From 1c8c477a5814420011fa034323e82d8eabc6bc5f Mon Sep 17 00:00:00 2001 From: Craig Ringer Date: Mon, 18 Jan 2021 14:14:46 +0800 Subject: [PATCH v1 1/4] Provide a hook for ProcessInterrupts() Code may now register a ProcessInterrupts_hook to fire its own logic before and/or after the main ProcessInterrupts handler for signal processing. The hook must call standard_ProcessInterrupts to execute the normal interrupt handling or set InterruptsPending to true to cause the interrupt to be re-processed at the next opportunity. This follows the consistent pattern used by other PostgreSQL hooks like the ProcessUtility_hook and standard_ProcessUtility() function. The purpose of this hook is to allow extensions to react to their own custom interrupt flags during CHECK_FOR_INTERRUPTS() calls invoked in main PostgreSQL code paths. --- src/backend/tcop/postgres.c | 20 ++++++++++++++++++++ src/include/miscadmin.h | 3 +++ 2 files changed, 23 insertions(+) diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 28055680aa..8cf1359e33 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -102,6 +102,8 @@ int max_stack_depth = 100; /* wait N seconds to allow attach from a debugger */ int PostAuthDelay = 0; +/* Intercept CHECK_FOR_INTERRUPTS() responses */ +ProcessInterrupts_hook_type ProcessInterrupts_hook = NULL; /* ---------------- @@ -3064,8 +3066,26 @@ ProcessInterrupts(void) /* OK to accept any interrupts now? */ if (InterruptHoldoffCount != 0 || CritSectionCount != 0) return; + InterruptPending = false; + if (ProcessInterrupts_hook) + ProcessInterrupts_hook(); + else + standard_ProcessInterrupts(); +} + +/* + * Implement the default signal handling behaviour for most backend types + * including user backends and bgworkers. + * + * This is where CHECK_FOR_INTERRUPTS() eventually lands up unless intercepted + * by ProcessInterrupts_hook. + */ +void +standard_ProcessInterrupts(void) +{ + if (ProcDiePending) { ProcDiePending = false; diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h index 1bdc97e308..f082d04448 100644 --- a/src/include/miscadmin.h +++ b/src/include/miscadmin.h @@ -94,6 +94,9 @@ extern PGDLLIMPORT volatile uint32 CritSectionCount; /* in tcop/postgres.c */ extern void ProcessInterrupts(void); +typedef void (*ProcessInterrupts_hook_type)(void); +extern ProcessInterrupts_hook_type ProcessInterrupts_hook; +extern void standard_ProcessInterrupts(void); #ifndef WIN32 -- 2.29.2