import errno
import pwd
import itertools
+import select
+import fcntl
+import resource
+import logging
+import signal
+
+from cStringIO import StringIO
-from ganeti import logger
from ganeti import errors
+from ganeti import constants
_locksheld = []
_re_shell_unquoted = re.compile('^[-.,=:/_+@A-Za-z0-9]+$')
+debug = False
+debug_locks = False
+no_fork = False
+
+
class RunResult(object):
"""Simple class for holding the result of running external programs.
"failed", "fail_reason", "cmd"]
- def __init__(self, exit_code, signal, stdout, stderr, cmd):
+ def __init__(self, exit_code, signal_, stdout, stderr, cmd):
self.cmd = cmd
self.exit_code = exit_code
- self.signal = signal
+ self.signal = signal_
self.stdout = stdout
self.stderr = stderr
- self.failed = (signal is not None or exit_code != 0)
+ self.failed = (signal_ is not None or exit_code != 0)
if self.signal is not None:
self.fail_reason = "terminated by signal %s" % self.signal
else:
self.fail_reason = "unable to determine termination reason"
+ if self.failed:
+ logging.debug("Command '%s' failed (%s); output: %s",
+ self.cmd, self.fail_reason, self.output)
+
def _GetOutput(self):
"""Returns the combined stdout and stderr for easier usage.
output = property(_GetOutput, None, None, "Return full output")
-def _GetLockFile(subsystem):
- """Compute the file name for a given lock name."""
- return "/var/lock/ganeti_lock_%s" % subsystem
-
-
-def Lock(name, max_retries=None, debug=False):
- """Lock a given subsystem.
-
- In case the lock is already held by an alive process, the function
- will sleep indefintely and poll with a one second interval.
-
- When the optional integer argument 'max_retries' is passed with a
- non-zero value, the function will sleep only for this number of
- times, and then it will will raise a LockError if the lock can't be
- acquired. Passing in a negative number will cause only one try to
- get the lock. Passing a positive number will make the function retry
- for approximately that number of seconds.
-
- """
- lockfile = _GetLockFile(name)
-
- if name in _locksheld:
- raise errors.LockError('Lock "%s" already held!' % (name,))
-
- errcount = 0
-
- retries = 0
- while True:
- try:
- fd = os.open(lockfile, os.O_CREAT | os.O_EXCL | os.O_RDWR | os.O_SYNC)
- break
- except OSError, creat_err:
- if creat_err.errno != errno.EEXIST:
- raise errors.LockError("Can't create the lock file. Error '%s'." %
- str(creat_err))
-
- try:
- pf = open(lockfile, 'r')
- except IOError, open_err:
- errcount += 1
- if errcount >= 5:
- raise errors.LockError("Lock file exists but cannot be opened."
- " Error: '%s'." % str(open_err))
- time.sleep(1)
- continue
-
- try:
- pid = int(pf.read())
- except ValueError:
- raise errors.LockError("Invalid pid string in %s" %
- (lockfile,))
-
- if not IsProcessAlive(pid):
- raise errors.LockError("Stale lockfile %s for pid %d?" %
- (lockfile, pid))
-
- if max_retries and max_retries <= retries:
- raise errors.LockError("Can't acquire lock during the specified"
- " time, aborting.")
- if retries == 5 and (debug or sys.stdin.isatty()):
- logger.ToStderr("Waiting for '%s' lock from pid %d..." % (name, pid))
-
- time.sleep(1)
- retries += 1
- continue
-
- os.write(fd, '%d\n' % (os.getpid(),))
- os.close(fd)
-
- _locksheld.append(name)
-
-
-def Unlock(name):
- """Unlock a given subsystem.
-
- """
- lockfile = _GetLockFile(name)
-
- try:
- fd = os.open(lockfile, os.O_RDONLY)
- except OSError:
- raise errors.LockError('Lock "%s" not held.' % (name,))
-
- f = os.fdopen(fd, 'r')
- pid_str = f.read()
-
- try:
- pid = int(pid_str)
- except ValueError:
- raise errors.LockError('Unable to determine PID of locking process.')
-
- if pid != os.getpid():
- raise errors.LockError('Lock not held by me (%d != %d)' %
- (os.getpid(), pid,))
-
- os.unlink(lockfile)
- _locksheld.remove(name)
-
-
-def LockCleanup():
- """Remove all locks.
-
- """
- for lock in _locksheld:
- Unlock(lock)
-
-
-def RunCmd(cmd):
+def RunCmd(cmd, env=None):
"""Execute a (shell) command.
The command should not read from its standard input, as it will be
closed.
- Args:
- cmd: command to run. (str)
-
- Returns: `RunResult` instance
+ @param cmd: Command to run
+ @type cmd: string or list
+ @param env: Additional environment
+ @type env: dict
+ @return: `RunResult` instance
+ @rtype: RunResult
"""
+ if no_fork:
+ raise errors.ProgrammerError("utils.RunCmd() called with fork() disabled")
+
if isinstance(cmd, list):
cmd = [str(val) for val in cmd]
strcmd = " ".join(cmd)
else:
strcmd = cmd
shell = True
- env = os.environ.copy()
- env["LC_ALL"] = "C"
+ logging.debug("RunCmd '%s'", strcmd)
+
+ cmd_env = os.environ.copy()
+ cmd_env["LC_ALL"] = "C"
+ if env is not None:
+ cmd_env.update(env)
+
+ poller = select.poll()
child = subprocess.Popen(cmd, shell=shell,
stderr=subprocess.PIPE,
stdout=subprocess.PIPE,
stdin=subprocess.PIPE,
- close_fds=True, env=env)
+ close_fds=True, env=cmd_env)
child.stdin.close()
- out = child.stdout.read()
- err = child.stderr.read()
+ poller.register(child.stdout, select.POLLIN)
+ poller.register(child.stderr, select.POLLIN)
+ out = StringIO()
+ err = StringIO()
+ fdmap = {
+ child.stdout.fileno(): (out, child.stdout),
+ child.stderr.fileno(): (err, child.stderr),
+ }
+ for fd in fdmap:
+ status = fcntl.fcntl(fd, fcntl.F_GETFL)
+ fcntl.fcntl(fd, fcntl.F_SETFL, status | os.O_NONBLOCK)
+
+ while fdmap:
+ for fd, event in poller.poll():
+ if event & select.POLLIN or event & select.POLLPRI:
+ data = fdmap[fd][1].read()
+ # no data from read signifies EOF (the same as POLLHUP)
+ if not data:
+ poller.unregister(fd)
+ del fdmap[fd]
+ continue
+ fdmap[fd][0].write(data)
+ if (event & select.POLLNVAL or event & select.POLLHUP or
+ event & select.POLLERR):
+ poller.unregister(fd)
+ del fdmap[fd]
+
+ out = out.getvalue()
+ err = err.getvalue()
status = child.wait()
if status >= 0:
exitcode = status
- signal = None
+ signal_ = None
else:
exitcode = None
- signal = -status
-
- return RunResult(exitcode, signal, out, err, strcmd)
-
+ signal_ = -status
-def RunCmdUnlocked(cmd):
- """Execute a shell command without the 'cmd' lock.
-
- This variant of `RunCmd()` drops the 'cmd' lock before running the
- command and re-aquires it afterwards, thus it can be used to call
- other ganeti commands.
-
- The argument and return values are the same as for the `RunCmd()`
- function.
-
- Args:
- cmd - command to run. (str)
-
- Returns:
- `RunResult`
-
- """
- Unlock('cmd')
- ret = RunCmd(cmd)
- Lock('cmd')
-
- return ret
+ return RunResult(exitcode, signal_, out, err, strcmd)
def RemoveFile(filename):
target[k] = template[k]
if missing and logname:
- logger.Debug('%s missing keys %s' %
- (logname, ', '.join(missing)))
+ logging.warning('%s missing keys %s', logname, ', '.join(missing))
def IsProcessAlive(pid):
Returns: true or false, depending on if the pid exists or not
- Remarks: zombie processes treated as not alive
+ Remarks: zombie processes treated as not alive, and giving a pid <=
+ 0 makes the function to return False.
"""
+ if pid <= 0:
+ return False
+
try:
f = open("/proc/%d/status" % pid)
except IOError, err:
return alive
+def ReadPidFile(pidfile):
+ """Read the pid from a file.
+
+ @param pidfile: Path to a file containing the pid to be checked
+ @type pidfile: string (filename)
+ @return: The process id, if the file exista and contains a valid PID,
+ otherwise 0
+ @rtype: int
+
+ """
+ try:
+ pf = open(pidfile, 'r')
+ except EnvironmentError, err:
+ if err.errno != errno.ENOENT:
+ logging.exception("Can't read pid file?!")
+ return 0
+
+ try:
+ pid = int(pf.read())
+ except ValueError, err:
+ logging.info("Can't parse pid file contents", exc_info=True)
+ return 0
+
+ return pid
+
+
def MatchNameComponent(key, name_list):
"""Try to match a name against a list.
name, size = line.split()
size = int(float(size))
except (IndexError, ValueError), err:
- logger.Error("Invalid output from vgs (%s): %s" % (err, line))
+ logging.error("Invalid output from vgs (%s): %s", err, line)
continue
retval[name] = size
return [tup[1] for tup in to_sort]
-def CheckDaemonAlive(pid_file, process_string):
- """Check wether the specified daemon is alive.
-
- Args:
- - pid_file: file to read the daemon pid from, the file is
- expected to contain only a single line containing
- only the PID
- - process_string: a substring that we expect to find in
- the command line of the daemon process
-
- Returns:
- - True if the daemon is judged to be alive (that is:
- - the PID file exists, is readable and contains a number
- - a process of the specified PID is running
- - that process contains the specified string in its
- command line
- - the process is not in state Z (zombie))
- - False otherwise
-
- """
- try:
- pid_file = file(pid_file, 'r')
- try:
- pid = int(pid_file.readline())
- finally:
- pid_file.close()
-
- cmdline_file_path = "/proc/%s/cmdline" % (pid)
- cmdline_file = open(cmdline_file_path, 'r')
- try:
- cmdline = cmdline_file.readline()
- finally:
- cmdline_file.close()
-
- if not process_string in cmdline:
- return False
-
- stat_file_path = "/proc/%s/stat" % (pid)
- stat_file = open(stat_file_path, 'r')
- try:
- process_state = stat_file.readline().split()[2]
- finally:
- stat_file.close()
-
- if process_state == 'Z':
- return False
-
- except (IndexError, IOError, ValueError):
- return False
-
- return True
-
-
def TryConvert(fn, val):
"""Try to convert a value ignoring errors.
raise
+def AddHostToEtcHosts(hostname):
+ """Wrapper around SetEtcHostsEntry.
+
+ """
+ hi = HostInfo(name=hostname)
+ SetEtcHostsEntry(constants.ETC_HOSTS, hi.ip, hi.name, [hi.ShortName()])
+
+
def RemoveEtcHostsEntry(file_name, hostname):
"""Removes a hostname from /etc/hosts.
raise
+def RemoveHostFromEtcHosts(hostname):
+ """Wrapper around RemoveEtcHostsEntry.
+
+ """
+ hi = HostInfo(name=hostname)
+ RemoveEtcHostsEntry(constants.ETC_HOSTS, hi.name)
+ RemoveEtcHostsEntry(constants.ETC_HOSTS, hi.ShortName())
+
+
def CreateBackup(file_name):
"""Creates a backup of a file.
return ' '.join([ShellQuote(i) for i in args])
-
-def TcpPing(source, target, port, timeout=10, live_port_needed=False):
+def TcpPing(target, port, timeout=10, live_port_needed=False, source=None):
"""Simple ping implementation using TCP connect(2).
- Try to do a TCP connect(2) from the specified source IP to the specified
- target IP and the specified target port. If live_port_needed is set to true,
- requires the remote end to accept the connection. The timeout is specified
- in seconds and defaults to 10 seconds
+ Try to do a TCP connect(2) from an optional source IP to the
+ specified target IP and the specified target port. If the optional
+ parameter live_port_needed is set to true, requires the remote end
+ to accept the connection. The timeout is specified in seconds and
+ defaults to 10 seconds. If the source optional argument is not
+ passed, the source address selection is left to the kernel,
+ otherwise we try to connect using the passed address (failures to
+ bind other than EADDRNOTAVAIL will be ignored).
"""
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sucess = False
- try:
- sock.bind((source, 0))
- except socket.error, (errcode, errstring):
- if errcode == errno.EADDRNOTAVAIL:
- success = False
+ if source is not None:
+ try:
+ sock.bind((source, 0))
+ except socket.error, (errcode, errstring):
+ if errcode == errno.EADDRNOTAVAIL:
+ success = False
sock.settimeout(timeout)
return success
+def OwnIpAddress(address):
+ """Check if the current host has the the given IP address.
+
+ Currently this is done by tcp-pinging the address from the loopback
+ address.
+
+ @type address: string
+ @param address: the addres to check
+ @rtype: bool
+
+ """
+ return TcpPing(address, constants.DEFAULT_NODED_PORT,
+ source=constants.LOCALHOST_IP_ADDRESS)
+
+
def ListVisibleFiles(path):
"""Returns a list of all visible files in a directory.
"""
- return [i for i in os.listdir(path) if not i.startswith(".")]
+ files = [i for i in os.listdir(path) if not i.startswith(".")]
+ files.sort()
+ return files
def GetHomeDir(user, default=None):
f.close()
+def GenerateSecret():
+ """Generates a random secret.
+
+ This will generate a pseudo-random secret, and return its sha digest
+ (so that it can be used where an ASCII string is needed).
+
+ """
+ return sha.new(os.urandom(64)).hexdigest()
+
+
+def ReadFile(file_name, size=None):
+ """Reads a file.
+
+ @type size: None or int
+ @param size: Read at most size bytes
+
+ """
+ f = open(file_name, "r")
+ try:
+ if size is None:
+ return f.read()
+ else:
+ return f.read(size)
+ finally:
+ f.close()
+
+
def WriteFile(file_name, fn=None, data=None,
mode=None, uid=-1, gid=-1,
- atime=None, mtime=None):
+ atime=None, mtime=None, close=True,
+ dry_run=False, backup=False,
+ prewrite=None, postwrite=None):
"""(Over)write a file atomically.
The file_name and either fn (a function taking one argument, the
exception, an existing target file should be unmodified and the
temporary file should be removed.
+ Args:
+ file_name: New filename
+ fn: Content writing function, called with file descriptor as parameter
+ data: Content as string
+ mode: File mode
+ uid: Owner
+ gid: Group
+ atime: Access time
+ mtime: Modification time
+ close: Whether to close file after writing it
+ prewrite: Function object called before writing content
+ postwrite: Function object called after writing content
+
+ Returns:
+ None if "close" parameter evaluates to True, otherwise file descriptor.
+
"""
if not os.path.isabs(file_name):
raise errors.ProgrammerError("Path passed to WriteFile is not"
raise errors.ProgrammerError("Both atime and mtime must be either"
" set or None")
+ if backup and not dry_run and os.path.isfile(file_name):
+ CreateBackup(file_name)
dir_name, base_name = os.path.split(file_name)
fd, new_name = tempfile.mkstemp('.new', base_name, dir_name)
os.chown(new_name, uid, gid)
if mode:
os.chmod(new_name, mode)
+ if callable(prewrite):
+ prewrite(fd)
if data is not None:
os.write(fd, data)
else:
fn(fd)
+ if callable(postwrite):
+ postwrite(fd)
os.fsync(fd)
if atime is not None and mtime is not None:
os.utime(new_name, (atime, mtime))
- os.rename(new_name, file_name)
+ if not dry_run:
+ os.rename(new_name, file_name)
finally:
- os.close(fd)
+ if close:
+ os.close(fd)
+ result = None
+ else:
+ result = fd
RemoveFile(new_name)
+ return result
+
+
+def FirstFree(seq, base=0):
+ """Returns the first non-existing integer from seq.
+
+ The seq argument should be a sorted list of positive integers. The
+ first time the index of an element is smaller than the element
+ value, the index will be returned.
+
+ The base argument is used to start at a different offset,
+ i.e. [3, 4, 6] with offset=3 will return 5.
+
+ Example: [0, 1, 3] will return 2.
+
+ """
+ for idx, elem in enumerate(seq):
+ assert elem >= base, "Passed element is higher than base offset"
+ if elem > idx + base:
+ # idx is not used
+ return idx + base
+ return None
+
def all(seq, pred=bool):
"Returns True if pred(x) is True for every element in the iterable"
"""
seen = set()
return [i for i in seq if i not in seen and not seen.add(i)]
+
+
+def IsValidMac(mac):
+ """Predicate to check if a MAC address is valid.
+
+ Checks wether the supplied MAC address is formally correct, only
+ accepts colon separated format.
+ """
+ mac_check = re.compile("^([0-9a-f]{2}(:|$)){6}$")
+ return mac_check.match(mac) is not None
+
+
+def TestDelay(duration):
+ """Sleep for a fixed amount of time.
+
+ """
+ if duration < 0:
+ return False
+ time.sleep(duration)
+ return True
+
+
+def Daemonize(logfile, noclose_fds=None):
+ """Daemonize the current process.
+
+ This detaches the current process from the controlling terminal and
+ runs it in the background as a daemon.
+
+ """
+ UMASK = 077
+ WORKDIR = "/"
+ # Default maximum for the number of available file descriptors.
+ if 'SC_OPEN_MAX' in os.sysconf_names:
+ try:
+ MAXFD = os.sysconf('SC_OPEN_MAX')
+ if MAXFD < 0:
+ MAXFD = 1024
+ except OSError:
+ MAXFD = 1024
+ else:
+ MAXFD = 1024
+
+ # this might fail
+ pid = os.fork()
+ if (pid == 0): # The first child.
+ os.setsid()
+ # this might fail
+ pid = os.fork() # Fork a second child.
+ if (pid == 0): # The second child.
+ os.chdir(WORKDIR)
+ os.umask(UMASK)
+ else:
+ # exit() or _exit()? See below.
+ os._exit(0) # Exit parent (the first child) of the second child.
+ else:
+ os._exit(0) # Exit parent of the first child.
+ maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
+ if (maxfd == resource.RLIM_INFINITY):
+ maxfd = MAXFD
+
+ # Iterate through and close all file descriptors.
+ for fd in range(0, maxfd):
+ if noclose_fds and fd in noclose_fds:
+ continue
+ try:
+ os.close(fd)
+ except OSError: # ERROR, fd wasn't open to begin with (ignored)
+ pass
+ os.open(logfile, os.O_RDWR|os.O_CREAT|os.O_APPEND, 0600)
+ # Duplicate standard input to standard output and standard error.
+ os.dup2(0, 1) # standard output (1)
+ os.dup2(0, 2) # standard error (2)
+ return 0
+
+
+def DaemonPidFileName(name):
+ """Compute a ganeti pid file absolute path, given the daemon name.
+
+ """
+ return os.path.join(constants.RUN_GANETI_DIR, "%s.pid" % name)
+
+
+def WritePidFile(name):
+ """Write the current process pidfile.
+
+ The file will be written to constants.RUN_GANETI_DIR/name.pid
+
+ """
+ pid = os.getpid()
+ pidfilename = DaemonPidFileName(name)
+ if IsProcessAlive(ReadPidFile(pidfilename)):
+ raise errors.GenericError("%s contains a live process" % pidfilename)
+
+ WriteFile(pidfilename, data="%d\n" % pid)
+
+
+def RemovePidFile(name):
+ """Remove the current process pidfile.
+
+ Any errors are ignored.
+
+ """
+ pid = os.getpid()
+ pidfilename = DaemonPidFileName(name)
+ # TODO: we could check here that the file contains our pid
+ try:
+ RemoveFile(pidfilename)
+ except:
+ pass
+
+
+def KillProcess(pid, signal_=signal.SIGTERM, timeout=30):
+ """Kill a process given by its pid.
+
+ @type pid: int
+ @param pid: The PID to terminate.
+ @type signal_: int
+ @param signal_: The signal to send, by default SIGTERM
+ @type timeout: int
+ @param timeout: The timeout after which, if the process is still alive,
+ a SIGKILL will be sent. If not positive, no such checking
+ will be done
+
+ """
+ if pid <= 0:
+ # kill with pid=0 == suicide
+ raise errors.ProgrammerError("Invalid pid given '%s'" % pid)
+
+ if not IsProcessAlive(pid):
+ return
+ os.kill(pid, signal_)
+ if timeout <= 0:
+ return
+ end = time.time() + timeout
+ while time.time() < end and IsProcessAlive(pid):
+ time.sleep(0.1)
+ if IsProcessAlive(pid):
+ os.kill(pid, signal.SIGKILL)
+
+
+def FindFile(name, search_path, test=os.path.exists):
+ """Look for a filesystem object in a given path.
+
+ This is an abstract method to search for filesystem object (files,
+ dirs) under a given search path.
+
+ Args:
+ - name: the name to look for
+ - search_path: list of directory names
+ - test: the test which the full path must satisfy
+ (defaults to os.path.exists)
+
+ Returns:
+ - full path to the item if found
+ - None otherwise
+
+ """
+ for dir_name in search_path:
+ item_name = os.path.sep.join([dir_name, name])
+ if test(item_name):
+ return item_name
+ return None
+
+
+def CheckVolumeGroupSize(vglist, vgname, minsize):
+ """Checks if the volume group list is valid.
+
+ A non-None return value means there's an error, and the return value
+ is the error message.
+
+ """
+ vgsize = vglist.get(vgname, None)
+ if vgsize is None:
+ return "volume group '%s' missing" % vgname
+ elif vgsize < minsize:
+ return ("volume group '%s' too small (%s MiB required, %d MiB found)" %
+ (vgname, minsize, vgsize))
+ return None
+
+
+def SplitTime(value):
+ """Splits time as floating point number into a tuple.
+
+ @param value: Time in seconds
+ @type value: int or float
+ @return: Tuple containing (seconds, microseconds)
+
+ """
+ (seconds, microseconds) = divmod(int(value * 1000000), 1000000)
+
+ assert 0 <= seconds, \
+ "Seconds must be larger than or equal to 0, but are %s" % seconds
+ assert 0 <= microseconds <= 999999, \
+ "Microseconds must be 0-999999, but are %s" % microseconds
+
+ return (int(seconds), int(microseconds))
+
+
+def MergeTime(timetuple):
+ """Merges a tuple into time as a floating point number.
+
+ @param timetuple: Time as tuple, (seconds, microseconds)
+ @type timetuple: tuple
+ @return: Time as a floating point number expressed in seconds
+
+ """
+ (seconds, microseconds) = timetuple
+
+ assert 0 <= seconds, \
+ "Seconds must be larger than or equal to 0, but are %s" % seconds
+ assert 0 <= microseconds <= 999999, \
+ "Microseconds must be 0-999999, but are %s" % microseconds
+
+ return float(seconds) + (float(microseconds) * 0.000001)
+
+
+def GetNodeDaemonPort():
+ """Get the node daemon port for this cluster.
+
+ Note that this routine does not read a ganeti-specific file, but
+ instead uses socket.getservbyname to allow pre-customization of
+ this parameter outside of Ganeti.
+
+ """
+ try:
+ port = socket.getservbyname("ganeti-noded", "tcp")
+ except socket.error:
+ port = constants.DEFAULT_NODED_PORT
+
+ return port
+
+
+def GetNodeDaemonPassword():
+ """Get the node password for the cluster.
+
+ """
+ return ReadFile(constants.CLUSTER_PASSWORD_FILE)
+
+
+def LockedMethod(fn):
+ """Synchronized object access decorator.
+
+ This decorator is intended to protect access to an object using the
+ object's own lock which is hardcoded to '_lock'.
+
+ """
+ def _LockDebug(*args, **kwargs):
+ if debug_locks:
+ logging.debug(*args, **kwargs)
+
+ def wrapper(self, *args, **kwargs):
+ assert hasattr(self, '_lock')
+ lock = self._lock
+ _LockDebug("Waiting for %s", lock)
+ lock.acquire()
+ try:
+ _LockDebug("Acquired %s", lock)
+ result = fn(self, *args, **kwargs)
+ finally:
+ _LockDebug("Releasing %s", lock)
+ lock.release()
+ _LockDebug("Released %s", lock)
+ return result
+ return wrapper
+
+
+def LockFile(fd):
+ """Locks a file using POSIX locks.
+
+ """
+ try:
+ fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
+ except IOError, err:
+ if err.errno == errno.EAGAIN:
+ raise errors.LockError("File already locked")
+ raise
+
+
+class FileLock(object):
+ """Utility class for file locks.
+
+ """
+ def __init__(self, filename):
+ self.filename = filename
+ self.fd = open(self.filename, "w")
+
+ def __del__(self):
+ self.Close()
+
+ def Close(self):
+ if self.fd:
+ self.fd.close()
+ self.fd = None
+
+ def _flock(self, flag, blocking, timeout, errmsg):
+ """Wrapper for fcntl.flock.
+
+ @type flag: int
+ @param flag: Operation flag
+ @type blocking: bool
+ @param blocking: Whether the operation should be done in blocking mode.
+ @type timeout: None or float
+ @param timeout: For how long the operation should be retried (implies
+ non-blocking mode).
+ @type errmsg: string
+ @param errmsg: Error message in case operation fails.
+
+ """
+ assert self.fd, "Lock was closed"
+ assert timeout is None or timeout >= 0, \
+ "If specified, timeout must be positive"
+
+ if timeout is not None:
+ flag |= fcntl.LOCK_NB
+ timeout_end = time.time() + timeout
+
+ # Blocking doesn't have effect with timeout
+ elif not blocking:
+ flag |= fcntl.LOCK_NB
+ timeout_end = None
+
+ retry = True
+ while retry:
+ try:
+ fcntl.flock(self.fd, flag)
+ retry = False
+ except IOError, err:
+ if err.errno in (errno.EAGAIN, ):
+ if timeout_end is not None and time.time() < timeout_end:
+ # Wait before trying again
+ time.sleep(max(0.1, min(1.0, timeout)))
+ else:
+ raise errors.LockError(errmsg)
+ else:
+ logging.exception("fcntl.flock failed")
+ raise
+
+ def Exclusive(self, blocking=False, timeout=None):
+ """Locks the file in exclusive mode.
+
+ """
+ self._flock(fcntl.LOCK_EX, blocking, timeout,
+ "Failed to lock %s in exclusive mode" % self.filename)
+
+ def Shared(self, blocking=False, timeout=None):
+ """Locks the file in shared mode.
+
+ """
+ self._flock(fcntl.LOCK_SH, blocking, timeout,
+ "Failed to lock %s in shared mode" % self.filename)
+
+ def Unlock(self, blocking=True, timeout=None):
+ """Unlocks the file.
+
+ According to "man flock", unlocking can also be a nonblocking operation:
+ "To make a non-blocking request, include LOCK_NB with any of the above
+ operations"
+
+ """
+ self._flock(fcntl.LOCK_UN, blocking, timeout,
+ "Failed to unlock %s" % self.filename)
+
+
+class SignalHandler(object):
+ """Generic signal handler class.
+
+ It automatically restores the original handler when deconstructed or when
+ Reset() is called. You can either pass your own handler function in or query
+ the "called" attribute to detect whether the signal was sent.
+
+ """
+ def __init__(self, signum):
+ """Constructs a new SignalHandler instance.
+
+ @param signum: Single signal number or set of signal numbers
+
+ """
+ if isinstance(signum, (int, long)):
+ self.signum = set([signum])
+ else:
+ self.signum = set(signum)
+
+ self.called = False
+
+ self._previous = {}
+ try:
+ for signum in self.signum:
+ # Setup handler
+ prev_handler = signal.signal(signum, self._HandleSignal)
+ try:
+ self._previous[signum] = prev_handler
+ except:
+ # Restore previous handler
+ signal.signal(signum, prev_handler)
+ raise
+ except:
+ # Reset all handlers
+ self.Reset()
+ # Here we have a race condition: a handler may have already been called,
+ # but there's not much we can do about it at this point.
+ raise
+
+ def __del__(self):
+ self.Reset()
+
+ def Reset(self):
+ """Restore previous handler.
+
+ """
+ for signum, prev_handler in self._previous.items():
+ signal.signal(signum, prev_handler)
+ # If successful, remove from dict
+ del self._previous[signum]
+
+ def Clear(self):
+ """Unsets "called" flag.
+
+ This function can be used in case a signal may arrive several times.
+
+ """
+ self.called = False
+
+ def _HandleSignal(self, signum, frame):
+ """Actual signal handling function.
+
+ """
+ # This is not nice and not absolutely atomic, but it appears to be the only
+ # solution in Python -- there are no atomic types.
+ self.called = True
projects / ganeti-local / blobdiff