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Add `loopback.runInContext` 

Refactor the core implementation of current context from
server/middleware/context.js into server/current-context.js.

Expose new public API:
 - loopback.runInContext
 - loopback.createContext
This commit is contained in:
Miroslav Bajtoš 2015-03-27 14:45:37 +01:00
parent 548cb6ef94
commit 2aa09ba574
8 changed files with 188 additions and 103 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Gruntfile.js
View File

@ -39,6 +39,9 @@ module.exports = function(grunt) {
common: {
src: ['common/**/*.js']
},
browser: {
src: ['browser/**/*.js']
},
server: {
src: ['server/**/*.js']
},
@ -51,6 +54,7 @@ module.exports = function(grunt) {
lib: ['lib/**/*.js'],
common: ['common/**/*.js'],
server: ['server/**/*.js'],
browser: ['browser/**/*.js'],
test: ['test/**/*.js']
},
watch: {

10
browser/current-context.js Normal file
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@ -0,0 +1,10 @@
module.exports = function(loopback) {
loopback.getCurrentContext = function() {
return null;
};
loopback.runInContext =
loopback.createContext = function() {
throw new Error('Current context is not supported in the browser.');
};
};

7
docs.json
View File

@ -5,6 +5,7 @@
"lib/server-app.js",
"lib/loopback.js",
"lib/registry.js",
"server/current-context.js",
"lib/access-context.js",
{ "title": "Base models", "depth": 2 },
"lib/model.js",
@ -13,7 +14,7 @@
"server/middleware/context.js",
"server/middleware/favicon.js",
"server/middleware/rest.js",
"server/middleware/static.js",
"server/middleware/static.js",
"server/middleware/status.js",
"server/middleware/token.js",
"server/middleware/url-not-found.js",
@ -21,11 +22,11 @@
"common/models/access-token.js",
"common/models/acl.js",
"common/models/application.js",
"common/models/change.js",
"common/models/change.js",
"common/models/email.js",
"common/models/role.js",
"common/models/role-mapping.js",
"common/models/scope.js",
"common/models/scope.js",
"common/models/user.js"
],
"assets": "/docs/assets"

5
lib/loopback.js
View File

@ -189,10 +189,7 @@ loopback.template = function(file) {
return ejs.compile(str);
};
loopback.getCurrentContext = function() {
// A placeholder method, see lib/middleware/context.js for the real version
return null;
};
require('../server/current-context')(loopback);
/*!
* Built in models / services

1
package.json
View File

@ -93,6 +93,7 @@
"browser": {
"express": "./lib/browser-express.js",
"./lib/server-app.js": "./lib/browser-express.js",
"./server/current-context.js": "./browser/current-context.js",
"connect": false,
"nodemailer": false,
"supertest": false,

138
server/current-context.js Normal file
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@ -0,0 +1,138 @@
var juggler = require('loopback-datasource-juggler');
var remoting = require('strong-remoting');
var cls = require('continuation-local-storage');
var domain = require('domain');
module.exports = function(loopback) {
/**
* Get the current context object. The context is preserved
* across async calls, it behaves like a thread-local storage.
*
* @returns {ChainedContext} The context object or null.
*/
loopback.getCurrentContext = function() {
// A placeholder method, see loopback.createContext() for the real version
return null;
};
/**
* Run the given function in such way that
* `loopback.getCurrentContext` returns the
* provided context object.
*
* **NOTE**
*
* The method is supported on the server only, it does not work
* in the browser at the moment.
*
* @param {Function} fn The function to run, it will receive arguments
* (currentContext, currentDomain).
* @param {ChainedContext} context An optional context object.
* When no value is provided, then the default global context is used.
*/
loopback.runInContext = function(fn, context) {
var currentDomain = domain.create();
currentDomain.oldBind = currentDomain.bind;
currentDomain.bind = function(callback, context) {
return currentDomain.oldBind(ns.bind(callback, context), context);
};
var ns = context || loopback.createContext('loopback');
currentDomain.run(function() {
ns.run(function executeInContext(context) {
fn(ns, currentDomain);
});
});
};
/**
* Create a new LoopBackContext instance that can be used
* for `loopback.runInContext`.
*
* **NOTES**
*
* At the moment, `loopback.getCurrentContext` supports
* a single global context instance only. If you call `createContext()`
* multiple times, `getCurrentContext` will return the last context
* created.
*
* The method is supported on the server only, it does not work
* in the browser at the moment.
*
* @param {String} scopeName An optional scope name.
* @return {ChainedContext} The new context object.
*/
loopback.createContext = function(scopeName) {
// Make the namespace globally visible via the process.context property
process.context = process.context || {};
var ns = process.context[scopeName];
if (!ns) {
ns = cls.createNamespace(scopeName);
process.context[scopeName] = ns;
// Set up loopback.getCurrentContext()
loopback.getCurrentContext = function() {
return ns && ns.active ? ns : null;
};
chain(juggler);
chain(remoting);
}
return ns;
};
/**
* Create a chained context
* @param {Object} child The child context
* @param {Object} parent The parent context
* @private
* @constructor
*/
function ChainedContext(child, parent) {
this.child = child;
this.parent = parent;
}
/**
* Get the value by name from the context. If it doesn't exist in the child
* context, try the parent one
* @param {String} name Name of the context property
* @returns {*} Value of the context property
* @private
*/
ChainedContext.prototype.get = function(name) {
var val = this.child && this.child.get(name);
if (val === undefined) {
return this.parent && this.parent.get(name);
}
};
ChainedContext.prototype.set = function(name, val) {
if (this.child) {
return this.child.set(name, val);
} else {
return this.parent && this.parent.set(name, val);
}
};
ChainedContext.prototype.reset = function(name, val) {
if (this.child) {
return this.child.reset(name, val);
} else {
return this.parent && this.parent.reset(name, val);
}
};
function chain(child) {
if (typeof child.getCurrentContext === 'function') {
var childContext = new ChainedContext(child.getCurrentContext(),
loopback.getCurrentContext());
child.getCurrentContext = function() {
return childContext;
};
} else {
child.getCurrentContext = loopback.getCurrentContext;
}
}
};

112
server/middleware/context.js
View File

@ -1,31 +1,9 @@
var loopback = require('../../lib/loopback');
var juggler = require('loopback-datasource-juggler');
var remoting = require('strong-remoting');
var cls = require('continuation-local-storage');
var domain = require('domain');
module.exports = context;
var name = 'loopback';
function createContext(scope) {
// Make the namespace globally visible via the process.context property
process.context = process.context || {};
var ns = process.context[scope];
if (!ns) {
ns = cls.createNamespace(scope);
process.context[scope] = ns;
// Set up loopback.getCurrentContext()
loopback.getCurrentContext = function() {
return ns && ns.active ? ns : null;
};
chain(juggler);
chain(remoting);
}
return ns;
}
/**
* Context middleware.
* ```js
@ -44,89 +22,31 @@ function context(options) {
options = options || {};
var scope = options.name || name;
var enableHttpContext = options.enableHttpContext || false;
var ns = createContext(scope);
var ns = loopback.createContext(scope);
// Return the middleware
return function contextHandler(req, res, next) {
if (req.loopbackContext) {
return next();
}
req.loopbackContext = ns;
// Bind req/res event emitters to the given namespace
ns.bindEmitter(req);
ns.bindEmitter(res);
var currentDomain = domain.create();
currentDomain.oldBind = currentDomain.bind;
currentDomain.bind = function(callback, context) {
return currentDomain.oldBind(ns.bind(callback, context), context);
};
loopback.runInContext(function processRequestInContext(ns, domain) {
req.loopbackContext = ns;
currentDomain.add(req);
currentDomain.add(res);
// Bind req/res event emitters to the given namespace
ns.bindEmitter(req);
ns.bindEmitter(res);
// Create namespace for the request context
currentDomain.run(function() {
ns.run(function processRequestInContext(context) {
// Run the code in the context of the namespace
if (enableHttpContext) {
ns.set('http', {req: req, res: res}); // Set up the transport context
}
next();
});
// Add req/res event emitters to the current domain
domain.add(req);
domain.add(res);
// Run the code in the context of the namespace
if (enableHttpContext) {
// Set up the transport context
ns.set('http', {req: req, res: res});
}
next();
});
};
}
/**
* Create a chained context
* @param {Object} child The child context
* @param {Object} parent The parent context
* @private
* @constructor
*/
function ChainedContext(child, parent) {
this.child = child;
this.parent = parent;
}
/*!
* Get the value by name from the context. If it doesn't exist in the child
* context, try the parent one
* @param {String} name Name of the context property
* @returns {*} Value of the context property
*/
ChainedContext.prototype.get = function(name) {
var val = this.child && this.child.get(name);
if (val === undefined) {
return this.parent && this.parent.get(name);
}
};
ChainedContext.prototype.set = function(name, val) {
if (this.child) {
return this.child.set(name, val);
} else {
return this.parent && this.parent.set(name, val);
}
};
ChainedContext.prototype.reset = function(name, val) {
if (this.child) {
return this.child.reset(name, val);
} else {
return this.parent && this.parent.reset(name, val);
}
};
function chain(child) {
if (typeof child.getCurrentContext === 'function') {
var childContext = new ChainedContext(child.getCurrentContext(),
loopback.getCurrentContext());
child.getCurrentContext = function() {
return childContext;
};
} else {
child.getCurrentContext = loopback.getCurrentContext;
}
}

14
test/loopback.test.js
View File

@ -462,5 +462,19 @@ describe('loopback', function() {
done();
});
});
it('works outside REST middleware', function(done) {
loopback.runInContext(function() {
var ctx = loopback.getCurrentContext();
expect(ctx).is.an('object');
ctx.set('test-key', 'test-value');
process.nextTick(function() {
var ctx = loopback.getCurrentContext();
expect(ctx).is.an('object');
expect(ctx.get('test-key')).to.equal('test-value');
done();
});
});
});
});
});