view tests/test-bundle-phases.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

  $ cat >> $HGRCPATH <<EOF
  > [experimental]
  > bundle-phases=yes
  > [extensions]
  > strip=
  > drawdag=$TESTDIR/drawdag.py
  > EOF

Set up repo with linear history
  $ hg init linear
  $ cd linear
  $ hg debugdrawdag <<'EOF'
  > E
  > |
  > D
  > |
  > C
  > |
  > B
  > |
  > A
  > EOF
  $ hg phase --public A
  $ hg phase --force --secret D
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Phases are restored when unbundling
  $ hg bundle --base B -r E bundle
  3 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 3, targetphase: 2, version: 02} (mandatory: True)
      26805aba1e600a82e93661149f2313866a221a7b
      f585351a92f85104bff7c284233c338b10eb1df7
      9bc730a19041f9ec7cb33c626e811aa233efb18c
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      26805aba1e600a82e93661149f2313866a221a7b draft
  $ hg strip --no-backup C
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Root revision's phase is preserved
  $ hg bundle -a bundle
  5 changesets found
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Completely public history can be restored
  $ hg phase --public E
  $ hg bundle -a bundle
  5 changesets found
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E public
  |
  o  D public
  |
  o  C public
  |
  o  B public
  |
  o  A public
  
Direct transition from public to secret can be restored
  $ hg phase --secret --force D
  $ hg bundle -a bundle
  5 changesets found
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C public
  |
  o  B public
  |
  o  A public
  
Revisions within bundle preserve their phase even if parent changes its phase
  $ hg phase --draft --force B
  $ hg bundle --base B -r E bundle
  3 changesets found
  $ hg strip --no-backup C
  $ hg phase --public B
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B public
  |
  o  A public
  
Phase of ancestors of stripped node get advanced to accommodate child
  $ hg bundle --base B -r E bundle
  3 changesets found
  $ hg strip --no-backup C
  $ hg phase --force --secret B
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Unbundling advances phases of changesets even if they were already in the repo.
To test that, create a bundle of everything in draft phase and then unbundle
to see that secret becomes draft, but public remains public.
  $ hg phase --draft --force A
  $ hg phase --draft E
  $ hg bundle -a bundle
  5 changesets found
  $ hg phase --public A
  $ hg phase --secret --force E
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E draft
  |
  o  D draft
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Unbundling change in the middle of a stack does not affect later changes
  $ hg strip --no-backup E
  $ hg phase --secret --force D
  $ hg log -G -T '{desc} {phase}\n'
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
  $ hg bundle --base A -r B bundle
  1 changesets found
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  

  $ cd ..

Set up repo with non-linear history
  $ hg init non-linear
  $ cd non-linear
  $ hg debugdrawdag <<'EOF'
  > D E
  > |\|
  > B C
  > |/
  > A
  > EOF
  $ hg phase --public C
  $ hg phase --force --secret B
  $ hg log -G -T '{node|short} {desc} {phase}\n'
  o  03ca77807e91 E draft
  |
  | o  4e4f9194f9f1 D secret
  |/|
  o |  dc0947a82db8 C public
  | |
  | o  112478962961 B secret
  |/
  o  426bada5c675 A public
  

Restore bundle of entire repo
  $ hg bundle -a bundle
  5 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 5, targetphase: 2, version: 02} (mandatory: True)
      426bada5c67598ca65036d57d9e4b64b0c1ce7a0
      112478962961147124edd43549aedd1a335e44bf
      dc0947a82db884575bb76ea10ac97b08536bfa03
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
      03ca77807e919db8807c3749086dc36fb478cac0
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      dc0947a82db884575bb76ea10ac97b08536bfa03 public
      03ca77807e919db8807c3749086dc36fb478cac0 draft
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{node|short} {desc} {phase}\n'
  o  03ca77807e91 E draft
  |
  | o  4e4f9194f9f1 D secret
  |/|
  o |  dc0947a82db8 C public
  | |
  | o  112478962961 B secret
  |/
  o  426bada5c675 A public
  

  $ hg bundle --base 'A + C' -r D bundle
  2 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 2, targetphase: 2, version: 02} (mandatory: True)
      112478962961147124edd43549aedd1a335e44bf
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
  $ rm bundle

  $ hg bundle --base A -r D bundle
  3 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 3, targetphase: 2, version: 02} (mandatory: True)
      112478962961147124edd43549aedd1a335e44bf
      dc0947a82db884575bb76ea10ac97b08536bfa03
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      dc0947a82db884575bb76ea10ac97b08536bfa03 public
  $ rm bundle

  $ hg bundle --base 'B + C' -r 'D + E' bundle
  2 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 2, targetphase: 2, version: 02} (mandatory: True)
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
      03ca77807e919db8807c3749086dc36fb478cac0
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      03ca77807e919db8807c3749086dc36fb478cac0 draft
  $ rm bundle