos_since_reference(0);
+    let main = profile.add_process(app, 0, last_timestamp);
+
+    let mut calls = HashMap::new();
+    let mut threads = HashMap::new();
+    let mut spans = HashMap::new();
+
+    let category = profile.add_category("general", fxprof_processed_profile::CategoryColor::Blue);
+    let subcategory = profile.add_subcategory(category, "subcategory");
+
+    // TODO kero: add counters profile.add_counters + last_memory_value
+
+    for entry in trace {
+        let entry = entry?;
+        match entry {
+            Entry::NewCallsite(callsite) => {
+                let string_handle = profile.intern_string(callsite.name.as_ref());
+                calls.insert(callsite.call_id, (callsite, string_handle));
+            }
+            Entry::NewThread(thread) => {
+                let thread_handle = profile.add_thread(
+                    main,
+                    thread.thread_id.to_usize() as u32,
+                    last_timestamp,
+                    threads.is_empty(),
+                );
+                if let Some(name) = &thread.name {
+                    profile.set_thread_name(thread_handle, name)
+                }
+                threads.insert(thread.thread_id, thread_handle);
+            }
+            Entry::NewSpan(span) => {
+                spans.insert(span.id, (span, SpanStatus::Outside));
+            }
+            Entry::SpanEnter(SpanEnter { id, time }) => {
+                let (_span, status) = spans.get_mut(&id).unwrap();
+
+                let SpanStatus::Outside = status else {
+                    continue;
+                };
+
+                *status = SpanStatus::Inside(time);
+
+                last_timestamp = Timestamp::from_nanos_since_reference(time.as_nanos() as u64);
+
+                /* TODO kero: compute delta and update them
+                profile.add_counter_sample(
+                    counter,
+                    timestamp,
+                    value_delta,
+                    number_of_operations_delta,
+                )
+                */
+            }
+            Entry::SpanExit(SpanExit { id, time }) => {
+                let (span, status) = spans.get_mut(&id).unwrap();
+
+                let SpanStatus::Inside(begin) = status else {
+                    continue;
+                };
+                last_timestamp = Timestamp::from_nanos_since_reference(time.as_nanos() as u64);
+
+                let begin = *begin;
+
+                *status = SpanStatus::Outside;
+
+                let span = *span;
+                let thread_handle = threads.get(&span.thread_id).unwrap();
+
+                let frames = make_frames(span, &spans, &calls, subcategory);
+
+                profile.add_sample(
+                    *thread_handle,
+                    to_timestamp(begin),
+                    frames.iter().rev().cloned(),
+                    CpuDelta::ZERO,
+                    1,
+                );
+                profile.add_sample(
+                    *thread_handle,
+                    to_timestamp(time),
+                    frames.iter().rev().cloned(),
+                    CpuDelta::from_nanos((time - begin).as_nanos() as u64),
+                    1,
+                );
+
+                /* TODO kero: compute delta and update them
+                profile.add_counter_sample(
+                    counter,
+                    timestamp,
+                    value_delta,
+                    number_of_operations_delta,
+                )
+                */
+
+                let (callsite, _) = calls.get(&span.call_id).unwrap();
+
+                let marker = SpanMarker { callsite, span: &span };
+
+                profile.add_marker_with_stack(
+                    *thread_handle,
+                    &callsite.name,
+                    marker,
+                    fxprof_processed_profile::MarkerTiming::Interval(
+                        to_timestamp(begin),
+                        to_timestamp(time),
+                    ),
+                    frames.iter().rev().cloned(),
+                )
+            }
+            Entry::SpanClose(SpanClose { id, time }) => {
+                spans.remove(&id);
+                last_timestamp = Timestamp::from_nanos_since_reference(time.as_nanos() as u64);
+            }
+        }
+    }
+
+    Ok(profile)
+}
+
+fn to_timestamp(time: std::time::Duration) -> Timestamp {
+    Timestamp::from_nanos_since_reference(time.as_nanos() as u64)
+}
+
+fn make_frames(
+    span: NewSpan,
+    spans: &HashMap<SpanId, (NewSpan, SpanStatus)>,
+    calls: &HashMap<ResourceId, (NewCallsite, StringHandle)>,
+    subcategory: CategoryPairHandle,
+) -> Vec<FrameInfo> {
+    let mut frames = Vec::new();
+    let mut current_span = span;
+    loop {
+        let frame = make_frame(current_span, calls, subcategory);
+        frames.push(frame);
+        if let Some(parent) = current_span.parent_id {
+            current_span = spans.get(&parent).unwrap().0;
+        } else {
+            break;
+        }
+    }
+    frames
+}
+
+fn make_frame(
+    span: NewSpan,
+    calls: &HashMap<ResourceId, (NewCallsite, StringHandle)>,
+    subcategory: CategoryPairHandle,
+) -> FrameInfo {
+    let (_, call) = calls.get(&span.call_id).unwrap();
+    FrameInfo { frame: Frame::Label(*call), category_pair: subcategory, flags: FrameFlags::empty() }
+}
+
+#[derive(Debug, Clone, Copy)]
+enum SpanStatus {
+    Outside,
+    Inside(std::time::Duration),
+}
+
+struct SpanMarker<'a> {
+    span: &'a NewSpan,
+    callsite: &'a NewCallsite,
+}
+
+impl<'a> ProfilerMarker for SpanMarker<'a> {
+    const MARKER_TYPE_NAME: &'static str = "span";
+
+    fn schema() -> MarkerSchema {
+        let fields = vec![
+            MarkerSchemaField::Dynamic(MarkerDynamicField {
+                key: "filename",
+                label: "File name",
+                format: MarkerFieldFormat::FilePath,
+                searchable: true,
+            }),
+            MarkerSchemaField::Dynamic(MarkerDynamicField {
+                key: "line",
+                label: "Line",
+                format: MarkerFieldFormat::Integer,
+                searchable: true,
+            }),
+            MarkerSchemaField::Dynamic(MarkerDynamicField {
+                key: "module_path",
+                label: "Module path",
+                format: MarkerFieldFormat::String,
+                searchable: true,
+            }),
+            MarkerSchemaField::Dynamic(MarkerDynamicField {
+                key: "span_id",
+                label: "Span ID",
+                format: MarkerFieldFormat::Integer,
+                searchable: true,
+            }),
+            MarkerSchemaField::Dynamic(MarkerDynamicField {
+                key: "thread_id",
+                label: "Thread ID",
+                format: MarkerFieldFormat::Integer,
+                searchable: true,
+            }),
+        ];
+
+        MarkerSchema {
+            type_name: Self::MARKER_TYPE_NAME,
+            locations: vec![
+                MarkerLocation::MarkerTable,
+                MarkerLocation::MarkerChart,
+                MarkerLocation::TimelineOverview,
+            ],
+            chart_label: None,
+            tooltip_label: Some("{marker.name} - {marker.data.filename}:{marker.data.line}"),
+            table_label: Some("{marker.data.filename}:{marker.data.line}"),
+            fields,
+        }
+    }
+
+    fn json_marker_data(&self) -> serde_json::Value {
+        let filename = self.callsite.file.as_deref();
+        let line = self.callsite.line;
+        let module_path = self.callsite.module_path.as_deref();
+        let span_id = self.span.id;
+        let thread_id = self.span.thread_id;
+        json!({
+            "type": Self::MARKER_TYPE_NAME,
+            "filename": filename,
+            "line": line,
+            "module_path": module_path,
+            "span_id": span_id,
+            "thread_id": thread_id,
+        })
+    }
+}

tracing-trace/src/processor/fmt.rs

@@ -0,0 +1,128 @@
+use std::collections::HashMap;
+use std::io::Read;
+
+use crate::entry::{
+    Entry, NewCallsite, NewSpan, NewThread, ResourceId, SpanClose, SpanEnter, SpanExit, SpanId,
+};
+use crate::{Error, TraceReader};
+
+#[derive(Debug, Clone, Copy)]
+enum SpanStatus {
+    Outside,
+    Inside(std::time::Duration),
+}
+
+pub fn print_trace<R: Read>(trace: TraceReader<R>) -> Result<(), Error> {
+    let mut calls = HashMap::new();
+    let mut threads = HashMap::new();
+    let mut spans = HashMap::new();
+    for entry in trace {
+        let entry = entry?;
+        match entry {
+            Entry::NewCallsite(callsite) => {
+                calls.insert(callsite.call_id, callsite);
+            }
+            Entry::NewThread(NewThread { thread_id, name }) => {
+                threads.insert(thread_id, name);
+            }
+            Entry::NewSpan(span) => {
+                spans.insert(span.id, (span, SpanStatus::Outside));
+            }
+            Entry::SpanEnter(SpanEnter { id, time }) => {
+                let (span, status) = spans.get_mut(&id).unwrap();
+
+                let SpanStatus::Outside = status else {
+                    continue;
+                };
+
+                *status = SpanStatus::Inside(time);
+
+                let span = *span;
+
+                println!(
+                    "[{}]{}::{} <-",
+                    print_thread(&threads, span.thread_id),
+                    print_backtrace(&spans, &calls, &span),
+                    print_span(&calls, &span)
+                );
+            }
+            Entry::SpanExit(SpanExit { id, time }) => {
+                let (span, status) = spans.get_mut(&id).unwrap();
+
+                let SpanStatus::Inside(begin) = status else {
+                    continue;
+                };
+                let begin = *begin;
+
+                *status = SpanStatus::Outside;
+
+                let span = *span;
+
+                println!(
+                    "[{}]{}::{} -> {}",
+                    print_thread(&threads, span.thread_id),
+                    print_backtrace(&spans, &calls, &span),
+                    print_span(&calls, &span),
+                    print_duration(time - begin),
+                )
+            }
+            Entry::SpanClose(SpanClose { id, time: _ }) => {
+                spans.remove(&id);
+            }
+        }
+    }
+    Ok(())
+}
+
+fn print_thread(threads: &HashMap<ResourceId, Option<String>>, thread_id: ResourceId) -> String {
+    let thread = threads.get(&thread_id).unwrap();
+    let thread =
+        thread.as_ref().cloned().unwrap_or_else(|| format!("ThreadId({})", thread_id.to_usize()));
+    thread
+}
+
+fn print_backtrace(
+    spans: &HashMap<SpanId, (NewSpan, SpanStatus)>,
+    calls: &HashMap<ResourceId, NewCallsite>,
+    span: &NewSpan,
+) -> String {
+    let mut parents = Vec::new();
+    let mut current = span.parent_id;
+    while let Some(current_id) = &current {
+        let (span, _) = spans.get(current_id).unwrap();
+        let callsite = calls.get(&span.call_id).unwrap();
+        parents.push(callsite.name.clone());
+
+        current = span.parent_id;
+    }
+
+    let x: Vec<String> = parents.into_iter().rev().map(|x| x.to_string()).collect();
+    x.join("::")
+}
+
+fn print_span(calls: &HashMap<ResourceId, NewCallsite>, span: &NewSpan) -> String {
+    let callsite = calls.get(&span.call_id).unwrap();
+    match (callsite.file.clone(), callsite.line) {
+        (Some(file), None) => format!("{} ({})", callsite.name, file),
+        (Some(file), Some(line)) => format!("{} ({}:{})", callsite.name, file, line),
+        _ => callsite.name.to_string(),
+    }
+}
+
+fn print_duration(duration: std::time::Duration) -> String {
+    if duration.as_nanos() < 1000 {
+        format!("{}ns", duration.as_nanos())
+    } else if duration.as_micros() < 1000 {
+        format!("{}μs", duration.as_micros())
+    } else if duration.as_millis() < 1000 {
+        format!("{}ms", duration.as_millis())
+    } else if duration.as_secs() < 120 {
+        format!("{}s", duration.as_secs())
+    } else if duration.as_secs_f64() / 60.0 < 60.0 {
+        format!("{}min", duration.as_secs_f64() / 60.0)
+    } else if duration.as_secs_f64() / 3600.0 < 8.0 {
+        format!("{}h", duration.as_secs_f64() / 3600.0)
+    } else {
+        format!("{}d", duration.as_secs_f64() / 3600.0 / 24.0)
+    }
+}

tracing-trace/src/processor/mod.rs

@@ -0,0 +1,2 @@
+pub mod firefox_profiler;
+pub mod fmt;