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			118 lines
		
	
	
		
			3.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			118 lines
		
	
	
		
			3.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
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/* Signal handling:
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This header file defines macros that allow your code to handle
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interrupts received during processing.  Interrupts that
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could reasonably be handled:
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SIGINT, SIGABRT, SIGALRM, SIGSEGV
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****Warning***************
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Do not allow code that creates temporary memory or increases reference
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counts of Python objects to be interrupted unless you handle it
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differently.
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**************************
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The mechanism for handling interrupts is conceptually simple:
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  - replace the signal handler with our own home-grown version
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     and store the old one.
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  - run the code to be interrupted -- if an interrupt occurs
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     the handler should basically just cause a return to the
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     calling function for finish work.
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  - restore the old signal handler
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Of course, every code that allows interrupts must account for
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returning via the interrupt and handle clean-up correctly.  But,
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even still, the simple paradigm is complicated by at least three
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factors.
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 1) platform portability (i.e. Microsoft says not to use longjmp
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     to return from signal handling.  They have a __try  and __except
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     extension to C instead but what about mingw?).
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 2) how to handle threads: apparently whether signals are delivered to
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    every thread of the process or the "invoking" thread is platform
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    dependent. --- we don't handle threads for now.
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 3) do we need to worry about re-entrance.  For now, assume the
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    code will not call-back into itself.
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Ideas:
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 1) Start by implementing an approach that works on platforms that
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    can use setjmp and longjmp functionality and does nothing
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    on other platforms.
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 2) Ignore threads --- i.e. do not mix interrupt handling and threads
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 3) Add a default signal_handler function to the C-API but have the rest
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    use macros.
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Simple Interface:
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In your C-extension: around a block of code you want to be interruptable
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with a SIGINT
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NPY_SIGINT_ON
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[code]
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NPY_SIGINT_OFF
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In order for this to work correctly, the
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[code] block must not allocate any memory or alter the reference count of any
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Python objects.  In other words [code] must be interruptible so that continuation
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after NPY_SIGINT_OFF will only be "missing some computations"
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Interrupt handling does not work well with threads.
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*/
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/* Add signal handling macros
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   Make the global variable and signal handler part of the C-API
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*/
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#ifndef NPY_INTERRUPT_H
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#define NPY_INTERRUPT_H
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#ifndef NPY_NO_SIGNAL
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#include <setjmp.h>
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#include <signal.h>
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#ifndef sigsetjmp
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#define NPY_SIGSETJMP(arg1, arg2) setjmp(arg1)
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#define NPY_SIGLONGJMP(arg1, arg2) longjmp(arg1, arg2)
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#define NPY_SIGJMP_BUF jmp_buf
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#else
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#define NPY_SIGSETJMP(arg1, arg2) sigsetjmp(arg1, arg2)
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#define NPY_SIGLONGJMP(arg1, arg2) siglongjmp(arg1, arg2)
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#define NPY_SIGJMP_BUF sigjmp_buf
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#endif
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#    define NPY_SIGINT_ON {                                             \
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                   PyOS_sighandler_t _npy_sig_save;                     \
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                   _npy_sig_save = PyOS_setsig(SIGINT, _PyArray_SigintHandler); \
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                   if (NPY_SIGSETJMP(*((NPY_SIGJMP_BUF *)_PyArray_GetSigintBuf()), \
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                                 1) == 0) {                             \
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#    define NPY_SIGINT_OFF }                                      \
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        PyOS_setsig(SIGINT, _npy_sig_save);                       \
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        }
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#else /* NPY_NO_SIGNAL  */
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#define NPY_SIGINT_ON
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#define NPY_SIGINT_OFF
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#endif /* HAVE_SIGSETJMP */
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#endif /* NPY_INTERRUPT_H */
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