xmrig-auto-pause: fix

services/monero/xmrig-auto-pause.nix

@@ -21,12 +21,14 @@ lib.mkIf config.services.xmrig.enable {
         "AF_UNIX" # systemctl talks to systemd over D-Bus unix socket
       ];
       MemoryDenyWriteExecute = true;
+      StateDirectory = "xmrig-auto-pause";
     };
     environment = {
       POLL_INTERVAL = "3";
       GRACE_PERIOD = "15";
       CPU_THRESHOLD = "5";
       STARTUP_COOLDOWN = "10";
+      STATE_DIR = "/var/lib/xmrig-auto-pause";
     };
   };
 }

services/monero/xmrig-auto-pause.py

@@ -35,6 +35,11 @@ CPU_THRESHOLD = float(os.environ.get("CPU_THRESHOLD", "5"))
 # RandomX dataset initialization complete (~4s on the target hardware)
 # without retriggering a stop.
 STARTUP_COOLDOWN = float(os.environ.get("STARTUP_COOLDOWN", "10"))
+# Directory for persisting pause state across script restarts.  Without
+# this, a restart while xmrig is paused loses the paused_by_us flag and
+# xmrig stays stopped permanently.
+STATE_DIR = os.environ.get("STATE_DIR", "")
+_PAUSE_FILE = os.path.join(STATE_DIR, "paused") if STATE_DIR else ""
 
 
 def log(msg):
@@ -78,13 +83,36 @@ def systemctl(action, unit):
     return result.returncode == 0
 
 
+def _save_paused(paused):
+    """Persist pause flag so a script restart can resume where we left off."""
+    if not _PAUSE_FILE:
+        return
+    try:
+        if paused:
+            open(_PAUSE_FILE, "w").close()
+        else:
+            os.remove(_PAUSE_FILE)
+    except OSError:
+        pass
+
+
+def _load_paused():
+    """Check if a previous instance left xmrig paused."""
+    if not _PAUSE_FILE:
+        return False
+    return os.path.isfile(_PAUSE_FILE)
+
+
 def main():
-    paused_by_us = False
+    paused_by_us = _load_paused()
     idle_since = None
     started_at = None  # monotonic time when we last started xmrig
     prev_total = None
     prev_work = None
 
+    if paused_by_us:
+        log("Recovered pause state from previous instance")
+
     log(
         f"Starting: poll={POLL_INTERVAL}s grace={GRACE_PERIOD}s "
         f"threshold={CPU_THRESHOLD}% cooldown={STARTUP_COOLDOWN}s"
@@ -116,6 +144,14 @@ def main():
             if time.monotonic() - started_at < STARTUP_COOLDOWN:
                 time.sleep(POLL_INTERVAL)
                 continue
+            # Cooldown expired — verify xmrig survived startup.  If it
+            # crashed during init (hugepage failure, pool unreachable, etc.),
+            # re-enter the pause/retry cycle rather than silently leaving
+            # xmrig dead.
+            if not is_active("xmrig.service"):
+                log("xmrig died during startup cooldown — will retry")
+                paused_by_us = True
+                _save_paused(True)
             started_at = None
 
         busy = real_work_pct > CPU_THRESHOLD
@@ -128,6 +164,7 @@ def main():
                 # manage it again.
                 log("xmrig was restarted externally while paused — reclaiming")
                 paused_by_us = False
+                _save_paused(False)
             if not paused_by_us:
                 # Only claim ownership if xmrig is actually running.
                 # If something else stopped it (e.g. UPS battery hook),
@@ -136,6 +173,7 @@ def main():
                     log(f"Real workload detected ({real_work_pct:.1f}% CPU) — stopping xmrig")
                     if systemctl("stop", "xmrig.service"):
                         paused_by_us = True
+                        _save_paused(True)
         else:
             if paused_by_us:
                 if idle_since is None:
@@ -144,6 +182,7 @@ def main():
                     log(f"Workload ended ({real_work_pct:.1f}% CPU) past grace period — starting xmrig")
                     if systemctl("start", "xmrig.service"):
                         paused_by_us = False
+                        _save_paused(False)
                         started_at = time.monotonic()
                     idle_since = None
 

tests/xmrig-auto-pause.nix

@@ -44,6 +44,7 @@ pkgs.testers.runNixOSTest {
     GRACE_PERIOD = "5"
     CPU_THRESHOLD = "10"
     STARTUP_COOLDOWN = "4"
+    STATE_DIR = "/tmp/xap-state"
 
     def start_cpu_load(name):
         """Start a non-nice CPU burn as a transient systemd unit."""
@@ -55,22 +56,28 @@ pkgs.testers.runNixOSTest {
     def stop_cpu_load(name):
         machine.succeed(f"systemctl stop {name}")
 
-    start_all()
+    def start_monitor(unit_name):
-    machine.wait_for_unit("multi-user.target")
+        """Start the auto-pause monitor as a transient unit."""
-    machine.wait_for_unit("xmrig.service")
-
-    with subtest("Start auto-pause monitor"):
         machine.succeed(
-            f"systemd-run --unit=xmrig-auto-pause "
+            f"systemd-run --unit={unit_name} "
             f"--setenv=POLL_INTERVAL={POLL_INTERVAL} "
             f"--setenv=GRACE_PERIOD={GRACE_PERIOD} "
             f"--setenv=CPU_THRESHOLD={CPU_THRESHOLD} "
             f"--setenv=STARTUP_COOLDOWN={STARTUP_COOLDOWN} "
+            f"--setenv=STATE_DIR={STATE_DIR} "
             f"{PYTHON} {SCRIPT}"
         )
         # Monitor needs two consecutive polls to compute a CPU delta.
         time.sleep(3)
 
+    start_all()
+    machine.wait_for_unit("multi-user.target")
+    machine.wait_for_unit("xmrig.service")
+    machine.succeed(f"mkdir -p {STATE_DIR}")
+
+    with subtest("Start auto-pause monitor"):
+        start_monitor("xmrig-auto-pause")
+
     with subtest("xmrig stays running while system is idle"):
         machine.succeed("systemctl is-active xmrig")
 
@@ -134,5 +141,61 @@ pkgs.testers.runNixOSTest {
 
         stop_cpu_load("cpu-load-4")
         machine.wait_until_succeeds("systemctl is-active xmrig", timeout=20)
+
+    # --- State persistence and crash recovery ---
+    machine.succeed("systemctl stop xmrig-auto-pause")
+
+    with subtest("xmrig recovers after crash during startup cooldown"):
+        machine.succeed(f"rm -rf {STATE_DIR} && mkdir -p {STATE_DIR}")
+        start_monitor("xmrig-auto-pause-crash")
+
+        # Load -> xmrig stops
+        start_cpu_load("cpu-crash")
+        machine.wait_until_fails("systemctl is-active xmrig", timeout=20)
+
+        # End load -> xmrig restarts after grace period
+        stop_cpu_load("cpu-crash")
+        machine.wait_until_succeeds("systemctl is-active xmrig", timeout=30)
+
+        # Kill xmrig immediately — simulates crash during startup cooldown.
+        # The script should detect the failure when cooldown expires and
+        # re-enter the retry cycle.
+        machine.succeed("systemctl kill --signal=KILL xmrig")
+        machine.wait_until_fails("systemctl is-active xmrig", timeout=5)
+
+        # After cooldown + grace period + restart, xmrig should be back.
+        machine.wait_until_succeeds("systemctl is-active xmrig", timeout=30)
+
+        machine.succeed("systemctl stop xmrig-auto-pause-crash")
+        machine.succeed("systemctl reset-failed xmrig.service || true")
+        machine.succeed("systemctl start xmrig")
+        machine.wait_for_unit("xmrig.service")
+
+    with subtest("Script restart preserves pause state"):
+        machine.succeed(f"rm -rf {STATE_DIR} && mkdir -p {STATE_DIR}")
+        start_monitor("xmrig-auto-pause-persist")
+
+        # Load -> xmrig stops
+        start_cpu_load("cpu-persist")
+        machine.wait_until_fails("systemctl is-active xmrig", timeout=20)
+
+        # Kill the monitor while xmrig is paused (simulates script crash)
+        machine.succeed("systemctl stop xmrig-auto-pause-persist")
+
+        # State file must exist — the monitor persisted the pause flag
+        machine.succeed(f"test -f {STATE_DIR}/paused")
+
+        # Start a fresh monitor instance (reads state file on startup)
+        start_monitor("xmrig-auto-pause-persist2")
+
+        # End load — the new monitor should pick up the paused state
+        # and restart xmrig after the grace period
+        stop_cpu_load("cpu-persist")
+        machine.wait_until_succeeds("systemctl is-active xmrig", timeout=30)
+
+        # State file should be cleaned up after successful restart
+        machine.fail(f"test -f {STATE_DIR}/paused")
+
+        machine.succeed("systemctl stop xmrig-auto-pause-persist2")
   '';
 }