Show thread ids and names

examples/basic.rs

@@ -6,6 +6,8 @@ fn main() {
     let layer = HierarchicalLayer::default()
         .with_indent_lines(true)
         .with_indent_amount(2)
+        .with_thread_names(true)
+        .with_thread_ids(true)
         .with_targets(true);
 
     let subscriber = Registry::default().with(layer);

src/format.rs

@@ -22,6 +22,10 @@ pub struct Config {
     pub indent_amount: usize,
     /// Whether to show the module paths.
     pub targets: bool,
+    /// Whether to show thread ids.
+    pub render_thread_ids: bool,
+    /// Whether to show thread names.
+    pub render_thread_names: bool,
 }
 
 impl Config {
@@ -39,6 +43,42 @@ impl Config {
     pub fn with_targets(self, targets: bool) -> Self {
         Self { targets, ..self }
     }
+
+    pub fn with_thread_ids(self, render_thread_ids: bool) -> Self {
+        Self {
+            render_thread_ids,
+            ..self
+        }
+    }
+
+    pub fn with_thread_names(self, render_thread_names: bool) -> Self {
+        Self {
+            render_thread_names,
+            ..self
+        }
+    }
+
+    pub(crate) fn prefix(&self) -> String {
+        let mut buf = String::new();
+        if self.render_thread_ids {
+            write!(buf, "{:?}", std::thread::current().id()).unwrap();
+            if buf.ends_with(')') {
+                buf.truncate(buf.len() - 1);
+            }
+            if buf.starts_with("ThreadId(") {
+                buf.drain(0.."ThreadId(".len());
+            }
+        }
+        if self.render_thread_names {
+            if let Some(name) = std::thread::current().name() {
+                if self.render_thread_ids {
+                    buf.push(':');
+                }
+                buf.push_str(name);
+            }
+        }
+        buf
+    }
 }
 
 impl Default for Config {
@@ -48,6 +88,8 @@ impl Default for Config {
             indent_lines: false,
             indent_amount: 2,
             targets: false,
+            render_thread_ids: false,
+            render_thread_names: false,
         }
     }
 }
@@ -77,14 +119,17 @@ impl Buffers {
     }
 
     pub fn indent_current(&mut self, indent: usize, config: &Config) {
+        self.current_buf.push('\n');
         indent_block(
             &mut self.current_buf,
             &mut self.indent_buf,
             indent,
             config.indent_amount,
             config.indent_lines,
+            &config.prefix(),
         );
         self.current_buf.clear();
+        self.flush_indent_buf();
     }
 }
 
@@ -108,14 +153,6 @@ impl<'a> Visit for FmtEvent<'a> {
     }
 }
 
-impl<'a> FmtEvent<'a> {
-    pub fn finish(&mut self, indent: usize, config: &Config) {
-        self.bufs.current_buf.push('\n');
-        self.bufs.indent_current(indent, config);
-        self.bufs.flush_indent_buf();
-    }
-}
-
 pub struct ColorLevel<'a>(pub &'a Level);
 
 impl<'a> fmt::Display for ColorLevel<'a> {
@@ -131,18 +168,26 @@ impl<'a> fmt::Display for ColorLevel<'a> {
     }
 }
 
-fn indent_block_with_lines(lines: &[&str], buf: &mut String, indent: usize, indent_amount: usize) {
+fn indent_block_with_lines(
+    lines: &[&str],
+    buf: &mut String,
+    indent: usize,
+    indent_amount: usize,
+    prefix: &str,
+) {
     let indent_spaces = indent * indent_amount;
     if lines.is_empty() {
         return;
     } else if indent_spaces == 0 {
         for line in lines {
+            buf.push_str(prefix);
             buf.push_str(line);
             buf.push('\n');
         }
         return;
     }
-    let mut s = String::with_capacity(indent_spaces);
+    let mut s = String::with_capacity(indent_spaces + prefix.len());
+    s.push_str(prefix);
 
     // instead of using all spaces to indent, draw a vertical line at every indent level
     // up until the last indent
@@ -189,15 +234,17 @@ fn indent_block(
     indent: usize,
     indent_amount: usize,
     indent_lines: bool,
+    prefix: &str,
 ) {
     let lines: Vec<&str> = block.lines().collect();
     let indent_spaces = indent * indent_amount;
     buf.reserve(block.len() + (lines.len() * indent_spaces));
     if indent_lines {
-        indent_block_with_lines(&lines, buf, indent, indent_amount);
+        indent_block_with_lines(&lines, buf, indent, indent_amount, prefix);
     } else {
         let indent_str = String::from(" ").repeat(indent_spaces);
         for line in lines {
+            buf.push_str(prefix);
             buf.push_str(&indent_str);
             buf.push_str(line);
             buf.push('\n');

src/lib.rs

@@ -53,19 +53,7 @@ where
 
 impl Default for HierarchicalLayer {
     fn default() -> Self {
-        let ansi = atty::is(atty::Stream::Stdout);
-        let indent_amount = 2;
-        let config = Config {
-            ansi,
-            indent_amount,
-            targets: false,
-            ..Default::default()
-        };
-        Self {
-            make_writer: io::stdout,
-            bufs: Mutex::new(Buffers::new()),
-            config,
-        }
+        Self::new(2)
     }
 }
 
@@ -133,6 +121,24 @@ where
         }
     }
 
+    /// Whether to render the thread id in the beginning of every line. This is helpful to
+    /// untangle the tracing statements emitted by each thread.
+    pub fn with_thread_ids(self, thread_ids: bool) -> Self {
+        Self {
+            config: self.config.with_thread_ids(thread_ids),
+            ..self
+        }
+    }
+
+    /// Whether to render the thread name in the beginning of every line. Not all threads have
+    /// names, but if they do, this may be more helpful than the generic thread ids.
+    pub fn with_thread_names(self, thread_names: bool) -> Self {
+        Self {
+            config: self.config.with_thread_names(thread_names),
+            ..self
+        }
+    }
+
     fn styled(&self, style: Style, text: impl AsRef<str>) -> String {
         if self.config.ansi {
             style.paint(text.as_ref()).to_string()
@@ -209,15 +215,14 @@ where
         .unwrap();
         self.print_kvs(&mut current_buf, data.kvs.iter().map(|(k, v)| (k, v)), "")
             .unwrap();
-        writeln!(
+        write!(
             current_buf,
             "{}",
             self.styled(Style::new().fg(Color::Green).bold(), "}") // Style::new().dimmed().paint("}")
         )
         .unwrap();
 
         bufs.indent_current(indent, &self.config);
-        bufs.flush_indent_buf();
         let writer = self.make_writer.make_writer();
         bufs.flush_current_buf(writer)
     }
@@ -226,6 +231,7 @@ where
         let mut guard = self.bufs.lock().unwrap();
         let mut bufs = &mut *guard;
         let mut event_buf = &mut bufs.current_buf;
+
         // printing the indentation
         let indent = if ctx.current_span().id().is_some() {
             // size hint isn't implemented on Scope.
@@ -287,7 +293,7 @@ where
             bufs: &mut bufs,
         };
         event.record(&mut visitor);
-        visitor.finish(indent, &self.config);
+        visitor.bufs.indent_current(indent, &self.config);
         let writer = self.make_writer.make_writer();
         bufs.flush_current_buf(writer)
     }