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8.1.6.2 Shared and Protected Objects

In the code below, we define two kinds of shared objects. External_Synchronization requires that the different partitions updating this data synchronize to avoid conflicting operations on shared objects. Internal_Synchronization provides a way to get an atomic operation on shared objects. Note that only entryless protected types are allowed in a shared passive unit; synchronization must be done with protected procedures.

     
     package SharedObjects is
        pragma Shared_Passive;
     
        Max : Positive := 10;
        type Index_Type is range 1 .. Max;
        type Rate_Type is new Float;
     
        type Rates_Type is array (Index_Type) of Rate_Type;
     
        External_Synchronization : Rates_Type;
     
        protected Internal_Synchronization is
           procedure Set
             (Index : in Index_Type;
              Rate  : in Rate_Type);
     
           procedure Get
             (Index : in Index_Type;
              Rate  : out Rate_Type);
        private
        --  implementation removed
     end SharedObjects;