view tests/test-merge-criss-cross.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

Criss cross merging

  $ hg init criss-cross
  $ cd criss-cross
  $ echo '0 base' > f1
  $ echo '0 base' > f2
  $ hg ci -Aqm '0 base'

  $ echo '1 first change' > f1
  $ hg ci -m '1 first change f1'

  $ hg up -qr0
  $ echo '2 first change' > f2
  $ mkdir d1
  $ echo '0 base' > d1/f3
  $ echo '0 base' > d1/f4
  $ hg add -q d1
  $ hg ci -qm '2 first change f2'

  $ hg merge -qr 1
  $ hg rm d1/f3
  $ hg mv -q d1 d2
  $ hg ci -m '3 merge'

  $ hg up -qr2
  $ hg merge -qr1
  $ hg ci -qm '4 merge'

  $ echo '5 second change' > f1
  $ hg ci -m '5 second change f1'

  $ hg up -r3
  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo '6 second change' > f2
  $ hg ci -m '6 second change f2'

  $ hg log -G
  @  changeset:   6:6373bbfdae1d
  |  tag:         tip
  |  parent:      3:c202c8af058d
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     6 second change f2
  |
  | o  changeset:   5:e673248094b1
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     5 second change f1
  | |
  | o    changeset:   4:177f58377c06
  | |\   parent:      2:d1d156401c1b
  | | |  parent:      1:0f6b37dbe527
  | | |  user:        test
  | | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | | |  summary:     4 merge
  | | |
  o---+  changeset:   3:c202c8af058d
  | | |  parent:      2:d1d156401c1b
  |/ /   parent:      1:0f6b37dbe527
  | |    user:        test
  | |    date:        Thu Jan 01 00:00:00 1970 +0000
  | |    summary:     3 merge
  | |
  | o  changeset:   2:d1d156401c1b
  | |  parent:      0:40494bf2444c
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     2 first change f2
  | |
  o |  changeset:   1:0f6b37dbe527
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     1 first change f1
  |
  o  changeset:   0:40494bf2444c
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     0 base
  

  $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor='!'
  note: using 0f6b37dbe527 as ancestor of 6373bbfdae1d and e673248094b1
        alternatively, use --config merge.preferancestor=d1d156401c1b
    searching for copies back to rev 3
    unmatched files in local:
     d2/f4
    unmatched files in other:
     d1/f3
     d1/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
     pending file src: 'd1/f3' -> dst: 'd2/f3'
     pending file src: 'd1/f4' -> dst: 'd2/f4'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
   preserving d2/f4 for resolve of d2/f4
   preserving f2 for resolve of f2
   f1: remote is newer -> g
  getting f1
   d2/f3: local directory rename - get from d1/f3 -> dg
  getting d1/f3 to d2/f3
   d2/f4: local directory rename, both created -> m (premerge)
   f2: versions differ -> m (premerge)
  picked tool ':dump' for f2 (binary False symlink False changedelete False)
  merging f2
  my f2@6373bbfdae1d+ other f2@e673248094b1 ancestor f2@0f6b37dbe527
   f2: versions differ -> m (merge)
  picked tool ':dump' for f2 (binary False symlink False changedelete False)
  my f2@6373bbfdae1d+ other f2@e673248094b1 ancestor f2@0f6b37dbe527
  3 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]

  $ f --dump --recurse *
  d2: directory with 2 files
  d2/f3:
  >>>
  0 base
  <<<
  d2/f4:
  >>>
  0 base
  <<<
  f1:
  >>>
  5 second change
  <<<
  f2:
  >>>
  6 second change
  <<<
  f2.base:
  >>>
  0 base
  <<<
  f2.local:
  >>>
  6 second change
  <<<
  f2.orig:
  >>>
  6 second change
  <<<
  f2.other:
  >>>
  2 first change
  <<<

  $ hg up -qC .
  $ hg merge -v --tool internal:dump 5 --config merge.preferancestor="null 40663881 3b08d"
  note: using 0f6b37dbe527 as ancestor of 6373bbfdae1d and e673248094b1
        alternatively, use --config merge.preferancestor=d1d156401c1b
  resolving manifests
  getting f1
  getting d1/f3 to d2/f3
  merging f2
  3 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]

Redo merge with merge.preferancestor="*" to enable bid merge

  $ rm f*
  $ hg up -qC .
  $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor="*"
  note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
  
  calculating bids for ancestor 0f6b37dbe527
    searching for copies back to rev 3
    unmatched files in local:
     d2/f4
    unmatched files in other:
     d1/f3
     d1/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
     pending file src: 'd1/f3' -> dst: 'd2/f3'
     pending file src: 'd1/f4' -> dst: 'd2/f4'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
   d2/f3: local directory rename - get from d1/f3 -> dg
   d2/f4: local directory rename, both created -> m
   f1: remote is newer -> g
   f2: versions differ -> m
  
  calculating bids for ancestor d1d156401c1b
    searching for copies back to rev 3
    unmatched files in local:
     d2/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: d1d156401c1b, local: 6373bbfdae1d+, remote: e673248094b1
   f1: versions differ -> m
   f2: remote unchanged -> k
  
  auction for merging merge bids
   d2/f3: consensus for dg
   d2/f4: consensus for m
   f1: picking 'get' action
   f2: picking 'keep' action
  end of auction
  
   preserving d2/f4 for resolve of d2/f4
   f1: remote is newer -> g
  getting f1
   f2: remote unchanged -> k
   d2/f3: local directory rename - get from d1/f3 -> dg
  getting d1/f3 to d2/f3
   d2/f4: local directory rename, both created -> m (premerge)
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ f --dump --recurse *
  d2: directory with 2 files
  d2/f3:
  >>>
  0 base
  <<<
  d2/f4:
  >>>
  0 base
  <<<
  f1:
  >>>
  5 second change
  <<<
  f2:
  >>>
  6 second change
  <<<


The other way around:

  $ hg up -C -r5
  4 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg merge -v --debug --config merge.preferancestor="*"
  note: merging e673248094b1+ and 6373bbfdae1d using bids from ancestors 0f6b37dbe527 and d1d156401c1b
  
  calculating bids for ancestor 0f6b37dbe527
    searching for copies back to rev 3
    unmatched files in local:
     d1/f3
     d1/f4
    unmatched files in other:
     d2/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
     pending file src: 'd1/f3' -> dst: 'd2/f3'
     pending file src: 'd1/f4' -> dst: 'd2/f4'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: e673248094b1+, remote: 6373bbfdae1d
   d2/f3: remote directory rename - move from d1/f3 -> dm
   d2/f4: remote directory rename, both created -> m
   f1: remote unchanged -> k
   f2: versions differ -> m
  
  calculating bids for ancestor d1d156401c1b
    searching for copies back to rev 3
    unmatched files in other:
     d2/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: d1d156401c1b, local: e673248094b1+, remote: 6373bbfdae1d
   d1/f3: other deleted -> r
   d1/f4: other deleted -> r
   d2/f4: remote created -> g
   f1: versions differ -> m
   f2: remote is newer -> g
  
  auction for merging merge bids
   d1/f3: consensus for r
   d1/f4: consensus for r
   d2/f3: consensus for dm
   d2/f4: picking 'get' action
   f1: picking 'keep' action
   f2: picking 'get' action
  end of auction
  
   d1/f3: other deleted -> r
  removing d1/f3
   d1/f4: other deleted -> r
  removing d1/f4
   d2/f4: remote created -> g
  getting d2/f4
   f2: remote is newer -> g
  getting f2
   f1: remote unchanged -> k
  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ f --dump --recurse *
  d2: directory with 2 files
  d2/f3:
  >>>
  0 base
  <<<
  d2/f4:
  >>>
  0 base
  <<<
  f1:
  >>>
  5 second change
  <<<
  f2:
  >>>
  6 second change
  <<<

Verify how the output looks and and how verbose it is:

  $ hg up -qC
  $ hg merge
  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg up -qC tip
  $ hg merge -v
  note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
  
  calculating bids for ancestor 0f6b37dbe527
  resolving manifests
  
  calculating bids for ancestor d1d156401c1b
  resolving manifests
  
  auction for merging merge bids
   d2/f3: consensus for dg
   d2/f4: consensus for m
   f1: picking 'get' action
   f2: picking 'keep' action
  end of auction
  
  getting f1
  getting d1/f3 to d2/f3
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg up -qC
  $ hg merge -v --debug --config merge.preferancestor="*"
  note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
  
  calculating bids for ancestor 0f6b37dbe527
    searching for copies back to rev 3
    unmatched files in local:
     d2/f4
    unmatched files in other:
     d1/f3
     d1/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
     pending file src: 'd1/f3' -> dst: 'd2/f3'
     pending file src: 'd1/f4' -> dst: 'd2/f4'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
   d2/f3: local directory rename - get from d1/f3 -> dg
   d2/f4: local directory rename, both created -> m
   f1: remote is newer -> g
   f2: versions differ -> m
  
  calculating bids for ancestor d1d156401c1b
    searching for copies back to rev 3
    unmatched files in local:
     d2/f4
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'd1/f4' -> dst: 'd2/f4' 
    checking for directory renames
     discovered dir src: 'd1/' -> dst: 'd2/'
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: d1d156401c1b, local: 6373bbfdae1d+, remote: e673248094b1
   f1: versions differ -> m
   f2: remote unchanged -> k
  
  auction for merging merge bids
   d2/f3: consensus for dg
   d2/f4: consensus for m
   f1: picking 'get' action
   f2: picking 'keep' action
  end of auction
  
   preserving d2/f4 for resolve of d2/f4
   f1: remote is newer -> g
  getting f1
   f2: remote unchanged -> k
   d2/f3: local directory rename - get from d1/f3 -> dg
  getting d1/f3 to d2/f3
   d2/f4: local directory rename, both created -> m (premerge)
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cd ..

http://stackoverflow.com/questions/9350005/how-do-i-specify-a-merge-base-to-use-in-a-hg-merge/9430810

  $ hg init ancestor-merging
  $ cd ancestor-merging
  $ echo a > x
  $ hg commit -A -m a x
  $ hg update -q 0
  $ echo b >> x
  $ hg commit -m b
  $ hg update -q 0
  $ echo c >> x
  $ hg commit -qm c
  $ hg update -q 1
  $ hg merge -q --tool internal:local 2
  $ echo c >> x
  $ hg commit -m bc
  $ hg update -q 2
  $ hg merge -q --tool internal:local 1
  $ echo b >> x
  $ hg commit -qm cb

  $ hg merge --config merge.preferancestor='!'
  note: using 70008a2163f6 as ancestor of 0d355fdef312 and 4b8b546a3eef
        alternatively, use --config merge.preferancestor=b211bbc6eb3c
  merging x
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat x
  a
  c
  b
  c

  $ hg up -qC .

  $ hg merge --config merge.preferancestor=b211bbc6eb3c
  note: using b211bbc6eb3c as ancestor of 0d355fdef312 and 4b8b546a3eef
        alternatively, use --config merge.preferancestor=70008a2163f6
  merging x
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat x
  a
  b
  c
  b

  $ hg up -qC .

  $ hg merge -v --config merge.preferancestor="*"
  note: merging 0d355fdef312+ and 4b8b546a3eef using bids from ancestors 70008a2163f6 and b211bbc6eb3c
  
  calculating bids for ancestor 70008a2163f6
  resolving manifests
  
  calculating bids for ancestor b211bbc6eb3c
  resolving manifests
  
  auction for merging merge bids
   x: multiple bids for merge action:
    versions differ -> m
    versions differ -> m
   x: ambiguous merge - picked m action
  end of auction
  
  merging x
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat x
  a
  c
  b
  c

Verify that the old context ancestor works with / despite preferancestor:

  $ hg log -r 'ancestor(head())' --config merge.preferancestor=1 -T '{rev}\n'
  1
  $ hg log -r 'ancestor(head())' --config merge.preferancestor=2 -T '{rev}\n'
  2
  $ hg log -r 'ancestor(head())' --config merge.preferancestor=3 -T '{rev}\n'
  1
  $ hg log -r 'ancestor(head())' --config merge.preferancestor='1337 * - 2' -T '{rev}\n'
  2

  $ cd ..