Merge branch 'log-trait-adapter' into 'main'

log: `Log` trait adapter around the GStreamer debug system

Closes #187

See merge request gstreamer/gstreamer-rs!1426

gstreamer/Cargo.toml

@@ -23,6 +23,7 @@ num-rational = { version = "0.4", default-features = false, features = [] }
 futures-core = "0.3"
 futures-channel = "0.3"
 futures-util = { version = "0.3", default-features = false }
+log = { version = "0.4", optional = true }
 muldiv = "1"
 opt-ops = { package = "option-operations", version = "0.5" }
 serde = { version = "1.0", optional = true, features = ["derive"] }
@@ -48,6 +49,7 @@ v1_20 = ["ffi/v1_20", "v1_18"]
 v1_22 = ["ffi/v1_22", "v1_20"]
 v1_24 = ["ffi/v1_24", "v1_22"]
 serde = ["num-rational/serde", "dep:serde", "serde_bytes"]
+log = ["dep:log"]
 
 [package.metadata.docs.rs]
 all-features = true

gstreamer/src/lib.rs

@@ -49,6 +49,8 @@ mod serde_macros;
 
 #[macro_use]
 pub mod log;
+#[cfg(feature = "log")]
+pub use crate::log::DebugCategoryLogger;
 pub use crate::log::{
     DebugCategory, DebugLogFunction, DebugMessage, LoggedObject, CAT_BUFFER, CAT_BUFFER_LIST,
     CAT_BUS, CAT_CALL_TRACE, CAT_CAPS, CAT_CLOCK, CAT_CONTEXT, CAT_DEFAULT, CAT_ELEMENT_PADS,

gstreamer/src/log.rs

@@ -4,6 +4,8 @@ use std::{borrow::Cow, ffi::CStr, fmt, ptr};
 
 use glib::{ffi::gpointer, prelude::*, translate::*};
 use libc::c_char;
+#[cfg(feature = "log")]
+use log;
 use once_cell::sync::Lazy;
 
 use crate::DebugLevel;
@@ -1064,6 +1066,54 @@ macro_rules! log_with_level(
     }};
 );
 
+#[cfg(feature = "log")]
+#[derive(Debug)]
+pub struct DebugCategoryLogger(DebugCategory);
+
+#[cfg(feature = "log")]
+impl DebugCategoryLogger {
+    pub fn new(cat: DebugCategory) -> Self {
+        Self(cat)
+    }
+
+    fn to_level(level: log::Level) -> crate::DebugLevel {
+        match level {
+            log::Level::Error => DebugLevel::Error,
+            log::Level::Warn => DebugLevel::Warning,
+            log::Level::Info => DebugLevel::Info,
+            log::Level::Debug => DebugLevel::Debug,
+            log::Level::Trace => DebugLevel::Trace,
+        }
+    }
+}
+
+#[cfg(feature = "log")]
+impl log::Log for DebugCategoryLogger {
+    fn enabled(&self, metadata: &log::Metadata) -> bool {
+        let lvl = DebugCategoryLogger::to_level(metadata.level());
+        is_active() && self.0.above_threshold(lvl)
+    }
+
+    fn log(&self, record: &log::Record) {
+        if !self.enabled(record.metadata()) {
+            return;
+        }
+        let lvl = DebugCategoryLogger::to_level(record.level());
+        let file = record.file().unwrap_or("");
+        let file = glib::GStr::from_str_until_nul(file).unwrap_or_default();
+        self.0.log(
+            None::<&glib::Object>,
+            lvl,
+            file,
+            record.module_path().unwrap_or(""),
+            record.line().unwrap_or(0),
+            record.args().clone(),
+        );
+    }
+
+    fn flush(&self) {}
+}
+
 unsafe extern "C" fn log_handler<T>(
     category: *mut ffi::GstDebugCategory,
     level: ffi::GstDebugLevel,
@@ -1308,6 +1358,65 @@ mod tests {
         memdump!(cat, obj: obj, "meh");
     }
 
+    #[cfg(feature = "log")]
+    static LOGGER: Lazy<DebugCategoryLogger> = Lazy::new(|| {
+        DebugCategoryLogger::new(DebugCategory::new(
+            "Log_trait",
+            crate::DebugColorFlags::empty(),
+            Some("Using the Log trait"),
+        ))
+    });
+
+    #[test]
+    #[cfg(feature = "log")]
+    fn log_trait() {
+        crate::init().unwrap();
+
+        log::set_logger(&(*LOGGER)).expect("Failed to set logger");
+        log::set_max_level(log::LevelFilter::Trace);
+        log::error!("meh");
+        log::warn!("fish");
+
+        let (sender, receiver) = mpsc::channel();
+        let sender = Arc::new(Mutex::new(sender));
+        let handler = move |category: DebugCategory,
+                            level: DebugLevel,
+                            _file: &glib::GStr,
+                            _function: &glib::GStr,
+                            _line: u32,
+                            _object: Option<&LoggedObject>,
+                            message: &DebugMessage| {
+            let cat = DebugCategory::get("Log_trait").unwrap();
+
+            if category != cat {
+                // This test can run in parallel with other tests, including new_and_log above.
+                // We cannot be certain we only see our own messages.
+                return;
+            }
+
+            assert_eq!(level, DebugLevel::Error);
+            assert_eq!(message.get().unwrap().as_ref(), "meh");
+            let _ = sender.lock().unwrap().send(());
+        };
+
+        remove_default_log_function();
+        add_log_function(handler);
+
+        let cat = LOGGER.0;
+
+        cat.set_threshold(crate::DebugLevel::Warning);
+        log::error!("meh");
+        receiver.recv().unwrap();
+
+        cat.set_threshold(crate::DebugLevel::Error);
+        log::error!("meh");
+        receiver.recv().unwrap();
+
+        cat.set_threshold(crate::DebugLevel::None);
+        log::error!("fish");
+        log::warn!("meh");
+    }
+
     #[test]
     fn log_handler() {
         crate::init().unwrap();