GenCode - Add an optional caching mode.

If CIVICRM_GENCODE_DIGEST is set, then GenCode will write out a digest of
all its inputs & templates. If someone tries to rerun with the same inputs,
then GenCode will do nothing.

CRM/Core/CodeGen/Main.php

@@ -11,11 +11,24 @@ class CRM_Core_CodeGen_Main {
   var $tplCodePath;
   var $schemaPath; // ex: schema/Schema.xml
 
-  function __construct($CoreDAOCodePath, $sqlCodePath, $phpCodePath, $tplCodePath, $smartyPluginDirs, $argCms, $argVersion, $schemaPath) {
+  /**
+   * @var string|NULL path in which to store a marker that indicates the last execution of
+   * GenCode. If a matching marker already exists, GenCode doesn't run.
+   */
+  var $digestPath;
+
+  /**
+   * @var string|NULL a digest of the inputs to the code-generator (eg the properties and source files)
+   */
+  var $digest;
+
+  function __construct($CoreDAOCodePath, $sqlCodePath, $phpCodePath, $tplCodePath, $smartyPluginDirs, $argCms, $argVersion, $schemaPath, $digestPath) {
     $this->CoreDAOCodePath = $CoreDAOCodePath;
     $this->sqlCodePath = $sqlCodePath;
     $this->phpCodePath = $phpCodePath;
     $this->tplCodePath = $tplCodePath;
+    $this->digestPath = $digestPath;
+    $this->digest = NULL;
 
     // default cms is 'drupal', if not specified
     $this->cms = isset($argCms) ? strtolower($argCms) : 'drupal';
@@ -39,6 +52,16 @@ class CRM_Core_CodeGen_Main {
    *
    */
   function main() {
+    if (!empty($this->digestPath) && file_exists($this->digestPath)) {
+      if ($this->getDigest() === file_get_contents($this->digestPath)) {
+        echo "GenCode has previously executed. To force execution, please (a) omit CIVICRM_GENCODE_DIGEST\n";
+        echo "or (b) remove {$this->digestPath} or (c) call GenCode with new parameters.\n";
+        exit();
+      }
+      // Once we start GenCode, the old build is invalid
+      unlink($this->digestPath);
+    }
+
     echo "\ncivicrm_domain.version := ". $this->db_version . "\n\n";
     if ($this->buildVersion < 1.1) {
       echo "The Database is not compatible for this version";
@@ -62,18 +85,15 @@ Alternatively you can get a version of CiviCRM that matches your PHP version
     $this->tables = $specification->tables;
 
     $this->runAllTasks();
+
+    if (!empty($this->digestPath)) {
+      file_put_contents($this->digestPath, $this->getDigest());
+    }
   }
 
   function runAllTasks() {
     // TODO: This configuration can be manipulated dynamically.
-    $components = array(
-      'CRM_Core_CodeGen_Config',
-      'CRM_Core_CodeGen_Reflection',
-      'CRM_Core_CodeGen_Schema',
-      'CRM_Core_CodeGen_DAO',
-      'CRM_Core_CodeGen_Test',
-      'CRM_Core_CodeGen_I18n',
-    );
+    $components = $this->getTasks();
     foreach ($components as $component) {
       $task = new $component($this);
 
@@ -86,4 +106,53 @@ Alternatively you can get a version of CiviCRM that matches your PHP version
       }
     }
   }
+
+  /**
+   * @return array of class names; each class implements CRM_Core_CodeGen_ITask
+   */
+  public function getTasks() {
+    $components = array(
+      'CRM_Core_CodeGen_Config',
+      'CRM_Core_CodeGen_Reflection',
+      'CRM_Core_CodeGen_Schema',
+      'CRM_Core_CodeGen_DAO',
+      'CRM_Core_CodeGen_Test',
+      'CRM_Core_CodeGen_I18n',
+    );
+    return $components;
+  }
+
+  /**
+   * Compute a digest based on the inputs to the code-generator (ie the properties
+   * of the codegen and the source files loaded by the codegen).
+   *
+   * @return string
+   */
+  function getDigest() {
+    if ($this->digest === NULL) {
+      $srcDir = CRM_Core_CodeGen_Util_File::findCoreSourceDir();
+      $files = CRM_Core_CodeGen_Util_File::findManyFiles(array(
+        array("$srcDir/CRM/Core/CodeGen", '*.php'),
+        array("$srcDir/xml", "*.php"),
+        array("$srcDir/xml", "*.tpl"),
+        array("$srcDir/xml", "*.xml"),
+      ));
+
+      $properties = var_export(array(
+        CRM_Core_CodeGen_Util_File::digestAll($files),
+        $this->buildVersion,
+        $this->db_version,
+        $this->cms,
+        $this->CoreDAOCodePath,
+        $this->sqlCodePath,
+        $this->phpCodePath,
+        $this->tplCodePath,
+        $this->schemaPath,
+        $this->getTasks(),
+      ), TRUE);
+
+      $this->digest = md5($properties);
+    }
+    return $this->digest;
+  }
 }

CRM/Core/CodeGen/Util/File.php

@@ -31,4 +31,50 @@ class CRM_Core_CodeGen_Util_File {
 
     return $newTempDir;
   }
+
+  /**
+   * Calculate a cumulative digest based on a collection of files
+   *
+   * @param array $files list of file names (strings)
+   * @param callable $digest a one-way hash function (string => string)
+   * @return string
+   */
+  static function digestAll($files, $digest = 'md5') {
+    $buffer = '';
+    foreach ($files as $file) {
+      $buffer .= $digest(file_get_contents($file));
+    }
+    return $digest($buffer);
+  }
+
+  /**
+   * Find the paths to all key files involved in the gen-code process
+   *
+   * @return array
+   * @throws RuntimeException
+   */
+  static function findCoreSourceDir() {
+    $path = str_replace(DIRECTORY_SEPARATOR, '/', __DIR__);
+    if (!preg_match(':(.*)/CRM/Core/CodeGen/Util:', $path, $matches)) {
+      throw new RuntimeException("Failed to determine path of code-gen");
+    }
+
+    return $matches[1];
+  }
+
+  /**
+   * Find files in several directories using several filename patterns
+   *
+   *
+   * @param array $pairs each item is an array(0 => $searchBaseDir, 1 => $filePattern)
+   * @return array of file paths
+   */
+  static function findManyFiles($pairs) {
+    $files = array();
+    foreach ($pairs as $pair) {
+      list ($dir, $pattern) = $pair;
+      $files = array_merge($files, CRM_Utils_File::findFiles($dir, $pattern));
+    }
+    return $files;
+  }
 }

xml/GenCode.php

@@ -29,6 +29,7 @@ $genCode = new CRM_Core_CodeGen_Main(
   array('../packages/Smarty/plugins', '../CRM/Core/Smarty/plugins'),  // smarty plugin dirs
   @$argv[3],                                                          // cms
   empty($argv[2]) ? NULL : $argv[2],                                  // db version
-  empty($argv[1]) ? 'schema/Schema.xml' : $argv[1]                    // schem afile
+  empty($argv[1]) ? 'schema/Schema.xml' : $argv[1],                    // schem afile
+  getenv('CIVICRM_GENCODE_DIGEST') ? getenv('CIVICRM_GENCODE_DIGEST') : NULL
 );
 $genCode->main();