text: /*-------------------------------------------------------------------------
   *
   * 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) 1996-2020, 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 */
  
  	/* some subsidiary information copied from the pg_type row */
  	int16		typlen;
  	bool		typbyval;
  	char		typalign;
  	char		typstorage;
  	char		typtype;
  	Oid			typrelid;
  	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 */
  
  	/*
  	 * 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			0x0001
  #define TYPECACHE_LT_OPR			0x0002
  #define TYPECACHE_GT_OPR			0x0004
  #define TYPECACHE_CMP_PROC			0x0008
  #define TYPECACHE_HASH_PROC			0x0010
  #define TYPECACHE_EQ_OPR_FINFO		0x0020
  #define TYPECACHE_CMP_PROC_FINFO	0x0040
  #define TYPECACHE_HASH_PROC_FINFO	0x0080
  #define TYPECACHE_TUPDESC			0x0100
  #define TYPECACHE_BTREE_OPFAMILY	0x0200
  #define TYPECACHE_HASH_OPFAMILY		0x0400
  #define TYPECACHE_RANGE_INFO		0x0800
  #define TYPECACHE_DOMAIN_BASE_INFO			0x1000
  #define TYPECACHE_DOMAIN_CONSTR_INFO		0x2000
  #define TYPECACHE_HASH_EXTENDED_PROC		0x4000
  #define TYPECACHE_HASH_EXTENDED_PROC_FINFO	0x8000
  
  /* 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 */
  