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16. Resources in the OpenSCADA system (Res, ResAlloc, AutoHD)

Most of the units and subsystems of the OpenSCADA are dynamic, ie they allow the creation/deletion/configuration while the system is working. Taking into account the multi-threading of the system, this functionality imposes stringent requirements for synchronization of threads. For synchronization in the system the resources are used, functions of which are localized in the objects <Res> and <ResAlloc>. Object <Res> provides storage of the resource, providing the functions of capture/release for the read and write. In object <ResAlloc> the automatic release of the resource functions are implemented. Automatic resource involves the creation of a local resource object with its automatic release at fracture (in the destructor). Using of automatic resource makes the work with resources when using the exceptions much easier.

Ëþáîé äèíàìè÷åñêèé îáúåêò ñèñòåìû íàñëåäóåòñÿ îò îáúåêòà TCntrNode, êîòîðûé ñîäåðæèò ìåõàíèçì ïîäêëþ÷åíèÿ ÷åðåç øàáëîí AutoHD. Îñíîâíîé ôóíêöèåé øàáëîíà ÿâëÿåòñÿ õðàíåíèå ññûëêè íà îáúåêò è çàõâàò ðåñóðñà, èñêëþ÷àþùåãî óäàëåíèå îáúåêòà íà ìîìåíò èñïîëüçîâàíèÿ. Øàáëîí ïîääåðæèâàåò êîïèðîâàíèå ðåñóðñà è àâòîìàòè÷åñêîå åãî îñâîáîæäåíèå â ñëó÷àå ðàçðóøåíèÿ îáúåêòà øàáëîíà. Äëÿ íàãëÿäíîñòè äîñòóïà ê îáúåêòàì ïîðîæä¸ííûì îò TCntrNode øàáëîí AutoHD ïîääåðæèâàåò ïðèâåäåíèå òèïîâ, îñíîâàííîå íà äèíàìè÷åñêîì ïðèâåäåíèè.

16.1. Îáúåêò ðåñóðñà (Res)

Ïóáëè÷íûå ìåòîäû:

• Res( ); -- Èíèöèàëèçàöèÿ ðåñóðñà.
• static void resRequestW( long tm = 0 ); -- Çàïðîñ ðåñóðñà íà çàïèñü/ìîäèôèêàöèþ.
• static void resRequestR( long tm = 0 ); -- Çàïðîñ ðåñóðñà íà ÷òåíèå.
• static void resRelease( ); -- Îñâîáîæäåíèå ðåñóðñà.

16.2. Îáúåêò ðåñóðñà (ResAlloc)

Ïóáëè÷íûå ìåòîäû:

• ResAlloc( Res &rid ); -- Èíèöèàëèçàöèÿ àâòîìàòè÷åñêè îñâîáîæäàþùåãîñÿ ðåñóðñà äëÿ ðàíåå âûäåëåííîãî èäåíòèôèêàòîðà <rid>.
• ResAlloc( Res &rid, bool write, long tm = 0 ); -- Èíèöèàëèçàöèÿ àâòîìàòè÷åñêè îñâîáîæäàþùåãîñÿ ðåñóðñà äëÿ ðàíåå âûäåëåííîãî èäåíòèôèêàòîðà <rid>. Ñ óêàçàíèåì òèïà ðåñóðñà <write> (÷òåíèå/çàïèñü).
• void request( bool write = false, long tm = 0 ); -- Çàïðîñ ðåñóðñà â óêàçàííîì ðåæèìå <write> (÷òåíèå/çàïèñü).
• void release( ); -- Îñâîáîæäåíèå ðåñóðñà.

16.3. Øàáëîí (AutoHD)

Ïóáëè÷íûå ìåòîäû:

• AutoHD( ); -- Èíèöèàëèçàöèÿ áåç ïðèâÿçêè ê îáúåêòó.
• AutoHD( ORes *node, const string &who = "" ); -- Èíèöèàëèçàöèÿ ñ ïðèâÿçêîé ê îáúåêòó <node>. Îáúåêò äîëæåí ñîäåðæàòü ôóíêöèþ AHDConnect() è AHDDisConnect().
• AutoHD( const AutoHD &hd ); -- Êîïèðóþùèé êîíñòðóêòîð.
• template <class ORes1> AutoHD( const AutoHD<ORes1> &hd_s, bool nosafe = false ); -- Êîíñòðóêòîð ïðèâåäåíèÿ òèïîâ â áåçîïàñíîì èëè ïðÿìîì ðåæèìå ïðèâåäåíèÿ <nosafe>.
• ORes &at( ) const; -- Ïîëó÷åíèå îáúåêòà çà ðåñóðñîì.
• void operator=( const AutoHD &hd ); -- Êîïèðîâàíèå ðåñóðñîâ.
• void free( ); -- Îñâîáîæäåíèå ðåñóðñà.
• bool freeStat( ) const; -- Ïðèçíàê «Ðåñóðñ ñâîáîäåí».

16.4. Îáúåêò ñòðîêè ñ äîñòóïîì ðàçäåë¸ííûì ðåñóðñîì (ResString)

Ïóáëè÷íûå ìåòîäû:

• ResString( const string &vl = "" ); -- Èíèöèàëèçàöèÿ ñòðîêè ñ óêàçàííûì çíà÷åíèåì <vl>.
• void setVal( const string &vl ); -- Óñòàíîâêà çíà÷åíèÿ ñòðîêè â <vl>.
• const string &getVal( ); -- Ïîëó÷åíèå çíà÷åíèÿ ñòðîêè.

Ïóáëè÷íûå àòðèáóòû:

• res -- Ðåñóðñ ñòðîêè.
• str -- Ñòðîêà.