D2720: debugcommands: introduce actions to perform deterministic reads

[mharbison72 (Matt Harbison)]

mharbison72 added a comment.


  This patch seems to deadlock on Windows when running test-ssh-proto-unbundle.t.  There are two python processes idling:
  
  c:\Python27\python.exe c:/Users/Matt/projects/hg/hg --verbose debugwireproto --localssh --noreadstderr
  CWD: C:\Users\Matt\AppData\Local\Temp\hgtests.1mtivg\child1\test-ssh-proto-unbundle.t\no-bundle1\
  
  and
  
  c:\Python27\python.exe c:/Users/Matt/projects/hg/hg -R C:\Users\Matt\AppData\Local\Temp\hgtests.1mtivg\child1\test-ssh-proto-unbundle.t\no-bundle1 debugserve --sshstdio
  CWD: C:\Users\Matt\AppData\Local\Temp\hgtests.1mtivg\child1\test-ssh-proto-unbundle.t\no-bundle1\
  
  Past experience says that something needs to be flushed- stdout (and maybe stderr?) are full buffered on Windows IIRC.  The following failure with this patch might also point to that:
  
    --- c:/Users/Matt/projects/hg/tests/test-ssh-proto.t
    +++ c:/Users/Matt/projects/hg/tests/test-ssh-proto.t.err
    @@ -100,12 +100,12 @@
       $ hg debugserve --sshstdio --logiofd 1 << EOF
       > hello
       > EOF
    -  o> write(4) -> 4:
    -  o>     384\n
    -  o> write(384) -> 384:
    -  o>     capabilities: lookup branchmap pushkey known getbundle unbundlehash batch changegroupsubset streamreqs=generaldelta,revlogv1 $USUAL_BUNDLE2_CAPS_SERVER$unbundle=HG10GZ,HG10BZ,HG10UN\n
       384
       capabilities: lookup branchmap pushkey known getbundle unbundlehash batch changegroupsubset streamreqs=generaldelta,revlogv1 $USUAL_BUNDLE2_CAPS_SERVER$ unbundle=HG10GZ,HG10BZ,HG10UN
    +  o> write(4) -> 4:
    +  o>     384\n
    +  o> write(384) -> 384:
    +  o>     capabilities: lookup branchmap pushkey known getbundle unbundlehash batch changegroupsubset streamreqs=generaldelta,revlogv1 $USUAL_BUNDLE2_CAPS_SERVER$ unbundle=HG10GZ,HG10BZ,HG10UN\n
       o> flush() -> None
    
       $ hg debugserve --sshstdio --logiofile $TESTTMP/io << EOF

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2720

To: indygreg, #hg-reviewers
Cc: mharbison72, mercurial-devel