www.digitalmars.com         C & C++   DMDScript  

digitalmars.D - Out-of-Memory recovery

reply bearophile <bearophileHUGS lycos.com> writes:
I have seen this:
http://dobbscodetalk.com/index.php?option=com_content&task=view&id=966

Walter (from a comment written by someone else):

A critical program, such as life support machines, flight control  systems,
etc., cannot be allowed to fail.<

Such software most probably works with a fixed amount of memory (or at compile time it's known the maximum amount of memory required), so that's not an example where recovering from out-of-bound errors is important.
The memory manager can have user supplied callbacks to release memory in such
cases.<

This is interesting. What's a possible API/semantics for such thing? Bye, bearophile
Jan 03 2009
parent Jason House <jason.james.house gmail.com> writes:
bearophile wrote:

 I have seen this:
 http://dobbscodetalk.com/index.php?option=com_content&task=view&id=966
 
 Walter (from a comment written by someone else):
 
A critical program, such as life support machines, flight control 
systems, etc., cannot be allowed to fail.<

Such software most probably works with a fixed amount of memory (or at compile time it's known the maximum amount of memory required), so that's not an example where recovering from out-of-bound errors is important.

That's a good point :)
The memory manager can have user supplied callbacks to release memory in
such cases.<

This is interesting. What's a possible API/semantics for such thing?

Based on what I see in the docs for core.memory, I'd envision something like the following: // Sample allocation logic void* allocate(int nBytes){ void* result = null; if (tryAllocate(nBytes, &result)) return result; onSoftOutOfMemory(); if (tryAllocate(nBytes, &result)) return result; onHardOutOfMemory(); } // Default handlers for out of memory void onSoftOutOfMemory(){ foreach(callback; registeredOutOfMemoryHandlers) callback(); GC.collect(); } void onHardOutOfMemory(){ abort(-1); } // Exposed functions to use this new functionality void addOutOfMemoryHandler(void function () callback); void addOutOfMemoryHandler(void delegate () callback); void removeOutOfMemoryHandler(void function () callback); void removeOutOfMemoryHandler(void delegate () callback); Theoretically, onHardOutOfMemory could be replaced with a version that throws for those who believe they can't live without it.
 
 Bye,
 bearophile

Jan 04 2009