mediawiki-extensions-Visual.../modules/parser/ext.core.TemplateHandler.js
Gabriel Wicke 06ae53fdfe Drastically reduce memory usage for template-heavy pages
Only call back a few callbacks per reactor iteration from the template fetch
request queue. This changes the expansion pattern from a (memory intensive)
breadth-first expansion to something quite close to depth-first expansion.
Additionally, retrieved pages are quickly added to the page cache so that a
lot of request queuing is avoided in favor of synchronous expansion from the
cache. On pages like Barack Obama that previously ran out of memory after
consuming node's 1.6G heap limit, expansion now runs in relatively constant
100-300M resident (so far, still running).

Change-Id: Ie34a1eeff00d868416de45ef8d289898258f560c
2012-04-13 14:31:03 +02:00

549 lines
16 KiB
JavaScript

/**
* Template and template argument handling, first cut.
*
* AsyncTokenTransformManager objects provide preprocessor-frame-like
* functionality once template args etc are fully expanded, and isolate
* individual transforms from concurrency issues. Template expansion is
* controlled using a tplExpandData structure created independently for each
* handled template tag.
*
* @author Gabriel Wicke <gwicke@wikimedia.org>
* @author Brion Vibber <brion@wikimedia.org>
*/
var $ = require('jquery'),
request = require('request'),
events = require('events'),
qs = require('querystring'),
ParserFunctions = require('./ext.core.ParserFunctions.js').ParserFunctions,
AttributeTransformManager = require('./mediawiki.TokenTransformManager.js')
.AttributeTransformManager,
defines = require('./mediawiki.parser.defines.js');
function TemplateHandler ( manager ) {
this.register( manager );
this.parserFunctions = new ParserFunctions( manager );
}
// constants
TemplateHandler.prototype.rank = 1.1;
TemplateHandler.prototype.register = function ( manager ) {
this.manager = manager;
// Register for template and templatearg tag tokens
manager.addTransform( this.onTemplate.bind(this),
this.rank, 'tag', 'template' );
// Template argument expansion
manager.addTransform( this.onTemplateArg.bind(this),
this.rank, 'tag', 'templatearg' );
};
/**
* Main template token handler
*
* Expands target and arguments (both keys and values) and either directly
* calls or sets up the callback to _expandTemplate, which then fetches and
* processes the template.
*/
TemplateHandler.prototype.onTemplate = function ( token, frame, cb ) {
//console.warn('onTemplate! ' + JSON.stringify( token, null, 2 ) +
// ' args: ' + JSON.stringify( this.manager.args ));
// create a new temporary frame for argument and title expansions
var tplExpandData = {
args: {},
manager: this.manager,
cb: cb,
origToken: token,
resultTokens: [],
attribsAsync: true,
overallAsync: false,
expandDone: false
},
transformCB,
i = 0,
res;
var attributes = [token.attribs.shift()];
if( token.attribs.length ) {
attributes = attributes.concat( this._nameArgs( token.attribs ) );
}
this.manager.env.dp( 'before AttributeTransformManager: ',
attributes );
new AttributeTransformManager(
this.manager,
this._returnAttributes.bind( this, tplExpandData )
).process( attributes );
// Unblock finish
if ( ! tplExpandData.attribsAsync ) {
// Attributes were transformed synchronously
this.manager.env.dp ( 'sync attribs for ', tplExpandData.target,
tplExpandData.expandedArgs
);
// All attributes are fully expanded synchronously (no IO was needed)
return this._expandTemplate ( tplExpandData );
} else {
// Async attribute expansion is going on
this.manager.env.dp( 'async return for ', token );
tplExpandData.overallAsync = true;
return { async: true };
}
};
/**
* Create positional (number) keys for arguments without explicit keys
*/
TemplateHandler.prototype._nameArgs = function ( attribs ) {
var n = 1,
out = [];
for ( var i = 0, l = attribs.length; i < l; i++ ) {
// FIXME: Also check for whitespace-only named args!
if ( ! attribs[i].k.length ) {
out.push( {k: [ n.toString() ], v: attribs[i].v } );
n++;
} else {
out.push( attribs[i] );
}
}
this.manager.env.dp( '_nameArgs: ', out );
return out;
};
/**
* Callback for argument (including target) expansion in AttributeTransformManager
*/
TemplateHandler.prototype._returnAttributes = function ( tplExpandData,
attributes )
{
this.manager.env.dp( 'TemplateHandler._returnAttributes: ', attributes );
// Remove the target from the attributes
tplExpandData.attribsAsync = false;
tplExpandData.target = attributes[0].v;
attributes.shift();
tplExpandData.expandedArgs = attributes;
if ( tplExpandData.overallAsync ) {
this._expandTemplate ( tplExpandData );
}
};
/**
* Fetch, tokenize and token-transform a template after all arguments and the
* target were expanded.
*/
TemplateHandler.prototype._expandTemplate = function ( tplExpandData ) {
//console.warn('TemplateHandler.expandTemplate: ' +
// JSON.stringify( tplExpandData, null, 2 ) );
var res;
if ( ! tplExpandData.target ) {
this.manager.env.dp( 'No target! ', tplExpandData );
console.trace();
}
// TODO:
// check for 'subst:'
// check for variable magic names
// check for msg, msgnw, raw magics
// check for parser functions
// First, check the target for loops
var target = this.manager.env.tokensToString( tplExpandData.target ).trim();
var args = this.manager.env.KVtoHash( tplExpandData.expandedArgs );
this.manager.env.dp( 'argHash: ', args );
var prefix = target.split(':', 1)[0].toLowerCase().trim();
if ( prefix && 'pf_' + prefix in this.parserFunctions ) {
var funcArg = target.substr( prefix.length + 1 );
this.manager.env.tp( 'func prefix/args: ', prefix,
tplExpandData.expandedArgs,
'funcArg:', funcArg);
//this.manager.env.dp( 'entering prefix', funcArg, args );
res = this.parserFunctions[ 'pf_' + prefix ]( funcArg,
tplExpandData.expandedArgs, args, tplExpandData.origToken.attribs );
// XXX: support async parser functions!
if ( tplExpandData.overallAsync ) {
this.manager.env.dp( 'TemplateHandler._expandTemplate: calling back ',
'after parser func ', prefix, ' with res:', res );
return tplExpandData.cb( res, false, true );
} else {
this.manager.env.dp( 'TemplateHandler._expandTemplate: sync return ',
'after parser func ', prefix, ' with res:', res );
return { tokens: res };
//data.reset();
}
}
this.manager.env.tp( 'template target: ' + target );
// now normalize the target before template processing
target = this.manager.env.normalizeTitle( target );
var checkRes = this.manager.loopAndDepthCheck.check( target, this.manager.env.maxDepth );
if( checkRes ) {
// Loop detected or depth limit exceeded, abort!
res = [
checkRes,
new TagTk( 'a', [{k: 'href', v: target}] ),
target,
new EndTagTk( 'a' )
];
if ( tplExpandData.overallAsync ) {
return tplExpandData.cb( res, false, true );
} else {
return { tokens: res };
}
}
// Get a nested transformation pipeline for the input type. The input
// pipeline includes the tokenizer, synchronous stage-1 transforms for
// 'text/wiki' input and asynchronous stage-2 transforms).
var inputPipeline = this.manager.newChildPipeline(
this.manager.inputType || 'text/wiki',
args,
tplExpandData.target
);
// Hook up the inputPipeline output events to our handlers
inputPipeline.addListener( 'chunk', this._onChunk.bind ( this, tplExpandData ) );
inputPipeline.addListener( 'end', this._onEnd.bind ( this, tplExpandData ) );
// Resolve a possibly relative link
var templateName = this.manager.env.resolveTitle(
target,
'Template'
);
// XXX: notes from brion's mediawiki.parser.environment
// resolve template name
// load template w/ canonical name
// load template w/ variant names (language variants)
// For now, just fetch the template and pass the callback for further
// processing along.
this._fetchTemplateAndTitle(
templateName,
this._processTemplateAndTitle.bind( this, inputPipeline ),
tplExpandData
);
// If nothing was async so far and the template source was retrieved and
// fully processed without async requests (using the cache), then
// expandDone is set to true in our _onEnd handler.
if ( tplExpandData.overallAsync ||
! tplExpandData.expandDone ) {
tplExpandData.overallAsync = true;
this.manager.env.dp( 'Async return from _expandTemplate for ',
tplExpandData.target );
return { async: true };
} else {
this.manager.env.dp( 'Sync return from _expandTemplate for ',
tplExpandData.target, ' : ',
tplExpandData.result
);
return tplExpandData.result;
}
};
/**
* Handle chunk emitted from the input pipeline after feeding it a template
*/
TemplateHandler.prototype._onChunk = function( tplExpandData, chunk ) {
// We encapsulate the output by default, so collect tokens here.
this.manager.env.dp( 'TemplateHandler._onChunk', chunk );
tplExpandData.resultTokens = tplExpandData.resultTokens.concat( chunk );
};
/**
* Handle the end event emitted by the parser pipeline after fully processing
* the template source.
*/
TemplateHandler.prototype._onEnd = function( tplExpandData, token ) {
this.manager.env.dp( 'TemplateHandler._onEnd', tplExpandData.resultTokens );
tplExpandData.expandDone = true;
var res = tplExpandData.resultTokens;
// Strip 'end' tokens and trailing newlines
var l = res[res.length - 1];
while ( res.length &&
( l.constructor === EOFTk || l.constructor === NlTk )
)
{
this.manager.env.dp( 'TemplateHandler, stripping end or whitespace tokens' );
res.pop();
l = res[res.length - 1];
}
// Could also encapsulate the template tokens here, if that turns out
// better for the editor.
//console.warn( 'TemplateHandler._onEnd: ' + JSON.stringify( res, null, 2 ) );
if ( tplExpandData.overallAsync ) {
this.manager.env.dp( 'TemplateHandler._onEnd: calling back with res:', res );
tplExpandData.cb( res, false, true );
} else {
this.manager.env.dp( 'TemplateHandler._onEnd: synchronous return!' );
tplExpandData.result = { tokens: res };
//data.reset();
}
};
/**
* Process a fetched template source
*/
TemplateHandler.prototype._processTemplateAndTitle = function( pipeline, src, title ) {
// Feed the pipeline. XXX: Support different formats.
this.manager.env.dp( 'TemplateHandler._processTemplateAndTitle: ', src );
pipeline.process ( src );
};
/**
* Fetch a template
*/
TemplateHandler.prototype._fetchTemplateAndTitle = function ( title, callback, tplExpandData ) {
// @fixme normalize name?
var self = this;
if ( title in this.manager.env.pageCache ) {
// Unwind the stack
process.nextTick(
function () {
callback( self.manager.env.pageCache[title], title );
}
);
} else if ( ! this.manager.env.fetchTemplates ) {
callback( 'Warning: Page/template fetching disabled, and no cache for ' +
title, title );
} else {
// We are about to start an async request for a template, so mark this
// template expansion as such.
tplExpandData.overallAsync = true;
this.manager.env.dp( 'Note: trying to fetch ', title );
// Start a new request if none is outstanding
this.manager.env.dp( 'requestQueue: ', this.manager.env.requestQueue );
if ( this.manager.env.requestQueue[title] === undefined ) {
this.manager.env.tp( 'Note: Starting new request for ' + title );
this.manager.env.requestQueue[title] = new TemplateRequest( this.manager, title );
}
// Append a listener to the request
this.manager.env.requestQueue[title].on( 'src', callback );
}
};
/*********************** Template argument expansion *******************/
/**
* Expand template arguments with tokens from the containing frame.
*/
TemplateHandler.prototype.onTemplateArg = function ( token, frame, cb ) {
token.resultTokens = false;
new AttributeTransformManager (
this.manager,
this._returnArgAttributes.bind( this, token, cb, frame )
).process( token.attribs );
if ( token.resultTokens !== false ) {
// synchronous return
//console.warn( 'synchronous attribute expand: ' + JSON.stringify( token.resultTokens ) );
return { tokens: token.resultTokens };
} else {
//console.warn( 'asynchronous attribute expand: ' + JSON.stringify( token, null, 2 ) );
// asynchronous return
token.resultTokens = [];
return { async: true };
}
};
TemplateHandler.prototype._returnArgAttributes = function ( token, cb, frame, attributes ) {
//console.warn( '_returnArgAttributes: ' + JSON.stringify( attributes ));
var argName = this.manager.env.tokensToString( attributes[0].v ).trim(),
res;
if ( argName in this.manager.args ) {
// return tokens for argument
//console.warn( 'templateArg found: ' + argName +
// ' vs. ' + JSON.stringify( this.manager.args ) );
res = this.manager.args[argName];
} else {
this.manager.env.dp( 'templateArg not found: ', argName,
' vs. ' );
if ( attributes.length > 1 ) {
res = attributes[1].v;
} else {
//console.warn('no default for ' + argName + JSON.stringify( attributes ));
res = [ '{{{' + argName + '}}}' ];
}
}
if ( token.resultTokens !== false ) {
cb( res );
} else {
token.resultTokens = res;
}
};
/***************** Template fetch request helper class ********/
function TemplateRequest ( manager, title ) {
// Increase the number of maximum listeners a bit..
this.setMaxListeners( 10000 );
var self = this,
url = manager.env.wgScript + '/api' +
manager.env.wgScriptExtension +
'?' +
qs.stringify( {
format: 'json',
action: 'query',
prop: 'revisions',
rvprop: 'content',
titles: title
} );
//'?format=json&action=query&prop=revisions&rvprop=content&titles=' + title;
request({
method: 'GET',
followRedirect: true,
url: url,
headers: {
'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64; rv:9.0.1) ' +
'Gecko/20100101 Firefox/9.0.1 Iceweasel/9.0.1'
}
},
function (error, response, body) {
//console.warn( 'response for ' + title + ' :' + body + ':' );
if(error) {
manager.env.dp(error);
self.emit('src', 'Page/template fetch failure for title ' + title, title);
} else if(response.statusCode == 200) {
var src = '',
data,
normalizedTitle;
try {
//console.warn( 'body: ' + body );
data = JSON.parse( body );
} catch(e) {
console.warn( "Error: while parsing result. Error was: " );
console.warn( e );
console.warn( "Response that didn't parse was:");
console.warn( "------------------------------------------\n" + body );
console.warn( "------------------------------------------" );
}
try {
$.each( data.query.pages, function(i, page) {
if (page.revisions && page.revisions.length) {
src = page.revisions[0]['*'];
normalizeTitle = page.title;
}
});
} catch ( e2 ) {
console.warn( 'Did not find page revisions in the returned body:' + body );
src = '';
}
//console.warn( 'Page ' + title + ': got ' + src );
manager.env.tp( 'Retrieved ' + title );
// Add the source to the cache
manager.env.pageCache[title] = src;
// Process only a few callbacks in each event loop iteration to
// reduce memory usage.
//
//
var listeners = self.listeners( 'src' );
var processSome = function () {
// Apparently dequeuing a single callback is fastest here
// XXX: experiment a bit with this!
var maxIters = Math.min(1, listeners.length);
for ( var it = 0; it < maxIters; it++ ) {
var nextListener = listeners.shift();
nextListener( src, title );
}
if ( listeners.length ) {
process.nextTick( processSome );
}
};
process.nextTick( processSome );
//processSome();
//self.emit( 'src', src, title );
}
// XXX: handle other status codes
// Remove self from request queue
manager.env.dp( 'trying to remove ', title, ' from requestQueue' );
delete manager.env.requestQueue[title];
manager.env.dp( 'after deletion:', manager.env.requestQueue );
});
}
/*
* XXX: The jQuery version does not quite work with node, but we keep
* it around for now.
$.ajax({
url: url,
data: {
format: 'json',
action: 'query',
prop: 'revisions',
rvprop: 'content',
titles: title
},
success: function(data, statusString, xhr) {
console.warn( 'Page ' + title + ' success ' + JSON.stringify( data ) );
var src = null, title = null;
$.each(data.query.pages, function(i, page) {
if (page.revisions && page.revisions.length) {
src = page.revisions[0]['*'];
title = page.title;
}
});
if (typeof src !== 'string') {
console.warn( 'Page ' + title + 'not found! Got ' + src );
callback( 'Page ' + title + ' not found' );
} else {
// Add to cache
console.warn( 'Page ' + title + ': got ' + src );
this.manager.env.pageCache[title] = src;
callback(src, title);
}
},
error: function(xhr, msg, err) {
console.warn( 'Page/template fetch failure for title ' +
title + ', url=' + url + JSON.stringify(xhr) + ', err=' + err );
callback('Page/template fetch failure for title ' + title);
},
dataType: 'json',
cache: false, // @fixme caching, versions etc?
crossDomain: true
});
*/
// Inherit from EventEmitter
TemplateRequest.prototype = new events.EventEmitter();
TemplateHandler.prototype.constructor = TemplateRequest;
if (typeof module == "object") {
module.exports.TemplateHandler = TemplateHandler;
}