# Copyright (C) 2010 The Regents of the University of California
# Written by Michael Vrable <mvrable@cs.ucsd.edu>
-import base64, os, struct, sys
+import base64, os, re, struct, sys
import boto
# The BlueSky 'struct cloudlog_header' data type.
fp = open(os.path.join(self.path, filename), 'rb')
return fp.read()
+ def write(self, filename, data):
+ fp = open(os.path.join(self.path, filename), 'wb')
+ fp.write(data)
+ fp.close()
+
class LogItem:
"""In-memory representation of a single item stored in a log file."""
def __str__(self):
return "<Item ty=%s location=%s size=%d id=%s...>" % (self.type, self.location, self.size, base64.b16encode(self.id).lower()[0:8])
+ @staticmethod
+ def random_id():
+ return open('/dev/urandom').read(16)
+
+ def serialize(self):
+ link_ids = []
+ link_locs = []
+ for (i, l) in self.links:
+ link_ids.append(i)
+ if i != '\0' * 16:
+ link_locs.append(struct.pack('<IIII', *l))
+ link_ids = ''.join(link_ids)
+ link_locs = ''.join(link_locs)
+
+ header = struct.pack(HEADER_FORMAT,
+ HEADER_MAGIC, ord(self.type), self.id, self.inum,
+ len(self.data), len(link_ids), len(link_locs))
+ return header + self.data + link_ids + link_locs
+
+class LogSegment:
+ def __init__(self, backend, location):
+ self.backend = backend
+ self.location = location
+ self.data = []
+
+ def __len__(self):
+ return sum(len(s) for s in self.data)
+
+ def write(self, item):
+ data = item.serialize()
+ offset = len(self)
+ self.data.append(data)
+ item.location = self.location + (offset, len(data))
+
+ def close(self):
+ data = ''.join(self.data)
+ filename = "log-%08d-%08d" % (self.location)
+ print "Would write %d bytes of data to %s" % (len(data), filename)
+ self.backend.write(filename, data)
+
+class LogDirectory:
+ TARGET_SIZE = 4 << 20
+
+ def __init__(self, backend, dir, seq):
+ self.backend = backend
+ self.dir_num = dir
+ self.seq_num = seq
+ self.groups = {}
+
+ def open_segment(self):
+ seg = LogSegment(self.backend, (self.dir_num, self.seq_num))
+ self.seq_num += 1
+ return seg
+
+ def write(self, item, segment_group=0):
+ if segment_group not in self.groups:
+ self.groups[segment_group] = self.open_segment()
+ seg = self.groups[segment_group]
+ seg.write(item)
+ if len(seg) >= LogDirectory.TARGET_SIZE:
+ seg.close()
+ del self.groups[segment_group]
+
+ def close_all(self):
+ for k in list(self.groups.keys()):
+ self.groups[k].close()
+ del self.groups[k]
+
class UtilizationTracker:
"""A simple object that tracks what fraction of each segment is used.
item = LogItem()
item.id = header[2]
+ item.inum = header[3]
item.location = None
item.type = chr(header[1])
item.size = size
item.location = location
return item
-def parse_log(data, logname=None):
+def parse_log(data, location=None):
"""Parse contents of a log file, yielding a sequence of log items."""
- location = None
- if logname is not None:
- m = re.match(r"^log-(\d+)-(\d+)$", logname)
+ if isinstance(location, str):
+ m = re.match(r"^log-(\d+)-(\d+)$", location)
if m:
location = (int(m.group(1)), int(m.group(2)))
+ else:
+ location = None
offset = 0
while len(data) - offset >= HEADER_SIZE:
def load_checkpoint_record(backend):
for (log, size) in reversed(backend.list()):
- for item in reversed(list(parse_log(backend.read(log)))):
+ for item in reversed(list(parse_log(backend.read(log), log))):
if item.type == ITEM_TYPE.CHECKPOINT:
return item
-def build_inode_map(backend, checkpoint_record):
- """Reconstruct the inode map, starting from the checkpoint record given.
-
- This will also build up information about segment utilization."""
-
- util = UtilizationTracker(backend)
- util.add_item(checkpoint_record)
-
- print "Inode map:"
- for i in range(len(checkpoint_record.data) // 16):
- (start, end) = struct.unpack_from("<QQ", checkpoint_record.data, 16*i)
- imap = load_item(backend, checkpoint_record.links[i][1])
- util.add_item(imap)
- print "[%d, %d]: %s" % (start, end, imap)
- for j in range(len(imap.data) // 8):
- (inum,) = struct.unpack_from("<Q", imap.data, 8*j)
- inode = load_item(backend, imap.links[j][1])
- data_segments = set()
- util.add_item(inode)
- for i in inode.links:
- util.add_item(i[1])
- data_segments.add(i[1][0:2])
- print " %d: %s (%d data segments)" % (inum, inode, len(data_segments))
-
- print
- print "Segment utilizations:"
- for (s, u) in sorted(util.segments.items()):
- print "%s: %s" % (s, u)
+class InodeMap:
+ def __init__(self):
+ pass
+
+ def build(self, backend, checkpoint_record):
+ """Reconstruct the inode map from the checkpoint record given.
+
+ This will also build up information about segment utilization."""
+
+ self.checkpoint_record = checkpoint_record
+
+ util = UtilizationTracker(backend)
+ util.add_item(checkpoint_record)
+ inodes = {}
+
+ print "Inode map:"
+ for i in range(len(checkpoint_record.data) // 16):
+ (start, end) = struct.unpack_from("<QQ", checkpoint_record.data, 16*i)
+ imap = load_item(backend, checkpoint_record.links[i][1])
+ util.add_item(imap)
+ print "[%d, %d]: %s" % (start, end, imap)
+ for j in range(len(imap.data) // 8):
+ (inum,) = struct.unpack_from("<Q", imap.data, 8*j)
+ inode = load_item(backend, imap.links[j][1])
+ inodes[inum] = inode
+ data_segments = set()
+ util.add_item(inode)
+ for i in inode.links:
+ util.add_item(i[1])
+ data_segments.add(i[1][0:2])
+ print " %d: %s (%d data segments)" % (inum, inode, len(data_segments))
+
+ print
+ print "Segment utilizations:"
+ for (s, u) in sorted(util.segments.items()):
+ #if u[1] > 0:
+ print "%s: %s %s" % (s, u, float(u[1]) / u[0])
+
+ self.inodes = inodes
+ self.util = util
+ self.updated_inodes = set()
+
+ def mark_updated(self, inum):
+ self.updated_inodes.add(inum)
+
+ def write(self, backend, log):
+ updated_inodes = sorted(self.updated_inodes, reverse=True)
+
+ new_checkpoint = LogItem()
+ new_checkpoint.id = LogItem.random_id()
+ new_checkpoint.inum = 0
+ new_checkpoint.type = ITEM_TYPE.CHECKPOINT
+ new_checkpoint.data = ""
+ new_checkpoint.links = []
+
+ for i in range(len(self.checkpoint_record.data) // 16):
+ (start, end) = struct.unpack_from("<QQ", self.checkpoint_record.data, 16*i)
+
+ new_checkpoint.data += self.checkpoint_record.data[16*i : 16*i + 16]
+
+ # Case 1: No inodes in this range of the old inode map have
+ # changed. Simply emit a new pointer to the same inode map block.
+ # TODO: Add the ability to rewrite the inode map block if we choose
+ # to do so for cleaning, even if no inodes have changed.
+ if len(updated_inodes) == 0 or updated_inodes[-1] > end:
+ new_checkpoint.links.append(self.checkpoint_record.links[i])
+ continue
+
+ # Case 2: Some inodes have been updated. Create a new inode map
+ # block, write it out, and point the new checkpoint at it.
+ inodes = [k for k in self.inodes if k >= start and k <= end]
+ inodes.sort()
+
+ block = LogItem()
+ block.id = LogItem.random_id()
+ block.inum = 0
+ block.type = ITEM_TYPE.INODE_MAP
+ block.links = []
+ block.data = ""
+ for j in inodes:
+ block.data += struct.pack("<Q", j)
+ block.links.append((self.inodes[j].id, self.inodes[j].location))
+ log.write(block, 2)
+
+ new_checkpoint.links.append((block.id, block.location))
+
+ while len(updated_inodes) > 0 and updated_inodes[-1] <= end:
+ updated_inodes.pop()
+
+ log.write(new_checkpoint, 2)
+ self.checkpoint_record = new_checkpoint
+
+def rewrite_inode(backend, inode_map, inum, log):
+ inode = inode_map.inodes[inum]
+ blocks = []
+ for l in inode.links:
+ data = load_item(backend, l[1])
+ blocks.append(data)
+ log.write(data, 0)
+ inode.links = [(b.id, b.location) for b in blocks]
+ log.write(inode, 1)
+ inode_map.mark_updated(inum)
if __name__ == '__main__':
backend = FileBackend(".")
chkpt = load_checkpoint_record(backend)
- build_inode_map(backend, chkpt)
+ imap = InodeMap()
+ imap.build(backend, chkpt)
+ print chkpt
+
+ print repr(chkpt.serialize())
+
+ log_dir = LogDirectory(backend, 1, 0)
+ rewrite_inode(backend, imap, 147, log_dir)
+ imap.write(backend, log_dir)
+ log_dir.close_all()
projects / bluesky.git / commitdiff