Cache the Releeph project edit page's help remarkup

Summary: I wrote some of the Releeph-project edit-page's help in remarkup.  This renders the remarkup using the `PhabricatorMarkupEngine` pipeline.

Test Plan:
* Edit a Releeph project.
* Feel the cool base of a laptop whose CPU is no longer being thrashed by onerous remarkup rendering duties.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T3098

Differential Revision: https://secure.phabricator.com/D5898

src/applications/releeph/controller/project/ReleephProjectEditController.php

@@ -252,18 +252,15 @@ final class ReleephProjectEditController extends ReleephController {
     $commit_author_inset = $this->buildCommitAuthorInset($commit_author);
 
     // Build the Template inset
-    $markup_engine = PhabricatorMarkupEngine::newDifferentialMarkupEngine();
-
-    // From DifferentialUnitFieldSpecification...
-    $markup_engine->setConfig('viewer', $request->getUser());
-
     $help_markup = phutil_tag(
       'div',
       array(
         'class' => 'phabricator-remarkup',
       ),
-      phutil_safe_html(
-        $markup_engine->markupText(ReleephBranchTemplate::getHelpRemarkup())));
+      PhabricatorMarkupEngine::renderOneObject(
+        new ReleephBranchTemplate(),
+        'field',
+        $request->getUser()));
 
     $branch_template_input = id(new AphrontFormTextControl())
       ->setName('branchTemplate')

src/applications/releeph/view/branch/ReleephBranchTemplate.php

@@ -1,6 +1,7 @@
 <?php
 
-final class ReleephBranchTemplate {
+final class ReleephBranchTemplate
+  implements PhabricatorMarkupInterface {
 
   const KEY = 'releeph.default-branch-template';
 
@@ -75,58 +76,6 @@ final class ReleephBranchTemplate {
     }
   }
 
-  public static function getHelpRemarkup() {
-    return <<<EOTEXT
-
-==== Interpolations ====
-
-| Code  | Meaning
-| ----- | -------
-| `%P`  | The name of your project, with spaces changed to "-".
-| `%p`  | Like %P, but all lowercase.
-| `%Y`  | The four digit year associated with the branch date.
-| `%m`  | The two digit month.
-| `%d`  | The two digit day.
-| `%v`  | The handle of the commit where the branch was cut ("rXYZa4b3c2d1").
-| `%V`  | The abbreviated commit id where the branch was cut ("a4b3c2d1").
-| `%..` | Any other sequence interpreted by `strftime()`.
-| `%%`  | A literal percent sign.
-
-
-==== Tips for Branch Templates ====
-
-Use a directory to separate your release branches from other branches:
-
-  lang=none
-  releases/%Y-%M-%d-%v
-  => releases/2012-30-16-rHERGE32cd512a52b7
-
-Include a second hierarchy if you share your repository with other projects:
-
-  lang=none
-  releases/%P/%p-release-%Y%m%d-%V
-  => releases/Tintin/tintin-release-20121116-32cd512a52b7
-
-Keep your branch names simple, avoiding strange punctuation, most of which is
-forbidden or escaped anyway:
-
-  lang=none, counterexample
-  releases//..clown-releases..//`date --iso=seconds`-$(sudo halt)
-
-Include the date early in your template, in an order which sorts properly:
-
-  lang=none
-  releases/%Y%m%d-%v
-  => releases/20121116-rHERGE32cd512a52b7 (good!)
-
-  releases/%V-%m.%d.%Y
-  => releases/32cd512a52b7-11.16.2012 (awful!)
-
-
-EOTEXT
-    ;
-  }
-
   /*
    * xsprintf() would be useful here, but that's for formatting concrete lists
    * of things in a certain way...
@@ -238,4 +187,82 @@ EOTEXT
     return $errors;
   }
 
+/* -(  Help Text and Markup Interface  )------------------------------------- */
+
+  public function getMarkupFieldKey($field) {
+    $text = $this->getMarkupText($field);
+    return sprintf(
+      '%s:%s',
+      get_class($this),
+      PhabricatorHash::digest($text));
+  }
+
+  public function newMarkupEngine($field) {
+    return PhabricatorMarkupEngine::newDifferentialMarkupEngine();
+  }
+
+  public function didMarkupText(
+    $field,
+    $output,
+    PhutilMarkupEngine $engine) {
+
+    return $output;
+  }
+
+  public function shouldUseMarkupCache($field) {
+    return true;
+  }
+
+  public function getMarkupText($field) {
+    return <<<EOTEXT
+
+==== Interpolations ====
+
+| Code  | Meaning
+| ----- | -------
+| `%P`  | The name of your project, with spaces changed to "-".
+| `%p`  | Like %P, but all lowercase.
+| `%Y`  | The four digit year associated with the branch date.
+| `%m`  | The two digit month.
+| `%d`  | The two digit day.
+| `%v`  | The handle of the commit where the branch was cut ("rXYZa4b3c2d1").
+| `%V`  | The abbreviated commit id where the branch was cut ("a4b3c2d1").
+| `%..` | Any other sequence interpreted by `strftime()`.
+| `%%`  | A literal percent sign.
+
+
+==== Tips for Branch Templates ====
+
+Use a directory to separate your release branches from other branches:
+
+  lang=none
+  releases/%Y-%M-%d-%v
+  => releases/2012-30-16-rHERGE32cd512a52b7
+
+Include a second hierarchy if you share your repository with other projects:
+
+  lang=none
+  releases/%P/%p-release-%Y%m%d-%V
+  => releases/Tintin/tintin-release-20121116-32cd512a52b7
+
+Keep your branch names simple, avoiding strange punctuation, most of which is
+forbidden or escaped anyway:
+
+  lang=none, counterexample
+  releases//..clown-releases..//`date --iso=seconds`-$(sudo halt)
+
+Include the date early in your template, in an order which sorts properly:
+
+  lang=none
+  releases/%Y%m%d-%v
+  => releases/20121116-rHERGE32cd512a52b7 (good!)
+
+  releases/%V-%m.%d.%Y
+  => releases/32cd512a52b7-11.16.2012 (awful!)
+
+
+EOTEXT
+    ;
+  }
+
 }