+++ /dev/null
-from __future__ import absolute_import, division
-
-import time
-import os
-
-try:
- unicode
-except NameError:
- unicode = str
-
-from . import LockBase, NotLocked, NotMyLock, LockTimeout, AlreadyLocked
-
-
-class SQLiteLockFile(LockBase):
- "Demonstrate SQL-based locking."
-
- testdb = None
-
- def __init__(self, path, threaded=True, timeout=None):
- """
- >>> lock = SQLiteLockFile('somefile')
- >>> lock = SQLiteLockFile('somefile', threaded=False)
- """
- LockBase.__init__(self, path, threaded, timeout)
- self.lock_file = unicode(self.lock_file)
- self.unique_name = unicode(self.unique_name)
-
- if SQLiteLockFile.testdb is None:
- import tempfile
- _fd, testdb = tempfile.mkstemp()
- os.close(_fd)
- os.unlink(testdb)
- del _fd, tempfile
- SQLiteLockFile.testdb = testdb
-
- import sqlite3
- self.connection = sqlite3.connect(SQLiteLockFile.testdb)
-
- c = self.connection.cursor()
- try:
- c.execute("create table locks"
- "("
- " lock_file varchar(32),"
- " unique_name varchar(32)"
- ")")
- except sqlite3.OperationalError:
- pass
- else:
- self.connection.commit()
- import atexit
- atexit.register(os.unlink, SQLiteLockFile.testdb)
-
- def acquire(self, timeout=None):
- timeout = timeout if timeout is not None else self.timeout
- end_time = time.time()
- if timeout is not None and timeout > 0:
- end_time += timeout
-
- if timeout is None:
- wait = 0.1
- elif timeout <= 0:
- wait = 0
- else:
- wait = timeout / 10
-
- cursor = self.connection.cursor()
-
- while True:
- if not self.is_locked():
- # Not locked. Try to lock it.
- cursor.execute("insert into locks"
- " (lock_file, unique_name)"
- " values"
- " (?, ?)",
- (self.lock_file, self.unique_name))
- self.connection.commit()
-
- # Check to see if we are the only lock holder.
- cursor.execute("select * from locks"
- " where unique_name = ?",
- (self.unique_name,))
- rows = cursor.fetchall()
- if len(rows) > 1:
- # Nope. Someone else got there. Remove our lock.
- cursor.execute("delete from locks"
- " where unique_name = ?",
- (self.unique_name,))
- self.connection.commit()
- else:
- # Yup. We're done, so go home.
- return
- else:
- # Check to see if we are the only lock holder.
- cursor.execute("select * from locks"
- " where unique_name = ?",
- (self.unique_name,))
- rows = cursor.fetchall()
- if len(rows) == 1:
- # We're the locker, so go home.
- return
-
- # Maybe we should wait a bit longer.
- if timeout is not None and time.time() > end_time:
- if timeout > 0:
- # No more waiting.
- raise LockTimeout("Timeout waiting to acquire"
- " lock for %s" %
- self.path)
- else:
- # Someone else has the lock and we are impatient..
- raise AlreadyLocked("%s is already locked" % self.path)
-
- # Well, okay. We'll give it a bit longer.
- time.sleep(wait)
-
- def release(self):
- if not self.is_locked():
- raise NotLocked("%s is not locked" % self.path)
- if not self.i_am_locking():
- raise NotMyLock("%s is locked, but not by me (by %s)" %
- (self.unique_name, self._who_is_locking()))
- cursor = self.connection.cursor()
- cursor.execute("delete from locks"
- " where unique_name = ?",
- (self.unique_name,))
- self.connection.commit()
-
- def _who_is_locking(self):
- cursor = self.connection.cursor()
- cursor.execute("select unique_name from locks"
- " where lock_file = ?",
- (self.lock_file,))
- return cursor.fetchone()[0]
-
- def is_locked(self):
- cursor = self.connection.cursor()
- cursor.execute("select * from locks"
- " where lock_file = ?",
- (self.lock_file,))
- rows = cursor.fetchall()
- return not not rows
-
- def i_am_locking(self):
- cursor = self.connection.cursor()
- cursor.execute("select * from locks"
- " where lock_file = ?"
- " and unique_name = ?",
- (self.lock_file, self.unique_name))
- return not not cursor.fetchall()
-
- def break_lock(self):
- cursor = self.connection.cursor()
- cursor.execute("delete from locks"
- " where lock_file = ?",
- (self.lock_file,))
- self.connection.commit()
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