tests/test-remotefilelog-corrupt-cache.t

copies: filter out copies from non-existent source later in _chain()

_changesetforwardcopies() repeatedly calls _chain(). That is very
expensive because _chain() does lookups in the manifest. I hope to
split up the function in two parts: 1) simple chaining, not
considering end points, and 2) filter out files that don't exist in
the end points (and ping-pong copies/renames).

This patches gets us closer to that by moving the check for
non-existent source later in the function. Now there are no more
checks for "src" and "dst" in the first loop; all the filtering of
invalid copies is done in the second loop. The code also looks much
more consistent now.

No measureable impact on `hg debugpathcopies 4.0 4.8`. That shouldn't
be surprising since the only case we're doing more checks now is in
case of chained copies/renames, which are quire rare in practice.

Differential Revision: https://phab.mercurial-scm.org/D6277

#require no-windows

  $ . "$TESTDIR/remotefilelog-library.sh"

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > EOF
  $ echo x > x
  $ echo y > y
  $ echo z > z
  $ hg commit -qAm xy

  $ cd ..

  $ hgcloneshallow ssh://user@dummy/master shallow -q
  3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
  $ cd shallow

Verify corrupt cache handling repairs by default

  $ hg up -q null
  $ chmod u+w $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0
  $ echo x > $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

Verify corrupt cache error message

  $ hg up -q null
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > validatecache=off
  > EOF
  $ chmod u+w $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0
  $ echo x > $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0
  $ hg up tip 2>&1 | egrep "^RuntimeError"
  RuntimeError: unexpected remotefilelog header: illegal format

Verify detection and remediation when remotefilelog.validatecachelog is set

  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > validatecachelog=$PWD/.hg/remotefilelog_cache.log
  > validatecache=strict
  > EOF
  $ chmod u+w $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0
  $ echo x > $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ cat .hg/remotefilelog_cache.log
  corrupt $TESTTMP/hgcache/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/1406e74118627694268417491f018a4a883152f0 during contains

Verify handling of corrupt server cache

  $ rm -f ../master/.hg/remotefilelogcache/y/076f5e2225b3ff0400b98c92aa6cdf403ee24cca
  $ touch ../master/.hg/remotefilelogcache/y/076f5e2225b3ff0400b98c92aa6cdf403ee24cca
  $ clearcache
  $ hg prefetch -r .
  3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
  $ test -s ../master/.hg/remotefilelogcache/y/076f5e2225b3ff0400b98c92aa6cdf403ee24cca
  $ hg debugremotefilelog $CACHEDIR/master/95/cb0bfd2977c761298d9624e4b4d4c72a39974a/076f5e2225b3ff0400b98c92aa6cdf403ee24cca
  size: 2 bytes
  path: $TESTTMP/hgcache/master/95/cb0bfd2977c761298d9624e4b4d4c72a39974a/076f5e2225b3ff0400b98c92aa6cdf403ee24cca 
  key: 076f5e2225b3 
  
          node =>           p1            p2      linknode     copyfrom
  076f5e2225b3 => 000000000000  000000000000  f3d0bb0d1e48