view tests/test-bookmarks-rebase.t @ 39561:d06834e0f48e

wireprotov2peer: stream decoded responses

Previously, wire protocol version 2 would buffer all response data.
Only once all data was received did we CBOR decode it and resolve
the future associated with the command. This was obviously not
desirable. In future commits that introduce large response payloads,
this caused significant memory bloat and slowed down client
operations due to waiting on the server.

This commit refactors the response handling code so that response
data can be streamed.

Command response objects now contain a buffered CBOR decoder. As
new data arrives, it is fed into the decoder. Decoded objects are
made available to the generator as they are decoded.

Because there is a separate thread processing incoming frames and
feeding data into the response object, there is the potential for
race conditions when mutating response objects. So a lock has been
added to guard access to critical state variables.

Because the generator emitting decoded objects needs to wait on
those objects to become available, we've added an Event for the
generator to wait on so it doesn't busy loop. This does mean
there is the potential for deadlocks. And I'm pretty sure they can
occur in some scenarios. We already have a handful of TODOs around
this. But I've added some more. Fixing this will likely require
moving the background thread receiving frames into clienthandler.
We likely would have done this anyway when implementing the client
bits for the SSH transport.

Test output changes because the initial CBOR map holding the overall
response state is now always handled internally by the response
object.

Differential Revision: https://phab.mercurial-scm.org/D4474

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "rebase=" >> $HGRCPATH

initialize repository

  $ hg init

  $ echo 'a' > a
  $ hg ci -A -m "0"
  adding a

  $ echo 'b' > b
  $ hg ci -A -m "1"
  adding b

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo 'c' > c
  $ hg ci -A -m "2"
  adding c
  created new head

  $ echo 'd' > d
  $ hg ci -A -m "3"
  adding d

  $ hg bookmark -r 1 one
  $ hg bookmark -r 3 two
  $ hg up -q two

bookmark list

  $ hg bookmark
     one                       1:925d80f479bb
   * two                       3:2ae46b1d99a7

rebase

  $ hg rebase -s two -d one
  rebasing 3:2ae46b1d99a7 "3" (two tip)
  saved backup bundle to $TESTTMP/.hg/strip-backup/2ae46b1d99a7-e6b057bc-rebase.hg

  $ hg log
  changeset:   3:42e5ed2cdcf4
  bookmark:    two
  tag:         tip
  parent:      1:925d80f479bb
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   2:db815d6d32e6
  parent:      0:f7b1eb17ad24
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   1:925d80f479bb
  bookmark:    one
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   0:f7b1eb17ad24
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
aborted rebase should restore active bookmark.

  $ hg up 1
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark two)
  $ echo 'e' > d
  $ hg ci -A -m "4"
  adding d
  created new head
  $ hg bookmark three
  $ hg rebase -s three -d two
  rebasing 4:dd7c838e8362 "4" (three tip)
  merging d
  warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ hg bookmark
     one                       1:925d80f479bb
   * three                     4:dd7c838e8362
     two                       3:42e5ed2cdcf4

after aborted rebase, restoring a bookmark that has been removed should not fail

  $ hg rebase -s three -d two
  rebasing 4:dd7c838e8362 "4" (three tip)
  merging d
  warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg bookmark -d three
  $ hg rebase --abort
  rebase aborted
  $ hg bookmark
     one                       1:925d80f479bb
     two                       3:42e5ed2cdcf4