Hello, On Fri, Dec 22, 2017 at 03:05:25PM +0300, Maksim Milyutin wrote: > Hi, hackers! > > > I want to propose the patch that allows to define custom signals and their > handlers on extension side. >
I've looked a little bit on the patch. The patch applyes and regression tests pass. I have a couple comments. > The relationship between custom signals and > assigned handlers (function addresses) is replicated from postmaster to > child processes including working backends. I think this happens only if a custom signal registered during initializing shared_preload_libraries. But from RegisterCustomProcSignalHandler()'s implementation I see that you can register the signal anytime. Am I wrong? If so then custom signal handlers may not work as expected. What is purpose of AssignCustomProcSignalHandler() function? This function can erase a handler set by another extension. For example, extension 1 set handler passing reason PROCSIG_CUSTOM_1, and extension 2 set another handler passing reason PROCSIG_CUSTOM_1 too. Here the handler of the extension 2 will be purged. > + > + Assert(reason >= PROCSIG_CUSTOM_1 && reason <= PROCSIG_CUSTOM_N); > + I think it is not good to use asserts within AssignCustomProcSignalHandler() and GetCustomProcSignalHandler(). Because this functions can be executed by an external extension, and it may pass a reason outside this boundary. It will be better if the reason will be checked in runtime. But it is fine for this assert within CustomSignalInterrupt(). -- Arthur Zakirov Postgres Professional: http://www.postgrespro.com Russian Postgres Company
