plpy_exec.h File Reference

#include "plpy_procedure.h"

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Functions
Datum	PLy_exec_function (FunctionCallInfo fcinfo, PLyProcedure *proc)
HeapTuple	PLy_exec_trigger (FunctionCallInfo fcinfo, PLyProcedure *proc)

Function Documentation

PLy_exec_function()

Datum PLy_exec_function	(	FunctionCallInfo	fcinfo,
		PLyProcedure *	proc
	)

Definition at line 55 of file plpy_exec.c.

{
    bool        is_setof = proc->is_setof;
    Datum       rv;
    PyObject   *volatile plargs = NULL;
    PyObject   *volatile plrv = NULL;
    FuncCallContext *volatile funcctx = NULL;
    PLySRFState *volatile srfstate = NULL;
    ErrorContextCallback plerrcontext;
 
    /*
     * If the function is called recursively, we must push outer-level
     * arguments into the stack.  This must be immediately before the PG_TRY
     * to ensure that the corresponding pop happens.
     */
    PLy_global_args_push(proc);
 
    PG_TRY();
    {
        if (is_setof)
        {
            /* First Call setup */
            if (SRF_IS_FIRSTCALL())
            {
                funcctx = SRF_FIRSTCALL_INIT();
                srfstate = (PLySRFState *)
                    MemoryContextAllocZero(funcctx->multi_call_memory_ctx,
                                           sizeof(PLySRFState));
                /* Immediately register cleanup callback */
                srfstate->callback.func = plpython_srf_cleanup_callback;
                srfstate->callback.arg = (void *) srfstate;
                MemoryContextRegisterResetCallback(funcctx->multi_call_memory_ctx,
                                                   &srfstate->callback);
                funcctx->user_fctx = (void *) srfstate;
            }
            /* Every call setup */
            funcctx = SRF_PERCALL_SETUP();
            Assert(funcctx != NULL);
            srfstate = (PLySRFState *) funcctx->user_fctx;
            Assert(srfstate != NULL);
        }
 
        if (srfstate == NULL || srfstate->iter == NULL)
        {
            /*
             * Non-SETOF function or first time for SETOF function: build
             * args, then actually execute the function.
             */
            plargs = PLy_function_build_args(fcinfo, proc);
            plrv = PLy_procedure_call(proc, "args", plargs);
            Assert(plrv != NULL);
        }
        else
        {
            /*
             * Second or later call for a SETOF function: restore arguments in
             * globals dict to what they were when we left off.  We must do
             * this in case multiple evaluations of the same SETOF function
             * are interleaved.  It's a bit annoying, since the iterator may
             * not look at the arguments at all, but we have no way to know
             * that.  Fortunately this isn't terribly expensive.
             */
            if (srfstate->savedargs)
                PLy_function_restore_args(proc, srfstate->savedargs);
            srfstate->savedargs = NULL; /* deleted by restore_args */
        }
 
        /*
         * If it returns a set, call the iterator to get the next return item.
         * We stay in the SPI context while doing this, because PyIter_Next()
         * calls back into Python code which might contain SPI calls.
         */
        if (is_setof)
        {
            if (srfstate->iter == NULL)
            {
                /* first time -- do checks and setup */
                ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
 
                if (!rsi || !IsA(rsi, ReturnSetInfo) ||
                    (rsi->allowedModes & SFRM_ValuePerCall) == 0)
                {
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("unsupported set function return mode"),
                             errdetail("PL/Python set-returning functions only support returning one value per call.")));
                }
                rsi->returnMode = SFRM_ValuePerCall;
 
                /* Make iterator out of returned object */
                srfstate->iter = PyObject_GetIter(plrv);
 
                Py_DECREF(plrv);
                plrv = NULL;
 
                if (srfstate->iter == NULL)
                    ereport(ERROR,
                            (errcode(ERRCODE_DATATYPE_MISMATCH),
                             errmsg("returned object cannot be iterated"),
                             errdetail("PL/Python set-returning functions must return an iterable object.")));
            }
 
            /* Fetch next from iterator */
            plrv = PyIter_Next(srfstate->iter);
            if (plrv == NULL)
            {
                /* Iterator is exhausted or error happened */
                bool        has_error = (PyErr_Occurred() != NULL);
 
                Py_DECREF(srfstate->iter);
                srfstate->iter = NULL;
 
                if (has_error)
                    PLy_elog(ERROR, "error fetching next item from iterator");
 
                /* Pass a null through the data-returning steps below */
                Py_INCREF(Py_None);
                plrv = Py_None;
            }
            else
            {
                /*
                 * This won't be last call, so save argument values.  We do
                 * this again each time in case the iterator is changing those
                 * values.
                 */
                srfstate->savedargs = PLy_function_save_args(proc);
            }
        }
 
        /*
         * Disconnect from SPI manager and then create the return values datum
         * (if the input function does a palloc for it this must not be
         * allocated in the SPI memory context because SPI_finish would free
         * it).
         */
        if (SPI_finish() != SPI_OK_FINISH)
            elog(ERROR, "SPI_finish failed");
 
        plerrcontext.callback = plpython_return_error_callback;
        plerrcontext.previous = error_context_stack;
        error_context_stack = &plerrcontext;
 
        /*
         * For a procedure or function declared to return void, the Python
         * return value must be None. For void-returning functions, we also
         * treat a None return value as a special "void datum" rather than
         * NULL (as is the case for non-void-returning functions).
         */
        if (proc->result.typoid == VOIDOID)
        {
            if (plrv != Py_None)
            {
                if (proc->is_procedure)
                    ereport(ERROR,
                            (errcode(ERRCODE_DATATYPE_MISMATCH),
                             errmsg("PL/Python procedure did not return None")));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_DATATYPE_MISMATCH),
                             errmsg("PL/Python function with return type \"void\" did not return None")));
            }
 
            fcinfo->isnull = false;
            rv = (Datum) 0;
        }
        else if (plrv == Py_None &&
                 srfstate && srfstate->iter == NULL)
        {
            /*
             * In a SETOF function, the iteration-ending null isn't a real
             * value; don't pass it through the input function, which might
             * complain.
             */
            fcinfo->isnull = true;
            rv = (Datum) 0;
        }
        else
        {
            /* Normal conversion of result */
            rv = PLy_output_convert(&proc->result, plrv,
                                    &fcinfo->isnull);
        }
    }
    PG_CATCH();
    {
        /* Pop old arguments from the stack if they were pushed above */
        PLy_global_args_pop(proc);
 
        Py_XDECREF(plargs);
        Py_XDECREF(plrv);
 
        /*
         * If there was an error within a SRF, the iterator might not have
         * been exhausted yet.  Clear it so the next invocation of the
         * function will start the iteration again.  (This code is probably
         * unnecessary now; plpython_srf_cleanup_callback should take care of
         * cleanup.  But it doesn't hurt anything to do it here.)
         */
        if (srfstate)
        {
            Py_XDECREF(srfstate->iter);
            srfstate->iter = NULL;
            /* And drop any saved args; we won't need them */
            if (srfstate->savedargs)
                PLy_function_drop_args(srfstate->savedargs);
            srfstate->savedargs = NULL;
        }
 
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    error_context_stack = plerrcontext.previous;
 
    /* Pop old arguments from the stack if they were pushed above */
    PLy_global_args_pop(proc);
 
    Py_XDECREF(plargs);
    Py_DECREF(plrv);
 
    if (srfstate)
    {
        /* We're in a SRF, exit appropriately */
        if (srfstate->iter == NULL)
        {
            /* Iterator exhausted, so we're done */
            SRF_RETURN_DONE(funcctx);
        }
        else if (fcinfo->isnull)
            SRF_RETURN_NEXT_NULL(funcctx);
        else
            SRF_RETURN_NEXT(funcctx, rv);
    }
 
    /* Plain function, just return the Datum value (possibly null) */
    return rv;
}

References ReturnSetInfo::allowedModes, MemoryContextCallback::arg, Assert, ErrorContextCallback::callback, PLySRFState::callback, elog, ereport, errcode(), errdetail(), errmsg(), ERROR, error_context_stack, MemoryContextCallback::func, if(), PLyProcedure::is_procedure, PLyProcedure::is_setof, IsA, FunctionCallInfoBaseData::isnull, PLySRFState::iter, MemoryContextAllocZero(), MemoryContextRegisterResetCallback(), FuncCallContext::multi_call_memory_ctx, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, plpython_return_error_callback(), plpython_srf_cleanup_callback(), PLy_elog, PLy_function_build_args(), PLy_function_drop_args(), PLy_function_restore_args(), PLy_function_save_args(), PLy_global_args_pop(), PLy_global_args_push(), PLy_output_convert(), PLy_procedure_call(), ErrorContextCallback::previous, PLyProcedure::result, FunctionCallInfoBaseData::resultinfo, ReturnSetInfo::returnMode, PLySRFState::savedargs, SFRM_ValuePerCall, SPI_finish(), SPI_OK_FINISH, SRF_FIRSTCALL_INIT, SRF_IS_FIRSTCALL, SRF_PERCALL_SETUP, SRF_RETURN_DONE, SRF_RETURN_NEXT, SRF_RETURN_NEXT_NULL, PLyObToDatum::typoid, and FuncCallContext::user_fctx.

Referenced by plpython3_call_handler(), and plpython3_inline_handler().

PLy_exec_trigger()

HeapTuple PLy_exec_trigger	(	FunctionCallInfo	fcinfo,
		PLyProcedure *	proc
	)

Definition at line 305 of file plpy_exec.c.

{
    HeapTuple   rv = NULL;
    PyObject   *volatile plargs = NULL;
    PyObject   *volatile plrv = NULL;
    TriggerData *tdata;
    TupleDesc   rel_descr;
 
    Assert(CALLED_AS_TRIGGER(fcinfo));
    tdata = (TriggerData *) fcinfo->context;
 
    /*
     * Input/output conversion for trigger tuples.  We use the result and
     * result_in fields to store the tuple conversion info.  We do this over
     * again on each call to cover the possibility that the relation's tupdesc
     * changed since the trigger was last called.  The PLy_xxx_setup_func
     * calls should only happen once, but PLy_input_setup_tuple and
     * PLy_output_setup_tuple are responsible for not doing repetitive work.
     */
    rel_descr = RelationGetDescr(tdata->tg_relation);
    if (proc->result.typoid != rel_descr->tdtypeid)
        PLy_output_setup_func(&proc->result, proc->mcxt,
                              rel_descr->tdtypeid,
                              rel_descr->tdtypmod,
                              proc);
    if (proc->result_in.typoid != rel_descr->tdtypeid)
        PLy_input_setup_func(&proc->result_in, proc->mcxt,
                             rel_descr->tdtypeid,
                             rel_descr->tdtypmod,
                             proc);
    PLy_output_setup_tuple(&proc->result, rel_descr, proc);
    PLy_input_setup_tuple(&proc->result_in, rel_descr, proc);
 
    PG_TRY();
    {
        int         rc PG_USED_FOR_ASSERTS_ONLY;
 
        rc = SPI_register_trigger_data(tdata);
        Assert(rc >= 0);
 
        plargs = PLy_trigger_build_args(fcinfo, proc, &rv);
        plrv = PLy_procedure_call(proc, "TD", plargs);
 
        Assert(plrv != NULL);
 
        /*
         * Disconnect from SPI manager
         */
        if (SPI_finish() != SPI_OK_FINISH)
            elog(ERROR, "SPI_finish failed");
 
        /*
         * return of None means we're happy with the tuple
         */
        if (plrv != Py_None)
        {
            char       *srv;
 
            if (PyUnicode_Check(plrv))
                srv = PLyUnicode_AsString(plrv);
            else
            {
                ereport(ERROR,
                        (errcode(ERRCODE_DATA_EXCEPTION),
                         errmsg("unexpected return value from trigger procedure"),
                         errdetail("Expected None or a string.")));
                srv = NULL;     /* keep compiler quiet */
            }
 
            if (pg_strcasecmp(srv, "SKIP") == 0)
                rv = NULL;
            else if (pg_strcasecmp(srv, "MODIFY") == 0)
            {
                if (TRIGGER_FIRED_BY_INSERT(tdata->tg_event) ||
                    TRIGGER_FIRED_BY_UPDATE(tdata->tg_event))
                    rv = PLy_modify_tuple(proc, plargs, tdata, rv);
                else
                    ereport(WARNING,
                            (errmsg("PL/Python trigger function returned \"MODIFY\" in a DELETE trigger -- ignored")));
            }
            else if (pg_strcasecmp(srv, "OK") != 0)
            {
                /*
                 * accept "OK" as an alternative to None; otherwise, raise an
                 * error
                 */
                ereport(ERROR,
                        (errcode(ERRCODE_DATA_EXCEPTION),
                         errmsg("unexpected return value from trigger procedure"),
                         errdetail("Expected None, \"OK\", \"SKIP\", or \"MODIFY\".")));
            }
        }
    }
    PG_FINALLY();
    {
        Py_XDECREF(plargs);
        Py_XDECREF(plrv);
    }
    PG_END_TRY();
 
    return rv;
}

References Assert, CALLED_AS_TRIGGER, FunctionCallInfoBaseData::context, elog, ereport, errcode(), errdetail(), errmsg(), ERROR, PLyProcedure::mcxt, PG_END_TRY, PG_FINALLY, pg_strcasecmp(), PG_TRY, PG_USED_FOR_ASSERTS_ONLY, PLy_input_setup_func(), PLy_input_setup_tuple(), PLy_modify_tuple(), PLy_output_setup_func(), PLy_output_setup_tuple(), PLy_procedure_call(), PLy_trigger_build_args(), PLyUnicode_AsString(), RelationGetDescr, PLyProcedure::result, PLyProcedure::result_in, SPI_finish(), SPI_OK_FINISH, SPI_register_trigger_data(), TupleDescData::tdtypeid, TupleDescData::tdtypmod, TriggerData::tg_event, TriggerData::tg_relation, TRIGGER_FIRED_BY_INSERT, TRIGGER_FIRED_BY_UPDATE, PLyDatumToOb::typoid, PLyObToDatum::typoid, and WARNING.

Referenced by plpython3_call_handler().