tests/test-hgweb-json.t

repoview: discard filtered changelog if index isn't shared with unfiltered

Before this patch, revisions rollbacked at failure of previous
transaction might be visible at subsequent operations unintentionally,
if repoview object is reused even after failure of transaction:
e.g. command server and HTTP server are typical cases.

'repoview' uses the tuple of values below of unfiltered changelog as
"the key" to examine validity of filtered changelog cache.

     - length
     - tip node
     - filtered revisions (as hashed value)
     - '_delayed' field

'repoview' compares between "the key" of unfiltered changelog at
previous caching and now, and reuses filtered changelog cache if no
change is detected.

But this comparison indicates only that there is no change between
unfiltered 'repo.changelog' at last caching and now, but not that
filtered changelog cache is valid for current unfiltered one.

'repoview' uses "shallow copy" of unfiltered changelog to create
filtered changelog cache. In this case, 'index' buffer of unfiltered
changelog is also referred by filtered changelog.

At failure of transaction, unfiltered changelog itself is invalidated
(= un-referred) on the 'repo' side (see 0a7610758c42 also). But
'index' of it still contains revisions to be rollbacked at this
failure, and is referred by filtered changelog.

Therefore, even if there is no change between unfiltered
'repo.changelog' at last caching and now, steps below makes rollbacked
revisions visible via filtered changelog unintentionally.

  1. instantiate unfiltered changelog as 'repo.changelog'
     (call it CL1)

  2. make filtered (= shallow copy of) CL1
     (call it FCL1)

  3. cache FCL1 with "the key" of CL1

  4. revisions are appended to 'index', which is shared by CL1 and FCL1

  5. invalidate 'repo.changelog' (= CL1) at failure of transaction

  6. instantiate 'repo.changelog' again at next operation
     (call it CL2)

     CL2 doesn't have revisions added at (4), because it is
     instantiated from '00changelog.i', which isn't changed while
     failed transaction.

  7. compare between "the key" of CL1 and CL2

  8. FCL1 cached at (3) is reused, because comparison at (7) doesn't
     detect change between CL1 at (1) and CL2

  9. revisions rollbacked at (5) are visible via FCL1 unintentionally,
     because FCL1 still refers 'index' changed at (4)

The root cause of this issue is that there is no examination about
validity of filtered changelog cache against current unfiltered one.

This patch discards filtered changelog cache, if its 'index' object
isn't shared with unfiltered one.

BTW, at the time of this patch, redundant truncation of
'00changelog.i' at failure of transaction (see 0a7610758c42 for
detail) often prevents "hg serve" from making already rollbacked
revisions visible, because updating timestamps of '00changelog.i' by
truncation makes "hg serve" discard old repoview object with invalid
filtered changelog cache.

This is reason why this issue is overlooked before this patch, even
though test-bundle2-exchange.t has tests in similar situation: failure
of "hg push" via HTTP by pretxnclose hook on server side doesn't
prevent subsequent commands from looking up outgoing revisions
correctly.

But timestamp on the filesystem doesn't have enough resolution for
recent computation power, and it can't be assumed that this avoidance
always works as expected.

Therefore, without this patch, this issue might appear occasionally.

#require serve

  $ request() {
  >   get-with-headers.py --json localhost:$HGPORT "$1"
  > }

  $ hg init test
  $ cd test
  $ mkdir da
  $ echo foo > da/foo
  $ echo foo > foo
  $ hg -q ci -A -m initial
  $ echo bar > foo
  $ hg ci -m 'modify foo'
  $ echo bar > da/foo
  $ hg ci -m 'modify da/foo'
  $ hg bookmark bookmark1
  $ hg up default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark bookmark1)
  $ hg mv foo foo-new
  $ hg commit -m 'move foo'
  $ hg tag -m 'create tag' tag1
  $ hg phase --public -r .
  $ echo baz > da/foo
  $ hg commit -m 'another commit to da/foo'
  $ hg tag -m 'create tag2' tag2
  $ hg bookmark bookmark2
  $ hg -q up -r 0
  $ hg -q branch test-branch
  $ echo branch > foo
  $ hg commit -m 'create test branch'
  $ echo branch_commit_2 > foo
  $ hg commit -m 'another commit in test-branch'
  $ hg -q up default
  $ hg merge --tool :local test-branch
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m 'merge test-branch into default'

  $ hg log -G
  @    changeset:   9:cc725e08502a
  |\   tag:         tip
  | |  parent:      6:ceed296fe500
  | |  parent:      8:ed66c30e87eb
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     merge test-branch into default
  | |
  | o  changeset:   8:ed66c30e87eb
  | |  branch:      test-branch
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     another commit in test-branch
  | |
  | o  changeset:   7:6ab967a8ab34
  | |  branch:      test-branch
  | |  parent:      0:06e557f3edf6
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     create test branch
  | |
  o |  changeset:   6:ceed296fe500
  | |  bookmark:    bookmark2
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     create tag2
  | |
  o |  changeset:   5:f2890a05fea4
  | |  tag:         tag2
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     another commit to da/foo
  | |
  o |  changeset:   4:93a8ce14f891
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     create tag
  | |
  o |  changeset:   3:78896eb0e102
  | |  tag:         tag1
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     move foo
  | |
  o |  changeset:   2:8d7c456572ac
  | |  bookmark:    bookmark1
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     modify da/foo
  | |
  o |  changeset:   1:f8bbb9024b10
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     modify foo
  |
  o  changeset:   0:06e557f3edf6
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     initial
  

  $ hg serve -p $HGPORT -d --pid-file=hg.pid -A access.log -E error.log
  $ cat hg.pid >> $DAEMON_PIDS

(Try to keep these in roughly the order they are defined in webcommands.py)

(log is handled by filelog/ and changelog/ - ignore it)

(rawfile/ doesn't use templating - nothing to test)

file/{revision}/{path} shows file revision

  $ request json-file/06e557f3edf6/foo
  200 Script output follows
  
  "not yet implemented"

file/{revision} shows root directory info

  $ request json-file/cc725e08502a
  200 Script output follows
  
  {
    "abspath": "/",
    "bookmarks": [],
    "directories": [
      {
        "abspath": "/da",
        "basename": "da",
        "emptydirs": ""
      }
    ],
    "files": [
      {
        "abspath": ".hgtags",
        "basename": ".hgtags",
        "date": [
          0.0,
          0
        ],
        "flags": "",
        "size": 92
      },
      {
        "abspath": "foo-new",
        "basename": "foo-new",
        "date": [
          0.0,
          0
        ],
        "flags": "",
        "size": 4
      }
    ],
    "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7",
    "tags": [
      "tip"
    ]
  }

changelog/ shows information about several changesets

  $ request json-changelog
  200 Script output follows
  
  {
    "changeset_count": 10,
    "changesets": [
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "merge test-branch into default",
        "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7",
        "tags": [
          "tip"
        ],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "another commit in test-branch",
        "node": "ed66c30e87eb65337c05a4229efaa5f1d5285a90",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "create test branch",
        "node": "6ab967a8ab3489227a83f80e920faa039a71819f",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [
          "bookmark2"
        ],
        "date": [
          0.0,
          0
        ],
        "desc": "create tag2",
        "node": "ceed296fe500c3fac9541e31dad860cb49c89e45",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "another commit to da/foo",
        "node": "f2890a05fea49bfaf9fb27ed5490894eba32da78",
        "tags": [
          "tag2"
        ],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "create tag",
        "node": "93a8ce14f89156426b7fa981af8042da53f03aa0",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "move foo",
        "node": "78896eb0e102174ce9278438a95e12543e4367a7",
        "tags": [
          "tag1"
        ],
        "user": "test"
      },
      {
        "bookmarks": [
          "bookmark1"
        ],
        "date": [
          0.0,
          0
        ],
        "desc": "modify da/foo",
        "node": "8d7c456572acf3557e8ed8a07286b10c408bcec5",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "modify foo",
        "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "initial",
        "node": "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e",
        "tags": [],
        "user": "test"
      }
    ],
    "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7"
  }

changelog/{revision} shows information starting at a specific changeset

  $ request json-changelog/f8bbb9024b10
  200 Script output follows
  
  {
    "changeset_count": 10,
    "changesets": [
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "modify foo",
        "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "initial",
        "node": "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e",
        "tags": [],
        "user": "test"
      }
    ],
    "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8"
  }

shortlog/ shows information about a set of changesets

  $ request json-shortlog
  200 Script output follows
  
  {
    "changeset_count": 10,
    "changesets": [
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "merge test-branch into default",
        "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7",
        "tags": [
          "tip"
        ],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "another commit in test-branch",
        "node": "ed66c30e87eb65337c05a4229efaa5f1d5285a90",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "create test branch",
        "node": "6ab967a8ab3489227a83f80e920faa039a71819f",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [
          "bookmark2"
        ],
        "date": [
          0.0,
          0
        ],
        "desc": "create tag2",
        "node": "ceed296fe500c3fac9541e31dad860cb49c89e45",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "another commit to da/foo",
        "node": "f2890a05fea49bfaf9fb27ed5490894eba32da78",
        "tags": [
          "tag2"
        ],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "create tag",
        "node": "93a8ce14f89156426b7fa981af8042da53f03aa0",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "move foo",
        "node": "78896eb0e102174ce9278438a95e12543e4367a7",
        "tags": [
          "tag1"
        ],
        "user": "test"
      },
      {
        "bookmarks": [
          "bookmark1"
        ],
        "date": [
          0.0,
          0
        ],
        "desc": "modify da/foo",
        "node": "8d7c456572acf3557e8ed8a07286b10c408bcec5",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "modify foo",
        "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
        "tags": [],
        "user": "test"
      },
      {
        "bookmarks": [],
        "date": [
          0.0,
          0
        ],
        "desc": "initial",
        "node": "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e",
        "tags": [],
        "user": "test"
      }
    ],
    "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7"
  }

changeset/ renders the tip changeset

  $ request json-rev
  200 Script output follows
  
  {
    "bookmarks": [],
    "branch": "default",
    "date": [
      0.0,
      0
    ],
    "desc": "merge test-branch into default",
    "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7",
    "parents": [
      "ceed296fe500c3fac9541e31dad860cb49c89e45",
      "ed66c30e87eb65337c05a4229efaa5f1d5285a90"
    ],
    "phase": "draft",
    "tags": [
      "tip"
    ],
    "user": "test"
  }

changeset/{revision} shows tags

  $ request json-rev/78896eb0e102
  200 Script output follows
  
  {
    "bookmarks": [],
    "branch": "default",
    "date": [
      0.0,
      0
    ],
    "desc": "move foo",
    "node": "78896eb0e102174ce9278438a95e12543e4367a7",
    "parents": [
      "8d7c456572acf3557e8ed8a07286b10c408bcec5"
    ],
    "phase": "public",
    "tags": [
      "tag1"
    ],
    "user": "test"
  }

changeset/{revision} shows bookmarks

  $ request json-rev/8d7c456572ac
  200 Script output follows
  
  {
    "bookmarks": [
      "bookmark1"
    ],
    "branch": "default",
    "date": [
      0.0,
      0
    ],
    "desc": "modify da/foo",
    "node": "8d7c456572acf3557e8ed8a07286b10c408bcec5",
    "parents": [
      "f8bbb9024b10f93cdbb8d940337398291d40dea8"
    ],
    "phase": "public",
    "tags": [],
    "user": "test"
  }

changeset/{revision} shows branches

  $ request json-rev/6ab967a8ab34
  200 Script output follows
  
  {
    "bookmarks": [],
    "branch": "test-branch",
    "date": [
      0.0,
      0
    ],
    "desc": "create test branch",
    "node": "6ab967a8ab3489227a83f80e920faa039a71819f",
    "parents": [
      "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e"
    ],
    "phase": "draft",
    "tags": [],
    "user": "test"
  }

manifest/{revision}/{path} shows info about a directory at a revision

  $ request json-manifest/06e557f3edf6/
  200 Script output follows
  
  {
    "abspath": "/",
    "bookmarks": [],
    "directories": [
      {
        "abspath": "/da",
        "basename": "da",
        "emptydirs": ""
      }
    ],
    "files": [
      {
        "abspath": "foo",
        "basename": "foo",
        "date": [
          0.0,
          0
        ],
        "flags": "",
        "size": 4
      }
    ],
    "node": "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e",
    "tags": []
  }

tags/ shows tags info

  $ request json-tags
  200 Script output follows
  
  {
    "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7",
    "tags": [
      {
        "date": [
          0.0,
          0
        ],
        "node": "f2890a05fea49bfaf9fb27ed5490894eba32da78",
        "tag": "tag2"
      },
      {
        "date": [
          0.0,
          0
        ],
        "node": "78896eb0e102174ce9278438a95e12543e4367a7",
        "tag": "tag1"
      }
    ]
  }

bookmarks/ shows bookmarks info

  $ request json-bookmarks
  200 Script output follows
  
  {
    "bookmarks": [
      {
        "bookmark": "bookmark1",
        "date": [
          0.0,
          0
        ],
        "node": "8d7c456572acf3557e8ed8a07286b10c408bcec5"
      },
      {
        "bookmark": "bookmark2",
        "date": [
          0.0,
          0
        ],
        "node": "ceed296fe500c3fac9541e31dad860cb49c89e45"
      }
    ],
    "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7"
  }

branches/ shows branches info

  $ request json-branches
  200 Script output follows
  
  {
    "branches": [
      {
        "branch": "default",
        "date": [
          0.0,
          0
        ],
        "node": "cc725e08502a79dd1eda913760fbe06ed7a9abc7",
        "status": "open"
      },
      {
        "branch": "test-branch",
        "date": [
          0.0,
          0
        ],
        "node": "ed66c30e87eb65337c05a4229efaa5f1d5285a90",
        "status": "inactive"
      }
    ]
  }

summary/ shows a summary of repository state

  $ request json-summary
  200 Script output follows
  
  "not yet implemented"

filediff/{revision}/{path} shows changes to a file in a revision

  $ request json-diff/f8bbb9024b10/foo
  200 Script output follows
  
  {
    "author": "test",
    "children": [],
    "date": [
      0.0,
      0
    ],
    "desc": "modify foo",
    "diff": [
      {
        "blockno": 1,
        "lines": [
          {
            "l": "--- a/foo\tThu Jan 01 00:00:00 1970 +0000\n",
            "n": 1,
            "t": "-"
          },
          {
            "l": "+++ b/foo\tThu Jan 01 00:00:00 1970 +0000\n",
            "n": 2,
            "t": "+"
          },
          {
            "l": "@@ -1,1 +1,1 @@\n",
            "n": 3,
            "t": "@"
          },
          {
            "l": "-foo\n",
            "n": 4,
            "t": "-"
          },
          {
            "l": "+bar\n",
            "n": 5,
            "t": "+"
          }
        ]
      }
    ],
    "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
    "parents": [
      "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e"
    ],
    "path": "foo"
  }

comparison/{revision}/{path} shows information about before and after for a file

  $ request json-comparison/f8bbb9024b10/foo
  200 Script output follows
  
  {
    "author": "test",
    "children": [],
    "comparison": [
      {
        "lines": [
          {
            "ll": "foo",
            "ln": 1,
            "rl": "bar",
            "rn": 1,
            "t": "replace"
          }
        ]
      }
    ],
    "date": [
      0.0,
      0
    ],
    "desc": "modify foo",
    "leftnode": "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e",
    "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
    "parents": [
      "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e"
    ],
    "path": "foo",
    "rightnode": "f8bbb9024b10f93cdbb8d940337398291d40dea8"
  }

annotate/{revision}/{path} shows annotations for each line

  $ request json-annotate/f8bbb9024b10/foo
  200 Script output follows
  
  {
    "abspath": "foo",
    "annotate": [
      {
        "abspath": "foo",
        "author": "test",
        "desc": "modify foo",
        "line": "bar\n",
        "lineno": 1,
        "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
        "revdate": [
          0.0,
          0
        ],
        "targetline": 1
      }
    ],
    "author": "test",
    "children": [],
    "date": [
      0.0,
      0
    ],
    "desc": "modify foo",
    "node": "f8bbb9024b10f93cdbb8d940337398291d40dea8",
    "parents": [
      "06e557f3edf66faa1ccaba5dd8c203c21cc79f1e"
    ],
    "permissions": ""
  }

filelog/{revision}/{path} shows history of a single file

  $ request json-filelog/f8bbb9024b10/foo
  200 Script output follows
  
  "not yet implemented"

(archive/ doesn't use templating, so ignore it)

(static/ doesn't use templating, so ignore it)

graph/ shows information that can be used to render a graph of the DAG

  $ request json-graph
  200 Script output follows
  
  "not yet implemented"

help/ shows help topics

  $ request json-help
  200 Script output follows
  
  {
    "earlycommands": [
      {
        "summary": "add the specified files on the next commit",
        "topic": "add"
      },
      {
        "summary": "show changeset information by line for each file",
        "topic": "annotate"
      },
      {
        "summary": "make a copy of an existing repository",
        "topic": "clone"
      },
      {
        "summary": "commit the specified files or all outstanding changes",
        "topic": "commit"
      },
      {
        "summary": "diff repository (or selected files)",
        "topic": "diff"
      },
      {
        "summary": "dump the header and diffs for one or more changesets",
        "topic": "export"
      },
      {
        "summary": "forget the specified files on the next commit",
        "topic": "forget"
      },
      {
        "summary": "create a new repository in the given directory",
        "topic": "init"
      },
      {
        "summary": "show revision history of entire repository or files",
        "topic": "log"
      },
      {
        "summary": "merge another revision into working directory",
        "topic": "merge"
      },
      {
        "summary": "pull changes from the specified source",
        "topic": "pull"
      },
      {
        "summary": "push changes to the specified destination",
        "topic": "push"
      },
      {
        "summary": "remove the specified files on the next commit",
        "topic": "remove"
      },
      {
        "summary": "start stand-alone webserver",
        "topic": "serve"
      },
      {
        "summary": "show changed files in the working directory",
        "topic": "status"
      },
      {
        "summary": "summarize working directory state",
        "topic": "summary"
      },
      {
        "summary": "update working directory (or switch revisions)",
        "topic": "update"
      }
    ],
    "othercommands": [
      {
        "summary": "add all new files, delete all missing files",
        "topic": "addremove"
      },
      {
        "summary": "create an unversioned archive of a repository revision",
        "topic": "archive"
      },
      {
        "summary": "reverse effect of earlier changeset",
        "topic": "backout"
      },
      {
        "summary": "subdivision search of changesets",
        "topic": "bisect"
      },
      {
        "summary": "create a new bookmark or list existing bookmarks",
        "topic": "bookmarks"
      },
      {
        "summary": "set or show the current branch name",
        "topic": "branch"
      },
      {
        "summary": "list repository named branches",
        "topic": "branches"
      },
      {
        "summary": "create a changegroup file",
        "topic": "bundle"
      },
      {
        "summary": "output the current or given revision of files",
        "topic": "cat"
      },
      {
        "summary": "show combined config settings from all hgrc files",
        "topic": "config"
      },
      {
        "summary": "mark files as copied for the next commit",
        "topic": "copy"
      },
      {
        "summary": "list tracked files",
        "topic": "files"
      },
      {
        "summary": "copy changes from other branches onto the current branch",
        "topic": "graft"
      },
      {
        "summary": "search for a pattern in specified files and revisions",
        "topic": "grep"
      },
      {
        "summary": "show branch heads",
        "topic": "heads"
      },
      {
        "summary": "show help for a given topic or a help overview",
        "topic": "help"
      },
      {
        "summary": "identify the working directory or specified revision",
        "topic": "identify"
      },
      {
        "summary": "import an ordered set of patches",
        "topic": "import"
      },
      {
        "summary": "show new changesets found in source",
        "topic": "incoming"
      },
      {
        "summary": "output the current or given revision of the project manifest",
        "topic": "manifest"
      },
      {
        "summary": "show changesets not found in the destination",
        "topic": "outgoing"
      },
      {
        "summary": "show aliases for remote repositories",
        "topic": "paths"
      },
      {
        "summary": "set or show the current phase name",
        "topic": "phase"
      },
      {
        "summary": "roll back an interrupted transaction",
        "topic": "recover"
      },
      {
        "summary": "rename files; equivalent of copy + remove",
        "topic": "rename"
      },
      {
        "summary": "redo merges or set/view the merge status of files",
        "topic": "resolve"
      },
      {
        "summary": "restore files to their checkout state",
        "topic": "revert"
      },
      {
        "summary": "print the root (top) of the current working directory",
        "topic": "root"
      },
      {
        "summary": "add one or more tags for the current or given revision",
        "topic": "tag"
      },
      {
        "summary": "list repository tags",
        "topic": "tags"
      },
      {
        "summary": "apply one or more changegroup files",
        "topic": "unbundle"
      },
      {
        "summary": "verify the integrity of the repository",
        "topic": "verify"
      },
      {
        "summary": "output version and copyright information",
        "topic": "version"
      }
    ],
    "topics": [
      {
        "summary": "Configuration Files",
        "topic": "config"
      },
      {
        "summary": "Date Formats",
        "topic": "dates"
      },
      {
        "summary": "Diff Formats",
        "topic": "diffs"
      },
      {
        "summary": "Environment Variables",
        "topic": "environment"
      },
      {
        "summary": "Using Additional Features",
        "topic": "extensions"
      },
      {
        "summary": "Specifying File Sets",
        "topic": "filesets"
      },
      {
        "summary": "Glossary",
        "topic": "glossary"
      },
      {
        "summary": "Syntax for Mercurial Ignore Files",
        "topic": "hgignore"
      },
      {
        "summary": "Configuring hgweb",
        "topic": "hgweb"
      },
      {
        "summary": "Technical implementation topics",
        "topic": "internals"
      },
      {
        "summary": "Merge Tools",
        "topic": "merge-tools"
      },
      {
        "summary": "Specifying Multiple Revisions",
        "topic": "multirevs"
      },
      {
        "summary": "File Name Patterns",
        "topic": "patterns"
      },
      {
        "summary": "Working with Phases",
        "topic": "phases"
      },
      {
        "summary": "Specifying Single Revisions",
        "topic": "revisions"
      },
      {
        "summary": "Specifying Revision Sets",
        "topic": "revsets"
      },
      {
        "summary": "Using Mercurial from scripts and automation",
        "topic": "scripting"
      },
      {
        "summary": "Subrepositories",
        "topic": "subrepos"
      },
      {
        "summary": "Template Usage",
        "topic": "templating"
      },
      {
        "summary": "URL Paths",
        "topic": "urls"
      }
    ]
  }

help/{topic} shows an individual help topic

  $ request json-help/phases
  200 Script output follows
  
  {
    "rawdoc": "Working with Phases\n*", (glob)
    "topic": "phases"
  }