Add "arc land" as a first-class workflow

Summary:
This is a fancy version of "land.sh" that uses "git merge --squash" and
"arc which" to cover more cases.

Test Plan:
Ran "arc land" against various repository states (no such branch, not
accepted, valid, etc). Things seemed OK. There are basically an infinite number
of states here so it's hard to test exhaustively.

Reviewers: cpiro, btrahan, jungejason, davidreuss

Reviewed By: davidreuss

CC: zeeg, aran, epriestley, davidreuss

Maniphest Tasks: T787, T723

Differential Revision: https://secure.phabricator.com/D1488

src/__phutil_library_map__.php

@@ -48,6 +48,7 @@ phutil_register_library_map(array(
     'ArcanistHookAPI' => 'repository/hookapi/base',
     'ArcanistInstallCertificateWorkflow' => 'workflow/install-certificate',
     'ArcanistJSHintLinter' => 'lint/linter/jshint',
+    'ArcanistLandWorkflow' => 'workflow/land',
     'ArcanistLiberateLintEngine' => 'lint/engine/liberate',
     'ArcanistLiberateWorkflow' => 'workflow/liberate',
     'ArcanistLicenseLinter' => 'lint/linter/license',
@@ -136,6 +137,7 @@ phutil_register_library_map(array(
     'ArcanistHelpWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistInstallCertificateWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistJSHintLinter' => 'ArcanistLinter',
+    'ArcanistLandWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistLiberateLintEngine' => 'ArcanistLintEngine',
     'ArcanistLiberateWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistLicenseLinter' => 'ArcanistLinter',

src/workflow/base/ArcanistBaseWorkflow.php

@@ -992,4 +992,12 @@ class ArcanistBaseWorkflow {
     return array_values($paths);
   }
 
+  protected function renderRevisionList(array $revisions) {
+    $list = array();
+    foreach ($revisions as $revision) {
+      $list[] = '     - D'.$revision['id'].': '.$revision['title']."\n";
+    }
+    return implode('', $list);
+  }
+
 }

src/workflow/land/ArcanistLandWorkflow.php

@@ -0,0 +1,274 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Lands a branch by rebasing, merging and amending it.
+ *
+ * @group workflow
+ */
+class ArcanistLandWorkflow extends ArcanistBaseWorkflow {
+
+  public function getCommandHelp() {
+    return phutil_console_format(<<<EOTEXT
+      **land** __branch__ [--interactive] [--onto __master__]
+          Supports: git
+
+          Land an accepted change (currently sitting in local feature branch
+          __branch__) onto __master__ and push it to the remote. Then, delete
+          the feature branch.
+
+          In mutable repositories, this will perform a --squash merge (the
+          entire branch will be represented by one commit on __master__). In
+          immutable repositories, it will perform a --no-ff merge (the branch
+          will always be merged into __master__ with a merge commit).
+
+EOTEXT
+      );
+  }
+
+  public function requiresWorkingCopy() {
+    return true;
+  }
+
+  public function requiresConduit() {
+    return true;
+  }
+
+  public function requiresAuthentication() {
+    return true;
+  }
+
+  public function requiresRepositoryAPI() {
+    return true;
+  }
+
+  public function getArguments() {
+    return array(
+      'onto' => array(
+        'param' => 'master',
+        'help' => "Land feature branch onto a branch other than ".
+                  "'master' (default).",
+      ),
+      'hold' => array(
+        'help' => "Prepare the change to be pushed, but do not actually ".
+                  "push it.",
+      ),
+      'keep-branch' => array(
+        'help' => "Keep the feature branch after pushing changes to the ".
+                  "remote (by default, it is deleted).",
+      ),
+      'remote' => array(
+        'param' => 'origin',
+        'help' => "Push to a remote other than 'origin' (default).",
+      ),
+      '*' => 'branch',
+    );
+  }
+
+  public function run() {
+    $this->writeStatusMessage(
+      phutil_console_format(
+        "**WARNING:** 'arc land' is new and experimental.\n"));
+
+    $branch = $this->getArgument('branch');
+    if (count($branch) !== 1) {
+      throw new ArcanistUsageException(
+        "Specify exactly one branch to land changes from.");
+    }
+    $branch = head($branch);
+
+    $remote = $this->getArgument('remote', 'origin');
+    $onto = $this->getArgument('onto', 'master');
+    $is_immutable = $this->isHistoryImmutable();
+
+    $repository_api = $this->getRepositoryAPI();
+    if (!($repository_api instanceof ArcanistGitAPI)) {
+      throw new ArcanistUsageException("'arc land' only supports git.");
+    }
+
+    list($err) = exec_manual(
+      '(cd %s && git rev-parse --verify %s)',
+      $repository_api->getPath(),
+      $branch);
+
+    if ($err) {
+      throw new ArcanistUsageException("Branch '{$branch}' does not exist.");
+    }
+
+    $this->requireCleanWorkingCopy();
+    $repository_api->parseRelativeLocalCommit(array($remote.'/'.$onto));
+
+    execx(
+      '(cd %s && git checkout %s)',
+      $repository_api->getPath(),
+      $onto);
+
+    echo phutil_console_format(
+      "Switched to branch **%s**. Updating branch...\n",
+      $onto);
+
+    execx(
+      '(cd %s && git pull --ff-only)',
+      $repository_api->getPath());
+
+    list($out) = execx(
+      '(cd %s && git log %s/%s..%s)',
+      $repository_api->getPath(),
+      $remote,
+      $onto,
+      $onto);
+    if (strlen(trim($out))) {
+      throw new ArcanistUsageException(
+        "Local branch '{$onto}' is ahead of '{$remote}/{$onto}', so landing ".
+        "a feature branch would push additional changes. Push or reset the ".
+        "changes in '{$onto}' before running 'arc land'.");
+    }
+
+    execx(
+      '(cd %s && git checkout %s)',
+      $repository_api->getPath(),
+      $branch);
+
+    echo phutil_console_format(
+      "Switched to branch **%s**. Identifying and merging...\n",
+      $branch);
+
+    if (!$is_immutable) {
+      $err = phutil_passthru(
+        '(cd %s && git rebase %s)',
+        $repository_api->getPath(),
+        $onto);
+      if ($err) {
+        throw new ArcanistUsageException(
+          "'git rebase {$onto}' failed. You can abort with 'git rebase ".
+          "--abort', or resolve conflicts and use 'git rebase --continue' to ".
+          "continue forward. After resolving the rebase, run 'arc land' ".
+          "again.");
+      }
+
+      // Now that we've rebased, the merge-base of origin/master and HEAD may
+      // be different. Reparse the relative commit.
+      $repository_api->parseRelativeLocalCommit(array($remote.'/'.$onto));
+    }
+
+    $revisions = $repository_api->loadWorkingCopyDifferentialRevisions(
+      $this->getConduit(),
+      array(
+        'authors' => array($this->getUserPHID()),
+      ));
+
+    if (!count($revisions)) {
+      throw new ArcanistUsageException(
+        "arc can not identify which revision exists on branch '{$branch}'. ".
+        "Update the revision with recent changes to synchronize the branch ".
+        "name and hashes, or use 'arc amend' to amend the commit message at ".
+        "HEAD.");
+    } else if (count($revisions) > 1) {
+      $message =
+        "There are multiple revisions on feature branch '{$branch}' which are ".
+        "not present on '{$onto}':\n\n".
+        $this->renderRevisionList($revisions)."\n".
+        "Separate these revisions onto different branches, or manually land ".
+        "them in '{$onto}'.";
+      throw new ArcanistUsageException($message);
+    }
+
+    $revision = head($revisions);
+    $rev_id = $revision['id'];
+    $rev_title = $revision['title'];
+
+    if ($revision['status'] != ArcanistDifferentialRevisionStatus::ACCEPTED) {
+      $ok = phutil_console_confirm(
+        "Revision 'D{$id}: {$rev_title}' has not been accepted. Continue ".
+        "anyway?");
+      if (!$ok) {
+        throw new ArcanistUserAbortException();
+      }
+    }
+
+    echo "Landing revision 'D{$rev_id}: {$rev_title}'...\n";
+
+    $message = $this->getConduit()->callMethodSynchronous(
+      'differential.getcommitmessage',
+      array(
+        'revision_id' => $revision['id'],
+      ));
+
+    execx(
+      '(cd %s && git checkout %s)',
+      $repository_api->getPath(),
+      $onto);
+
+    if ($is_immutable) {
+      // In immutable histories, do a --no-ff merge to force a merge commit with
+      // the right message.
+      execx(
+        '(cd %s && git merge --no-ff -m %s %s)',
+        $repository_api->getPath(),
+        $message,
+        $branch);
+    } else {
+      // In mutable histories, do a --squash merge.
+      execx(
+        '(cd %s && git merge --squash --ff-only %s)',
+        $repository_api->getPath(),
+        $branch);
+      execx(
+        '(cd %s && git commit -m %s)',
+        $repository_api->getPath(),
+        $message);
+    }
+
+    if ($this->getArgument('hold')) {
+      echo phutil_console_format(
+        "Holding change in **%s**: it has NOT been pushed yet.\n",
+        $onto);
+    } else {
+      echo "Pushing change...\n\n";
+
+      $err = phutil_passthru(
+        '(cd %s && git push %s %s)',
+        $repository_api->getPath(),
+        $remote,
+        $onto);
+
+      if ($err) {
+        throw new ArcanistUsageException("'git push' failed.");
+      }
+
+      echo "\n";
+    }
+
+    if (!$this->getArgument('keep-branch')) {
+      echo "Cleaning up feature branch...\n";
+      execx(
+        '(cd %s && git branch -D %s)',
+        $repository_api->getPath(),
+        $branch);
+    }
+
+    echo "Done.\n";
+
+    return 0;
+  }
+
+  protected function getSupportedRevisionControlSystems() {
+    return array('git');
+  }
+
+}

src/workflow/land/__init__.php

@@ -0,0 +1,19 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('arcanist', 'differential/constants/revisionstatus');
+phutil_require_module('arcanist', 'exception/usage');
+phutil_require_module('arcanist', 'exception/usage/userabort');
+phutil_require_module('arcanist', 'workflow/base');
+
+phutil_require_module('phutil', 'console');
+phutil_require_module('phutil', 'future/exec');
+phutil_require_module('phutil', 'utils');
+
+
+phutil_require_source('ArcanistLandWorkflow.php');