@ -256,9 +256,20 @@
} ;
startup . processAsyncListener = function ( ) {
var asyncStack = [ ] ;
var asyncQueue = [ ] ;
var uid = 0 ;
// new Array() is used here because it is more efficient for sparse
// arrays. Please *do not* change these to simple bracket notation.
// Track the active queue of AsyncListeners that have been added.
var asyncStack = new Array ( ) ;
var asyncQueue = undefined ;
// Keep the stack of all contexts that have been loaded in the
// execution chain of asynchronous events.
var contextStack = new Array ( ) ;
var currentContext = undefined ;
// Incremental uid for new AsyncListener instances.
var alUid = 0 ;
// Stateful flags shared with Environment for quick JS/C++
// communication.
@ -272,7 +283,13 @@
var inErrorTick = false ;
// Needs to be the same as src/env.h
var kCount = 0 ;
var kHasListener = 0 ;
// Flags to determine what async listeners are available.
var HAS_CREATE_AL = 1 << 0 ;
var HAS_BEFORE_AL = 1 << 1 ;
var HAS_AFTER_AL = 1 << 2 ;
var HAS_ERROR_AL = 1 << 3 ;
// _errorHandler is scoped so it's also accessible by _fatalException.
_ errorHandler = errorHandler ;
@ -298,115 +315,249 @@
pushListener ,
stripListener ) ;
function popQueue ( ) {
if ( asyncStack . length > 0 )
// Load the currently executing context as the current context, and
// create a new asyncQueue that can receive any added queue items
// during the executing of the callback.
function loadContext ( ctx ) {
contextStack . push ( currentContext ) ;
currentContext = ctx ;
asyncStack . push ( asyncQueue ) ;
asyncQueue = new Array ( ) ;
asyncFlags [ kHasListener ] = 1 ;
}
function unloadContext ( ) {
currentContext = contextStack . pop ( ) ;
asyncQueue = asyncStack . pop ( ) ;
else
asyncQueue = [ ] ;
if ( typeof currentContext === 'undefined' &&
typeof asyncQueue === 'undefined' )
asyncFlags [ kHasListener ] = 0 ;
}
// Run all the async listeners attached when an asynchronous event is
// instantiated.
function runAsyncQueue ( context ) {
var queue = [ ] ;
var queueItem , item , i , value ;
var queue = new Array ( ) ;
var data = new Array ( ) ;
var ccQueue , i , item , queueItem , value ;
context . _ asyncQueue = queue ;
context . _ asyncData = data ;
context . _ asyncFlags = 0 ;
inAsyncTick = true ;
// First run through all callbacks in the currentContext. These may
// add new AsyncListeners to the asyncQueue during execution. Hence
// why they need to be evaluated first.
if ( currentContext ) {
ccQueue = currentContext . _ asyncQueue ;
context . _ asyncFlags |= currentContext . _ asyncFlags ;
for ( i = 0 ; i < ccQueue . length ; i ++ ) {
queueItem = ccQueue [ i ] ;
queue [ queue . length ] = queueItem ;
if ( ( queueItem . flags & HAS_CREATE_AL ) === 0 ) {
data [ queueItem . uid ] = queueItem . data ;
continue ;
}
value = queueItem . create ( queueItem . data ) ;
data [ queueItem . uid ] = ( value === undefined ) ? queueItem . data : value ;
}
}
// Then run through all items in the asyncQueue
if ( asyncQueue ) {
for ( i = 0 ; i < asyncQueue . length ; i ++ ) {
queueItem = asyncQueue [ i ] ;
if ( ! queueItem . callbacks . create ) {
queue [ i ] = queueItem ;
queue [ queue . length ] = queueItem ;
context . _ asyncFlags |= queueItem . flags ;
if ( ( queueItem . flags & HAS_CREATE_AL ) === 0 ) {
data [ queueItem . uid ] = queueItem . data ;
continue ;
}
// Not passing "this" context because it hasn't actually been
// instantiated yet, so accessing some of the object properties
// can cause a segfault.
// Passing the original value will allow users to manipulate the
// original value object, while also allowing them to return a
// new value for current async call tracking.
value = queueItem . callbacks . create ( queueItem . value ) ;
if ( typeof value !== 'undefined' ) {
item = {
callbacks : queueItem . callbacks ,
value : value ,
uid : queueItem . uid
} ;
} else {
item = queueItem ;
value = queueItem . create ( queueItem . data ) ;
data [ queueItem . uid ] = ( value === undefined ) ? queueItem . data : value ;
}
queue [ i ] = item ;
}
inAsyncTick = false ;
context . _ asyncQueue = queu e;
inAsyncTick = false ;
}
// Uses the _asyncQueue object attached by runAsyncQueue.
// Load the AsyncListener queue attached to context and run all
// "before" callbacks, if they exist.
function loadAsyncQueue ( context ) {
var queue = context . _ asyncQueue ;
var item , before , i ;
loadContext ( context ) ;
asyncStack . push ( asyncQueue ) ;
asyncQueue = queue . slice ( ) ;
// Since the async listener callback is required, the number of
// objects in the asyncQueue implies the number of async listeners
// there are to be processed.
asyncFlags [ kCount ] = queue . length ;
if ( ( context . _ asyncFlags & HAS_BEFORE_AL ) === 0 )
return ;
var queue = context . _ asyncQueue ;
var data = context . _ asyncData ;
var i , queueItem ;
// Run "before" callbacks.
inAsyncTick = true ;
for ( i = 0 ; i < queue . length ; i ++ ) {
item = queue [ i ] ;
if ( ! item . callbacks )
continue ;
before = item . callbacks . before ;
if ( typeof before === 'function' )
before ( context , item . value ) ;
queueItem = queue [ i ] ;
if ( ( queueItem . flags & HAS_BEFORE_AL ) > 0 )
queueItem . before ( context , data [ queueItem . uid ] ) ;
}
inAsyncTick = false ;
}
// Unload one level of the async stack. Returns true if there are
// still listeners somewhere in the stack .
// Unload the AsyncListener queue attached to context and run all
// "after" callbacks, if they exist .
function unloadAsyncQueue ( context ) {
if ( ( context . _ asyncFlags & HAS_AFTER_AL ) === 0 ) {
unloadContext ( ) ;
return ;
}
var queue = context . _ asyncQueue ;
var item , after , i ;
var data = context . _ asyncData ;
var i , queueItem ;
// Run "after" callbacks.
inAsyncTick = true ;
for ( i = 0 ; i < queue . length ; i ++ ) {
item = queue [ i ] ;
if ( ! item . callbacks )
continue ;
after = item . callbacks . after ;
if ( typeof after === 'function' )
after ( context , item . value ) ;
queueItem = queue [ i ] ;
if ( ( queueItem . flags & HAS_AFTER_AL ) > 0 )
queueItem . after ( context , data [ queueItem . uid ] ) ;
}
inAsyncTick = false ;
// Unload the current queue from the stack.
popQueue ( ) ;
unloadContext ( ) ;
}
asyncFlags [ kCount ] = asyncQueue . length ;
// Handle errors that are thrown while in the context of an
// AsyncListener. If an error is thrown from an AsyncListener
// callback error handlers will be called once more to report
// the error, then the application will die forcefully.
function errorHandler ( er ) {
if ( inErrorTick )
return false ;
var handled = false ;
var i , queueItem , threw ;
return asyncQueue . length > 0 || asyncStack . length > 0 ;
inErrorTick = true ;
// First process error callbacks from the current context.
if ( currentContext && ( currentContext . _ asyncFlags & HAS_ERROR_AL ) > 0 ) {
var queue = currentContext . _ asyncQueue ;
var data = currentContext . _ asyncData ;
for ( i = 0 ; i < queue . length ; i ++ ) {
queueItem = queue [ i ] ;
if ( ( queueItem . flags & HAS_ERROR_AL ) === 0 )
continue ;
try {
threw = true ;
// While it would be possible to pass in currentContext, if
// the error is thrown from the "create" callback then there's
// a chance the object hasn't been fully constructed.
handled = queueItem . error ( data [ queueItem . uid ] , er ) || handled ;
threw = false ;
} finally {
// If the error callback thew then die quickly. Only allow the
// exit events to be processed.
if ( threw ) {
process . _ exiting = true ;
process . emit ( 'exit' , 1 ) ;
}
}
}
}
// Now process callbacks from any existing queue.
if ( asyncQueue ) {
for ( i = 0 ; i < asyncQueue . length ; i ++ ) {
queueItem = asyncQueue [ i ] ;
if ( ( queueItem . flags & HAS_ERROR_AL ) === 0 )
continue ;
try {
threw = true ;
handled = queueItem . error ( queueItem . data , er ) || handled ;
threw = false ;
} finally {
// If the error callback thew then die quickly. Only allow the
// exit events to be processed.
if ( threw ) {
process . _ exiting = true ;
process . emit ( 'exit' , 1 ) ;
}
}
}
}
inErrorTick = false ;
unloadContext ( ) ;
// TODO(trevnorris): If the error was handled, should the after callbacks
// be fired anyways?
return handled && ! inAsyncTick ;
}
// Instance function of an AsyncListener object.
function AsyncListenerInst ( callbacks , data ) {
if ( typeof callbacks . create === 'function' ) {
this . create = callbacks . create ;
this . flags |= HAS_CREATE_AL ;
}
if ( typeof callbacks . before === 'function' ) {
this . before = callbacks . before ;
this . flags |= HAS_BEFORE_AL ;
}
if ( typeof callbacks . after === 'function' ) {
this . after = callbacks . after ;
this . flags |= HAS_AFTER_AL ;
}
if ( typeof callbacks . error === 'function' ) {
this . error = callbacks . error ;
this . flags |= HAS_ERROR_AL ;
}
this . uid = ++ alUid ;
this . data = data ;
}
AsyncListenerInst . prototype . create = undefined ;
AsyncListenerInst . prototype . before = undefined ;
AsyncListenerInst . prototype . after = undefined ;
AsyncListenerInst . prototype . error = undefined ;
AsyncListenerInst . prototype . uid = 0 ;
AsyncListenerInst . prototype . flags = 0 ;
// Create new async listener object. Useful when instantiating a new
// object and want the listener instance, but not add it to the stack.
function createAsyncListener ( callbacks , value ) {
return {
callbacks : callbacks ,
value : value ,
uid : uid ++
} ;
// If an existing AsyncListenerInst is passed then any new "data" is
// ignored.
function createAsyncListener ( callbacks , data ) {
if ( typeof callbacks !== 'object' || callbacks == null )
throw new TypeError ( 'callbacks argument must be an object' ) ;
if ( callbacks instanceof AsyncListenerInst )
return callbacks ;
else
return new AsyncListenerInst ( callbacks , data ) ;
}
// Add a listener to the current queue.
function addAsyncListener ( callbacks , value ) {
// Accept new listeners or previous created listeners.
if ( typeof callbacks . uid !== 'number' )
callbacks = createAsyncListener ( callbacks , value ) ;
function addAsyncListener ( callbacks , data ) {
if ( ! asyncQueue ) {
asyncStack . push ( asyncQueue ) ;
asyncQueue = new Array ( ) ;
}
// Fast track if a new AsyncListenerInst has to be created.
if ( ! ( callbacks instanceof AsyncListenerInst ) ) {
callbacks = createAsyncListener ( callbacks , data ) ;
asyncQueue . push ( callbacks ) ;
asyncFlags [ kHasListener ] = 1 ;
return callbacks ;
}
var inQueue = false ;
// The asyncQueue will be small. Probably always <= 3 items.
@ -418,10 +569,11 @@
}
// Make sure the callback doesn't already exist in the queue.
if ( ! inQueue )
if ( ! inQueue ) {
asyncQueue . push ( callbacks ) ;
asyncFlags [ kHasListener ] = 1 ;
}
asyncFlags [ kCount ] = asyncQueue . length ;
return callbacks ;
}
@ -429,14 +581,19 @@
function removeAsyncListener ( obj ) {
var i , j ;
if ( asyncQueue ) {
for ( i = 0 ; i < asyncQueue . length ; i ++ ) {
if ( obj . uid === asyncQueue [ i ] . uid ) {
asyncQueue . splice ( i , 1 ) ;
break ;
}
}
}
// TODO(trevnorris): Why remove the AL from the entire stack?
for ( i = 0 ; i < asyncStack . length ; i ++ ) {
if ( asyncStack [ i ] === undefined )
continue ;
for ( j = 0 ; j < asyncStack [ i ] . length ; j ++ ) {
if ( obj . uid === asyncStack [ i ] [ j ] . uid ) {
asyncStack [ i ] . splice ( j , 1 ) ;
@ -445,54 +602,25 @@
}
}
asyncFlags [ kCount ] = asyncQueue . length ;
}
// Error handler used by _fatalException to run through all error
// callbacks in the current asyncQueue.
function errorHandler ( er ) {
var handled = false ;
var error , item , i ;
if ( inErrorTick )
return false ;
inErrorTick = true ;
for ( i = 0 ; i < asyncQueue . length ; i ++ ) {
item = asyncQueue [ i ] ;
if ( ! item . callbacks )
continue ;
error = item . callbacks . error ;
if ( typeof error === 'function' ) {
try {
var threw = true ;
handled = error ( item . value , er ) || handled ;
threw = false ;
} finally {
// If the error callback throws then we're going to die
// quickly with no chance of recovery. Only thing we're going
// to allow is execution of process exit event callbacks.
if ( threw ) {
process . _ exiting = true ;
process . emit ( 'exit' , 1 ) ;
}
}
}
}
inErrorTick = false ;
// Unload the current queue from the stack.
popQueue ( ) ;
return handled && ! inAsyncTick ;
if ( ( asyncQueue && asyncQueue . length > 0 ) ||
( currentContext && currentContext . _ asyncQueue . length ) )
asyncFlags [ kHasListener ] = 1 ;
}
// Used by AsyncWrap::AddAsyncListener() to add an individual listener
// to the async queue. It will check the uid of the listener and only
// allow it to be added once.
function pushListener ( obj ) {
if ( ! this . _ asyncQueue )
this . _ asyncQueue = [ ] ;
if ( ! this . _ asyncQueue ) {
this . _ asyncQueue = [ obj ] ;
this . _ asyncData = new Array ( ) ;
this . _ asyncData [ obj . uid ] = obj . data ;
this . _ asyncFlags = obj . flags ;
return ;
}
if ( ! this . _ asyncData )
this . _ asyncData = new Array ( ) ;
var queue = this . _ asyncQueue ;
var inQueue = false ;
@ -504,26 +632,32 @@
}
}
if ( ! inQueue )
// Not in the queue so push it on and set the default storage.
if ( ! inQueue ) {
queue . push ( obj ) ;
this . _ asyncData [ obj . uid ] = obj . data ;
this . _ asyncFlags |= obj . flags ;
}
}
// Used by AsyncWrap::RemoveAsyncListener() to remove an individual
// listener from the async queue, and return whether there are still
// listeners in the queue.
function stripListener ( obj ) {
if ( ! this . _ asyncQueue || this . _ asyncQueue . length === 0 )
// No queue exists, so nothing to do.
if ( ! this . _ asyncQueue )
return false ;
var queue = this . _ asyncQueue ;
// The asyncQueue will be small. Probably always <= 3 items.
for ( var i = 0 ; i < this . _ asyncQueue . length ; i ++ ) {
if ( obj . uid === this . _ asyncQueue [ i ] . uid ) {
this . _ asyncQueue . splice ( i , 1 ) ;
break ;
for ( var i = 0 ; i < queue . length ; i ++ ) {
if ( obj . uid === queue [ i ] . uid ) {
this . _ asyncData [ queue [ i ] . uid ] = undefined ;
queue . splice ( i , 1 ) ;
return queue . length > 0 ;
}
}
return this . _ asyncQueue . length > 0 ;
}
} ;
Trevor Norris
11 years ago