view tests/test-histedit-no-change.t @ 37631:2f626233859b

wireproto: implement batching on peer executor interface

This is a bit more complicated than non-batch requests because we
need to buffer sends until the last request arrives *and* we need
to support resolving futures as data arrives from the remote.

In a classical concurrent.futures executor model, the future
"starts" as soon as it is submitted. However, we have nothing to
start until the last command is submitted.

If we did nothing, calling result() would deadlock, since the future
hasn't "started." So in the case where we queue the command, we return
a special future type whose result() will trigger sendcommands().
This eliminates the deadlock potential. It also serves as a check
against callers who may be calling result() prematurely, as it will
prevent any subsequent callcommands() from working. This behavior
is slightly annoying and a bit restrictive. But it's the world
that half duplex connections forces on us.

In order to support streaming responses, we were previously using
a generator. But with a futures-based API, we're using futures
and not generators. So in order to get streaming, we need a
background thread to read data from the server.

The approach taken in this patch is to leverage the ThreadPoolExecutor
from concurrent.futures for managing a background thread. We create
an executor and future that resolves when all response data is
processed (or an error occurs). When exiting the context manager,
we wait on that background reading before returning.

I was hoping we could manually spin up a threading.Thread and this
would be simple. But I ran into a few deadlocks when implementing.
After looking at the source code to concurrent.futures, I figured
it would just be easier to use a ThreadPoolExecutor than implement
all the code needed to manually manage a thread.

To prove this works, a use of the batch API in discovery has been
updated.

Differential Revision: https://phab.mercurial-scm.org/D3269

test for old histedit issue #6:
editing a changeset without any actual change would corrupt the repository

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > histedit=
  > EOF

  $ initrepo ()
  > {
  >     dir="$1"
  >     comment="$2"
  >     if [ -n "${comment}" ]; then
  >         echo % ${comment}
  >         echo % ${comment} | sed 's:.:-:g'
  >     fi
  >     hg init ${dir}
  >     cd ${dir}
  >     for x in a b c d e f ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  >     cd ..
  > }

  $ geneditor ()
  > {
  >     # generate an editor script for selecting changesets to be edited
  >     choice=$1  # changesets that should be edited (using sed line ranges)
  >     cat <<EOF | sed 's:^....::'
  >     # editing the rules, replacing 'pick' with 'edit' for the chosen lines
  >     sed '${choice}s:^pick:edit:' "\$1" > "\${1}.tmp"
  >     mv "\${1}.tmp" "\$1"
  >     # displaying the resulting rules, minus comments and empty lines
  >     sed '/^#/d;/^$/d;s:^:| :' "\$1" >&2
  > EOF
  > }

  $ startediting ()
  > {
  >     # begin an editing session
  >     choice="$1"  # changesets that should be edited
  >     number="$2"  # number of changesets considered (from tip)
  >     comment="$3"
  >     geneditor "${choice}" > edit.sh
  >     echo % start editing the history ${comment}
  >     HGEDITOR="sh ./edit.sh" hg histedit -- -${number} 2>&1 | fixbundle
  > }

  $ continueediting ()
  > {
  >     # continue an edit already in progress
  >     editor="$1"  # message editor when finalizing editing
  >     comment="$2"
  >     echo % finalize changeset editing ${comment}
  >     HGEDITOR=${editor} hg histedit --continue 2>&1 | fixbundle
  > }

  $ graphlog ()
  > {
  >     comment="${1:-log}"
  >     echo % "${comment}"
  >     hg log -G --template '{rev} {node} \"{desc|firstline}\"\n'
  > }


  $ initrepo r1 "test editing with no change"
  % test editing with no change
  -----------------------------
  $ cd r1
  $ graphlog "log before editing"
  % log before editing
  @  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  |
  o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  
  $ startediting 2 3 "(not changing anything)" # edit the 2nd of 3 changesets
  % start editing the history (not changing anything)
  | pick 055a42cdd887 3 d
  | edit e860deea161a 4 e
  | pick 652413bf663e 5 f
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  Editing (e860deea161a), you may commit or record as needed now.
  (hg histedit --continue to resume)
  $ continueediting true "(leaving commit message unaltered)"
  % finalize changeset editing (leaving commit message unaltered)


check state of working copy
  $ hg id
  794fe033d0a0 tip

  $ graphlog "log after history editing"
  % log after history editing
  @  5 794fe033d0a030f8df77c5de945fca35c9181c30 "f"
  |
  o  4 04d2fab980779f332dec458cc944f28de8b43435 "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  

  $ cd ..

  $ initrepo r2 "test editing with no change, then abort"
  % test editing with no change, then abort
  -----------------------------------------
  $ cd r2
  $ graphlog "log before editing"
  % log before editing
  @  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  |
  o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  
  $ startediting 1,2 3 "(not changing anything)" # edit the 1st two of 3 changesets
  % start editing the history (not changing anything)
  | edit 055a42cdd887 3 d
  | edit e860deea161a 4 e
  | pick 652413bf663e 5 f
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  Editing (055a42cdd887), you may commit or record as needed now.
  (hg histedit --continue to resume)
  $ continueediting true "(leaving commit message unaltered)"
  % finalize changeset editing (leaving commit message unaltered)
  Editing (e860deea161a), you may commit or record as needed now.
  (hg histedit --continue to resume)
  $ graphlog "log after first edit"
  % log after first edit
  @  6 e5ae3ca2f1ffdbd89ec41ebc273a231f7c3022f2 "d"
  |
  | o  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  | |
  | o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  | |
  | o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |/
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  

abort editing session, after first forcibly updating away
  $ hg up 0
  abort: histedit in progress
  (use 'hg histedit --continue' or 'hg histedit --abort')
  [255]
  $ mv .hg/histedit-state .hg/histedit-state-ignore
  $ hg up 0
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ mv .hg/histedit-state-ignore .hg/histedit-state
  $ hg sum
  parent: 0:cb9a9f314b8b 
   a
  branch: default
  commit: 1 added, 1 unknown (new branch head)
  update: 6 new changesets (update)
  phases: 7 draft
  hist:   2 remaining (histedit --continue)

  $ hg histedit --abort 2>&1 | fixbundle

modified files should survive the abort when we've moved away already
  $ hg st
  A e
  ? edit.sh

  $ graphlog "log after abort"
  % log after abort
  o  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  |
  o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  @  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  
aborting and not changing files can skip mentioning updating (no) files
  $ hg up
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg commit --close-branch -m 'closebranch'
  $ startediting 1 1 "(not changing anything)" # edit the 3rd of 3 changesets
  % start editing the history (not changing anything)
  | edit 292aec348d9e 6 closebranch
  Editing (292aec348d9e), you may commit or record as needed now.
  (hg histedit --continue to resume)
  $ hg histedit --abort

  $ cd ..