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Make execution of plpython interruptible #7

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Make execution of plpython interruptible #7

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49 changes: 49 additions & 0 deletions src/pl/plpython/plpy_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -74,13 +74,19 @@ PyObject *PLy_interp_globals = NULL;
/* this doesn't need to be global; use PLy_current_execution_context() */
static PLyExecutionContext *PLy_execution_contexts = NULL;

/* postgres backend handler for interruption */
static pqsigfunc coreIntHandler = 0;
static void PLy_handle_interrupt(int sig);

void
_PG_init(void)
{
int **bitmask_ptr;
const int **version_ptr;

/* Catch and process SIGINT signals */
coreIntHandler = pqsignal(SIGINT, PLy_handle_interrupt);

/*
* Set up a shared bitmask variable telling which Python version(s) are
* loaded into this process's address space. If there's more than one, we
Expand Down Expand Up @@ -425,6 +431,9 @@ PLy_current_execution_context(void)
return PLy_execution_contexts;
}

/* Indicate tha a python interruption is pending */
static int PLy_pending_interrupt = 0;

static PLyExecutionContext *
PLy_push_execution_context(void)
{
Expand All @@ -451,6 +460,46 @@ PLy_pop_execution_context(void)

PLy_execution_contexts = context->next;

if (PLy_execution_contexts == NULL) {
// Clear pending interrupts when top level context exits
PLy_pending_interrupt = 0;
}

MemoryContextDelete(context->scratch_ctx);
PLy_free(context);
}

void
_PG_fini(void)
{
// Restore previous SIGINT handler
pqsignal(SIGINT, coreIntHandler);
}

static int
PLy_python_interruption_handler()
{
if (!PLy_pending_interrupt) {
return 0;
}

PLy_pending_interrupt = 0;
PyErr_SetString(PyExc_RuntimeError, "Execution of function interrupted by signal");
return -1;
}

static void
PLy_handle_interrupt(int sig)
{
if (PLy_execution_contexts != NULL && !PLy_pending_interrupt) {
PLy_pending_interrupt = 1;
Py_AddPendingCall(PLy_python_interruption_handler, NULL);
}
// Fallback to execute prior handlers
if (coreIntHandler != SIG_DFL && coreIntHandler != SIG_IGN) {
// There's a catch here: if the prior handler was SIG_DFL we have no easy way
// of invoking it here;
// As that's an unlikely situation we'll just treat SIG_DFL as SIG_IGN.
(*coreIntHandler)(sig);
}
}