contrib/packaging/inno/requirements.txt

store: don't read the whole fncache in memory

In large repositories with lot of files, the fncache grows more than 100 MB and
reading that whole thing into memory slows things down. Let's not read the whole
thing into memory.

This patch changes fncache loading code to read 1 MB at once. Loading 1 MB at
once saves ~1 sec on perffncacheload for our internal repository. I tried
various values such as 0.5 MB, 5 MB, 10 MB but best results were produced using
1 MB as the chunksize.

On a narrow clone with fncache around 40 MB, this patch saves ~0.04 seconds on
average on perffncacheload.

To test the code, I have coded an extension in test-fncache.t which set
chunksize to 1 byte, and the test passes with that.

Differential Revision: https://phab.mercurial-scm.org/D5296

#
# This file is autogenerated by pip-compile
# To update, run:
#
#    pip-compile --generate-hashes contrib/packaging/inno/requirements.txt.in -o contrib/packaging/inno/requirements.txt
#
certifi==2018.11.29 \
    --hash=sha256:47f9c83ef4c0c621eaef743f133f09fa8a74a9b75f037e8624f83bd1b6626cb7 \
    --hash=sha256:993f830721089fef441cdfeb4b2c8c9df86f0c63239f06bd025a76a7daddb033 \
    # via dulwich
configparser==3.7.3 \
    --hash=sha256:27594cf4fc279f321974061ac69164aaebd2749af962ac8686b20503ac0bcf2d \
    --hash=sha256:9d51fe0a382f05b6b117c5e601fc219fede4a8c71703324af3f7d883aef476a3 \
    # via entrypoints
docutils==0.14 \
    --hash=sha256:02aec4bd92ab067f6ff27a38a38a41173bf01bed8f89157768c1573f53e474a6 \
    --hash=sha256:51e64ef2ebfb29cae1faa133b3710143496eca21c530f3f71424d77687764274 \
    --hash=sha256:7a4bd47eaf6596e1295ecb11361139febe29b084a87bf005bf899f9a42edc3c6
dulwich==0.19.11 \
    --hash=sha256:afbe070f6899357e33f63f3f3696e601731fef66c64a489dea1bc9f539f4a725
entrypoints==0.3 \
    --hash=sha256:589f874b313739ad35be6e0cd7efde2a4e9b6fea91edcc34e58ecbb8dbe56d19 \
    --hash=sha256:c70dd71abe5a8c85e55e12c19bd91ccfeec11a6e99044204511f9ed547d48451 \
    # via keyring
keyring==18.0.0 \
    --hash=sha256:12833d2b05d2055e0e25931184af9cd6a738f320a2264853cabbd8a3a0f0b65d \
    --hash=sha256:ca33f5ccc542b9ffaa196ee9a33488069e5e7eac77d5b81969f8a3ce74d0230c
pygments==2.3.1 \
    --hash=sha256:5ffada19f6203563680669ee7f53b64dabbeb100eb51b61996085e99c03b284a \
    --hash=sha256:e8218dd399a61674745138520d0d4cf2621d7e032439341bc3f647bff125818d
pywin32-ctypes==0.2.0 \
    --hash=sha256:24ffc3b341d457d48e8922352130cf2644024a4ff09762a2261fd34c36ee5942 \
    --hash=sha256:9dc2d991b3479cc2df15930958b674a48a227d5361d413827a4cfd0b5876fc98 \
    # via keyring
urllib3==1.24.1 \
    --hash=sha256:61bf29cada3fc2fbefad4fdf059ea4bd1b4a86d2b6d15e1c7c0b582b9752fe39 \
    --hash=sha256:de9529817c93f27c8ccbfead6985011db27bd0ddfcdb2d86f3f663385c6a9c22 \
    # via dulwich