refactor: move ancillary subplot files to subplot/

This way, the root of the source tree is less cluttered.

I'm leaving the subplot.md file in the root, though, since it's meant
to be more visible, more "in your face".

1 files changed, 84 insertions, 0 deletions

diff --git a/subplot/daemon.py b/subplot/daemon.py
new file mode 100644
index 0000000..e223505
--- /dev/null
+++ b/subplot/daemon.py
@@ -0,0 +1,84 @@
+#############################################################################
+# Start and stop daemons, or background processes.
+
+
+import logging
+import os
+import signal
+import time
+
+
+# Start a process in the background.
+def start_daemon(ctx, name, argv):
+    runcmd = globals()["runcmd"]
+    exit_code_is = globals()["exit_code_is"]
+
+    logging.debug(f"Starting daemon {name}")
+    logging.debug(f"  ctx={ctx.as_dict()}")
+    logging.debug(f"  name={name}")
+    logging.debug(f"  argv={argv}")
+
+    if "daemon" not in ctx.as_dict():
+        ctx["daemon"] = {}
+    assert name not in ctx["daemon"]
+    this = ctx["daemon"][name] = {
+        "pid-file": f"{name}.pid",
+        "stderr": f"{name}.stderr",
+        "stdout": f"{name}.stdout",
+    }
+    runcmd(
+        ctx,
+        [
+            "/usr/sbin/daemonize",
+            "-c",
+            os.getcwd(),
+            "-p",
+            this["pid-file"],
+            "-e",
+            this["stderr"],
+            "-o",
+            this["stdout"],
+        ]
+        + argv,
+    )
+
+    # Wait for a bit for daemon to start and maybe find a problem and die.
+    time.sleep(3)
+    if ctx["exit"] != 0:
+        logging.error(f"obnam-server stderr: {ctx['stderr']}")
+
+    exit_code_is(ctx, 0)
+    this["pid"] = int(open(this["pid-file"]).read().strip())
+    assert process_exists(this["pid"])
+
+    logging.debug(f"Started daemon {name}")
+    logging.debug(f"  ctx={ctx.as_dict()}")
+
+
+# Stop a daemon.
+def stop_daemon(ctx, name):
+    logging.debug(f"Stopping daemon {name}")
+    logging.debug(f"  ctx={ctx.as_dict()}")
+    logging.debug(f"  ctx['daemon']={ctx.as_dict()['daemon']}")
+
+    this = ctx["daemon"][name]
+    terminate_process(this["pid"], signal.SIGKILL)
+
+
+# Does a process exist?
+def process_exists(pid):
+    try:
+        os.kill(pid, 0)
+    except ProcessLookupError:
+        return False
+    return True
+
+
+# Terminate process.
+def terminate_process(pid, signalno):
+    logging.debug(f"Terminating process {pid} with signal {signalno}")
+    try:
+        os.kill(pid, signalno)
+    except ProcessLookupError:
+        logging.debug("Process did not actually exist (anymore?)")
+        pass