Mercurial > hg
view tests/test-update-reverse.t @ 27475:a2e2a8fa5fd1
revlog: avoid string slice when decompressing u* chunks
Revlog chunks can be stored uncompressed. If the first byte of the
raw data is \0, we store the data as is. Else we prefix it with 'u'.
Before, we performed a string slice to strip out the 'u' prefix.
With this patch, we use a buffer to avoid an extra memory copy and
associated garbage collection overhead.
I was unable to verify any performance impact of this patch. For both
mozilla-central and the hg repos, the number of manifest revisions
with 'u' prefixes is very small - under 1%. So this change likely
isn't called enough to have an impact on manifest reading. However,
the reasoning behind this change is solid, so it should be safe.
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Sun, 20 Dec 2015 16:00:27 -0800 |
parents | bd625cd4e5e7 |
children | 5c2a4f37eace |
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$ hg init $ touch a $ hg add a $ hg commit -m "Added a" $ touch main $ hg add main $ hg commit -m "Added main" $ hg checkout 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved 'main' should be gone: $ ls a $ touch side1 $ hg add side1 $ hg commit -m "Added side1" created new head $ touch side2 $ hg add side2 $ hg commit -m "Added side2" $ hg log changeset: 3:91ebc10ed028 tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added side2 changeset: 2:b932d7dbb1e1 parent: 0:c2eda428b523 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added side1 changeset: 1:71a760306caf user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added main changeset: 0:c2eda428b523 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added a $ hg heads changeset: 3:91ebc10ed028 tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added side2 changeset: 1:71a760306caf user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added main $ ls a side1 side2 $ hg update --debug -C 1 resolving manifests branchmerge: False, force: True, partial: False ancestor: 91ebc10ed028+, local: 91ebc10ed028+, remote: 71a760306caf side1: other deleted -> r removing side1 side2: other deleted -> r removing side2 main: remote created -> g getting main 1 files updated, 0 files merged, 2 files removed, 0 files unresolved $ ls a main