view tests/test-show.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

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

No arguments shows available views

  $ hg init empty
  $ cd empty
  $ hg show
  available views:
  
  bookmarks -- bookmarks and their associated changeset
  stack -- current line of work
  work -- changesets that aren't finished
  
  abort: no view requested
  (use "hg show VIEW" to choose a view)
  [255]

`hg help show` prints available views

  $ hg help show
  hg show VIEW
  
  show various repository information
  
      A requested view of repository data is displayed.
  
      If no view is requested, the list of available views is shown and the
      command aborts.
  
      Note:
         There are no backwards compatibility guarantees for the output of this
         command. Output may change in any future Mercurial release.
  
         Consumers wanting stable command output should specify a template via
         "-T/--template".
  
      List of available views:
  
      bookmarks   bookmarks and their associated changeset
  
      stack       current line of work
  
      work        changesets that aren't finished
  
  (use 'hg help -e show' to show help for the show extension)
  
  options:
  
   -T --template TEMPLATE display with template
  
  (some details hidden, use --verbose to show complete help)

Unknown view prints error

  $ hg show badview
  abort: unknown view: badview
  (run "hg show" to see available views)
  [255]

HGPLAIN results in abort

  $ HGPLAIN=1 hg show bookmarks
  abort: must specify a template in plain mode
  (invoke with -T/--template to control output format)
  [255]

But not if a template is specified

  $ HGPLAIN=1 hg show bookmarks -T '{bookmark}\n'
  (no bookmarks set)

  $ cd ..

bookmarks view with no bookmarks prints empty message

  $ hg init books
  $ cd books
  $ touch f0
  $ hg -q commit -A -m initial

  $ hg show bookmarks
  (no bookmarks set)

bookmarks view shows bookmarks in an aligned table

  $ echo book1 > f0
  $ hg commit -m 'commit for book1'
  $ echo book2 > f0
  $ hg commit -m 'commit for book2'

  $ hg bookmark -r 1 book1
  $ hg bookmark a-longer-bookmark

  $ hg show bookmarks
  * a-longer-bookmark    7b57
    book1                b757

A custom bookmarks template works

  $ hg show bookmarks -T '{node} {bookmark} {active}\n'
  7b5709ab64cbc34da9b4367b64afff47f2c4ee83 a-longer-bookmark True
  b757f780b8ffd71267c6ccb32e0882d9d32a8cc0 book1 False

bookmarks JSON works

  $ hg show bookmarks -T json
  [
   {
    "active": true,
    "bookmark": "a-longer-bookmark",
    "longestbookmarklen": 17,
    "node": "7b5709ab64cbc34da9b4367b64afff47f2c4ee83",
    "nodelen": 4
   },
   {
    "active": false,
    "bookmark": "book1",
    "longestbookmarklen": 17,
    "node": "b757f780b8ffd71267c6ccb32e0882d9d32a8cc0",
    "nodelen": 4
   }
  ]

JSON works with no bookmarks

  $ hg book -d a-longer-bookmark
  $ hg book -d book1
  $ hg show bookmarks -T json
  [
  ]

commands.show.aliasprefix aliases values to `show <view>`

  $ hg --config commands.show.aliasprefix=s sbookmarks
  (no bookmarks set)

  $ hg --config commands.show.aliasprefix=sh shwork
  @  7b57 commit for book2
  o  b757 commit for book1
  o  ba59 initial

  $ hg --config commands.show.aliasprefix='s sh' swork
  @  7b57 commit for book2
  o  b757 commit for book1
  o  ba59 initial

  $ hg --config commands.show.aliasprefix='s sh' shwork
  @  7b57 commit for book2
  o  b757 commit for book1
  o  ba59 initial

The aliases don't appear in `hg config`

  $ hg --config commands.show.aliasprefix=s config alias
  [1]

Doesn't overwrite existing alias

  $ hg --config alias.swork='log -r .' --config commands.show.aliasprefix=s swork
  changeset:   2:7b5709ab64cb
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit for book2
  

  $ hg --config alias.swork='log -r .' --config commands.show.aliasprefix=s config alias
  alias.swork=log -r .

  $ cd ..