| Message ID | 20180813172054.17767-1-ross.burton@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/3] utils/md5_file: don't iterate line-by-line | expand |
On 08/13/2018 10:20 AM, Ross Burton wrote: > Opening a file in binary mode and iterating it seems like the simple solution > but will still break on newlines, which for binary files isn't really useful as > the size of the chunks could be huge or tiny. > > Instead, let's be a bit more clever: we'll be MD5ing lots of files, but we don't > want to fill up memory: use mmap() to open the file and read the file in 8k > blocks. > > Signed-off-by: Ross Burton <ross.burton@intel.com> shouldn't this go to the bitbake mailing list ? > --- > bitbake/lib/bb/utils.py | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py > index 9903183213b..b20cdabcf01 100644 > --- a/bitbake/lib/bb/utils.py > +++ b/bitbake/lib/bb/utils.py > @@ -524,12 +524,17 @@ def md5_file(filename): > """ > Return the hex string representation of the MD5 checksum of filename. > """ > - import hashlib > - m = hashlib.md5() > + import hashlib, mmap > > with open(filename, "rb") as f: > - for line in f: > - m.update(line) > + m = hashlib.md5() > + try: > + with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mm: > + for chunk in iter(lambda: mm.read(8192), b''): > + m.update(chunk) > + except ValueError: > + # You can't mmap() an empty file so silence this exception > + pass > return m.hexdigest() > > def sha256_file(filename): -- _______________________________________________ Openembedded-core mailing list Openembedded-core@lists.openembedded.org http://lists.openembedded.org/mailman/listinfo/openembedded-core
Yeah, just sent it there, sorry On 13 August 2018 at 19:03, akuster808 <akuster808@gmail.com> wrote: > > > On 08/13/2018 10:20 AM, Ross Burton wrote: >> Opening a file in binary mode and iterating it seems like the simple solution >> but will still break on newlines, which for binary files isn't really useful as >> the size of the chunks could be huge or tiny. >> >> Instead, let's be a bit more clever: we'll be MD5ing lots of files, but we don't >> want to fill up memory: use mmap() to open the file and read the file in 8k >> blocks. >> >> Signed-off-by: Ross Burton <ross.burton@intel.com> > > shouldn't this go to the bitbake mailing list ? >> --- >> bitbake/lib/bb/utils.py | 13 +++++++++---- >> 1 file changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py >> index 9903183213b..b20cdabcf01 100644 >> --- a/bitbake/lib/bb/utils.py >> +++ b/bitbake/lib/bb/utils.py >> @@ -524,12 +524,17 @@ def md5_file(filename): >> """ >> Return the hex string representation of the MD5 checksum of filename. >> """ >> - import hashlib >> - m = hashlib.md5() >> + import hashlib, mmap >> >> with open(filename, "rb") as f: >> - for line in f: >> - m.update(line) >> + m = hashlib.md5() >> + try: >> + with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mm: >> + for chunk in iter(lambda: mm.read(8192), b''): >> + m.update(chunk) >> + except ValueError: >> + # You can't mmap() an empty file so silence this exception >> + pass >> return m.hexdigest() >> >> def sha256_file(filename): > -- _______________________________________________ Openembedded-core mailing list Openembedded-core@lists.openembedded.org http://lists.openembedded.org/mailman/listinfo/openembedded-core
diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py index 9903183213b..b20cdabcf01 100644 --- a/bitbake/lib/bb/utils.py +++ b/bitbake/lib/bb/utils.py @@ -524,12 +524,17 @@ def md5_file(filename): """ Return the hex string representation of the MD5 checksum of filename. """ - import hashlib - m = hashlib.md5() + import hashlib, mmap with open(filename, "rb") as f: - for line in f: - m.update(line) + m = hashlib.md5() + try: + with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mm: + for chunk in iter(lambda: mm.read(8192), b''): + m.update(chunk) + except ValueError: + # You can't mmap() an empty file so silence this exception + pass return m.hexdigest() def sha256_file(filename):
Opening a file in binary mode and iterating it seems like the simple solution but will still break on newlines, which for binary files isn't really useful as the size of the chunks could be huge or tiny. Instead, let's be a bit more clever: we'll be MD5ing lots of files, but we don't want to fill up memory: use mmap() to open the file and read the file in 8k blocks. Signed-off-by: Ross Burton <ross.burton@intel.com> --- bitbake/lib/bb/utils.py | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) -- 2.11.0 -- _______________________________________________ Openembedded-core mailing list Openembedded-core@lists.openembedded.org http://lists.openembedded.org/mailman/listinfo/openembedded-core