X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=lbs.py;h=4224cf93dd2141052f4f48c34362ca62ac59130c;hb=030ddd80e04aa65738bf21557dd541bec757de5b;hp=712b07287be07fc073979f06f9ce13df1c439988;hpb=d3c10b747ecec0acc14863fc12db9661c3f88128;p=cumulus.git diff --git a/lbs.py b/lbs.py index 712b072..4224cf9 100644 --- a/lbs.py +++ b/lbs.py @@ -18,6 +18,9 @@ FORMAT_VERSION = (0, 6) # LBS Snapshot v0.6 # Maximum number of nested indirect references allowed in a snapshot. MAX_RECURSION_DEPTH = 3 +# All segments which have been accessed this session. +accessed_segments = set() + class Struct: """A class which merely acts as a data container. @@ -136,11 +139,11 @@ class ObjectStore: @staticmethod def parse_ref(refstr): - m = re.match(r"^zero\[(\d+)\+(\d+)\]$", refstr) + m = re.match(r"^zero\[(\d+)\]$", refstr) if m: - return ("zero", None, None, (int(m.group(1)), int(m.group(2)))) + return ("zero", None, None, (0, int(m.group(1)))) - m = re.match(r"^([-0-9a-f]+)\/([0-9a-f]+)(\(\S+\))?(\[(\d+)\+(\d+)\])?$", refstr) + m = re.match(r"^([-0-9a-f]+)\/([0-9a-f]+)(\(\S+\))?(\[((\d+)\+)?(\d+)\])?$", refstr) if not m: return segment = m.group(1) @@ -152,11 +155,16 @@ class ObjectStore: checksum = checksum.lstrip("(").rstrip(")") if slice is not None: - slice = (int(m.group(5)), int(m.group(6))) + if m.group(5) is None: + # Abbreviated slice + slice = (0, int(m.group(7))) + else: + slice = (int(m.group(6)), int(m.group(7))) return (segment, object, checksum, slice) def get_segment(self, segment): + accessed_segments.add(segment) raw = self.store.lowlevel_open(segment + ".tar.gpg") (input, output) = os.popen2("lbs-filter-gpg --decrypt") @@ -192,6 +200,7 @@ class ObjectStore: f.close() def load_object(self, segment, object): + accessed_segments.add(segment) path = os.path.join(self.get_cachedir(), segment, object) if not os.access(path, os.R_OK): self.extract_segment(segment) @@ -451,15 +460,64 @@ class LocalDatabase: "Return a DB-API cursor for directly accessing the local database." return self.db_connection.cursor() - def garbage_collect(self): - """Delete entries from old snapshots from the database.""" + def list_schemes(self): + """Return the list of snapshots found in the local database. + + The returned value is a list of tuples (id, scheme, name, time, intent). + """ + + cur = self.cursor() + cur.execute("select distinct scheme from snapshots") + schemes = [row[0] for row in cur.fetchall()] + schemes.sort() + return schemes + + def garbage_collect(self, scheme, intent=1.0): + """Delete entries from old snapshots from the database. + + Only snapshots with the specified scheme name will be deleted. If + intent is given, it gives the intended next snapshot type, to determine + how aggressively to clean (for example, intent=7 could be used if the + next snapshot will be a weekly snapshot). + """ cur = self.cursor() - # Delete old snapshots. - cur.execute("""delete from snapshots - where snapshotid < (select max(snapshotid) - from snapshots)""") + # Find the id of the last snapshot to be created. This is used for + # measuring time in a way: we record this value in each segment we + # expire on this run, and then on a future run can tell if there have + # been intervening backups made. + cur.execute("select max(snapshotid) from snapshots") + last_snapshotid = cur.fetchone()[0] + + # Get the list of old snapshots for this scheme. Delete all the old + # ones. Rules for what to keep: + # - Always keep the most recent snapshot. + # - If snapshot X is younger than Y, and X has higher intent, then Y + # can be deleted. + cur.execute("""select snapshotid, name, intent, + julianday('now') - timestamp as age + from snapshots where scheme = ? + order by age""", (scheme,)) + + first = True + max_intent = intent + for (id, name, snap_intent, snap_age) in cur.fetchall(): + can_delete = False + if snap_intent < max_intent: + # Delete small-intent snapshots if there is a more recent + # large-intent snapshot. + can_delete = True + elif snap_intent == intent: + # Delete previous snapshots with the specified intent level. + can_delete = True + + if can_delete and not first: + print "Delete snapshot %d (%s)" % (id, name) + cur.execute("delete from snapshots where snapshotid = ?", + (id,)) + first = False + max_intent = max(max_intent, snap_intent) # Delete entries in the segments_used table which are for non-existent # snapshots. @@ -472,12 +530,16 @@ class LocalDatabase: cur.execute("""delete from segments where segmentid not in (select segmentid from segments_used)""") - # Finally, delete objects contained in non-existent segments. We can't - # simply delete unused objects, since we use the set of unused objects - # to determine the used/free ratio of segments. + # Delete unused objects in the block_index table. By "unused", we mean + # any object which was stored in a segment which has been deleted, and + # any object in a segment which was marked for cleaning and has had + # cleaning performed already (the expired time is less than the current + # largest snapshot id). cur.execute("""delete from block_index - where segmentid not in - (select segmentid from segments)""") + where segmentid not in (select segmentid from segments) + or segmentid in (select segmentid from segments + where expire_time < ?)""", + (last_snapshotid,)) # Segment cleaning. class SegmentInfo(Struct): pass @@ -511,6 +573,10 @@ class LocalDatabase: info.mtime = row[3] info.age_days = row[4] + # If age is not available for whatever reason, treat it as 0.0. + if info.age_days is None: + info.age_days = 0.0 + # Benefit calculation: u is the estimated fraction of each segment # which is utilized (bytes belonging to objects still in use # divided by total size; this doesn't take compression or storage @@ -549,7 +615,11 @@ class LocalDatabase: raise TypeError("Invalid segment: %s, must be of type int or SegmentInfo, not %s" % (segment, type(segment))) cur = self.cursor() - cur.execute("update block_index set expired = 1 where segmentid = ?", + cur.execute("select max(snapshotid) from snapshots") + last_snapshotid = cur.fetchone()[0] + cur.execute("update segments set expire_time = ? where segmentid = ?", + (last_snapshotid, id)) + cur.execute("update block_index set expired = 0 where segmentid = ?", (id,)) def balance_expired_objects(self): @@ -678,5 +748,6 @@ class LocalDatabase: cutoffs.reverse() for i in range(len(cutoffs)): cur.execute("""update block_index set expired = ? - where round(? - timestamp) > ?""", + where round(? - timestamp) > ? + and expired is not null""", (i, now, cutoffs[i]))