1 files changed, 172 insertions, 1 deletions

diff --git a/src/logging.rs b/src/logging.rs
index 4496125..093d49e 100644
--- a/src/logging.rs
+++ b/src/logging.rs
@@ -3,16 +3,161 @@
 //!
 //! The filter starts from `RUST_LOG`, or `info` without it. It applies to the fmt
 //! logger only, so the console layer keeps getting the runtime events it needs.
+//!
+//! Each line is written with members named by their alias (`Renaming`): wherever a
+//! member's node ID or one of its addresses appears, in a field, a message or a dump of
+//! a value, it reads `<scheme>:<alias>` (`continuum:<alias>` for the node ID,
+//! `libp2p:<alias>` for its libp2p peer ID, with its scheme or bare). The names and
+//! aliases are as `set_aliases` last gave them (`swarm::topology`, whenever it looks at
+//! the member list); at start, as the state file remembers them, so they show from the
+//! first line (stale, perhaps: a member's alias that changed meanwhile is logged as such
+//! once the member list says so). `--log-raw-ids` leaves IDs as they are.
 
-use std::sync::OnceLock;
+use std::borrow::Cow;
+use std::collections::{BTreeMap, HashMap};
+use std::io::Write;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{OnceLock, RwLock};
 
 use anyhow::{Result, anyhow};
+use tracing_subscriber::fmt::MakeWriter;
 use tracing_subscriber::{EnvFilter, Registry, prelude::*, reload};
 
+use crate::locks::RwLockExt;
+
 type FilterHandle = reload::Handle<EnvFilter, Registry>;
 
 static FILTER: OnceLock<FilterHandle> = OnceLock::new();
 
+/// Members' aliases, by the names that stand for them (`set_aliases`), and the
+/// replacements made of them, longest first.
+static ALIASES: RwLock<Aliases> = RwLock::new(Aliases {
+    given: None,
+    renames: Vec::new(),
+});
+/// `--log-raw-ids`.
+static RAW_IDS: AtomicBool = AtomicBool::new(false);
+
+struct Aliases {
+    given: Option<HashMap<String, String>>,
+    renames: Vec<(String, String)>,
+}
+
+/// Leave IDs in the log as they are (`--log-raw-ids`).
+pub(crate) fn set_raw_ids(raw: bool) {
+    RAW_IDS.store(raw, Ordering::Relaxed);
+}
+
+/// The aliases to name members by from now on, by the names that stand for them: node
+/// IDs and addresses (`<scheme>:<transport identity>`).
+pub(crate) fn set_aliases(aliases: HashMap<String, String>) {
+    let previous = {
+        let mut current = ALIASES.write_or_recover();
+        if current.given.as_ref() == Some(&aliases) {
+            return;
+        }
+        current.renames = renames(&aliases);
+        current.given.replace(aliases.clone())
+    };
+    // A member's alias that changed, after the lock: the line itself is renamed.
+    let Some(previous) = previous else {
+        return;
+    };
+    for (name, before) in &previous {
+        if !crate::identity::is_node_id(name) {
+            continue;
+        }
+        match aliases.get(name) {
+            Some(after) if after != before => {
+                tracing::info!(peer = %name, previous = %before, "A member's alias changed");
+            }
+            None => tracing::info!(peer = %name, previous = %before, "A member's alias is gone"),
+            _ => {}
+        }
+    }
+}
+
+/// What each name becomes: `<scheme>:<alias>`, for the name with its scheme and bare.
+/// Longest first, so that an address is renamed whole before its bare identity could be.
+fn renames(aliases: &HashMap<String, String>) -> Vec<(String, String)> {
+    let mut renames: BTreeMap<String, String> = BTreeMap::new();
+    for (name, alias) in aliases {
+        let Some((scheme, identity)) = name.split_once(':') else {
+            continue;
+        };
+        let renamed = format!("{scheme}:{alias}");
+        renames.insert(name.clone(), renamed.clone());
+        // A node ID's hex alone is no name of it.
+        if !crate::identity::is_node_id(name) && !identity.is_empty() {
+            renames.entry(identity.to_owned()).or_insert(renamed);
+        }
+    }
+    let mut renames: Vec<(String, String)> = renames.into_iter().collect();
+    renames.sort_by(|a, b| b.0.len().cmp(&a.0.len()).then_with(|| a.0.cmp(&b.0)));
+    renames
+}
+
+/// The aliases `set_aliases` was last given, sorted (for the state file).
+pub(crate) fn aliases() -> BTreeMap<String, String> {
+    ALIASES
+        .read_or_recover()
+        .given
+        .iter()
+        .flatten()
+        .map(|(name, alias)| (name.clone(), alias.clone()))
+        .collect()
+}
+
+/// `line` with members named by their alias (module docs).
+fn rename(line: &str) -> Cow<'_, str> {
+    if RAW_IDS.load(Ordering::Relaxed) {
+        return Cow::Borrowed(line);
+    }
+    rename_with(line, &ALIASES.read_or_recover().renames)
+}
+
+fn rename_with<'a>(line: &'a str, renames: &[(String, String)]) -> Cow<'a, str> {
+    let mut renamed = Cow::Borrowed(line);
+    for (name, alias) in renames {
+        if renamed.contains(name.as_str()) {
+            renamed = Cow::Owned(renamed.replace(name.as_str(), alias));
+        }
+    }
+    renamed
+}
+
+/// Writes the log to stdout, a line (one event) at a time, renamed (`rename`).
+struct Renaming;
+
+impl<'a> MakeWriter<'a> for Renaming {
+    type Writer = RenamingLine;
+
+    fn make_writer(&'a self) -> Self::Writer {
+        RenamingLine(Vec::new())
+    }
+}
+
+/// One event's text, written renamed when the logger is done with it.
+struct RenamingLine(Vec<u8>);
+
+impl Write for RenamingLine {
+    fn write(&mut self, bytes: &[u8]) -> std::io::Result<usize> {
+        self.0.extend_from_slice(bytes);
+        Ok(bytes.len())
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        Ok(())
+    }
+}
+
+impl Drop for RenamingLine {
+    fn drop(&mut self) {
+        let text = String::from_utf8_lossy(&self.0);
+        let _ = std::io::stdout().write_all(rename(&text).as_bytes());
+    }
+}
+
 /// Installs the global subscriber. Call once, first thing in main.
 pub(crate) fn init() {
     let filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
@@ -21,6 +166,7 @@ pub(crate) fn init() {
     let registry = tracing_subscriber::registry().with(
         tracing_subscriber::fmt::layer()
             .compact()
+            .with_writer(Renaming)
             .with_filter(filter),
     );
 
@@ -56,3 +202,28 @@ fn handle() -> Result<&'static FilterHandle> {
         .get()
         .ok_or_else(|| anyhow!("Logging is not initialised"))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn members_are_named_by_their_alias() {
+        let node = crate::identity::node_id_of(&[1; 32]);
+        let renames = renames(&HashMap::from([
+            (node.clone(), "kitchen".to_owned()),
+            ("libp2p:12D3KooWexample".to_owned(), "kitchen".to_owned()),
+            ("tor:abc.onion:9662".to_owned(), "kitchen".to_owned()),
+        ]));
+        let line = format!(
+            "peer={node} to=libp2p:12D3KooWexample event=PeerId(\"12D3KooWexample\") at=abc.onion:9662 other=12D3KooWother"
+        );
+        assert_eq!(
+            rename_with(&line, &renames),
+            "peer=continuum:kitchen to=libp2p:kitchen event=PeerId(\"libp2p:kitchen\") at=tor:kitchen other=12D3KooWother"
+        );
+        // A node ID's hex alone stays.
+        let hex = node.split_once(':').unwrap().1;
+        assert_eq!(rename_with(hex, &renames), hex);
+    }
+}