Merge pull request #84 from tekktrik/dev/fix-fast-error

Improve start speed, fix quick stop error

circlink/backend.py

@@ -10,7 +10,6 @@
 
 import os
 import signal
-import time
 from datetime import datetime, timedelta
 from typing import Iterable, List
 
@@ -101,9 +100,8 @@ def start_backend(
         # Attempt to wait for spawned process to be confirmed
         start_time = datetime.now()
         error_time = start_time + timedelta(seconds=5)
-        while not link.confirmed:
+        while not link or not link.confirmed:
             link = CircuitPythonLink.load_link_by_num(link_id)
-            time.sleep(0.5)  # Slight delay
             if datetime.now() >= error_time:
                 try:
                     os.kill(pid, signal.SIGTERM)
@@ -116,9 +114,8 @@ def start_backend(
     else:  # Spawned process, PID is 0
 
         # Wait for the process ID to be avaiable
-        while not link.process_id:
+        while not link or not link.process_id:
             link = CircuitPythonLink.load_link_by_num(link_id)
-            time.sleep(0.3)
 
         # Mark the link is confirmed and save it
         link.confirmed = True
@@ -177,9 +174,8 @@ def stop_backend(link_id: int, *, hard_fault: bool = True) -> bool:
     # Wait for confirmation that the link has stopped
     start_time = datetime.now()
     error_time = start_time + timedelta(seconds=5)
-    while not link.stopped:
+    while not link or not link.stopped:
         link = CircuitPythonLink.load_link_by_num(link_id)
-        time.sleep(0.1)  # Slight delay
         if datetime.now() >= error_time:
             print(f"Link #{link.link_id} could not be stopped!")
             if hard_fault:

circlink/link.py

@@ -8,12 +8,12 @@
 Author(s): Alec Delaney (Tekktrik)
 """
 
+import fcntl
 import json
 import os
 import pathlib
 import shutil
-import time
-from typing import Dict, List, Tuple, Union
+from typing import Dict, List, Optional, Tuple, Union
 
 from typer import Exit
 from typing_extensions import TypeAlias
@@ -144,16 +144,21 @@ def save_link(self, *, save_directory: str = LINKS_DIRECTORY) -> pathlib.Path:
 
         # Save the object as a JSON file
         with open(save_filepath, mode="w", encoding="utf-8") as linkfile:
+            fcntl.lockf(linkfile, fcntl.LOCK_EX)
             json.dump(link_obj, linkfile, indent=4)
+            fcntl.lockf(linkfile, fcntl.LOCK_UN)
 
         # Return the save filepath
         return pathlib.Path(save_filepath)
 
     @classmethod
-    def load_link_by_filepath(cls, link_filepath: str) -> "CircuitPythonLink":
+    def load_link_by_filepath(cls, link_filepath: str) -> Optional["CircuitPythonLink"]:
         """Create a CircuitPythonLink from a JSON file, by filepath."""
         with open(link_filepath, encoding="utf-8") as linkfile:
-            link_obj = json.load(linkfile)
+            link_contents = linkfile.read()
+            if not link_contents:
+                return None
+            link_obj = json.loads(link_contents)
 
         link = cls(
             name=link_obj["name"],
@@ -237,11 +242,10 @@ def begin_monitoring(self) -> None:
 
         # Load the link and repeatedly load while not flagged to stop
         temp_link = self.load_link_by_num(self._link_id)
-        while not temp_link.end_flag:
+        while not temp_link or not temp_link.end_flag:
 
             # Load the link
             temp_link = self.load_link_by_num(self._link_id)
-            time.sleep(0.1)
 
             # Detect new files
             read_files = self.get_files_monitored()