/* ------------------------------------------------------------------------

 *

 * nodeCustom.c

 *    Routines to handle execution of custom scan node

 *

 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group

 * Portions Copyright (c) 1994, Regents of the University of California

 *

 * ------------------------------------------------------------------------

 */

#include "postgres.h"

#include "access/parallel.h"

#include "executor/executor.h"

#include "executor/nodeCustom.h"

#include "miscadmin.h"

#include "nodes/execnodes.h"

#include "nodes/extensible.h"

#include "nodes/plannodes.h"

#include "utils/rel.h"

static TupleTableSlot *ExecCustomScan(PlanState *pstate);

CustomScanState *

ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)

{

  CustomScanState *css;

  const TupleTableSlotOps *slotOps;

  Relation  scan_rel = NULL;

  Index   scanrelid = cscan->scan.scanrelid;

  int     tlistvarno;

  /*

   * Allocate the CustomScanState object.  We let the custom scan provider

   * do the palloc, in case it wants to make a larger object that embeds

   * CustomScanState as the first field.  It must set the node tag and the

   * methods field correctly at this time.  Other standard fields should be

   * set to zero.

   */

  css = castNode(CustomScanState,

           cscan->methods->CreateCustomScanState(cscan));

  /* ensure flags is filled correctly */

  css->flags = cscan->flags;

  /* fill up fields of ScanState */

  css->ss.ps.plan = &cscan->scan.plan;

  css->ss.ps.state = estate;

  css->ss.ps.ExecProcNode = ExecCustomScan;

  /* create expression context for node */

  ExecAssignExprContext(estate, &css->ss.ps);

  /*

   * open the scan relation, if any

   */

  if (scanrelid > 0)

  {

    scan_rel = ExecOpenScanRelation(estate, scanrelid, eflags);

    css->ss.ss_currentRelation = scan_rel;

  }

  /*

   * Use a custom slot if specified in CustomScanState or use virtual slot

   * otherwise.

   */

  slotOps = css->slotOps;

  if (!slotOps)

    slotOps = &TTSOpsVirtual;

  /*

   * Determine the scan tuple type.  If the custom scan provider provided a

   * targetlist describing the scan tuples, use that; else use base

   * relation's rowtype.

   */

  if (cscan->custom_scan_tlist != NIL || scan_rel == NULL)

  {

    TupleDesc scan_tupdesc;

    scan_tupdesc = ExecTypeFromTL(cscan->custom_scan_tlist);

    ExecInitScanTupleSlot(estate, &css->ss, scan_tupdesc, slotOps);

    /* Node's targetlist will contain Vars with varno = INDEX_VAR */

    tlistvarno = INDEX_VAR;

  }

  else

  {

    ExecInitScanTupleSlot(estate, &css->ss, RelationGetDescr(scan_rel),

                slotOps);

    /* Node's targetlist will contain Vars with varno = scanrelid */

    tlistvarno = scanrelid;

  }

  /*

   * Initialize result slot, type and projection.

   */

  ExecInitResultTupleSlotTL(&css->ss.ps, &TTSOpsVirtual);

  ExecAssignScanProjectionInfoWithVarno(&css->ss, tlistvarno);

  /* initialize child expressions */

  css->ss.ps.qual =

    ExecInitQual(cscan->scan.plan.qual, (PlanState *) css);

  /*

   * The callback of custom-scan provider applies the final initialization

   * of the custom-scan-state node according to its logic.

   */

  css->methods->BeginCustomScan(css, estate, eflags);

  return css;

}

static TupleTableSlot *

ExecCustomScan(PlanState *pstate)

{

  CustomScanState *node = castNode(CustomScanState, pstate);

  CHECK_FOR_INTERRUPTS();

  Assert(node->methods->ExecCustomScan != NULL);

  return node->methods->ExecCustomScan(node);

}

void

ExecEndCustomScan(CustomScanState *node)

{

  Assert(node->methods->EndCustomScan != NULL);

  node->methods->EndCustomScan(node);

}

void

ExecReScanCustomScan(CustomScanState *node)

{

  Assert(node->methods->ReScanCustomScan != NULL);

  node->methods->ReScanCustomScan(node);

}

void

ExecCustomMarkPos(CustomScanState *node)

{

  if (!node->methods->MarkPosCustomScan)

    ereport(ERROR,

        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

         errmsg("custom scan \"%s\" does not support MarkPos",

            node->methods->CustomName)));

  node->methods->MarkPosCustomScan(node);

}

void

ExecCustomRestrPos(CustomScanState *node)

{

  if (!node->methods->RestrPosCustomScan)

    ereport(ERROR,

        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

         errmsg("custom scan \"%s\" does not support MarkPos",

            node->methods->CustomName)));

  node->methods->RestrPosCustomScan(node);

}

void

ExecCustomScanEstimate(CustomScanState *node, ParallelContext *pcxt)

{

  const CustomExecMethods *methods = node->methods;

  if (methods->EstimateDSMCustomScan)

  {

    node->pscan_len = methods->EstimateDSMCustomScan(node, pcxt);

    shm_toc_estimate_chunk(&pcxt->estimator, node->pscan_len);

    shm_toc_estimate_keys(&pcxt->estimator, 1);

  }

}

void

ExecCustomScanInitializeDSM(CustomScanState *node, ParallelContext *pcxt)

{

  const CustomExecMethods *methods = node->methods;

  if (methods->InitializeDSMCustomScan)

  {

    int     plan_node_id = node->ss.ps.plan->plan_node_id;

    void     *coordinate;

    coordinate = shm_toc_allocate(pcxt->toc, node->pscan_len);

    methods->InitializeDSMCustomScan(node, pcxt, coordinate);

    shm_toc_insert(pcxt->toc, plan_node_id, coordinate);

  }

}

void

ExecCustomScanReInitializeDSM(CustomScanState *node, ParallelContext *pcxt)

{

  const CustomExecMethods *methods = node->methods;

  if (methods->ReInitializeDSMCustomScan)

  {

    int     plan_node_id = node->ss.ps.plan->plan_node_id;

    void     *coordinate;

    coordinate = shm_toc_lookup(pcxt->toc, plan_node_id, false);

    methods->ReInitializeDSMCustomScan(node, pcxt, coordinate);

  }

}

void

ExecCustomScanInitializeWorker(CustomScanState *node,

                 ParallelWorkerContext *pwcxt)

{

  const CustomExecMethods *methods = node->methods;

  if (methods->InitializeWorkerCustomScan)

  {

    int     plan_node_id = node->ss.ps.plan->plan_node_id;

    void     *coordinate;

    coordinate = shm_toc_lookup(pwcxt->toc, plan_node_id, false);

    methods->InitializeWorkerCustomScan(node, pwcxt->toc, coordinate);

  }

}

void

ExecShutdownCustomScan(CustomScanState *node)

{

  const CustomExecMethods *methods = node->methods;

  if (methods->ShutdownCustomScan)

    methods->ShutdownCustomScan(node);

}