sapling/eden/scm/tests/test-mmapindexthreshold-strip.t

#chg-compatible

  $ configure modern
  $ enable rebase
  $ setconfig experimental.mmapindexthreshold=1

  $ hg init
  $ hg debugdrawdag <<'EOS'
  > a1    # a1/a = a1
  > |
  > a     # a/a = a
  > EOS

  $ hg debugindex -c
     rev    offset  length   base linkrev nodeid       p1           p2
       0         0      55      0       0 b173517d0057 000000000000 000000000000
       1        55      59      1       1 18d792233a72 b173517d0057 000000000000
  $ hg debugstrip -r a1 -q
  $ hg debugindex -c
     rev    offset  length   base linkrev nodeid       p1           p2
       0         0      55      0       0 b173517d0057 000000000000 000000000000
transaction: copy files before truncation Summary: On Windows, if a file is memory mapped it cannot be truncated, unfortunately, with the 00changelog.i being almost 500MB, this means that every time Mercurial starts, the file needs to be read entirely. With the code being moved to Rust, this read is done twice, resulting in a memory consumption of over 900MB. Instead of always trying truncate the file in place, let's just try to truncate it first, and then copy it, truncate it and then move it back in place. This will allow us to memory map the 00changelog.i on Windows, which should significantly reduce the memory consumption of Mercurial. Reviewed By: DurhamG Differential Revision: D21953553 fbshipit-source-id: e0f447fea017a34c8da8cdbbc6914cee7b5b2bee 2020-06-10 05:42:12 +03:00			`#chg-compatible`

			`$ configure modern`
			`$ enable rebase`
			`$ setconfig experimental.mmapindexthreshold=1`

			`$ hg init`
			`$ hg debugdrawdag <<'EOS'`
			`> a1 # a1/a = a1`
			`> \|`
			`> a # a/a = a`
			`> EOS`

			`$ hg debugindex -c`
			`rev offset length base linkrev nodeid p1 p2`
			`0 0 55 0 0 b173517d0057 000000000000 000000000000`
			`1 55 59 1 1 18d792233a72 b173517d0057 000000000000`
			`$ hg debugstrip -r a1 -q`
			`$ hg debugindex -c`
			`rev offset length base linkrev nodeid p1 p2`
			`0 0 55 0 0 b173517d0057 000000000000 000000000000`