Merge pull request #1565 from bungoboingo/feat/tracing

[Feature] Profiling

1 files changed, 101 insertions, 0 deletions

diff --git a/winit/src/application/profiler.rs b/winit/src/application/profiler.rs
new file mode 100644
index 00000000..23eaa390
--- /dev/null
+++ b/winit/src/application/profiler.rs
@@ -0,0 +1,101 @@
+//! A simple profiler for Iced.
+use std::ffi::OsStr;
+use std::path::Path;
+use std::time::Duration;
+use tracing_subscriber::prelude::*;
+use tracing_subscriber::Registry;
+#[cfg(feature = "chrome-trace")]
+use {
+    tracing_chrome::FlushGuard,
+    tracing_subscriber::fmt::{format::DefaultFields, FormattedFields},
+};
+
+/// Profiler state. This will likely need to be updated or reworked when adding new tracing backends.
+#[allow(missing_debug_implementations)]
+pub struct Profiler {
+    #[cfg(feature = "chrome-trace")]
+    /// [`FlushGuard`] must not be dropped until the application scope is dropped for accurate tracing.
+    _guard: FlushGuard,
+}
+
+impl Profiler {
+    /// Initializes the [`Profiler`].
+    pub fn init() -> Self {
+        // Registry stores the spans & generates unique span IDs
+        let subscriber = Registry::default();
+
+        let default_path = Path::new(env!("CARGO_MANIFEST_DIR"));
+        let curr_exe = std::env::current_exe()
+            .unwrap_or_else(|_| default_path.to_path_buf());
+        let out_dir = curr_exe.parent().unwrap_or(default_path).join("traces");
+
+        #[cfg(feature = "chrome-trace")]
+        let (chrome_layer, guard) = {
+            let mut layer = tracing_chrome::ChromeLayerBuilder::new();
+
+            // Optional configurable env var: CHROME_TRACE_FILE=/path/to/trace_file/file.json,
+            // for uploading to chrome://tracing (old) or ui.perfetto.dev (new).
+            if let Ok(path) = std::env::var("CHROME_TRACE_FILE") {
+                layer = layer.file(path);
+            } else if std::fs::create_dir_all(&out_dir).is_ok() {
+                let time = std::time::SystemTime::now()
+                    .duration_since(std::time::UNIX_EPOCH)
+                    .unwrap_or(Duration::from_millis(0))
+                    .as_millis();
+
+                let curr_exe_name = curr_exe
+                    .file_name()
+                    .unwrap_or_else(|| OsStr::new("trace"))
+                    .to_str()
+                    .unwrap_or("trace");
+
+                let path = out_dir
+                    .join(format!("{}_trace_{}.json", curr_exe_name, time));
+
+                layer = layer.file(path);
+            } else {
+                layer = layer.file(env!("CARGO_MANIFEST_DIR"))
+            }
+
+            let (chrome_layer, guard) = layer
+                .name_fn(Box::new(|event_or_span| match event_or_span {
+                    tracing_chrome::EventOrSpan::Event(event) => {
+                        event.metadata().name().into()
+                    }
+                    tracing_chrome::EventOrSpan::Span(span) => {
+                        if let Some(fields) = span
+                            .extensions()
+                            .get::<FormattedFields<DefaultFields>>()
+                        {
+                            format!(
+                                "{}: {}",
+                                span.metadata().name(),
+                                fields.fields.as_str()
+                            )
+                        } else {
+                            span.metadata().name().into()
+                        }
+                    }
+                }))
+                .build();
+
+            (chrome_layer, guard)
+        };
+
+        let fmt_layer = tracing_subscriber::fmt::Layer::default();
+        let subscriber = subscriber.with(fmt_layer);
+
+        #[cfg(feature = "chrome-trace")]
+        let subscriber = subscriber.with(chrome_layer);
+
+        // create dispatcher which will forward span events to the subscriber
+        // this can only be set once or will panic
+        tracing::subscriber::set_global_default(subscriber)
+            .expect("Tracer could not set the global default subscriber.");
+
+        Profiler {
+            #[cfg(feature = "chrome-trace")]
+            _guard: guard,
+        }
+    }
+}