replacement cache subsystem that's gestated in 2.1 and 3.0.

it rocks your world, baby.

svn path=/main/branches/2.0/; revision=2257

1 files changed, 171 insertions, 0 deletions

diff --git a/pym/cache/template.py b/pym/cache/template.py
new file mode 100644
index 000000000..c230b9389
--- /dev/null
+++ b/pym/cache/template.py
@@ -0,0 +1,171 @@
+# Copyright: 2005 Gentoo Foundation
+# Author(s): Brian Harring (ferringb@gentoo.org)
+# License: GPL2
+# $Id: template.py 1911 2005-08-25 03:44:21Z ferringb $
+
+import cache_errors
+from mappings import ProtectedDict
+
+class database(object):
+	# this is for metadata/cache transfer.
+	# basically flags the cache needs be updated when transfered cache to cache.
+	# leave this.
+
+	complete_eclass_entries_ = True
+	autocommits = False
+	cleanse_keys = False
+
+	def __init__(self, location, label, auxdbkeys, readonly=False):
+		""" initialize the derived class; specifically, store label/keys"""
+		self._known_keys = auxdbkeys
+		self.location = location
+		self.label = label
+		self.readonly = readonly
+		self.sync_rate = 0
+		self.updates = 0
+
+	
+	def __getitem__(self, cpv):
+		"""set a cpv to values
+		This shouldn't be overriden in derived classes since it handles the __eclasses__ conversion.
+		that said, if the class handles it, they can override it."""
+		if self.updates > self.sync_rate:
+			self.commit()
+			self.updates = 0
+		d=self._getitem(cpv)
+		if "_eclasses_" in d:
+			d["_eclasses_"] = reconstruct_eclasses(cpv, d["_eclasses_"])
+		return d
+
+	def _getitem(self, cpv):
+		"""get cpv's values.
+		override this in derived classess"""
+		raise NotImplementedError
+
+
+	def __setitem__(self, cpv, values):
+		"""set a cpv to values
+		This shouldn't be overriden in derived classes since it handles the readonly checks"""
+		if self.readonly:
+			raise cache_errors.ReadOnlyRestriction()
+		if self.cleanse_keys:
+			d=ProtectedDict(values)
+			for k in d.keys():
+				if d[k] == '':
+					del d[k]
+			if "_eclasses_" in values:
+				d["_eclasses_"] = serialize_eclasses(d["_eclasses_"])
+		elif "_eclasses_" in values:
+			d = ProtectedDict(values)
+			d["_eclasses_"] = serialize_eclasses(d["_eclasses_"])
+		else:
+			d = values
+		self._setitem(cpv, d)
+		if not self.autocommits:
+			self.updates += 1
+			if self.updates > self.sync_rate:
+				self.commit()
+				self.updates = 0
+
+
+	def _setitem(self, name, values):
+		"""__setitem__ calls this after readonly checks.  override it in derived classes
+		note _eclassees_ key *must* be handled"""
+		raise NotImplementedError
+
+
+	def __delitem__(self, cpv):
+		"""delete a key from the cache.
+		This shouldn't be overriden in derived classes since it handles the readonly checks"""
+		if self.readonly:
+			raise cache_errors.ReadOnlyRestriction()
+		if not self.autocommits:
+			self.updates += 1
+		self._delitem(cpv)
+		if self.updates > self.sync_rate:
+			self.commit()
+			self.updates = 0
+
+
+	def _delitem(self,cpv):
+		"""__delitem__ calls this after readonly checks.  override it in derived classes"""
+		raise NotImplementedError
+
+
+	def has_key(self, cpv):
+		raise NotImplementedError
+
+
+	def keys(self):
+		return tuple(self.iterkeys())
+
+	def iterkeys(self):
+		raise NotImplementedError
+
+	def iteritems(self):
+		for x in self.iterkeys():
+			yield (x, self[x])
+
+	def items(self):
+		return list(self.iteritems())
+
+	def sync(self, rate=0):
+		self.sync_rate = rate
+		if(rate == 0):
+			self.commit()
+
+	def commit(self):
+		if not self.autocommits:
+			raise NotImplementedError
+
+	def get_matches(self, match_dict):
+		"""generic function for walking the entire cache db, matching restrictions to
+		filter what cpv's are returned.  Derived classes should override this if they
+		can implement a faster method then pulling each cpv:values, and checking it.
+		
+		For example, RDBMS derived classes should push the matching logic down to the
+		actual RDBM."""
+
+		import re
+		restricts = {}
+		for key,match in match_dict.iteritems():
+			# XXX this sucks.
+			try:
+				if isinstance(match, str):
+					restricts[key] = re.compile(match).match
+				else:
+					restricts[key] = re.compile(match[0],match[1]).match
+			except re.error, e:
+				raise InvalidRestriction(key, match, e)
+			if key not in self.__known_keys:
+				raise InvalidRestriction(key, match, "Key isn't valid")
+
+		for cpv in self.keys():
+			cont = True
+			vals = self[cpv]
+			for key, match in restricts.iteritems():
+				if not match(vals[key]):
+					cont = False
+					break
+			if cont:
+#				yield cpv,vals
+				yield cpv
+
+
+def serialize_eclasses(eclass_dict):
+	"""takes a dict, returns a string representing said dict"""
+	return "\t".join(["%s\t%s\t%s" % (k, v[0], str(v[1])) for k,v in eclass_dict.items()])
+
+def reconstruct_eclasses(cpv, eclass_string):
+	"""returns a dict when handed a string generated by serialize_eclasses"""
+	eclasses = eclass_string.rstrip().lstrip().split("\t")
+	if eclasses == [""]:
+		# occasionally this occurs in the fs backends.  they suck.
+		return {}
+	if len(eclasses) % 3 != 0:
+		raise cache_errors.CacheCorruption(cpv, "_eclasses_ was of invalid len %i" % len(eclasses))
+	d={}
+	for x in range(0, len(eclasses), 3):
+		d[eclasses[x]] = (eclasses[x + 1], long(eclasses[x + 2]))
+	del eclasses
+	return d