diff env/lib/python3.9/site-packages/galaxy/util/filelock.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/galaxy/util/filelock.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,82 @@
+"""Code obtained from https://github.com/dmfrey/FileLock.
+
+See full license at:
+
+https://github.com/dmfrey/FileLock/blob/master/LICENSE.txt
+
+"""
+import errno
+import os
+import time
+
+
+class FileLockException(Exception):
+    pass
+
+
+class FileLock:
+    """ A file locking mechanism that has context-manager support so
+        you can use it in a with statement. This should be relatively cross
+        compatible as it doesn't rely on msvcrt or fcntl for the locking.
+    """
+
+    def __init__(self, file_name, timeout=10, delay=.05):
+        """ Prepare the file locker. Specify the file to lock and optionally
+            the maximum timeout and the delay between each attempt to lock.
+        """
+        self.is_locked = False
+        full_path = os.path.abspath(file_name)
+        self.lockfile = "%s.lock" % full_path
+        self.file_name = full_path
+        self.timeout = timeout
+        self.delay = delay
+
+    def acquire(self):
+        """ Acquire the lock, if possible. If the lock is in use, it check again
+            every `wait` seconds. It does this until it either gets the lock or
+            exceeds `timeout` number of seconds, in which case it throws
+            an exception.
+        """
+        start_time = time.time()
+        while True:
+            try:
+                self.fd = os.open(self.lockfile, os.O_CREAT | os.O_EXCL | os.O_RDWR)
+                break
+            except OSError as e:
+                if e.errno != errno.EEXIST:
+                    raise
+                if (time.time() - start_time) >= self.timeout:
+                    raise FileLockException("Timeout occurred.")
+                time.sleep(self.delay)
+        self.is_locked = True
+
+    def release(self):
+        """ Get rid of the lock by deleting the lockfile.
+            When working in a `with` statement, this gets automatically
+            called at the end.
+        """
+        if self.is_locked:
+            os.close(self.fd)
+            os.unlink(self.lockfile)
+            self.is_locked = False
+
+    def __enter__(self):
+        """ Activated when used in the with statement.
+            Should automatically acquire a lock to be used in the with block.
+        """
+        if not self.is_locked:
+            self.acquire()
+        return self
+
+    def __exit__(self, type, value, traceback):
+        """ Activated at the end of the with statement.
+            It automatically releases the lock if it isn't locked.
+        """
+        if self.is_locked:
+            self.release()
+
+    def __del__(self):
+        """ Make sure that the FileLock instance doesn't leave a lockfile
+            lying around.
+        """
+        self.release()