[PATCH 2/3] vfs._ChunkReader: build next() result by joining parts

[Rob Browning]

Signed-off-by: Rob Browning <r...@defaultvalue.org>
Tested-by: Rob Browning <r...@defaultvalue.org>
---
lib/bup/vfs.py | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/lib/bup/vfs.py b/lib/bup/vfs.py
index 7062b595..cd58397d 100644
--- a/lib/bup/vfs.py
+++ b/lib/bup/vfs.py
@@ -205,9 +205,8 @@ def _tree_chunks(repo, tree_data, startofs):
class _ChunkReader:
def __init__(self, repo, oid, startofs):
_, obj_t, _, it = get_oidx(repo, hexlify(oid))
- isdir = obj_t == b'tree'
data = b''.join(it)
- if isdir:
+ if obj_t == b'tree':
self.it = _tree_chunks(repo, data, startofs)
self.blob = None
self.blobofs = None
@@ -218,26 +217,30 @@ class _ChunkReader:
self.ofs = startofs

def next(self, size):
- out = b''
- while len(out) < size:
+ out_parts = []
+ out_len = 0
+ while out_len < size:
if self.it and not self.blob:
- try:
- self.blob = next(self.it)
- self.blobofs = 0
- except StopIteration:
+ self.blob = next(self.it, None)
+ if self.blob is None:
self.it = None
+ else:
+ self.blobofs = 0
if self.blob:
- want = size - len(out)
- out += self.blob[self.blobofs:self.blobofs + want]
+ want = size - out_len
+ out_parts.append(self.blob[self.blobofs:self.blobofs + want])
+ out_len += len(out_parts[-1])
self.blobofs += want
if self.blobofs >= len(self.blob):
self.blob = None
self.blobofs = None
if not self.it:
break
- debug2('next(%d) returned %d\n' % (size, len(out)))
- self.ofs += len(out)
- return out
+ debug2(f'next({size}) returned {out_len}\n')
+ self.ofs += out_len
+ if len(out_parts) == 1:
+ return out_parts[0]
+ return b''.join(out_parts)

class _FileReader:
def __init__(self, repo, oid, known_size=None):
--
2.47.3