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IPDL/Getting started: Difference between revisions
Ctor/dtor declarations must be in IPDL for managing protocol.
(Clarified the behaviour of blocking actors) |
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The second new statement is a "manages statement." Here we declare that the Plugin protocol manages the PluginInstance protocol (which is defined in the included "PluginInstance.ipdl" specification). This means that the Plugin protocol must provide a "constructor" and "destructor" for PluginInstance actors; these are akin to factory methods. The "manages" statement also means that PluginInstance actors are tied to the lifetime of the Plugin actor that creates them --- that is, once the Plugin actor dies, all the PluginInstances become invalid. | The second new statement is a "manages statement." Here we declare that the Plugin protocol manages the PluginInstance protocol (which is defined in the included "PluginInstance.ipdl" specification). This means that the Plugin protocol must provide a "constructor" and "destructor" for PluginInstance actors; these are akin to factory methods. The "manages" statement also means that PluginInstance actors are tied to the lifetime of the Plugin actor that creates them --- that is, once the Plugin actor dies, all the PluginInstances become invalid. | ||
The third and fourth new statements are "constructor" and "destructor" message declarations. The syntax was borrowed from C++, but the semantics are | The third and fourth new statements are "constructor" and "destructor" message declarations. The syntax was borrowed from C++, but the semantics are different. The first difference is that constructors and destructors have a direction, like other IPDL messages. They also can have arbitrary parameters and return values, and can additionally have any IPDL messaging semantics. Take our word that this is useful; the reason that constructors and destructors behave like other messages will be explained below. | ||
Managed protocols require constructor and destructor declarations. The IPDL compiler ensures this. The constructor declaration for a managed protocol must appear in the managing protocol's IPDL file. Similarly for the destructor declaration. | |||
Constructors and destructors turn into C++ interface methods that are almost the same as other IPDL interface methods generated for message declarations, with one notable exception: the implementing C++ class must provide actual methods for allocating and deallocating the sub-protocol actors. This is shown below. | Constructors and destructors turn into C++ interface methods that are almost the same as other IPDL interface methods generated for message declarations, with one notable exception: the implementing C++ class must provide actual methods for allocating and deallocating the sub-protocol actors. This is shown below. | ||