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# Copyright (c) 2000 Petru Paler (ppetru@coltronix.com) All rights reserved.
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# To-do list:
# Critical:
#    - Most I/O operations are not atomic. This means that I/O errors (and, for
#    that matter, any exceptions occured in _finish) leave the storage in an
#    undefined state
#
# Not critical:
#    - Performance tuning -- add caches where apropiate
#    - make sure locking is ok
#    - provide directory splitting to enable use on non-reiser filesystems
#
# ... and probably many others

"""ReiserFS storage"""

__version__ = "0.01"

from BaseStorage import BaseStorage
import POSException
import os, struct, stat, operator
from posix import fsync

def oid2str(oid):
	return "%02X"*8 % struct.unpack("!8B", oid)

class ReiserStorage(BaseStorage):

	def __init__(self, dirname):
		
		if dirname[-1] != '/':
			dirname = dirname + '/'
		BaseStorage.__init__(self, dirname)
		self._oid_dir = dirname + 'oid/'
		self._tindex = []
		self._oid = '\0\0\0\0\0\0\0\0'
		try:
			f = open(dirname+'last_oid', 'rt')
			self._oid = f.read()
			f.close()
		except:
			pass
		self.lof = open(dirname+'last_oid', 'wt')

	def __len__(self):
		print '__len__'
		return len(os.listdir(self._oid_dir))

	def getSize(self):
		print 'getSize'
		files = os.listdir(self._oid_dir)
		files = map(lambda x,d=self._oid_dir: d+x, files)
		sizes = map(lambda x: os.stat(x)[stat.ST_SIZE], files)
		return reduce(operator.add, sizes)

	def load(self, oid, version):
		self._lock_acquire()
		try:
			f = open(self._oid_dir+oid2str(oid), 'rb')
			p = f.read()
			f.close()
			return p[8:], p[:8]
		finally:
			self._lock_release()

	def store(self, oid, serial, data, version, transaction):
		if transaction is not self._transaction:
			raise POSException.StorageTransactionError(self, transaction)

		if version:
			raise POSException.Unsupported, "Versions aren't supported"

		self._lock_acquire()
		try:
			fname = self._oid_dir+oid2str(oid)
			if os.path.exists(fname):
				try:
					f = open(fname, 'rb')
					if serial != f.read(8):
						raise POSException.ConflictError
					f.close()
				except IOError:
					raise POSException.StorageSystemError, 'I/O error while checking for conflicts'
			serial = self._serial
			self._tindex.append((oid, serial+data))
		finally:
			self._lock_release()

		return serial

	def _begin(self, tid, u, d, e):
		pass

	def _clear_temp(self):
		self._tindex = []

	def _finish(self, tid, user, desc, ext):
		try:
			for oid, data in self._tindex:
				f = open(self._oid_dir+oid2str(oid), 'wb')
				f.write(data)
				fsync(f.fileno())
				f.close()
			self.lof.seek(0)
			self.lof.write(self._oid)
			fsync(self.lof.fileno())
		except:
			raise POSException.TransactionError, 'I/O error commiting transaction -- your storage is likely corrupt'

	def pack(self, t, referencesf):
		maxoid = oid2str(self._oid)

		rootl = ['\0\0\0\0\0\0\0\0']
		pop = rootl.pop
		pindex = {}
		referenced = pindex.has_key
		while rootl:
			oid = pop()
			if referenced(oid):
				continue

			# scan pickle for references
			f = open(self._oid_dir+oid2str(oid))
			r = f.read()
			f.close()
			pindex[oid2str(oid)] = r
			p = r[8:]
			referencesf(p, rootl)

		# now delete any unreferenced entries
		deleted = []
		for oid in os.listdir(self._oid_dir):
			if not referenced(oid) and (oid <= maxoid):
				deleted.append(oid)

		try:
			for i in deleted:
				os.unlink(self._oid_dir+i)
		except:
			raise POSException.TransactionError, 'I/O error during pack -- your storage is probably screwed up'