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

 *

 * walsummaryfuncs.c

 *    SQL-callable functions for accessing WAL summary data.

 *

 * Portions Copyright (c) 2010-2025, PostgreSQL Global Development Group

 *

 * src/backend/backup/walsummaryfuncs.c

 *

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

 */

#include "postgres.h"

#include "backup/walsummary.h"

#include "common/blkreftable.h"

#include "funcapi.h"

#include "miscadmin.h"

#include "postmaster/walsummarizer.h"

#include "utils/fmgrprotos.h"

#include "utils/pg_lsn.h"

#define NUM_WS_ATTS     3

#define NUM_SUMMARY_ATTS  6

#define NUM_STATE_ATTS    4

#define MAX_BLOCKS_PER_CALL 256

/*

 * List the WAL summary files available in pg_wal/summaries.

 */

Datum

pg_available_wal_summaries(PG_FUNCTION_ARGS)

{

  ReturnSetInfo *rsi;

  List     *wslist;

  ListCell   *lc;

  Datum   values[NUM_WS_ATTS];

  bool    nulls[NUM_WS_ATTS];

  InitMaterializedSRF(fcinfo, 0);

  rsi = (ReturnSetInfo *) fcinfo->resultinfo;

  memset(nulls, 0, sizeof(nulls));

  wslist = GetWalSummaries(0, InvalidXLogRecPtr, InvalidXLogRecPtr);

  foreach(lc, wslist)

  {

    WalSummaryFile *ws = (WalSummaryFile *) lfirst(lc);

    HeapTuple tuple;

    CHECK_FOR_INTERRUPTS();

    values[0] = Int64GetDatum((int64) ws->tli);

    values[1] = LSNGetDatum(ws->start_lsn);

    values[2] = LSNGetDatum(ws->end_lsn);

    tuple = heap_form_tuple(rsi->setDesc, values, nulls);

    tuplestore_puttuple(rsi->setResult, tuple);

  }

  return (Datum) 0;

}

/*

 * List the contents of a WAL summary file identified by TLI, start LSN,

 * and end LSN.

 */

Datum

pg_wal_summary_contents(PG_FUNCTION_ARGS)

{

  ReturnSetInfo *rsi;

  Datum   values[NUM_SUMMARY_ATTS];

  bool    nulls[NUM_SUMMARY_ATTS];

  WalSummaryFile ws;

  WalSummaryIO io;

  BlockRefTableReader *reader;

  int64   raw_tli;

  RelFileLocator rlocator;

  ForkNumber  forknum;

  BlockNumber limit_block;

  InitMaterializedSRF(fcinfo, 0);

  rsi = (ReturnSetInfo *) fcinfo->resultinfo;

  memset(nulls, 0, sizeof(nulls));

  /*

   * Since the timeline could at least in theory be more than 2^31, and

   * since we don't have unsigned types at the SQL level, it is passed as a

   * 64-bit integer. Test whether it's out of range.

   */

  raw_tli = PG_GETARG_INT64(0);

  if (raw_tli < 1 || raw_tli > PG_INT32_MAX)

    ereport(ERROR,

        errcode(ERRCODE_INVALID_PARAMETER_VALUE),

        errmsg("invalid timeline %" PRId64, raw_tli));

  /* Prepare to read the specified WAL summary file. */

  ws.tli = (TimeLineID) raw_tli;

  ws.start_lsn = PG_GETARG_LSN(1);

  ws.end_lsn = PG_GETARG_LSN(2);

  io.filepos = 0;

  io.file = OpenWalSummaryFile(&ws, false);

  reader = CreateBlockRefTableReader(ReadWalSummary, &io,

                     FilePathName(io.file),

                     ReportWalSummaryError, NULL);

  /* Loop over relation forks. */

  while (BlockRefTableReaderNextRelation(reader, &rlocator, &forknum,

                       &limit_block))

  {

    BlockNumber blocks[MAX_BLOCKS_PER_CALL];

    HeapTuple tuple;

    CHECK_FOR_INTERRUPTS();

    values[0] = ObjectIdGetDatum(rlocator.relNumber);

    values[1] = ObjectIdGetDatum(rlocator.spcOid);

    values[2] = ObjectIdGetDatum(rlocator.dbOid);

    values[3] = Int16GetDatum((int16) forknum);

    /*

     * If the limit block is not InvalidBlockNumber, emit an extra row

     * with that block number and limit_block = true.

     *

     * There is no point in doing this when the limit_block is

     * InvalidBlockNumber, because no block with that number or any higher

     * number can ever exist.

     */

    if (BlockNumberIsValid(limit_block))

    {

      values[4] = Int64GetDatum((int64) limit_block);

      values[5] = BoolGetDatum(true);

      tuple = heap_form_tuple(rsi->setDesc, values, nulls);

      tuplestore_puttuple(rsi->setResult, tuple);

    }

    /* Loop over blocks within the current relation fork. */

    while (1)

    {

      unsigned  nblocks;

      unsigned  i;

      CHECK_FOR_INTERRUPTS();

      nblocks = BlockRefTableReaderGetBlocks(reader, blocks,

                           MAX_BLOCKS_PER_CALL);

      if (nblocks == 0)

        break;

      /*

       * For each block that we specifically know to have been modified,

       * emit a row with that block number and limit_block = false.

       */

      values[5] = BoolGetDatum(false);

      for (i = 0; i < nblocks; ++i)

      {

        values[4] = Int64GetDatum((int64) blocks[i]);

        tuple = heap_form_tuple(rsi->setDesc, values, nulls);

        tuplestore_puttuple(rsi->setResult, tuple);

      }

    }

  }

  /* Cleanup */

  DestroyBlockRefTableReader(reader);

  FileClose(io.file);

  return (Datum) 0;

}

/*

 * Returns information about the state of the WAL summarizer process.

 */

Datum

pg_get_wal_summarizer_state(PG_FUNCTION_ARGS)

{

  Datum   values[NUM_STATE_ATTS];

  bool    nulls[NUM_STATE_ATTS];

  TimeLineID  summarized_tli;

  XLogRecPtr  summarized_lsn;

  XLogRecPtr  pending_lsn;

  int     summarizer_pid;

  TupleDesc tupdesc;

  HeapTuple htup;

  GetWalSummarizerState(&summarized_tli, &summarized_lsn, &pending_lsn,

              &summarizer_pid);

  if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)

    elog(ERROR, "return type must be a row type");

  memset(nulls, 0, sizeof(nulls));

  values[0] = Int64GetDatum((int64) summarized_tli);

  values[1] = LSNGetDatum(summarized_lsn);

  values[2] = LSNGetDatum(pending_lsn);

  if (summarizer_pid < 0)

    nulls[3] = true;

  else

    values[3] = Int32GetDatum(summarizer_pid);

  htup = heap_form_tuple(tupdesc, values, nulls);

  PG_RETURN_DATUM(HeapTupleGetDatum(htup));

}