From 09bd022f5a713c24ab376f0d0901aba436dc151a Mon Sep 17 00:00:00 2001
From: Frederick Yin <fkfd@fkfd.me>
Date: Wed, 27 Oct 2021 09:31:04 +0800
Subject: Separate Lockfile into new class

---
 jimbrella/database.py | 35 ++++-------------------------------
 1 file changed, 4 insertions(+), 31 deletions(-)

(limited to 'jimbrella/database.py')

diff --git a/jimbrella/database.py b/jimbrella/database.py
index 37f6c82..fd8f35c 100644
--- a/jimbrella/database.py
+++ b/jimbrella/database.py
@@ -1,6 +1,7 @@
 import csv
 import os
 from datetime import datetime, timedelta
+from .lockfile import Lockfile
 from .utils import human_datetime, human_timedelta
 from .config import DUE_HOURS
 from .exceptions import *
@@ -43,33 +44,7 @@ class Database:
                         | jForm answer sheet. is blank otherwise.
         """
         self.path = path
-
-    def _lock(self) -> int:
-        """Create a lockfile for database.
-
-        If the database is called "db.csv", the lockfile, located in the same
-        directory, would be called "db.csv.lock".
-
-        Returns 1 if the lockfile is successfully created, 0 if the lockfile
-        already exists (strong hint of unrecovered crash or potential race
-        condition - caller of this method should abort whatever it is doing)
-        """
-        try:
-            f = open(self.path + ".lock", "x")
-            f.close()
-            return 1
-        except FileExistsError:
-            return 0
-
-    def _unlock(self) -> None:
-        """Remove lockfile created by _lock.
-
-        If there is no lockfile, simply ignore.
-        """
-        try:
-            os.remove(self.path + ".lock")
-        except FileNotFoundError:
-            pass
+        self.lockfile = Lockfile(self.path)
 
     def _read(self) -> list:
         """Deserialize database."""
@@ -106,9 +81,7 @@ class Database:
             backup = f.read()
             f.close()
 
-        # wait until database is locked for this write
-        while not self._lock():
-            continue
+        self.lockfile.lock()
 
         f = open(self.path, "w")
         try:
@@ -140,7 +113,7 @@ class Database:
             f.close()
             raise e
 
-        self._unlock()
+        self.lockfile.unlock()
 
     def _update(self, update: dict) -> list:
         """Update status of one umbrella, and return the entire updated database."""
-- 
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