Conditionally use hg files vs. hg locate depending on version of Mercurial

Summary:
In Mercurial 3.2 the `locate` command was deprecated in favor of `files` command. This change updates the DiffusionLowLevelMercurialPathsQuery command to conditionally use `locate` or `files` based on the version of Mercurial used.

Closes T7375

Test Plan:
My test/develop Phabricator instance is setup to run Mercurial 3.5.1.

The test procedure to verify valid file listings are being returned:
 1. I navigated to `http://192.168.0.133/conduit/method/diffusion.querypaths/`
 2. I populated the following fields:
  - path: `"/"`
  - commit: `"d721d5b57fc9ef72e47ff9d4e0c583d74a46590c"`
  - callsign: `"HGTEST"`
 3. I submitted request and verified that result contained all files in the repository:
```
{
  "0": "README",
  "1": "alpha/beta/trifle",
  "2": "test/Chupacabra.cow",
  "3": "test/socket.ks"
}
```

I repeated the above steps after setting up Mercurial 2.6.2, which I installed in the following manner:
 1. I downloaded Mercurial 2.6.2 source and run `make local` which will only compile it to work from its own directory (`/opt/mercurial-2.6.2`)
 2. I linked `/usr/local/bin/hg -> /opt/mercurial-2.6.2/hg` (there's also a `/usr/bin/hg` which is a link to `/usr/local/bin/hg`)
 3. I navigated to my home directory and verify that `hg --version` returns 2.6.2.
 4. I restarted phabricator services (probably unnecessary).

With the Multimeter application active
 1. I verified that `/usr/local/bin/hg` referred to version 2.6
 2. I ran the same conduit call from the conduit application
 3. I verified that `http://192.168.0.133/multimeter/?type=2&group=label` incremented values for `bin.hg locate`.
 4. I swapped out mercurial versions for 3.5.1
 5. I ran the same conduit call from the conduit application
 6. I verified that `http://192.168.0.133/multimeter/?type=2&group=label` incremented values for `bin.hg files`

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin

Maniphest Tasks: T7375

Differential Revision: https://secure.phabricator.com/D14253

src/__phutil_library_map__.php

@@ -607,6 +607,7 @@ phutil_register_library_map(array(
     'DiffusionLowLevelGitRefQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelGitRefQuery.php',
     'DiffusionLowLevelMercurialBranchesQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelMercurialBranchesQuery.php',
     'DiffusionLowLevelMercurialPathsQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelMercurialPathsQuery.php',
+    'DiffusionLowLevelMercurialPathsQueryTests' => 'applications/diffusion/query/lowlevel/__tests__/DiffusionLowLevelMercurialPathsQueryTests.php',
     'DiffusionLowLevelParentsQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelParentsQuery.php',
     'DiffusionLowLevelQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelQuery.php',
     'DiffusionLowLevelResolveRefsQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelResolveRefsQuery.php',
@@ -4342,6 +4343,7 @@ phutil_register_library_map(array(
     'DiffusionLowLevelGitRefQuery' => 'DiffusionLowLevelQuery',
     'DiffusionLowLevelMercurialBranchesQuery' => 'DiffusionLowLevelQuery',
     'DiffusionLowLevelMercurialPathsQuery' => 'DiffusionLowLevelQuery',
+    'DiffusionLowLevelMercurialPathsQueryTests' => 'PhabricatorTestCase',
     'DiffusionLowLevelParentsQuery' => 'DiffusionLowLevelQuery',
     'DiffusionLowLevelQuery' => 'Phobject',
     'DiffusionLowLevelResolveRefsQuery' => 'DiffusionLowLevelQuery',

src/applications/diffusion/query/lowlevel/DiffusionLowLevelMercurialPathsQuery.php

@@ -24,10 +24,17 @@ final class DiffusionLowLevelMercurialPathsQuery
     $path = $this->path;
     $commit = $this->commit;
 
+    $hg_paths_command = 'locate --print0 --rev %s -I %s';
+    $hg_version = PhabricatorRepositoryVersion::getMercurialVersion();
+    if (PhabricatorRepositoryVersion::isMercurialFilesCommandAvailable(
+      $hg_version)) {
+      $hg_paths_command = 'files --print0 --rev %s -I %s';
+    }
+
     $match_against = trim($path, '/');
     $prefix = trim('./'.$match_against, '/');
     list($entire_manifest) = $repository->execxLocalCommand(
-      'locate --print0 --rev %s -I %s',
+      $hg_paths_command,
       hgsprintf('%s', $commit),
       $prefix);
     return explode("\0", $entire_manifest);

src/applications/diffusion/query/lowlevel/__tests__/DiffusionLowLevelMercurialPathsQueryTests.php

@@ -0,0 +1,31 @@
+<?php
+
+final class DiffusionLowLevelMercurialPathsQueryTests
+  extends PhabricatorTestCase {
+
+  public function testCommandByVersion() {
+    $cases = array(
+      array(
+        'name' => pht('Versions which should not use `files`'),
+        'versions' => array('2.6.2', '2.9', '3.1'),
+        'match' => false,
+      ),
+
+      array(
+        'name' => pht('Versions which should use `files`'),
+        'versions' => array('3.2', '3.3', '3.5.2'),
+        'match' => true,
+      ),
+    );
+
+    foreach ($cases as $case) {
+      foreach ($case['versions'] as $version) {
+        $actual = PhabricatorRepositoryVersion
+          ::isMercurialFilesCommandAvailable($version);
+        $expect = $case['match'];
+        $this->assertEqual($expect, $actual, $case['name']);
+      }
+    }
+  }
+
+}

src/applications/multimeter/data/MultimeterControl.php

@@ -265,6 +265,7 @@ final class MultimeterControl extends Phobject {
         'init' => true,
         'diff' => true,
         'cat' => true,
+        'files' => true,
       ),
       'svnadmin' => array(
         'create' => true,

src/applications/repository/constants/PhabricatorRepositoryVersion.php

@@ -19,4 +19,22 @@ final class PhabricatorRepositoryVersion extends Phobject {
     return null;
   }
 
+  /**
+   * The `locate` command is deprecated as of Mercurial 3.2, to be
+   * replaced with `files` command, which supports most of the same
+   * arguments. This determines whether the new `files` command should
+   * be used instead of the `locate` command.
+   *
+   * @param string  $mercurial_version - The current version of mercurial
+   *   which can be retrieved by calling:
+   *   PhabricatorRepositoryVersion::getMercurialVersion()
+   *
+   * @return boolean  True if the version of Mercurial is new enough to support
+   *   the `files` command, or false if otherwise.
+   */
+  public static function isMercurialFilesCommandAvailable($mercurial_version) {
+    $min_version_for_files = '3.2';
+    return version_compare($mercurial_version, $min_version_for_files, '>=');
+  }
+
 }