huskies: merge 831

server/src/agents/pool/pipeline/merge/time.rs

@@ -0,0 +1,37 @@
+//! Server-start-time utilities for stale-merge detection.
+
+/// Wall-clock time captured the first time this server process touches the
+/// merge subsystem. Used to detect merge_jobs left over from a previous
+/// server instance: a re-exec on `rebuild_and_restart` keeps the same PID,
+/// so PID alone cannot distinguish "current" vs "previous" server. This
+/// timestamp is fresh per-process (the static is reset by execve) and is
+/// the source of truth for stale-merge detection.
+static SERVER_START_TIME: std::sync::OnceLock<f64> = std::sync::OnceLock::new();
+
+/// Return this server process's start time (lazily captured on first call).
+pub(crate) fn server_start_time() -> f64 {
+    *SERVER_START_TIME.get_or_init(unix_now)
+}
+
+/// Encode the current server's start-time into the CRDT `error` field for
+/// a Running merge job.
+pub(crate) fn encode_server_start_time(t: f64) -> String {
+    format!("{{\"server_start\":{t}}}")
+}
+
+/// Decode the server-start-time from a Running merge job's `error` field.
+/// Returns `None` for legacy entries (which encoded `pid` instead) — those
+/// are treated as stale by the cleanup pass.
+pub(crate) fn decode_server_start_time(error: Option<&str>) -> Option<f64> {
+    error
+        .and_then(|e| serde_json::from_str::<serde_json::Value>(e).ok())
+        .and_then(|v| v["server_start"].as_f64())
+}
+
+/// Current Unix timestamp in seconds as `f64`.
+pub(crate) fn unix_now() -> f64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs_f64()
+}