feat(plugins): add basic support for plugins and improve performance

Some libraries have been changed to be delay loaded. DB-Migrate is back to the minimal load time possible again, if no command at all is entered.

Basic plugin support and the first hook, in this case of the type overwrite has been added. An functional example of a yaml config plugin
has been published.
Also some old functions have been cleaned up which are not necessary any more.

refers to #397

Author: wzrdtales

api.js

@@ -4,23 +4,70 @@ var path = require('path');
 var util = require('util');
 var mkdirp = require('mkdirp');
 var optimist = require('optimist');
-var index = require('./connect');
-var Migration = require('./lib/migration.js');
-var Seeder = require('./lib/seeder.js');
-var Migrator = require('./lib/migrator.js');
 var log = require('db-migrate-shared').log;
 var pkginfo = require('pkginfo')(module, 'version'); // jshint ignore:line
 var dotenv = require('dotenv');
-var Promise = require('bluebird');
+var Promise = Promise;
 
-function dbmigrate(isModule, options, callback) {
+function registerPluginLoader(plugins) {
+
+  return {
+
+    overwrite: function(name) {
+
+      if(plugins[name] && plugins[name].length) {
+
+        var plugin = plugins[name];
+
+        if(plugin.length !== 1) {
+          log.warn(
+            'Attention, multiple overwrites registered for %s, we are ' +
+            'only loading the first plugin %s!',
+            name,
+            plugin.name
+          );
+        }
+
+        plugin = plugin[0];
+        if(typeof(plugin.loadPlugin) === 'function')
+          plugin.loadPlugin();
+
+        return plugin;
+      }
+
+      return false;
+    },
+
+    hook: function(name) {
+
+      if(plugins[name] && plugins[name].length) {
+
+        var plugin = plugins[name];
+
+        plugin.map(function(plugin) {
+
+          if(typeof(plugin.loadPlugin) === 'function')
+            plugin.loadPlugin();
+        });
+
+        return plugin;
+      }
+
+      return false;
+    }
+  };
+}
+
+function dbmigrate(plugins, isModule, options, callback) {
 
   this.internals = {
 
     onComplete: onComplete
   };
   var internals = this.internals;
 
+  this.internals.plugins = registerPluginLoader(plugins);
+
   if (typeof(callback) === 'function')
     this.internals.onComplete = callback;
   else if (typeof(options) === 'function')
@@ -60,8 +107,8 @@ function dbmigrate(isModule, options, callback) {
 
   this.config = loadConfig( require('./lib/config.js'), this.internals );
 
-  index.exportInternals(internals);
-
+  //delayed loading of bluebird
+  Promise = require('bluebird');
   this.internals.migrationOptions = {
     dbmigrate: this.internals.dbm,
     ignoreOnInit: this.internals.argv['ignore-on-init'],
@@ -411,7 +458,7 @@ function setDefaultArgv(internals, isModule) {
       'force-exit': false,
       'sql-file': false,
       'non-transactional': false,
-      config: internals.configFile || internals.cwd + '/database.json',
+      config: internals.configFile || 'database.json',
       'migrations-dir': internals.cwd + '/migrations',
       'vcseeder-dir': internals.cwd + '/VCSeeder',
       'staticseeder-dir': internals.cwd + '/Seeder',
@@ -545,7 +592,7 @@ function loadConfig( config, internals ) {
   } else if (internals.configObject) {
     out = config.loadObject(internals.configObject, currentEnv);
   } else {
-    out = config.loadFile(internals.argv.config, currentEnv);
+    out = config.loadFile(internals.argv.config, currentEnv, internals.plugins);
   }
   if (internals.verbose) {
     var current = out.getCurrent();
@@ -579,6 +626,10 @@ function executeCreateMigration(internals, config, callback) {
   }
 
   createMigrationDir(migrationsDir, function(err) {
+
+    var index = require('./connect');
+    var Migration = require('./lib/migration.js');
+
     if (err) {
       log.error('Failed to create migration directory at ', migrationsDir,
         err);
@@ -661,6 +712,10 @@ function createSqlFiles(internals, config, callback) {
 
   var sqlDir = migrationsDir + '/sqls';
   createMigrationDir(sqlDir, function(err) {
+
+    var index = require('./connect');
+    var Migration = require('./lib/migration.js');
+
     if (err) {
       log.error('Failed to create migration directory at ', sqlDir, err);
 
@@ -718,6 +773,9 @@ function _assert(err, callback) {
 
 function executeUp(internals, config, callback) {
 
+  var Migrator = require('./lib/migrator.js');
+  var index = require('./connect');
+
   if (!internals.argv.count) {
     internals.argv.count = Number.MAX_VALUE;
   }
@@ -747,6 +805,9 @@ function executeUp(internals, config, callback) {
 
 function executeDown(internals, config, callback) {
 
+  var Migrator = require('./lib/migrator.js');
+  var index = require('./connect');
+
   if (!internals.argv.count) {
     log.info('Defaulting to running 1 down migration.');
     internals.argv.count = 1;
@@ -770,6 +831,8 @@ function executeDown(internals, config, callback) {
 
 function executeDB(internals, config, callback) {
 
+  var index = require('./connect');
+
   if (internals.argv._.length > 0) {
     internals.argv.dbname = internals.argv._.shift().toString();
   } else {
@@ -819,6 +882,9 @@ function executeDB(internals, config, callback) {
 
 function executeSeed(internals, config, callback) {
 
+  var index = require('./connect');
+  var Seeder = require('./lib/seeder.js');
+
   if (internals.argv._.length > 0) {
     internals.argv.destination = internals.argv._.shift().toString();
   }
@@ -850,6 +916,9 @@ function executeSeed(internals, config, callback) {
 
 function executeUndoSeed(internals, config, callback) {
 
+  var index = require('./connect');
+  var Seeder = require('./lib/seeder.js');
+
   if (!internals.argv.count) {
     log.info('Defaulting to running 1 down seed.');
     internals.argv.count = 1;

bin/db-migrate

@@ -4,33 +4,34 @@ var resolve = require( 'resolve' );
 var log = require('db-migrate-shared').log;
 
 process.title = 'db-migrate';
-
-if ( process.argv.indexOf( '--verbose' ) !== -1 || process.argv.indexOf( '-v' ) !== -1 )
+if ( process.argv.indexOf( '--verbose' ) !== -1 ||
+     process.argv.indexOf( '-v' ) !== -1
+   )
   global.verbose = true;
 
 resolve( 'db-migrate', {
 
-basedir: process.cwd()
+  basedir: process.cwd()
 }, function ( error, localModule ) {
 
-var DBMigrate, dbmigrate;
+  var DBMigrate, dbmigrate;
 
-if ( error ) {
-  DBMigrate = require( '../' );
-}
-else {
-  DBMigrate = require( localModule );
-  log.verbose( 'Detected and using the projects local version of db-migrate. ' +
-    '\'' + localModule + '\'');
-}
+  if ( error ) {
+    DBMigrate = require( '../' );
+  }
+  else {
+    DBMigrate = require( localModule );
+    log.verbose( 'Detected and using the projects local version of db-migrate. ' +
+      '\'' + localModule + '\'');
+  }
 
-if ( typeof( DBMigrate.getInstance ) !== 'function' ) {
-  DBMigrate = require( '../' );
+  if ( typeof( DBMigrate.getInstance ) !== 'function' ) {
+    DBMigrate = require( '../' );
 
-  log.warn( 'Using global instead of local detected version as you have a ' +
-    'version older than 0.10.0 in your projects package.json!' );
-}
+    log.warn( 'Using global instead of local detected version as you have a ' +
+      'version older than 0.10.0 in your projects package.json!' );
+  }
 
-dbmigrate = DBMigrate.getInstance();
-dbmigrate.run();
+  dbmigrate = DBMigrate.getInstance();
+  dbmigrate.run();
 } );

connect.js

@@ -138,13 +138,3 @@ exports.createMigration = function(migration, callback) {
     callback(null, migration);
   });
 };
-
-exports.exportInternals = function( intern ) {
-
-  internals = intern;
-};
-
-exports.importInternals = function() {
-
-  return internals;
-};

index.js

@@ -1,11 +1,70 @@
 var pkginfo = require('pkginfo')(module, 'version'); // jshint ignore:line
+var fs = require('fs');
+var path = require('path');
 
 exports.dataType = require('db-migrate-shared').dataType;
 
+function loadPluginList() {
+
+  var plugins = JSON.parse(fs.readFileSync(
+          path.join(process.cwd(), 'package.json'),
+          'utf-8'
+        )
+      ),
+      targets = [];
+
+  plugins = Object.assign(plugins.dependencies, plugins.devDependencies);
+
+  for(var plugin in plugins) {
+
+    if(plugin.startsWith('db-migrate-plugin'))
+      targets.push(plugin);
+  }
+
+  return targets;
+}
+
+function loadPlugins() {
+
+  var plugins = loadPluginList(),
+      i = 0,
+      length = plugins.length,
+      hooks = {};
+
+  for(; i < length; ++i) {
+
+    var plugin = require(plugins[i]);
+    if(typeof(plugin.name) !== 'string' || !plugin.hooks || !plugin.loadPlugin)
+      continue;
+
+    plugin.hooks.map(function(hook) {
+
+      hooks[hook] = hooks[hook] || [];
+      hooks[hook].push(plugin);
+    });
+  }
+
+  return hooks;
+}
+
 module.exports.getInstance = function(isModule, options, callback) {
 
   delete require.cache[require.resolve('./api.js')];
   delete require.cache[require.resolve('optimist')];
-  var mod = require( './api.js' );
-  return new mod(isModule, options, callback);
+  var mod = require('./api.js'),
+      plugins = {};
+
+  try {
+
+    if(!options || !options.noPlugins)
+      plugins = loadPlugins();
+  }
+  catch(ex) {}
+
+  if(options && options.plugins) {
+
+    plugins = Object.assign(plugins, options.plugins);
+  }
+
+  return new mod(plugins, isModule, options, callback);
 };

lib/config.js

@@ -2,6 +2,7 @@ var fs = require('fs');
 var path = require('path');
 var parseDatabaseUrl = require('parse-database-url');
 var dbmUtil = require('db-migrate-shared').util;
+var log = require('db-migrate-shared').log;
 
 var setCurrent = exports.setCurrent = function (env) {
   env = dbmUtil.isArray(env) ? env : [env];
@@ -36,7 +37,7 @@ exports.load = function(config, currentEnv) {
   }
 };
 
-exports.loadFile = function(fileName, currentEnv) {
+exports.loadFile = function(fileName, currentEnv, plugins) {
   var config;
 
   try {
@@ -46,7 +47,30 @@ exports.loadFile = function(fileName, currentEnv) {
   }
 
   try {
-    config = require(fileName);
+
+    var plugin = false;
+
+    if(plugins)
+      plugin = plugins.overwrite('init:config:overwrite:require');
+
+    if(plugin !== false) {
+
+      try {
+
+        config = plugin['init:config:overwrite:require'](fileName);
+      }
+      catch(ex) {
+
+        log.warn('Plugin failure "' + plugin.name +
+          '", falling back to default behavior!');
+        log.verbose(ex);
+
+        config = require(fileName);
+      }
+    }
+    else
+      config = require(fileName);
+
   } catch(e) {
     // distinguish broken files from missing ones
     if (e instanceof SyntaxError){

package.json

@@ -44,6 +44,7 @@
     "url": "https://github.com/db-migrate/node-db-migrate.git"
   },
   "dependencies": {
+    "db-migrate-plugin-test": "1.0.0",
     "bluebird": "^3.1.1",
     "db-migrate-shared": "^1.0.2",
     "dotenv": "^2.0.0",