view tests/test-narrow-clone-nonlinear.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

Testing narrow clones when changesets modifying a matching file exist on
multiple branches

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

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [narrow]
  > serveellipses=True
  > EOF

  $ hg branch default
  marked working directory as branch default
  (branches are permanent and global, did you want a bookmark?)
  $ for x in `$TESTDIR/seq.py 10`; do
  >   echo $x > "f$x"
  >   hg add "f$x"
  >   hg commit -m "Add $x"
  > done

  $ hg branch release-v1
  marked working directory as branch release-v1
  (branches are permanent and global, did you want a bookmark?)
  $ hg commit -m "Start release for v1"

  $ hg update default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ for x in `$TESTDIR/seq.py 10`; do
  >   echo "$x v2" > "f$x"
  >   hg commit -m "Update $x to v2"
  > done

  $ hg update release-v1
  10 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch release-v1
  marked working directory as branch release-v1
  $ for x in `$TESTDIR/seq.py 1 5`; do
  >   echo "$x v1 hotfix" > "f$x"
  >   hg commit -m "Hotfix $x in v1"
  > done

  $ hg update default
  10 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch release-v2
  marked working directory as branch release-v2
  $ hg commit -m "Start release for v2"

  $ hg update default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch default
  marked working directory as branch default
  $ for x in `$TESTDIR/seq.py 10`; do
  >   echo "$x v3" > "f$x"
  >   hg commit -m "Update $x to v3"
  > done

  $ hg update release-v2
  10 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch release-v2
  marked working directory as branch release-v2
  $ for x in `$TESTDIR/seq.py 4 9`; do
  >   echo "$x v2 hotfix" > "f$x"
  >   hg commit -m "Hotfix $x in v2"
  > done

  $ hg heads -T '{rev} <- {p1rev} ({branch}): {desc}\n'
  42 <- 41 (release-v2): Hotfix 9 in v2
  36 <- 35 (default): Update 10 to v3
  25 <- 24 (release-v1): Hotfix 5 in v1

  $ cd ..

We now have 3 branches: default, which has v3 of all files, release-v1 which
has v1 of all files, and release-v2 with v2 of all files.

Narrow clone which should get all branches

  $ hg clone --narrow ssh://user@dummy/master narrow --include "f5"
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 12 changesets with 5 changes to 1 files (+2 heads)
  new changesets *:* (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow
  $ hg log -G -T "{if(ellipsis, '...')}{node|short} ({branch}): {desc}\n"
  o  ...031f516143fe (release-v2): Hotfix 9 in v2
  |
  o  9cd7f7bb9ca1 (release-v2): Hotfix 5 in v2
  |
  o  ...37bbc88f3ef0 (release-v2): Hotfix 4 in v2
  |
  | @  ...dae2f368ca07 (default): Update 10 to v3
  | |
  | o  9c224e89cb31 (default): Update 5 to v3
  | |
  | o  ...04fb59c7c9dc (default): Update 4 to v3
  |/
  | o  b2253e82401f (release-v1): Hotfix 5 in v1
  | |
  | o  ...960ac37d74fd (release-v1): Hotfix 4 in v1
  | |
  o |  986298e3f347 (default): Update 5 to v2
  | |
  o |  ...75d539c667ec (default): Update 4 to v2
  |/
  o  04c71bd5707f (default): Add 5
  |
  o  ...881b3891d041 (default): Add 4
  

Narrow clone the first file, hitting edge condition where unaligned
changeset and manifest revnums cross branches.

  $ hg clone --narrow ssh://user@dummy/master narrow --include "f1"
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 10 changesets with 4 changes to 1 files (+2 heads)
  new changesets *:* (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow
  $ hg log -G -T "{if(ellipsis, '...')}{node|short} ({branch}): {desc}\n"
  o  ...031f516143fe (release-v2): Hotfix 9 in v2
  |
  | @  ...dae2f368ca07 (default): Update 10 to v3
  | |
  | o  1f5d184b8e96 (default): Update 1 to v3
  |/
  | o  ...b2253e82401f (release-v1): Hotfix 5 in v1
  | |
  | o  133502f6b7e5 (release-v1): Hotfix 1 in v1
  | |
  o |  ...79165c83d644 (default): Update 10 to v2
  | |
  o |  c7b7a5f2f088 (default): Update 1 to v2
  | |
  | o  ...f0531a3db7a9 (release-v1): Start release for v1
  |/
  o  ...6a3f0f0abef3 (default): Add 10
  |
  o  e012ac15eaaa (default): Add 1