install py files
This commit is contained in:
Michael Davidsaver
327
devsupApp/src/devsup/db.py
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327
devsupApp/src/devsup/db.py
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import threading, sys, traceback, time
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from devsup.util import Worker
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try:
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import _dbapi
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except ImportError:
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import _nullapi as _dbapi
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_rec_cache = {}
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_no_such_field = object()
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__all__ = [
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'Record', 'getRecord',
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'Field',
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'IOScanListBlock',
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'IOScanListThread',
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]
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def getRecord(name):
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"""Retrieve a :class:`Record` instance by the
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full record name.
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The result is cached so the future calls will return the same instance.
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This is the prefered way to get :class:`Record` instances.
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>>> R = getRecord("my:record:name")
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Record("my:record:name")
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"""
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try:
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return _rec_cache[name]
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except KeyError:
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rec = Record(name)
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_rec_cache[name] = rec
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return rec
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class IOScanListBlock(object):
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"""A list of records which will be processed together.
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This convienence class to handle the accounting to
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maintain a list of records.
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"""
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def __init__(self):
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super(IOScanListBlock,self).__init__()
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self._recs, self._recs_add, self._recs_remove = set(), set(), set()
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self.force, self._running = 2, False
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def add(self, rec):
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"""Add a record to the scan list.
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This method is designed to be consistent
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with :meth:`allowScan <DeviceSupport.allowScan>`
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by returning its :meth:`remove` method.
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If fact this function can be completely delegated. ::
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class MyDriver(util.StoppableThread):
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def __init__(self):
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super(MyDriver,self).__init__()
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self.lock = threading.Lock()
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self.scan1 = IOScanListBlock()
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def run(self):
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while self.shouldRun():
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time.sleep(1)
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with self.lock:
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self.scan1.interrupt()
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class MySup(object):
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def __init__(self, driver):
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self.driver = driver
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def allowScan(rec):
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with self.driver.lock:
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return self.driver.scan1.add(rec)
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"""
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assert isinstance(rec, Record)
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if self._running:
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self._recs_remove.discard(rec)
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self._recs_add.add(rec)
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else:
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self._recs.add(rec)
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return self.remove
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def remove(self, rec):
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"""Remove a record from the scan list.
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"""
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if self._running:
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self._recs_add.discard(rec)
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self._recs_add._recs_remove(rec)
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else:
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self._recs.discard(rec)
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def interrupt(self, reason=None, mask=None):
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"""Scan the records in this list.
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:param reason: Passed to :meth:`Record.scan`.
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:param mask: A *list* or *set* or records which should not be scanned.
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This method will call :meth:`Record.scan` of each of the records
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currently in the list. This is done synchronously in the current
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thread. It should **never** be call when any record locks are held.
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"""
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self._running = True
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try:
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for R in self._recs:
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if mask and R in mask:
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continue
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R.scan(sync=True, reason=reason, force=self.force)
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finally:
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self._running = False
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if self._recs_add or self._recs_remove:
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assert len(self._recs_add.interaction(self._recs_remove))==0
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self._recs.update(self._recs_add)
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self._recs_add.clear()
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self._recs.difference_update(self._recs_remove)
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self._recs_remove.clear()
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def _default_whendone(type, val, tb):
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if type or val or tb:
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traceback.print_exception(type, val, tb)
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class IOScanListThread(IOScanListBlock):
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"""A list of records w/ a worker thread to run them.
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All methods are thread-safe.
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"""
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_worker = None
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_worker_lock = threading.Lock()
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queuelength=100
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@classmethod
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def getworker(cls):
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with cls._worker_lock:
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if cls._worker is not None:
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return cls._worker
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import devsup.hooks
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T = Worker(max=cls.queuelength)
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devsup.hooks.addHook('AtIocExit', T.join)
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T.start()
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cls._worker = T
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return T
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def __init__(self):
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super(IOScanListThread,self).__init__()
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self._lock = threading.Lock()
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def add(self, rec):
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"""Add a record to the scan list.
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This method is thread-safe and may be used
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without additional locking. ::
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class MyDriver(util.StoppableThread):
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def __init__(self):
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super(MyDriver,self).__init__()
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self.scan1 = IOScanListThread()
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def run(self):
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while self.shouldRun():
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time.sleep(1)
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self.scan1.interrupt()
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class MySup(object):
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def __init__(self, driver):
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self.driver = driver
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self.allowScan = self.driver.scan1.add
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"""
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with self._lock:
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return super(IOScanListThread,self).add(rec)
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def remove(self, rec):
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with self._lock:
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return super(IOScanListThread,self).remove(rec)
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def interrupt(self, reason=None, mask=None, whendone=_default_whendone):
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"""Queue a request to process the scan list.
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:param reason: Passed to :meth:`Record.scan`.
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:param mask: A *list* or *set* or records which should not be scanned.
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:param whendone: A callable which will be invoked after all records are processed.
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:throws: RuntimeError is the request can't be queued.
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Calling this method will cause a request to be sent to a
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worker thread. This method can be called several times
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to queue several requests.
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If provided, the *whendone* callable is invoked with three arguments.
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These will be None except in the case an interrupt is raised in the
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worker in which case they are: exception type, value, and traceback.
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.. note::
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This method may be safely called while record locks are held.
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"""
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W = self.getworker()
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W.add(self._X, (reason, mask, whendone))
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def _X(self, reason, mask, whendone):
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try:
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#print 'XXXXX',self
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with self._lock:
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super(IOScanListThread,self).interrupt(reason, mask)
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finally:
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#print 'YYYYY',self,sys.exc_info()
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whendone(*sys.exc_info())
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class Record(_dbapi._Record):
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def __init__(self, *args, **kws):
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super(Record, self).__init__(*args, **kws)
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super(Record, self).__setattr__('_fld_cache', {})
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def field(self, name):
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"""Lookup field in this record
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:rtype: :class:`Field`
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:throws: KeyError for non-existant fields.
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The returned object is cached so future calls will
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return the same instance.
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>>> getRecord("rec").field('HOPR')
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Field("rec.HOPR")
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"""
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try:
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F = self._fld_cache[name]
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if F is _no_such_field:
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raise ValueError()
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return F
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except KeyError as e:
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try:
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fld = Field("%s.%s"%(self.name(), name))
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except ValueError:
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self._fld_cache[name] = _no_such_field
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raise e
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else:
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self._fld_cache[name] = fld
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return fld
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def setTime(self, ts):
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"""Set record timestamp.
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:param ts: datetime, float, or (sec, nsec).
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Has not effect if the TSE field is not set to -2.
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All inputs must be referenced to the posix epoch.
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"""
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if hasattr(ts, 'timetuple'):
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ts = time.mktime(ts.timetuple())
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try:
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sec, nsec = ts
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except TypeError:
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sec = int(ts)
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nsec = int(ts*1e9)%1000000000
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super(Record, self).setTime(sec, nsec)
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def __getattr__(self, name):
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try:
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F = self.field(name)
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except ValueError:
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raise AttributeError('No such field')
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else:
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return F.getval()
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def __setattr__(self, name, val):
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try:
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F=self.field(name)
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except ValueError:
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super(Record, self).__setattr__(name, val)
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else:
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F.putval(val)
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def __repr__(self):
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return 'Record("%s")'%self.name()
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class Field(_dbapi._Field):
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@property
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def record(self):
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"""Fetch the :class:`Record` associated with this field
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"""
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try:
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return self._record
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except AttributeError:
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rec, _ = self.name()
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self._record = getRecord(rec)
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return self._record
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def getTime(self):
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"""Get timestamp of link target.
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Only works for DBF_INLINK fields.
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Returns the time in seconds since the posix epoch.
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:rtype: float
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"""
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def __cmp__(self, B):
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if isinstance(B, Field):
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B=B.getval()
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return cmp(self.getval(), B)
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def __int__(self):
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return int(self.getval())
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def __long__(self):
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return long(self.getval())
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def __float__(self):
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return float(self.getval())
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def __repr__(self):
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return 'Field("%s.%s")'%self.name()
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def processLink(name, lstr):
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"""Process the INP or OUT link
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Expects lstr to be "module arg1 arg2"
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Returns (callable, Record, "arg1 arg2")
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"""
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rec = getRecord(name)
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parts = lstr.split(None,1)
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modname, args = parts[0], parts[1] if len(parts)>1 else None
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mod = __import__(modname, fromlist=['__should_not_exist'])
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return rec, mod.build(rec, args)
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