Cache remoting descriptions to speed up tests

Calling strong-globalize is relatively expensive (about 300
microseconds for each call). When using per-app local registry in
unit-tests, each app creation requires about 500 calls of `g.t` just
for remoting metadata, i.e. about 150ms.

In this commit, we introduce `g.s` that caches the results from
strong-globalize to speed up creation of remoting metadata.

Author: bajtos

lib/persisted-model.js

@@ -16,6 +16,16 @@ var debug = require('debug')('loopback:persisted-model');
 var PassThrough = require('stream').PassThrough;
 var utils = require('./utils');
 
+// workaround for low performance of strong-globalize
+// see https://github.com/strongloop/strong-globalize/issues/66
+var stringCache = Object.create(null);
+g.s = function(str) {
+  assert.equal(1, arguments.length, 'g.s() does not support parameters');
+  if (str in stringCache)
+    return stringCache[str];
+  return stringCache[str] = g.t(str);
+};
+
 module.exports = function(registry) {
   var Model = registry.getModel('Model');
 
@@ -560,7 +570,7 @@ module.exports = function(registry) {
     }
 
     setRemoting(PersistedModel, 'create', {
-      description: g.f('Create a new instance of the model and persist it into the data source.'),
+      description: g.s('Create a new instance of the model and persist it into the data source.'),
       accessType: 'WRITE',
       accepts: {arg: 'data', type: 'object', description: 'Model instance data', http: {source: 'body'}},
       returns: {arg: 'data', type: typeName, root: true},
@@ -569,7 +579,7 @@ module.exports = function(registry) {
 
     setRemoting(PersistedModel, 'upsert', {
       aliases: ['updateOrCreate'],
-      description: g.f('Update an existing model instance or insert a new one ' +
+      description: g.s('Update an existing model instance or insert a new one ' +
         'into the data source.'),
       accessType: 'WRITE',
       accepts: {arg: 'data', type: 'object', description: 'Model instance data', http: {source: 'body'}},
@@ -578,7 +588,7 @@ module.exports = function(registry) {
     });
 
     setRemoting(PersistedModel, 'exists', {
-      description: g.f('Check whether a model instance exists in the data source.'),
+      description: g.s('Check whether a model instance exists in the data source.'),
       accessType: 'READ',
       accepts: {arg: 'id', type: 'any', description: 'Model id', required: true},
       returns: {arg: 'exists', type: 'boolean'},
@@ -609,29 +619,29 @@ module.exports = function(registry) {
     });
 
     setRemoting(PersistedModel, 'findById', {
-      description: g.f('Find a model instance by {{id}} from the data source.'),
+      description: g.s('Find a model instance by {{id}} from the data source.'),
       accessType: 'READ',
       accepts: [
         { arg: 'id', type: 'any', description: 'Model id', required: true,
           http: {source: 'path'}},
         { arg: 'filter', type: 'object',
-          description: g.f('Filter defining fields and include') },
+          description: g.s('Filter defining fields and include') },
       ],
       returns: {arg: 'data', type: typeName, root: true},
       http: {verb: 'get', path: '/:id'},
       rest: {after: convertNullToNotFoundError}
     });
 
     setRemoting(PersistedModel, 'find', {
-      description: g.f('Find all instances of the model matched by filter from the data source.'),
+      description: g.s('Find all instances of the model matched by filter from the data source.'),
       accessType: 'READ',
       accepts: {arg: 'filter', type: 'object', description: 'Filter defining fields, where, include, order, offset, and limit'},
       returns: {arg: 'data', type: [typeName], root: true},
       http: {verb: 'get', path: '/'}
     });
 
     setRemoting(PersistedModel, 'findOne', {
-      description: g.f('Find first instance of the model matched by filter from the data source.'),
+      description: g.s('Find first instance of the model matched by filter from the data source.'),
       accessType: 'READ',
       accepts: {arg: 'filter', type: 'object', description: 'Filter defining fields, where, include, order, offset, and limit'},
       returns: {arg: 'data', type: typeName, root: true},
@@ -640,7 +650,7 @@ module.exports = function(registry) {
     });
 
     setRemoting(PersistedModel, 'destroyAll', {
-      description: g.f('Delete all matching records.'),
+      description: g.s('Delete all matching records.'),
       accessType: 'WRITE',
       accepts: {arg: 'where', type: 'object', description: 'filter.where object'},
       returns: {
@@ -655,17 +665,17 @@ module.exports = function(registry) {
 
     setRemoting(PersistedModel, 'updateAll', {
       aliases: ['update'],
-      description: g.f('Update instances of the model matched by {{where}} from the data source.'),
+      description: g.s('Update instances of the model matched by {{where}} from the data source.'),
       accessType: 'WRITE',
       accepts: [
         {arg: 'where', type: 'object', http: { source: 'query'},
-          description: g.f('Criteria to match model instances')},
+          description: g.s('Criteria to match model instances')},
         {arg: 'data', type: 'object', http: {source: 'body'},
-          description: g.f('An object of model property name/value pairs')},
+          description: g.s('An object of model property name/value pairs')},
       ],
       returns: {
         arg: 'count',
-        description: g.f('The number of instances updated'),
+        description: g.s('The number of instances updated'),
         type: 'object',
         root: true
       },
@@ -674,7 +684,7 @@ module.exports = function(registry) {
 
     setRemoting(PersistedModel, 'deleteById', {
       aliases: ['destroyById', 'removeById'],
-      description: g.f('Delete a model instance by {{id}} from the data source.'),
+      description: g.s('Delete a model instance by {{id}} from the data source.'),
       accessType: 'WRITE',
       accepts: {arg: 'id', type: 'any', description: 'Model id', required: true,
                 http: {source: 'path'}},
@@ -683,15 +693,15 @@ module.exports = function(registry) {
     });
 
     setRemoting(PersistedModel, 'count', {
-      description: g.f('Count instances of the model matched by where from the data source.'),
+      description: g.s('Count instances of the model matched by where from the data source.'),
       accessType: 'READ',
       accepts: {arg: 'where', type: 'object', description: 'Criteria to match model instances'},
       returns: {arg: 'count', type: 'number'},
       http: {verb: 'get', path: '/count'}
     });
 
     setRemoting(PersistedModel.prototype, 'updateAttributes', {
-      description: g.f('Update attributes for a model instance and persist it into ' +
+      description: g.s('Update attributes for a model instance and persist it into ' +
         'the data source.'),
       accessType: 'WRITE',
       accepts: {arg: 'data', type: 'object', http: {source: 'body'}, description: 'An object of model property name/value pairs'},
@@ -701,7 +711,7 @@ module.exports = function(registry) {
 
     if (options.trackChanges || options.enableRemoteReplication) {
       setRemoting(PersistedModel, 'diff', {
-        description: g.f('Get a set of deltas and conflicts since the given checkpoint.'),
+        description: g.s('Get a set of deltas and conflicts since the given checkpoint.'),
         accessType: 'READ',
         accepts: [
           {arg: 'since', type: 'number', description: 'Find deltas since this checkpoint'},
@@ -713,7 +723,7 @@ module.exports = function(registry) {
       });
 
       setRemoting(PersistedModel, 'changes', {
-        description: g.f('Get the changes to a model since a given checkpoint.' +
+        description: g.s('Get the changes to a model since a given checkpoint.' +
           'Provide a filter object to reduce the number of results returned.'),
         accessType: 'READ',
         accepts: [
@@ -725,7 +735,7 @@ module.exports = function(registry) {
       });
 
       setRemoting(PersistedModel, 'checkpoint', {
-        description: g.f('Create a checkpoint.'),
+        description: g.s('Create a checkpoint.'),
         // The replication algorithm needs to create a source checkpoint,
         // even though it is otherwise not making any source changes.
         // We need to allow this method for users that don't have full
@@ -736,14 +746,14 @@ module.exports = function(registry) {
       });
 
       setRemoting(PersistedModel, 'currentCheckpoint', {
-        description: g.f('Get the current checkpoint.'),
+        description: g.s('Get the current checkpoint.'),
         accessType: 'READ',
         returns: {arg: 'checkpoint', type: 'object', root: true},
         http: {verb: 'get', path: '/checkpoint'}
       });
 
       setRemoting(PersistedModel, 'createUpdates', {
-        description: g.f('Create an update list from a delta list.'),
+        description: g.s('Create an update list from a delta list.'),
         // This operation is read-only, it does not change any local data.
         // It is called by the replication algorithm to compile a list
         // of changes to apply on the target.
@@ -754,14 +764,14 @@ module.exports = function(registry) {
       });
 
       setRemoting(PersistedModel, 'bulkUpdate', {
-        description: g.f('Run multiple updates at once. Note: this is not atomic.'),
+        description: g.s('Run multiple updates at once. Note: this is not atomic.'),
         accessType: 'WRITE',
         accepts: {arg: 'updates', type: 'array'},
         http: {verb: 'post', path: '/bulk-update'}
       });
 
       setRemoting(PersistedModel, 'findLastChange', {
-        description: g.f('Get the most recent change record for this instance.'),
+        description: g.s('Get the most recent change record for this instance.'),
         accessType: 'READ',
         accepts: {
           arg: 'id', type: 'any', required: true, http: { source: 'path' },
@@ -773,7 +783,7 @@ module.exports = function(registry) {
 
       setRemoting(PersistedModel, 'updateLastChange', {
         description: [
-          g.f('Update the properties of the most recent change record ' +
+          g.s('Update the properties of the most recent change record ' +
           'kept for this instance.'),
         ],
         accessType: 'WRITE',
@@ -784,7 +794,7 @@ module.exports = function(registry) {
           },
           {
             arg: 'data', type: 'object', http: {source: 'body'},
-            description: g.f('An object of Change property name/value pairs'),
+            description: g.s('An object of Change property name/value pairs'),
           },
         ],
         returns: { arg: 'result', type: this.Change.modelName, root: true },
@@ -810,7 +820,7 @@ module.exports = function(registry) {
     }
 
     setRemoting(PersistedModel, 'createChangeStream', {
-      description: g.f('Create a change stream.'),
+      description: g.s('Create a change stream.'),
       accessType: 'READ',
       http: [
         {verb: 'post', path: '/change-stream'},