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Repository: don't read+verify old entries for size retrieval

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This commit is contained in:
Marian Beermann 2016-05-21 19:17:14 +02:00
parent f99ad4ca6f
commit b8d1bc1ca8
1 changed files with 48 additions and 19 deletions
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67
borg/repository.py
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@ -358,7 +358,7 @@ class Repository:
# the old index is not necessarily valid for this transaction (e.g. compaction); if the segment
# is already gone, then it was already compacted.
self.segments[s] -= 1
size = len(self.io.read(s, offset, key))
size = self.io.read(s, offset, key, read_data=False)
self.compact[s] += size
elif tag == TAG_COMMIT:
continue
@ -377,7 +377,7 @@ class Repository:
if self.segments[segment] == 0:
self.compact[segment] += self.io.segment_size(segment)
return
for tag, key, offset, size in self.io.iter_objects(segment):
for tag, key, offset, size in self.io.iter_objects(segment, read_data=False):
if tag == TAG_PUT:
if self.index.get(key, (-1, -1)) != (segment, offset):
# This PUT is superseded later
@ -504,7 +504,7 @@ class Repository:
pass
else:
self.segments[segment] -= 1
size = len(self.io.read(segment, offset, id))
size = self.io.read(segment, offset, id, read_data=False)
self.compact[segment] += size
segment, size = self.io.write_delete(id)
self.compact[segment] += size
@ -522,7 +522,7 @@ class Repository:
except KeyError:
raise self.ObjectNotFound(id, self.path) from None
self.segments[segment] -= 1
size = len(self.io.read(segment, offset, id))
size = self.io.read(segment, offset, id, read_data=False)
self.compact[segment] += size
segment, size = self.io.write_delete(id)
self.compact[segment] += size
@ -683,7 +683,15 @@ class LoggedIO:
def segment_size(self, segment):
return os.path.getsize(self.segment_filename(segment))
def iter_objects(self, segment, include_data=False):
def iter_objects(self, segment, include_data=False, read_data=True):
"""
Return object iterator for *segment*.
If read_data is False then include_data must be False as well.
Integrity checks are skipped: all data obtained from the iterator must be considered informational.
The iterator returns four-tuples of (tag, key, offset, data|size).
"""
fd = self.get_fd(segment)
fd.seek(0)
if fd.read(MAGIC_LEN) != MAGIC:
@ -692,7 +700,8 @@ class LoggedIO:
header = fd.read(self.header_fmt.size)
while header:
size, tag, key, data = self._read(fd, self.header_fmt, header, segment, offset,
(TAG_PUT, TAG_DELETE, TAG_COMMIT))
(TAG_PUT, TAG_DELETE, TAG_COMMIT),
read_data=read_data)
if include_data:
yield tag, key, offset, data
else:
@ -720,19 +729,25 @@ class LoggedIO:
fd.write(data[:size])
data = data[size:]
def read(self, segment, offset, id):
def read(self, segment, offset, id, read_data=True):
"""
Read entry from *segment* at *offset* with *id*.
If read_data is False the size of the entry is returned instead and integrity checks are skipped.
The return value should thus be considered informational.
"""
if segment == self.segment and self._write_fd:
self._write_fd.sync()
fd = self.get_fd(segment)
fd.seek(offset)
header = fd.read(self.put_header_fmt.size)
size, tag, key, data = self._read(fd, self.put_header_fmt, header, segment, offset, (TAG_PUT, ))
size, tag, key, data = self._read(fd, self.put_header_fmt, header, segment, offset, (TAG_PUT, ), read_data)
if id != key:
raise IntegrityError('Invalid segment entry header, is not for wanted id [segment {}, offset {}]'.format(
segment, offset))
return data
return data if read_data else size
def _read(self, fd, fmt, header, segment, offset, acceptable_tags):
def _read(self, fd, fmt, header, segment, offset, acceptable_tags, read_data=True):
# some code shared by read() and iter_objects()
try:
hdr_tuple = fmt.unpack(header)
@ -750,18 +765,32 @@ class LoggedIO:
raise IntegrityError('Invalid segment entry size [segment {}, offset {}]'.format(
segment, offset))
length = size - fmt.size
data = fd.read(length)
if len(data) != length:
raise IntegrityError('Segment entry data short read [segment {}, offset {}]: expected {}, got {} bytes'.format(
segment, offset, length, len(data)))
if crc32(data, crc32(memoryview(header)[4:])) & 0xffffffff != crc:
raise IntegrityError('Segment entry checksum mismatch [segment {}, offset {}]'.format(
segment, offset))
if read_data:
data = fd.read(length)
if len(data) != length:
raise IntegrityError('Segment entry data short read [segment {}, offset {}]: expected {}, got {} bytes'.format(
segment, offset, length, len(data)))
if crc32(data, crc32(memoryview(header)[4:])) & 0xffffffff != crc:
raise IntegrityError('Segment entry checksum mismatch [segment {}, offset {}]'.format(
segment, offset))
if key is None and tag in (TAG_PUT, TAG_DELETE):
key, data = data[:32], data[32:]
else:
if key is None and tag in (TAG_PUT, TAG_DELETE):
key = fd.read(32)
length -= 32
if len(key) != 32:
raise IntegrityError('Segment entry key short read [segment {}, offset {}]: expected {}, got {} bytes'.format(
segment, offset, 32, len(key)))
oldpos = fd.tell()
seeked = fd.seek(length, os.SEEK_CUR) - oldpos
data = None
if seeked != length:
raise IntegrityError('Segment entry data short seek [segment {}, offset {}]: expected {}, got {} bytes'.format(
segment, offset, length, seeked))
if tag not in acceptable_tags:
raise IntegrityError('Invalid segment entry header, did not get acceptable tag [segment {}, offset {}]'.format(
segment, offset))
if key is None and tag in (TAG_PUT, TAG_DELETE):
key, data = data[:32], data[32:]
return size, tag, key, data
def write_put(self, id, data, raise_full=False):