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3b42bdb471
Commit 6b80394781 introduced integer comparison functions designed
to be as efficient as possible while avoiding overflow. This
commit makes use of these functions in many of the in-tree qsort()
comparators to help ensure transitivity. Many of these comparator
functions should also see a small performance boost.
Author: Mats Kindahl
Reviewed-by: Andres Freund, Fabrízio de Royes Mello
Discussion: https://postgr.es/m/CA%2B14426g2Wa9QuUpmakwPxXFWG_1FaY0AsApkvcTBy-YfS6uaw%40mail.gmail.com
377 lines
8.3 KiB
C
377 lines
8.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* xid.c
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* POSTGRES transaction identifier and command identifier datatypes.
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* src/backend/utils/adt/xid.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <limits.h>
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#include "access/multixact.h"
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#include "access/transam.h"
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#include "access/xact.h"
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#include "common/int.h"
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#include "libpq/pqformat.h"
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#include "utils/builtins.h"
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#include "utils/xid8.h"
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#define PG_GETARG_COMMANDID(n) DatumGetCommandId(PG_GETARG_DATUM(n))
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#define PG_RETURN_COMMANDID(x) return CommandIdGetDatum(x)
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Datum
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xidin(PG_FUNCTION_ARGS)
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{
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char *str = PG_GETARG_CSTRING(0);
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TransactionId result;
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result = uint32in_subr(str, NULL, "xid", fcinfo->context);
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PG_RETURN_TRANSACTIONID(result);
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}
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Datum
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xidout(PG_FUNCTION_ARGS)
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{
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TransactionId transactionId = PG_GETARG_TRANSACTIONID(0);
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char *result = (char *) palloc(16);
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snprintf(result, 16, "%lu", (unsigned long) transactionId);
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PG_RETURN_CSTRING(result);
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}
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/*
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* xidrecv - converts external binary format to xid
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*/
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Datum
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xidrecv(PG_FUNCTION_ARGS)
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{
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StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
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PG_RETURN_TRANSACTIONID((TransactionId) pq_getmsgint(buf, sizeof(TransactionId)));
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}
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/*
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* xidsend - converts xid to binary format
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*/
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Datum
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xidsend(PG_FUNCTION_ARGS)
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{
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TransactionId arg1 = PG_GETARG_TRANSACTIONID(0);
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StringInfoData buf;
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pq_begintypsend(&buf);
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pq_sendint32(&buf, arg1);
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PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
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}
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/*
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* xideq - are two xids equal?
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*/
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Datum
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xideq(PG_FUNCTION_ARGS)
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{
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TransactionId xid1 = PG_GETARG_TRANSACTIONID(0);
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TransactionId xid2 = PG_GETARG_TRANSACTIONID(1);
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PG_RETURN_BOOL(TransactionIdEquals(xid1, xid2));
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}
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/*
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* xidneq - are two xids different?
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*/
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Datum
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xidneq(PG_FUNCTION_ARGS)
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{
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TransactionId xid1 = PG_GETARG_TRANSACTIONID(0);
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TransactionId xid2 = PG_GETARG_TRANSACTIONID(1);
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PG_RETURN_BOOL(!TransactionIdEquals(xid1, xid2));
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}
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/*
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* xid_age - compute age of an XID (relative to latest stable xid)
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*/
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Datum
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xid_age(PG_FUNCTION_ARGS)
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{
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TransactionId xid = PG_GETARG_TRANSACTIONID(0);
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TransactionId now = GetStableLatestTransactionId();
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/* Permanent XIDs are always infinitely old */
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if (!TransactionIdIsNormal(xid))
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PG_RETURN_INT32(INT_MAX);
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PG_RETURN_INT32((int32) (now - xid));
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}
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/*
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* mxid_age - compute age of a multi XID (relative to latest stable mxid)
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*/
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Datum
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mxid_age(PG_FUNCTION_ARGS)
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{
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TransactionId xid = PG_GETARG_TRANSACTIONID(0);
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MultiXactId now = ReadNextMultiXactId();
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if (!MultiXactIdIsValid(xid))
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PG_RETURN_INT32(INT_MAX);
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PG_RETURN_INT32((int32) (now - xid));
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}
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/*
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* xidComparator
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* qsort comparison function for XIDs
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*
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* We can't use wraparound comparison for XIDs because that does not respect
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* the triangle inequality! Any old sort order will do.
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*/
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int
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xidComparator(const void *arg1, const void *arg2)
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{
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TransactionId xid1 = *(const TransactionId *) arg1;
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TransactionId xid2 = *(const TransactionId *) arg2;
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return pg_cmp_u32(xid1, xid2);
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}
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/*
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* xidLogicalComparator
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* qsort comparison function for XIDs
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*
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* This is used to compare only XIDs from the same epoch (e.g. for backends
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* running at the same time). So there must be only normal XIDs, so there's
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* no issue with triangle inequality.
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*/
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int
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xidLogicalComparator(const void *arg1, const void *arg2)
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{
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TransactionId xid1 = *(const TransactionId *) arg1;
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TransactionId xid2 = *(const TransactionId *) arg2;
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Assert(TransactionIdIsNormal(xid1));
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Assert(TransactionIdIsNormal(xid2));
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if (TransactionIdPrecedes(xid1, xid2))
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return -1;
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if (TransactionIdPrecedes(xid2, xid1))
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return 1;
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return 0;
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}
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Datum
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xid8toxid(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid = PG_GETARG_FULLTRANSACTIONID(0);
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PG_RETURN_TRANSACTIONID(XidFromFullTransactionId(fxid));
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}
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Datum
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xid8in(PG_FUNCTION_ARGS)
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{
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char *str = PG_GETARG_CSTRING(0);
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uint64 result;
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result = uint64in_subr(str, NULL, "xid8", fcinfo->context);
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PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromU64(result));
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}
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Datum
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xid8out(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid = PG_GETARG_FULLTRANSACTIONID(0);
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char *result = (char *) palloc(21);
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snprintf(result, 21, UINT64_FORMAT, U64FromFullTransactionId(fxid));
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PG_RETURN_CSTRING(result);
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}
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Datum
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xid8recv(PG_FUNCTION_ARGS)
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{
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StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
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uint64 value;
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value = (uint64) pq_getmsgint64(buf);
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PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromU64(value));
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}
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Datum
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xid8send(PG_FUNCTION_ARGS)
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{
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FullTransactionId arg1 = PG_GETARG_FULLTRANSACTIONID(0);
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StringInfoData buf;
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pq_begintypsend(&buf);
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pq_sendint64(&buf, (uint64) U64FromFullTransactionId(arg1));
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PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
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}
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Datum
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xid8eq(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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PG_RETURN_BOOL(FullTransactionIdEquals(fxid1, fxid2));
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}
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Datum
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xid8ne(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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PG_RETURN_BOOL(!FullTransactionIdEquals(fxid1, fxid2));
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}
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Datum
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xid8lt(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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PG_RETURN_BOOL(FullTransactionIdPrecedes(fxid1, fxid2));
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}
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Datum
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xid8gt(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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PG_RETURN_BOOL(FullTransactionIdFollows(fxid1, fxid2));
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}
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Datum
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xid8le(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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PG_RETURN_BOOL(FullTransactionIdPrecedesOrEquals(fxid1, fxid2));
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}
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Datum
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xid8ge(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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PG_RETURN_BOOL(FullTransactionIdFollowsOrEquals(fxid1, fxid2));
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}
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Datum
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xid8cmp(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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if (FullTransactionIdFollows(fxid1, fxid2))
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PG_RETURN_INT32(1);
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else if (FullTransactionIdEquals(fxid1, fxid2))
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PG_RETURN_INT32(0);
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else
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PG_RETURN_INT32(-1);
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}
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Datum
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xid8_larger(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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if (FullTransactionIdFollows(fxid1, fxid2))
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PG_RETURN_FULLTRANSACTIONID(fxid1);
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else
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PG_RETURN_FULLTRANSACTIONID(fxid2);
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}
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Datum
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xid8_smaller(PG_FUNCTION_ARGS)
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{
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FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
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FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
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if (FullTransactionIdPrecedes(fxid1, fxid2))
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PG_RETURN_FULLTRANSACTIONID(fxid1);
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else
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PG_RETURN_FULLTRANSACTIONID(fxid2);
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}
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/*****************************************************************************
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* COMMAND IDENTIFIER ROUTINES *
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*****************************************************************************/
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/*
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* cidin - converts CommandId to internal representation.
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*/
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Datum
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cidin(PG_FUNCTION_ARGS)
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{
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char *str = PG_GETARG_CSTRING(0);
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CommandId result;
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result = uint32in_subr(str, NULL, "cid", fcinfo->context);
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PG_RETURN_COMMANDID(result);
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}
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/*
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* cidout - converts a cid to external representation.
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*/
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Datum
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cidout(PG_FUNCTION_ARGS)
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{
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CommandId c = PG_GETARG_COMMANDID(0);
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char *result = (char *) palloc(16);
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snprintf(result, 16, "%lu", (unsigned long) c);
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PG_RETURN_CSTRING(result);
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}
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/*
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* cidrecv - converts external binary format to cid
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*/
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Datum
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cidrecv(PG_FUNCTION_ARGS)
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{
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StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
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PG_RETURN_COMMANDID((CommandId) pq_getmsgint(buf, sizeof(CommandId)));
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}
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/*
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* cidsend - converts cid to binary format
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*/
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Datum
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cidsend(PG_FUNCTION_ARGS)
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{
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CommandId arg1 = PG_GETARG_COMMANDID(0);
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StringInfoData buf;
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pq_begintypsend(&buf);
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pq_sendint32(&buf, arg1);
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PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
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}
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Datum
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cideq(PG_FUNCTION_ARGS)
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{
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CommandId arg1 = PG_GETARG_COMMANDID(0);
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CommandId arg2 = PG_GETARG_COMMANDID(1);
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PG_RETURN_BOOL(arg1 == arg2);
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}
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