CODEWITHSUNDEEP
multithreadingconcurrencyadamemory-model
Max
Max

Reputation: 691

Did Ada83 or Ada95 define a memory model to support multitasking?

With the "recent" changes to C and C++ adding memory models (similar to Java and C#), I was wondering whether Ada83 or Ada95 inbuilt support for concurrency also defined a memory model.

Does anybody know of any references about whether Ada defined a memory model?

Bonus question: was Ada83 the first general programming language to offer INBUILT support for shared-state concurrency?

Upvotes: 2

Views: 369

Answers (2)

user571138
user571138

Reputation:

Regarding Tasking & Shared memory, I think you should be looking at Protected Types. For concurrency this allows different threads (tasks) to share a resource without the need for explicit mutexes.

Upvotes: 2

Simon Wright
Simon Wright

Reputation: 25501

I think the nearest to a memory model in the sense you're asking about is the Dynamic Semantics section of the ARM.

Ada 83 had pragma Shared.

Ada 95 replaced this with pragmas Atomic, Volatile, Atomic_Components, and Volatile_Components; Ada 2005 was the same with (in a Correction) pragmas Independent and Independent_Components (that is, the referenced object, or each of its components, is independently addressable).

Ada 2012 replaces the pragmas with aspects, for good but not immediately relevant reasons:

Imported_Variable : Integer with
  Import, Convention => C, External_Name => "exported_variable", Volatile;

Upvotes: 5

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