typcache.h

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/*-------------------------------------------------------------------------
 *
 * typcache.h
 *    Type cache definitions.
 *
 * The type cache exists to speed lookup of certain information about data
 * types that is not directly available from a type's pg_type row.
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/utils/typcache.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef TYPCACHE_H
#define TYPCACHE_H

#include "access/tupdesc.h"
#include "fmgr.h"
#include "storage/dsm.h"
#include "utils/dsa.h"


/* DomainConstraintCache is an opaque struct known only within typcache.c */
typedef struct DomainConstraintCache DomainConstraintCache;

/* TypeCacheEnumData is an opaque struct known only within typcache.c */
struct TypeCacheEnumData;

typedef struct TypeCacheEntry
{
    /* typeId is the hash lookup key and MUST BE FIRST */
    Oid         type_id;        /* OID of the data type */

    uint32      type_id_hash;   /* hashed value of the OID */

    /* some subsidiary information copied from the pg_type row */
    int16       typlen;
    bool        typbyval;
    char        typalign;
    char        typstorage;
    char        typtype;
    Oid         typrelid;
    Oid         typsubscript;
    Oid         typelem;
    Oid         typcollation;

    /*
     * Information obtained from opfamily entries
     *
     * These will be InvalidOid if no match could be found, or if the
     * information hasn't yet been requested.  Also note that for array and
     * composite types, typcache.c checks that the contained types are
     * comparable or hashable before allowing eq_opr etc to become set.
     */
    Oid         btree_opf;      /* the default btree opclass' family */
    Oid         btree_opintype; /* the default btree opclass' opcintype */
    Oid         hash_opf;       /* the default hash opclass' family */
    Oid         hash_opintype;  /* the default hash opclass' opcintype */
    Oid         eq_opr;         /* the equality operator */
    Oid         lt_opr;         /* the less-than operator */
    Oid         gt_opr;         /* the greater-than operator */
    Oid         cmp_proc;       /* the btree comparison function */
    Oid         hash_proc;      /* the hash calculation function */
    Oid         hash_extended_proc; /* the extended hash calculation function */

    /*
     * Pre-set-up fmgr call info for the equality operator, the btree
     * comparison function, and the hash calculation function.  These are kept
     * in the type cache to avoid problems with memory leaks in repeated calls
     * to functions such as array_eq, array_cmp, hash_array.  There is not
     * currently a need to maintain call info for the lt_opr or gt_opr.
     */
    FmgrInfo    eq_opr_finfo;
    FmgrInfo    cmp_proc_finfo;
    FmgrInfo    hash_proc_finfo;
    FmgrInfo    hash_extended_proc_finfo;

    /*
     * Tuple descriptor if it's a composite type (row type).  NULL if not
     * composite or information hasn't yet been requested.  (NOTE: this is a
     * reference-counted tupledesc.)
     *
     * To simplify caching dependent info, tupDesc_identifier is an identifier
     * for this tupledesc that is unique for the life of the process, and
     * changes anytime the tupledesc does.  Zero if not yet determined.
     */
    TupleDesc   tupDesc;
    uint64      tupDesc_identifier;

    /*
     * Fields computed when TYPECACHE_RANGE_INFO is requested.  Zeroes if not
     * a range type or information hasn't yet been requested.  Note that
     * rng_cmp_proc_finfo could be different from the element type's default
     * btree comparison function.
     */
    struct TypeCacheEntry *rngelemtype; /* range's element type */
    Oid         rng_collation;  /* collation for comparisons, if any */
    FmgrInfo    rng_cmp_proc_finfo; /* comparison function */
    FmgrInfo    rng_canonical_finfo;    /* canonicalization function, if any */
    FmgrInfo    rng_subdiff_finfo;  /* difference function, if any */

    /*
     * Fields computed when TYPECACHE_MULTIRANGE_INFO is required.
     */
    struct TypeCacheEntry *rngtype; /* multirange's range underlying type */

    /*
     * Domain's base type and typmod if it's a domain type.  Zeroes if not
     * domain, or if information hasn't been requested.
     */
    Oid         domainBaseType;
    int32       domainBaseTypmod;

    /*
     * Domain constraint data if it's a domain type.  NULL if not domain, or
     * if domain has no constraints, or if information hasn't been requested.
     */
    DomainConstraintCache *domainData;

    /* Private data, for internal use of typcache.c only */
    int         flags;          /* flags about what we've computed */

    /*
     * Private information about an enum type.  NULL if not enum or
     * information hasn't been requested.
     */
    struct TypeCacheEnumData *enumData;

    /* We also maintain a list of all known domain-type cache entries */
    struct TypeCacheEntry *nextDomain;
} TypeCacheEntry;

/* Bit flags to indicate which fields a given caller needs to have set */
#define TYPECACHE_EQ_OPR            0x00001
#define TYPECACHE_LT_OPR            0x00002
#define TYPECACHE_GT_OPR            0x00004
#define TYPECACHE_CMP_PROC          0x00008
#define TYPECACHE_HASH_PROC         0x00010
#define TYPECACHE_EQ_OPR_FINFO      0x00020
#define TYPECACHE_CMP_PROC_FINFO    0x00040
#define TYPECACHE_HASH_PROC_FINFO   0x00080
#define TYPECACHE_TUPDESC           0x00100
#define TYPECACHE_BTREE_OPFAMILY    0x00200
#define TYPECACHE_HASH_OPFAMILY     0x00400
#define TYPECACHE_RANGE_INFO        0x00800
#define TYPECACHE_DOMAIN_BASE_INFO          0x01000
#define TYPECACHE_DOMAIN_CONSTR_INFO        0x02000
#define TYPECACHE_HASH_EXTENDED_PROC        0x04000
#define TYPECACHE_HASH_EXTENDED_PROC_FINFO  0x08000
#define TYPECACHE_MULTIRANGE_INFO           0x10000

/* This value will not equal any valid tupledesc identifier, nor 0 */
#define INVALID_TUPLEDESC_IDENTIFIER ((uint64) 1)

/*
 * Callers wishing to maintain a long-lived reference to a domain's constraint
 * set must store it in one of these.  Use InitDomainConstraintRef() and
 * UpdateDomainConstraintRef() to manage it.  Note: DomainConstraintState is
 * considered an executable expression type, so it's defined in execnodes.h.
 */
typedef struct DomainConstraintRef
{
    List       *constraints;    /* list of DomainConstraintState nodes */
    MemoryContext refctx;       /* context holding DomainConstraintRef */
    TypeCacheEntry *tcache;     /* typcache entry for domain type */
    bool        need_exprstate; /* does caller need check_exprstate? */

    /* Management data --- treat these fields as private to typcache.c */
    DomainConstraintCache *dcc; /* current constraints, or NULL if none */
    MemoryContextCallback callback; /* used to release refcount when done */
} DomainConstraintRef;

typedef struct SharedRecordTypmodRegistry SharedRecordTypmodRegistry;

extern TypeCacheEntry *lookup_type_cache(Oid type_id, int flags);

extern void InitDomainConstraintRef(Oid type_id, DomainConstraintRef *ref,
                                    MemoryContext refctx, bool need_exprstate);

extern void UpdateDomainConstraintRef(DomainConstraintRef *ref);

extern bool DomainHasConstraints(Oid type_id);

extern TupleDesc lookup_rowtype_tupdesc(Oid type_id, int32 typmod);

extern TupleDesc lookup_rowtype_tupdesc_noerror(Oid type_id, int32 typmod,
                                                bool noError);

extern TupleDesc lookup_rowtype_tupdesc_copy(Oid type_id, int32 typmod);

extern TupleDesc lookup_rowtype_tupdesc_domain(Oid type_id, int32 typmod,
                                               bool noError);

extern void assign_record_type_typmod(TupleDesc tupDesc);

extern uint64 assign_record_type_identifier(Oid type_id, int32 typmod);

extern int  compare_values_of_enum(TypeCacheEntry *tcache, Oid arg1, Oid arg2);

extern size_t SharedRecordTypmodRegistryEstimate(void);

extern void SharedRecordTypmodRegistryInit(SharedRecordTypmodRegistry *,
                                           dsm_segment *segment, dsa_area *area);

extern void SharedRecordTypmodRegistryAttach(SharedRecordTypmodRegistry *);

#endif                          /* TYPCACHE_H */