tests/test-url-download.t

dirstate-tree: Avoid BTreeMap double-lookup when inserting a dirstate entry

The child nodes of a given node in the tree-shaped dirstate are kept in a
`BTreeMap` where keys are file names as strings. Finding or inserting a value
in the map takes `O(log(n))` string comparisons, which adds up when constructing
the tree.

The `entry` API allows finding a "spot" in the map that may or may not be
occupied and then access that value or insert a new one without doing map
lookup again. However the current API is limited in that calling `entry`
requires an owned key (and so a memory allocation), even if it ends up not
being used in the case where the map already has a value with an equal key.

This is still a win, with 4% better end-to-end time for `hg status` measured
here with hyperfine:

```
Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
  Time (mean ± σ):      1.337 s ±  0.018 s    [User: 892.9 ms, System: 437.5 ms]
  Range (min … max):    1.316 s …  1.373 s    10 runs

Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
  Time (mean ± σ):      1.291 s ±  0.008 s    [User: 853.4 ms, System: 431.1 ms]
  Range (min … max):    1.283 s …  1.309 s    10 runs

Summary
  './hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran
    1.04 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1'
```

* ./hg is this revision
* ../hg2/hg is its parent
* $REPO is an old snapshot of mozilla-central

Differential Revision: https://phab.mercurial-scm.org/D10550

#require serve

  $ hg init server
  $ hg serve -R server -p $HGPORT -d --pid-file=hg1.pid -E ../error.log
  $ cat hg1.pid >> $DAEMON_PIDS

Check basic fetching

  $ hg debugdownload "http://localhost:$HGPORT/?cmd=lookup&key=tip"
  1 0000000000000000000000000000000000000000
  $ hg debugdownload  -o null.txt "http://localhost:$HGPORT/?cmd=lookup&key=null"
  $ cat null.txt
  1 0000000000000000000000000000000000000000

Check the request is made from the usual Mercurial logic
(rev details, give different content if the request has a Mercurial user agent)

  $ get-with-headers.py --headeronly "localhost:$HGPORT" "rev/tip" content-type
  200 Script output follows
  content-type: text/html; charset=ascii
  $ hg debugdownload "http://localhost:$HGPORT/rev/tip"
  
  # HG changeset patch
  # User 
  # Date 0 0
  # Node ID 0000000000000000000000000000000000000000
  
  
  
  

Check other kind of compatible url

  $ hg debugdownload ./null.txt
  1 0000000000000000000000000000000000000000

  $ cat ../error.log

Test largefile URL
------------------

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

  $ killdaemons.py
  $ rm -f error.log hg1.pid
  $ hg serve -R server -p $HGPORT -d --pid-file=hg1.pid -E error.log
  $ cat hg1.pid >> $DAEMON_PIDS

  $ hg -R server debuglfput null.txt
  a57b57b39ee4dc3da1e03526596007f480ecdbe8

  $ hg --traceback debugdownload "largefile://a57b57b39ee4dc3da1e03526596007f480ecdbe8" --config paths.default=http://localhost:$HGPORT/
  1 0000000000000000000000000000000000000000

from within a repository

  $ hg clone http://localhost:$HGPORT/ client
  no changes found
  updating to branch default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd client
  $ hg path
  default = http://localhost:$HGPORT/
  $ hg debugdownload "largefile://a57b57b39ee4dc3da1e03526596007f480ecdbe8"
  1 0000000000000000000000000000000000000000
  $ cd ..

  $ cat error.log