Sequence numbers generators code.
This commit is contained in:
Vadim B. Mikheev
parent
1a3c7371e8
commit
e8647c45d6
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@ -4,7 +4,7 @@
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# Makefile for commands
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#
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# IDENTIFICATION
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# $Header: /cvsroot/pgsql/src/backend/commands/Makefile,v 1.2 1996/11/03 23:57:17 scrappy Exp $
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# $Header: /cvsroot/pgsql/src/backend/commands/Makefile,v 1.3 1997/04/02 03:51:23 vadim Exp $
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#
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#-------------------------------------------------------------------------
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@ -19,7 +19,7 @@ CFLAGS+=$(INCLUDE_OPT)
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OBJS = async.o creatinh.o command.o copy.o defind.o define.o \
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purge.o remove.o rename.o vacuum.o version.o view.o cluster.o \
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recipe.o explain.o
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recipe.o explain.o sequence.o
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all: SUBSYS.o
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@ -0,0 +1,552 @@
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/*-------------------------------------------------------------------------
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*
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* sequence.c--
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* PostgreSQL sequences support code.
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*
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*-------------------------------------------------------------------------
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*/
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#include <stdio.h>
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#include <string.h>
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#include <postgres.h>
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#include <storage/bufmgr.h>
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#include <storage/bufpage.h>
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#include <storage/lmgr.h>
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#include <access/heapam.h>
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#include <nodes/parsenodes.h>
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#include <commands/creatinh.h>
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#include <commands/sequence.h>
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#include <utils/builtins.h>
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#define SEQ_MAGIC 0x1717
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#define SEQ_MAXVALUE ((int4)0x7FFFFFFF)
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#define SEQ_MINVALUE -(SEQ_MAXVALUE)
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bool ItsSequenceCreation = false;
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typedef struct FormData_pg_sequence {
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NameData sequence_name;
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int4 last_value;
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int4 increment_by;
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int4 max_value;
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int4 min_value;
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int4 cache_value;
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char is_cycled;
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char is_called;
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} FormData_pg_sequence;
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typedef FormData_pg_sequence *SequenceTupleForm;
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typedef struct sequence_magic {
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uint32 magic;
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} sequence_magic;
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typedef struct SeqTableData {
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char *name;
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Oid relid;
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Relation rel;
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int4 cached;
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int4 last;
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int4 increment;
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struct SeqTableData *next;
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} SeqTableData;
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typedef SeqTableData *SeqTable;
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static SeqTable seqtab = NULL;
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static SeqTable init_sequence (char *caller, char *name);
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static SequenceTupleForm read_info (char * caller, SeqTable elm, Buffer * buf);
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static void init_params (CreateSeqStmt *seq, SequenceTupleForm new);
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static int get_param (DefElem *def);
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/*
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* DefineSequence --
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* Creates a new sequence relation
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*/
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void
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DefineSequence (CreateSeqStmt *seq)
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{
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FormData_pg_sequence new;
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CreateStmt *stmt = makeNode (CreateStmt);
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ColumnDef *coldef;
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TypeName *typnam;
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Relation rel;
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Buffer buf;
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PageHeader page;
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sequence_magic *sm;
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HeapTuple tuple;
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TupleDesc tupDesc;
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Datum value[SEQ_COL_LASTCOL];
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char null[SEQ_COL_LASTCOL];
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int i;
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/* Check and set values */
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init_params (seq, &new);
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/*
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* Create relation (and fill null[] & value[])
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*/
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stmt->tableElts = NIL;
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for (i = SEQ_COL_FIRSTCOL; i <= SEQ_COL_LASTCOL; i++)
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{
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typnam = makeNode(TypeName);
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typnam->setof = FALSE;
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typnam->arrayBounds = NULL;
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coldef = makeNode(ColumnDef);
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coldef->typename = typnam;
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null[i-1] = ' ';
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switch (i)
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{
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case SEQ_COL_NAME:
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typnam->name = "name";
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coldef->colname = "sequence_name";
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value[i-1] = PointerGetDatum (seq->seqname);
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break;
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case SEQ_COL_LASTVAL:
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typnam->name = "int4";
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coldef->colname = "last_value";
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value[i-1] = Int32GetDatum (new.last_value);
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break;
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case SEQ_COL_INCBY:
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typnam->name = "int4";
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coldef->colname = "increment_by";
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value[i-1] = Int32GetDatum (new.increment_by);
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break;
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case SEQ_COL_MAXVALUE:
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typnam->name = "int4";
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coldef->colname = "max_value";
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value[i-1] = Int32GetDatum (new.max_value);
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break;
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case SEQ_COL_MINVALUE:
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typnam->name = "int4";
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coldef->colname = "min_value";
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value[i-1] = Int32GetDatum (new.min_value);
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break;
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case SEQ_COL_CACHE:
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typnam->name = "int4";
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coldef->colname = "cache_value";
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value[i-1] = Int32GetDatum (new.cache_value);
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break;
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case SEQ_COL_CYCLE:
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typnam->name = "char";
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coldef->colname = "is_cycled";
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value[i-1] = CharGetDatum (new.is_cycled);
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break;
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case SEQ_COL_CALLED:
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typnam->name = "char";
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coldef->colname = "is_called";
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value[i-1] = CharGetDatum ('f');
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break;
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}
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stmt->tableElts = lappend (stmt->tableElts, coldef);
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}
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stmt->relname = seq->seqname;
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stmt->archiveLoc = -1; /* default */
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stmt->archiveType = ARCH_NONE;
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stmt->inhRelnames = NIL;
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ItsSequenceCreation = true; /* hack */
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DefineRelation (stmt);
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/* Xact abort calls CloseSequences, which turns ItsSequenceCreation off */
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ItsSequenceCreation = false; /* hack */
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rel = heap_openr (seq->seqname);
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Assert ( RelationIsValid (rel) );
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RelationSetLockForWrite (rel);
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tupDesc = RelationGetTupleDescriptor(rel);
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Assert ( RelationGetNumberOfBlocks (rel) == 0 );
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buf = ReadBuffer (rel, P_NEW);
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if ( !BufferIsValid (buf) )
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elog (WARN, "DefineSequence: ReadBuffer failed");
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page = (PageHeader) BufferGetPage (buf);
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PageInit((Page)page, BufferGetPageSize(buf), sizeof(sequence_magic));
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sm = (sequence_magic *) PageGetSpecialPointer (page);
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sm->magic = SEQ_MAGIC;
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/* Now - form & insert sequence tuple */
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tuple = heap_formtuple (tupDesc, value, null);
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heap_insert (rel, tuple);
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if ( WriteBuffer (buf) == STATUS_ERROR )
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elog (WARN, "DefineSequence: WriteBuffer failed");
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RelationUnsetLockForWrite (rel);
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heap_close (rel);
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return;
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}
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int4
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nextval (struct varlena * seqin)
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{
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char *seqname = textout(seqin);
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SeqTable elm;
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Buffer buf;
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SequenceTupleForm seq;
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ItemPointerData iptr;
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int4 incby, maxv, minv, cache;
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int4 result, next, rescnt = 0;
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/* open and WIntentLock sequence */
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elm = init_sequence ("nextval", seqname);
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if ( elm->last != elm->cached ) /* some numbers were cached */
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{
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elm->last += elm->increment;
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return (elm->last);
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}
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seq = read_info ("nextval", elm, &buf); /* lock page and read tuple */
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next = result = seq->last_value;
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incby = seq->increment_by;
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maxv = seq->max_value;
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minv = seq->min_value;
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cache = seq->cache_value;
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if ( seq->is_called != 't' )
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rescnt++; /* last_value if not called */
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while ( rescnt < cache ) /* try to fetch cache numbers */
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{
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/*
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* Check MAXVALUE for ascending sequences
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* and MINVALUE for descending sequences
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*/
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if ( incby > 0 ) /* ascending sequence */
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{
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if ( ( maxv >= 0 && next > maxv - incby) ||
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( maxv < 0 && next + incby > maxv ) )
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{
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if ( rescnt > 0 )
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break; /* stop caching */
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if ( seq->is_cycled != 't' )
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elog (WARN, "%s.nextval: got MAXVALUE (%d)",
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seqname, maxv);
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next = minv;
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}
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else
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next += incby;
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}
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else /* descending sequence */
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{
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if ( ( minv < 0 && next < minv - incby ) ||
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( minv >= 0 && next + incby < minv ) )
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{
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if ( rescnt > 0 )
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break; /* stop caching */
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if ( seq->is_cycled != 't' )
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elog (WARN, "%s.nextval: got MINVALUE (%d)",
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seqname, minv);
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next = maxv;
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}
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else
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next += incby;
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}
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rescnt++; /* got result */
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if ( rescnt == 1 ) /* if it's first one - */
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result = next; /* it's what to return */
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}
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/* save info in local cache */
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elm->last = result; /* last returned number */
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elm->cached = next; /* last cached number */
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/* save info in sequence relation */
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seq->last_value = next; /* last fetched number */
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seq->is_called = 't';
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if ( WriteBuffer (buf) == STATUS_ERROR )
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elog (WARN, "%s.nextval: WriteBuffer failed", elm->name);
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ItemPointerSet(&iptr, 0, FirstOffsetNumber);
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RelationUnsetSingleWLockPage (elm->rel, &iptr);
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return (result);
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}
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int4
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currval (struct varlena * seqin)
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{
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char *seqname = textout(seqin);
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SeqTable elm;
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Buffer buf;
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SequenceTupleForm seq;
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ItemPointerData iptr;
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int4 result;
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/* open and WIntentLock sequence */
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elm = init_sequence ("currval", seqname);
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if ( elm->last != elm->cached ) /* some numbers were cached */
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{
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return (elm->last); /* return last returned by nextval */
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}
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seq = read_info ("currval", elm, &buf);
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if ( seq->is_called != 't' )
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{
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elog (WARN, "%s.currval: yet undefined (%s.nextval never called)",
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seqname, seqname);
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}
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result = seq->last_value;
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if ( ReleaseBuffer (buf) == STATUS_ERROR )
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elog (WARN, "%s.currval: ReleaseBuffer failed", seqname);
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ItemPointerSet(&iptr, 0, FirstOffsetNumber);
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RelationUnsetSingleWLockPage (elm->rel, &iptr);
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return (result);
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}
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static SequenceTupleForm
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read_info (char * caller, SeqTable elm, Buffer * buf)
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{
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ItemPointerData iptr;
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PageHeader page;
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ItemId lp;
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HeapTuple tuple;
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sequence_magic *sm;
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SequenceTupleForm seq;
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ItemPointerSet(&iptr, 0, FirstOffsetNumber);
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RelationSetSingleWLockPage (elm->rel, &iptr);
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if ( RelationGetNumberOfBlocks (elm->rel) != 1 )
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elog (WARN, "%s.%s: invalid number of blocks in sequence",
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elm->name, caller);
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*buf = ReadBuffer (elm->rel, 0);
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if ( !BufferIsValid (*buf) )
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elog (WARN, "%s.%s: ReadBuffer failed", elm->name, caller);
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page = (PageHeader) BufferGetPage (*buf);
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sm = (sequence_magic *) PageGetSpecialPointer (page);
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if ( sm->magic != SEQ_MAGIC )
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elog (WARN, "%s.%s: bad magic (%08X)", elm->name, caller, sm->magic);
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lp = PageGetItemId (page, FirstOffsetNumber);
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Assert (ItemIdIsUsed (lp));
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tuple = (HeapTuple) PageGetItem ((Page) page, lp);
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seq = (SequenceTupleForm) GETSTRUCT(tuple);
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elm->increment = seq->increment_by;
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return (seq);
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}
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static SeqTable
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init_sequence (char * caller, char * name)
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{
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SeqTable elm, priv = (SeqTable) NULL;
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SeqTable temp;
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for (elm = seqtab; elm != (SeqTable) NULL; )
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{
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if ( strcmp (elm->name, name) == 0 )
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break;
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priv = elm;
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elm = elm->next;
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}
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if ( elm == (SeqTable) NULL ) /* not found */
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{
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temp = (SeqTable) malloc (sizeof(SeqTableData));
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temp->name = malloc (strlen(name) + 1);
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strcpy (temp->name, name);
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temp->rel = (Relation) NULL;
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temp->cached = temp->last = temp->increment = 0;
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temp->next = (SeqTable) NULL;
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}
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else /* found */
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{
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if ( elm->rel != (Relation) NULL) /* already opened */
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return (elm);
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temp = elm;
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}
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temp->rel = heap_openr (name);
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if ( ! RelationIsValid (temp->rel) )
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elog (WARN, "%s.%s: sequence does not exist", name, caller);
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RelationSetWIntentLock (temp->rel);
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if ( temp->rel->rd_rel->relkind != RELKIND_SEQUENCE )
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elog (WARN, "%s.%s: %s is not sequence !", name, caller, name);
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if ( elm != (SeqTable) NULL ) /* we opened sequence from our */
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{ /* SeqTable - check relid ! */
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if ( RelationGetRelationId (elm->rel) != elm->relid )
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{
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elog (NOTICE, "%s.%s: sequence was re-created",
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name, caller, name);
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elm->cached = elm->last = elm->increment = 0;
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elm->relid = RelationGetRelationId (elm->rel);
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}
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}
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else
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{
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elm = temp;
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elm->relid = RelationGetRelationId (elm->rel);
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if ( seqtab == (SeqTable) NULL )
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seqtab = elm;
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else
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priv->next = elm;
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}
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return (elm);
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}
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/*
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* CloseSequences --
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* is calling by xact mgr at commit/abort.
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*/
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void
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CloseSequences (void)
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{
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SeqTable elm;
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Relation rel;
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ItsSequenceCreation = false;
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for (elm = seqtab; elm != (SeqTable) NULL; )
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{
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if ( elm->rel != (Relation) NULL ) /* opened in current xact */
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{
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rel = elm->rel;
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elm->rel = (Relation) NULL;
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RelationUnsetWIntentLock (rel);
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heap_close (rel);
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}
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elm = elm->next;
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}
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return;
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}
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static void
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init_params (CreateSeqStmt *seq, SequenceTupleForm new)
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{
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DefElem *last_value = NULL;
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DefElem *increment_by = NULL;
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DefElem *max_value = NULL;
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DefElem *min_value = NULL;
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DefElem *cache_value = NULL;
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List *option;
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new->is_cycled = 'f';
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foreach (option, seq->options)
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{
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DefElem *defel = (DefElem *)lfirst(option);
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if ( !strcasecmp(defel->defname, "increment") )
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increment_by = defel;
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else if ( !strcasecmp(defel->defname, "start") )
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last_value = defel;
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else if ( !strcasecmp(defel->defname, "maxvalue") )
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max_value = defel;
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else if ( !strcasecmp(defel->defname, "minvalue") )
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min_value = defel;
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else if ( !strcasecmp(defel->defname, "cache") )
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cache_value = defel;
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else if ( !strcasecmp(defel->defname, "cycle") )
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{
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if ( defel->arg != (Node*) NULL )
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elog (WARN, "DefineSequence: CYCLE ??");
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new->is_cycled = 't';
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}
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else
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elog (WARN, "DefineSequence: option \"%s\" not recognized",
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defel->defname);
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}
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if ( increment_by == (DefElem*) NULL ) /* INCREMENT BY */
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new->increment_by = 1;
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else if ( ( new->increment_by = get_param (increment_by) ) == 0 )
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elog (WARN, "DefineSequence: can't INCREMENT by 0");
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||||
|
||||
if ( max_value == (DefElem*) NULL ) /* MAXVALUE */
|
||||
if ( new->increment_by > 0 )
|
||||
new->max_value = SEQ_MAXVALUE; /* ascending seq */
|
||||
else
|
||||
new->max_value = -1; /* descending seq */
|
||||
else
|
||||
new->max_value = get_param (max_value);
|
||||
|
||||
if ( min_value == (DefElem*) NULL ) /* MINVALUE */
|
||||
if ( new->increment_by > 0 )
|
||||
new->min_value = 1; /* ascending seq */
|
||||
else
|
||||
new->min_value = SEQ_MINVALUE; /* descending seq */
|
||||
else
|
||||
new->min_value = get_param (min_value);
|
||||
|
||||
if ( new->min_value >= new->max_value )
|
||||
elog (WARN, "DefineSequence: MINVALUE (%d) can't be >= MAXVALUE (%d)",
|
||||
new->min_value, new->max_value);
|
||||
|
||||
if ( last_value == (DefElem*) NULL ) /* START WITH */
|
||||
if ( new->increment_by > 0 )
|
||||
new->last_value = new->min_value; /* ascending seq */
|
||||
else
|
||||
new->last_value = new->max_value; /* descending seq */
|
||||
else
|
||||
new->last_value = get_param (last_value);
|
||||
|
||||
if ( new->last_value < new->min_value )
|
||||
elog (WARN, "DefineSequence: START value (%d) can't be < MINVALUE (%d)",
|
||||
new->last_value, new->min_value);
|
||||
if ( new->last_value > new->max_value )
|
||||
elog (WARN, "DefineSequence: START value (%d) can't be > MAXVALUE (%d)",
|
||||
new->last_value, new->max_value);
|
||||
|
||||
if ( cache_value == (DefElem*) NULL ) /* CACHE */
|
||||
new->cache_value = 1;
|
||||
else if ( ( new->cache_value = get_param (cache_value) ) <= 0 )
|
||||
elog (WARN, "DefineSequence: CACHE (%d) can't be <= 0",
|
||||
new->cache_value);
|
||||
|
||||
}
|
||||
|
||||
|
||||
static int
|
||||
get_param (DefElem *def)
|
||||
{
|
||||
if ( def->arg == (Node*) NULL )
|
||||
elog (WARN, "DefineSequence: \"%s\" value unspecified", def->defname);
|
||||
|
||||
if ( nodeTag (def->arg) == T_Integer )
|
||||
return (intVal (def->arg));
|
||||
|
||||
elog (WARN, "DefineSequence: \"%s\" is to be integer", def->defname);
|
||||
return (-1);
|
||||
}
|
||||
Loading…
Reference in New Issue