OpenSCADAWiki: Home Page En/Doc/API/part16 ...

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.

Any dynamic system object is inherited from TCntrNode object, which contains a mechanism to connect via the AutoHD template. The main function of the template is to store the link to the object and the capture of the resource, excluding the deleting of the object at the time of use. Template supports copying the resource and its release in case of destruction of the template object. For clarity of the access to the objects generated by TCntrNode the AutoHD template supports casting, based on the dynamic cast.

16.1. Resource object (Res)

Public methods:

• 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.