Adblock plus規則管理類FilterManager

Adblock plus的文檔

http://adblockplus.org/en/documentation

這裡介紹了很多資訊，其中

http://adblockplus.org/en/faq_internal#filters

介紹了如何快速查找規則，我也按照這種方式實作了一個HashMap來管理這些規則，

#ifndef FILTERMANAGER_H

#define FILTERMANAGER_H

#include "PlatformString.h"

#include <wtf/Vector.h>

#include "StringHash.h"

#include <wtf/HashMap.h>

#include <wtf/HashSet.h>

#include "KURL.h"

//#define ADB_NO_QT_DEBUG

namespace WebCore {

       /*

     比對類型，目前暫時隻支援，script，image，stylesheet，以及third_party,

        */

       #define FILTER_TYPE_SCRIPT 0x0001

       #define FILTER_TYPE_IMAGE 0X0002

       #define FILTER_TYPE_BACKGROUND 0x0004

       #define FILTER_TYPE_STYLESHEET 0X0008

       #define FILTER_TYPE_OBJECT 0X0010

       #define FILTER_TYPE_XBL 0X0020 //不會支援

       #define FILTER_TYPE_PING 0X0040

       #define FILTER_TYPE_XMLHTTPREQUEST 0x0080

       #define FILTER_TYPE_OBJECT_SUBREQUEST 0X0100

       #define FILTER_TYPE_DTD 0X0200

       #define FILTER_TYPE_SUBDOCUMENT 0X0400

       #define FILTER_TYPE_DOCUMENT 0X0800

       #define FILTER_TYPE_ELEMHIDE 0X1000

       #define FILTER_TYPE_THIRD_PARTY 0x2000

//     #define FILTER_TYPE_DOMAIN 0X4000

//     #define FILTER_TYPE_MATCH_CASE 0X8000

//     #define FILTER_TYPE_COLLAPSE 0x10000

       typedef unsigned int FilterType;

       typedef Vector<String> StringVector;

       class FilterRule;

       class HideRule;

       class FilterRuleList;

       class HideRuleList;

       //隻應該有一個執行個體,

        這裡需要考慮的是保證該類是多線程安全的，正常查詢可以保證

        隻是動态删除以及添加時如何保證多線程安全,内部适用map來管理各種規則

        或者hash來管理。

       class FilterManager {

              //typedef HashMap<String,FilterRuleList* , CaseFoldingHash

> FilterRuleMap;

              typedef HashMap<String,HideRuleList* ,CaseFoldingHash>

HideRuleMap;

              typedef Vector<FilterRule *> FilterRuleVector;

              class FilterRuleMap: public HashMap<String,FilterRuleList*

, CaseFoldingHash > {

            HashSet<unsigned int > unMatchRules;

              public:

                     ~FilterRuleMap();

             //prepare to start find

            inline void prepareStartFind() { this->unMatchRules.clear();}

            // release resource

            //inline void endFind() {}

            bool doFilter(const KURL & mainURL,const

String & key,const KURL & url,FilterType t);

              };

       private:

              HideRuleMap hiderules;

              FilterRuleMap m_ShortcutWhiteRules; //white list, can use

shortcut

              FilterRuleVector m_UnshortcutWhiteRules;

              FilterRuleMap m_ShortcutFilterRules;

              FilterRuleVector m_UnshortcutFilterRules;

              FilterRuleVector m_AllFilterRules;

              Vector<HideRule * > m_AllHideRules;

              /*

               從檔案讀取規則,string要是有qt的隐含共享就好了，webkit使用的string

               就是隐含共享，可以直接傳值

               */

              FilterManager(const String & filename);

              //規則集合

              FilterManager(const StringVector & rules);

       public:

              static FilterManager* getManager(const String & filename);

              static FilterManager * getManager(const StringVector &

rules);

              ~FilterManager();

              bool addRule(String rule);

              //哪個規則，運作時不能隐藏，隻能删除

              bool hideRule(int id);

               是否應該過濾,

               目前暫不考慮類型比對，因為類型資訊無法擷取

               因為很多規則無法明确知道，比如background，必須來自css的請求，目前無法确知

               * Besides of translating

filters into regular expressions Adblock Plus also

tries to extract text information

from them. What it needs is a unique

string of eight characters (a “shortcut”)

that must be present in every

address matched by the filter (the

length is arbitrary, eight just seems

reasonable here). For example, if

you have a filter |http://ad.* then

Adblock Plus has the choice between

“http://a”, “ttp://ad” and “tp://ad.”,

any of these strings will always

be present in whatever this filter will

match. Unfortunately finding a shortcut

for filters that simply don’t have

eight characters unbroken by wildcards

or for filters that have been

specified as regular expressions

is impossible.

All shortcuts are put into a lookup

table, Adblock Plus can find the filter

by its shortcut very efficiently.

Then, when a specific address has to be

tested Adblock Plus will first look

for known shortcuts there (this can be

done very fast, the time needed

is almost independent from the number of

shortcuts). Only when a shortcut

is found the string will be tested against

the regular expression of the corresponding

filter. However, filters

without a shortcut still have to

be tested one after another which is slow.

To sum up: which filters should

be used to make a filter list fast? You

should use as few regular expressions

as possible, those are always slow.

You also should make sure that simple

filters have at least eight

characters of unbroken text (meaning

that these don’t contain any

characters with a special meaning

like *), otherwise they will be just as

slow as regular expressions. But

with filters that qualify it doesn’t

matter how many filters you have,

the processing time is always the same.

That means that if you need 20 simple

filters to replace one regular

expression then it is still worth

it. Speaking of which — the deregifier is

very recommendable.

        bool shouldFilter(const KURL & mainURL,const

KURL & url, FilterType t=0);

              //使用webkit内部的指針管理辦法來管理傳回值？

              //根據域名來确定适用的css規則，如果不支援的css規則，暫時忽略.

              String cssrules(const String & domain);

              void addRule(FilterRule * r);

              void addRule(HideRule * r);

       };

}

#endif // FILTERMANAGER_H