1 files changed, 139 insertions, 0 deletions
diff --git a/subplot/vendored/daemon.py b/subplot/vendored/daemon.py
new file mode 100644
index 0000000..febf392
--- /dev/null
+++ b/subplot/vendored/daemon.py
@@ -0,0 +1,139 @@
+import logging
+import os
+import signal
+import socket
+import subprocess
+import time
+
+
+# Start a daemon that will open a port on localhost.
+def daemon_start_on_port(ctx, path=None, args=None, name=None, port=None):
+    daemon_start(ctx, path=path, args=args, name=name)
+    daemon_wait_for_port("localhost", port)
+
+
+# Start a daeamon, get its PID. Don't wait for a port or anything. This is
+# meant for background processes that don't have port. Useful for testing the
+# lib/daemon library of Subplot, but not much else.
+def daemon_start(ctx, path=None, args=None, name=None):
+    runcmd_run = globals()["runcmd_run"]
+    runcmd_exit_code_is = globals()["runcmd_exit_code_is"]
+    runcmd_get_exit_code = globals()["runcmd_get_exit_code"]
+    runcmd_get_stderr = globals()["runcmd_get_stderr"]
+    runcmd_prepend_to_path = globals()["runcmd_prepend_to_path"]
+
+    argv = [path] + args.split()
+
+    logging.debug(f"Starting daemon {name}")
+    logging.debug(f"  ctx={ctx.as_dict()}")
+    logging.debug(f"  name={name}")
+    logging.debug(f"  path={path}")
+    logging.debug(f"  args={args}")
+    logging.debug(f"  argv={argv}")
+
+    ns = ctx.declare("_daemon")
+
+    this = ns[name] = {
+        "pid-file": f"{name}.pid",
+        "stderr": f"{name}.stderr",
+        "stdout": f"{name}.stdout",
+    }
+
+    # Debian installs `daemonize` to /usr/sbin, which isn't part of the minimal
+    # environment that Subplot sets up. So we add /usr/sbin to the PATH.
+    runcmd_prepend_to_path(ctx, "/usr/sbin")
+    runcmd_run(
+        ctx,
+        [
+            "daemonize",
+            "-c",
+            os.getcwd(),
+            "-p",
+            this["pid-file"],
+            "-e",
+            this["stderr"],
+            "-o",
+            this["stdout"],
+        ]
+        + argv,
+    )
+
+    # Check that daemonize has exited OK. If it hasn't, it didn't start the
+    # background process at all. If so, log the stderr in case there was
+    # something useful there for debugging.
+    exit = runcmd_get_exit_code(ctx)
+    if exit != 0:
+        stderr = runcmd_get_stderr(ctx)
+        logging.error(f"daemon {name} stderr: {stderr}")
+    runcmd_exit_code_is(ctx, 0)
+
+    # Get the pid of the background process, from the pid file created by
+    # daemonize. We don't need to wait for it, since we know daemonize already
+    # exited. If it isn't there now, it's won't appear later.
+    if not os.path.exists(this["pid-file"]):
+        raise Exception("daemonize didn't create a PID file")
+
+    this["pid"] = _daemon_wait_for_pid(this["pid-file"], 10.0)
+
+    logging.debug(f"Started daemon {name}")
+    logging.debug(f"  pid={this['pid']}")
+    logging.debug(f"  ctx={ctx.as_dict()}")
+
+
+def _daemon_wait_for_pid(filename, timeout):
+    start = time.time()
+    while time.time() < start + timeout:
+        with open(filename) as f:
+            data = f.read().strip()
+            if data:
+                return int(data)
+    raise Exception("daemonize created a PID file without a PID")
+
+
+def daemon_wait_for_port(host, port, timeout=3.0):
+    addr = (host, port)
+    until = time.time() + timeout
+    while True:
+        try:
+            s = socket.create_connection(addr, timeout=timeout)
+            s.close()
+            return
+        except socket.timeout:
+            logging.error(f"daemon did not respond at port {port} within {timeout} seconds")
+            raise
+        except socket.error as e:
+            logging.info(f"could not connect to daemon at {port}: {e}")
+            pass
+        if time.time() >= until:
+            logging.error(f"could not connect to daemon at {port} within {timeout} seconds")
+            raise ConnectionRefusedError()
+
+
+# Stop a daemon.
+def daemon_stop(ctx, name=None):
+    logging.debug(f"Stopping daemon {name}")
+    ns = ctx.declare("_daemon")
+    logging.debug(f"  ns={ns}")
+    pid = ns[name]["pid"]
+    signo = signal.SIGKILL
+
+    logging.debug(f"Terminating process {pid} with signal {signo}")
+    try:
+        os.kill(pid, signo)
+    except ProcessLookupError:
+        logging.warning("Process did not actually exist (anymore?)")
+
+
+def daemon_no_such_process(ctx, args=None):
+    assert not _daemon_pgrep(args)
+
+
+def daemon_process_exists(ctx, args=None):
+    assert _daemon_pgrep(args)
+
+
+def _daemon_pgrep(pattern):
+    logging.info(f"checking if process exists: pattern={pattern}")
+    exit = subprocess.call(["pgrep", "-laf", pattern])
+    logging.info(f"exit code: {exit}")
+    return exit == 0