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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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