feature: adds state and locking

update_server.py

@@ -4,6 +4,7 @@ import logging
 import os
 import subprocess
 import time
+import threading
 
 RCSTACK_PATH_NAME = "RCSTACK_PATH"
 RCSTACK_PATH = os.environ.get(RCSTACK_PATH_NAME)
@@ -16,64 +17,118 @@ except ImportError:
     # Py2
     from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
 
+try:
+    from shlex import quote as shell_quote  # Py3
+except ImportError:
+    from pipes import quote as shell_quote  # Py2 (Unix)
 
-log = logging.getLogger("mini-server")
+STATUS = {"state": "ready"}  # "ready" or "processing"
+
+
+def _log_line(text, log_path):
+    # compatible with python 2
+    out = open(log_path, "ab")
+    try:
+        if not isinstance(text, bytes):
+            text = text.encode("utf-8")
+        out.write(text + b"\n")
+        out.flush()
+    finally:
+        out.close()
+
+
+def _watch_process(popen_obj, log_path):
+    try:
+        rc = popen_obj.wait()
+        stamp = time.strftime("%Y-%m-%d %H:%M:%S")
+        _log_line("[" + stamp + "] finished rc=" + str(rc), log_path=log_path)
+    except Exception as e:
+        stamp = time.strftime("%Y-%m-%d %H:%M:%S")
+        _log_line("[" + stamp + "] watcher error: " + str(e), log_path=log_path)
+    finally:
+        STATUS["state"] = "ready"
 
 
 class RcstackUpdater(BaseHTTPRequestHandler):
     def __init__(self, request, client_address, server):
-        super().__init__(request, client_address, server)
+        BaseHTTPRequestHandler.__init__(self, request, client_address, server)
 
-    def _send_json_ok(self):
-        body = json.dumps({"status": "ok"}).encode("utf-8")
-        self.send_response(200)
+    def _send_json(self, obj, code=200):
+        body = json.dumps(obj).encode("utf-8")
+        self.send_response(code)
         self.send_header("Content-Type", "application/json")
         self.send_header("Content-Length", str(len(body)))
         self.end_headers()
         self.wfile.write(body)
 
+    def _send_json_ok(self):
+        return self._send_json({"status": "ok"})
+
     def do_GET(self):
         if self.path == "/health":
             return self._send_json_ok()
-        elif self.path == "/update-rcstack":
-            ok, err_msg = self.spawn_rcstack_status()
-            if not ok:
-                self._send_http_error(err_msg.encode("utf-8"), status_code=500)
-                return
 
-        self._send_http_error(b"not found", status_code=404)
+        elif self.path == "/state":
+            return self._send_json({"state": STATUS["state"]})
+
+        elif self.path == "/update-rcstack":
+            # If already processing, return ok and do not spawn a new process.
+            if STATUS["state"] != "ready":
+                return self._send_json({"status": "ok", "state": STATUS["state"]})
+
+            ok, err_msg = self.spawn_rcstack_status()
+            # If spawn failed for real reasons (bad env/path/etc.), return 500
+            if not ok:
+                return self._send_http_error(err_msg.encode("utf-8"), status_code=500)
+
+            return self._send_json({"status": "ok", "state": STATUS["state"]})
+
+        return self._send_http_error(b"not found", status_code=404)
 
     def spawn_rcstack_status(self):
         if not RCSTACK_PATH:
-            return False, f"{RCSTACK_PATH_NAME} env variable not set"
+            return False, "%s env variable not set" % (RCSTACK_PATH_NAME,)
 
         if not os.path.exists(RCSTACK_PATH) or not os.path.isfile(RCSTACK_PATH):
-            return False, f"{RCSTACK_PATH} does not exist"
+            return False, "%s does not exist" % (RCSTACK_PATH,)
 
         rcstack = os.path.expanduser(RCSTACK_PATH)
+        rcstack_dir = os.path.dirname(rcstack)
+        log_path = os.path.join(rcstack_dir, RCSTACK_LOG)
 
-        # Append mode; don't use PIPE unless you read it.
-        out = open(RCSTACK_LOG, "ab")
+        STATUS["state"] = "processing"
 
-        stamp = time.strftime("%Y-%m-%d %H:%M:%S").encode("utf-8")
-        out.write(b"[" + stamp + b"] spawn: " + rcstack.encode("utf-8") + b" status\n")
-        out.flush()
+        stamp = time.strftime("%Y-%m-%d %H:%M:%S")
+        _log_line("[%s] spawn: %s status" % (stamp, rcstack), log_path=log_path)
 
-        # Detach from the request handler process group/session.
-        # start_new_session=True is Py3; preexec_fn=os.setsid works in Py2/3 on Unix.
+        out = open(log_path, "ab")
         try:
-            rcstack_dir = os.path.dirname(rcstack)
+            cmd = "%s self-update && %s self-upgrade" % (shell_quote(rcstack), shell_quote(rcstack))
 
-            subprocess.Popen(
-                [rcstack, "status"],
+            p = subprocess.Popen(
+                ["/bin/sh", "-c", cmd],
                 cwd=rcstack_dir,
                 stdout=out,
                 stderr=out,
                 close_fds=True,
                 preexec_fn=os.setsid,  # Unix only
             )
+        except Exception as e:
+            STATUS["state"] = "ready"
+            _log_line("[%s] spawn error: %s" % (stamp, str(e)), log_path=log_path)
+            return False, "spawn failed: %s" % (str(e),)
         finally:
-            out.close()
+            try:
+                out.close()
+            except Exception:
+                pass
+
+        t = threading.Thread(target=_watch_process, args=(p, log_path))
+        try:
+            t.daemon = True
+        except Exception:
+            t.setDaemon(True)  # Py2
+        t.start()
 
         return True, None
 
@@ -83,18 +138,16 @@ class RcstackUpdater(BaseHTTPRequestHandler):
         self.end_headers()
         self.wfile.write(msg)
 
-    def log_message(self, fmt, *args):
-        log.info("%s - %s", self.address_string(), fmt % args)
-
 
 def main():
     logging.basicConfig(
         level=logging.INFO,
         format="%(asctime)s %(levelname)s %(name)s: %(message)s",
     )
-    host = "127.0.0.1"  # allow only run within the system, no external connections allowed
+    host = "127.0.0.1"
     port = 10025
     httpd = HTTPServer((host, port), RcstackUpdater)
+    log = logging.getLogger("mini-server")
     log.info("listening on http://%s:%d", host, port)
     httpd.serve_forever()