guc_tables.h

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/*-------------------------------------------------------------------------
 *
 * guc_tables.h
 *      Declarations of tables used by GUC.
 *
 * See src/backend/utils/misc/README for design notes.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 *    src/include/utils/guc_tables.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef GUC_TABLES_H
#define GUC_TABLES_H 1
 
#include "lib/ilist.h"
#include "utils/guc.h"
 
/*
 * GUC supports these types of variables:
 */
enum config_type
{
    PGC_BOOL,
    PGC_INT,
    PGC_REAL,
    PGC_STRING,
    PGC_ENUM,
};
 
union config_var_val
{
    bool        boolval;
    int         intval;
    double      realval;
    char       *stringval;
    int         enumval;
};
 
/*
 * The actual value of a GUC variable can include a malloc'd opaque struct
 * "extra", which is created by its check_hook and used by its assign_hook.
 */
typedef struct config_var_value
{
    union config_var_val val;
    void       *extra;
} config_var_value;
 
/*
 * Groupings to help organize all the run-time options for display.
 * Be sure this agrees with the way the options are categorized in config.sgml!
 */
enum config_group
{
    UNGROUPED,                  /* use for options not shown in pg_settings */
    FILE_LOCATIONS,
    CONN_AUTH_SETTINGS,
    CONN_AUTH_TCP,
    CONN_AUTH_AUTH,
    CONN_AUTH_SSL,
    RESOURCES_MEM,
    RESOURCES_DISK,
    RESOURCES_KERNEL,
    RESOURCES_BGWRITER,
    RESOURCES_IO,
    RESOURCES_WORKER_PROCESSES,
    WAL_SETTINGS,
    WAL_CHECKPOINTS,
    WAL_ARCHIVING,
    WAL_RECOVERY,
    WAL_ARCHIVE_RECOVERY,
    WAL_RECOVERY_TARGET,
    WAL_SUMMARIZATION,
    REPLICATION_SENDING,
    REPLICATION_PRIMARY,
    REPLICATION_STANDBY,
    REPLICATION_SUBSCRIBERS,
    QUERY_TUNING_METHOD,
    QUERY_TUNING_COST,
    QUERY_TUNING_GEQO,
    QUERY_TUNING_OTHER,
    LOGGING_WHERE,
    LOGGING_WHEN,
    LOGGING_WHAT,
    PROCESS_TITLE,
    STATS_MONITORING,
    STATS_CUMULATIVE,
    VACUUM_AUTOVACUUM,
    VACUUM_COST_DELAY,
    VACUUM_DEFAULT,
    VACUUM_FREEZING,
    CLIENT_CONN_STATEMENT,
    CLIENT_CONN_LOCALE,
    CLIENT_CONN_PRELOAD,
    CLIENT_CONN_OTHER,
    LOCK_MANAGEMENT,
    COMPAT_OPTIONS_PREVIOUS,
    COMPAT_OPTIONS_OTHER,
    ERROR_HANDLING_OPTIONS,
    PRESET_OPTIONS,
    CUSTOM_OPTIONS,
    DEVELOPER_OPTIONS,
};
 
/*
 * Stack entry for saving the state a variable had prior to an uncommitted
 * transactional change
 */
typedef enum
{
    /* This is almost GucAction, but we need a fourth state for SET+LOCAL */
    GUC_SAVE,                   /* entry caused by function SET option */
    GUC_SET,                    /* entry caused by plain SET command */
    GUC_LOCAL,                  /* entry caused by SET LOCAL command */
    GUC_SET_LOCAL,              /* entry caused by SET then SET LOCAL */
} GucStackState;
 
typedef struct guc_stack
{
    struct guc_stack *prev;     /* previous stack item, if any */
    int         nest_level;     /* nesting depth at which we made entry */
    GucStackState state;        /* see enum above */
    GucSource   source;         /* source of the prior value */
    /* masked value's source must be PGC_S_SESSION, so no need to store it */
    GucContext  scontext;       /* context that set the prior value */
    GucContext  masked_scontext;    /* context that set the masked value */
    Oid         srole;          /* role that set the prior value */
    Oid         masked_srole;   /* role that set the masked value */
    config_var_value prior;     /* previous value of variable */
    config_var_value masked;    /* SET value in a GUC_SET_LOCAL entry */
} GucStack;
 
 
/* GUC records for specific variable types */
 
struct config_bool
{
    /* constant fields, must be set correctly in initial value: */
    bool       *variable;
    bool        boot_val;
    GucBoolCheckHook check_hook;
    GucBoolAssignHook assign_hook;
    GucShowHook show_hook;
    /* variable fields, initialized at runtime: */
    bool        reset_val;
};
 
struct config_int
{
    /* constant fields, must be set correctly in initial value: */
    int        *variable;
    int         boot_val;
    int         min;
    int         max;
    GucIntCheckHook check_hook;
    GucIntAssignHook assign_hook;
    GucShowHook show_hook;
    /* variable fields, initialized at runtime: */
    int         reset_val;
};
 
struct config_real
{
    /* constant fields, must be set correctly in initial value: */
    double     *variable;
    double      boot_val;
    double      min;
    double      max;
    GucRealCheckHook check_hook;
    GucRealAssignHook assign_hook;
    GucShowHook show_hook;
    /* variable fields, initialized at runtime: */
    double      reset_val;
};
 
/*
 * A note about string GUCs: the boot_val is allowed to be NULL, which leads
 * to the reset_val and the actual variable value (*variable) also being NULL.
 * However, there is no way to set a NULL value subsequently using
 * set_config_option or any other GUC API.  Also, GUC APIs such as SHOW will
 * display a NULL value as an empty string.  Callers that choose to use a NULL
 * boot_val should overwrite the setting later in startup, or else be careful
 * that NULL doesn't have semantics that are visibly different from an empty
 * string.
 */
struct config_string
{
    /* constant fields, must be set correctly in initial value: */
    char      **variable;
    const char *boot_val;
    GucStringCheckHook check_hook;
    GucStringAssignHook assign_hook;
    GucShowHook show_hook;
    /* variable fields, initialized at runtime: */
    char       *reset_val;
};
 
struct config_enum
{
    /* constant fields, must be set correctly in initial value: */
    int        *variable;
    int         boot_val;
    const struct config_enum_entry *options;
    GucEnumCheckHook check_hook;
    GucEnumAssignHook assign_hook;
    GucShowHook show_hook;
    /* variable fields, initialized at runtime: */
    int         reset_val;
};
 
/*
 * Generic fields applicable to all types of variables
 *
 * The short description should be less than 80 chars in length. Some
 * applications may use the long description as well, and will append
 * it to the short description. (separated by a newline or '. ')
 *
 * If the GUC accepts a special value like -1 to disable the feature, use a
 * system default, etc., it should be mentioned in the long description with
 * the following style:
 *
 *  - Special values should be listed at the end of the long description.
 *  - Descriptions should use numerals (e.g., "0") instead of words (e.g.,
 *    "zero").
 *  - Special value mentions should be concise and direct (e.g., "0 disables
 *    the timeout.", "An empty string means use the operating system
 *    setting.").
 *  - Multiple special values should be listed in ascending order.
 *
 * As an exception, special values should _not_ be mentioned if the description
 * would be too complex or if the meaning is sufficiently obvious.
 *
 * srole is the role that set the current value, or BOOTSTRAP_SUPERUSERID
 * if the value came from an internal source or the config file.  Similarly
 * for reset_srole (which is usually BOOTSTRAP_SUPERUSERID, but not always).
 *
 * Variables that are currently of active interest for maintenance
 * operations are linked into various lists using the xxx_link fields.
 * The link fields are unused/garbage in variables not currently having
 * the specified properties.
 *
 * Note that sourcefile/sourceline are kept here, and not pushed into stacked
 * values, although in principle they belong with some stacked value if the
 * active value is session- or transaction-local.  This is to avoid bloating
 * stack entries.  We know they are only relevant when source == PGC_S_FILE.
 */
struct config_generic
{
    /* constant fields, must be set correctly in initial value: */
    const char *name;           /* name of variable */
    GucContext  context;        /* context required to set the variable */
    enum config_group group;    /* to help organize variables by function */
    const char *short_desc;     /* short desc. of this variable's purpose */
    const char *long_desc;      /* long desc. of this variable's purpose */
    int         flags;          /* flag bits, see guc.h */
    enum config_type vartype;   /* type of variable */
    /* variable fields, initialized at runtime: */
    int         status;         /* status bits, see below */
    GucSource   source;         /* source of the current actual value */
    GucSource   reset_source;   /* source of the reset_value */
    GucContext  scontext;       /* context that set the current value */
    GucContext  reset_scontext; /* context that set the reset value */
    Oid         srole;          /* role that set the current value */
    Oid         reset_srole;    /* role that set the reset value */
    GucStack   *stack;          /* stacked prior values */
    void       *extra;          /* "extra" pointer for current actual value */
    void       *reset_extra;
    dlist_node  nondef_link;    /* list link for variables that have source
                                 * different from PGC_S_DEFAULT */
    slist_node  stack_link;     /* list link for variables that have non-NULL
                                 * stack */
    slist_node  report_link;    /* list link for variables that have the
                                 * GUC_NEEDS_REPORT bit set in status */
    char       *last_reported;  /* if variable is GUC_REPORT, value last sent
                                 * to client (NULL if not yet sent) */
    char       *sourcefile;     /* file current setting is from (NULL if not
                                 * set in config file) */
    int         sourceline;     /* line in source file */
 
    /* fields for specific variable types */
    union
    {
        struct config_bool _bool;
        struct config_int _int;
        struct config_real _real;
        struct config_string _string;
        struct config_enum _enum;
    };
};
 
/* bit values in status field */
#define GUC_IS_IN_FILE      0x0001  /* found it in config file */
/*
 * Caution: the GUC_IS_IN_FILE bit is transient state for ProcessConfigFile.
 * Do not assume that its value represents useful information elsewhere.
 */
#define GUC_PENDING_RESTART 0x0002  /* changed value cannot be applied yet */
#define GUC_NEEDS_REPORT    0x0004  /* new value must be reported to client */
 
 
/* constant tables corresponding to enums above and in guc.h */
extern PGDLLIMPORT const char *const config_group_names[];
extern PGDLLIMPORT const char *const config_type_names[];
extern PGDLLIMPORT const char *const GucContext_Names[];
extern PGDLLIMPORT const char *const GucSource_Names[];
 
/* data array defining all the built-in GUC variables */
extern PGDLLIMPORT struct config_generic ConfigureNames[];
 
/* lookup GUC variables, returning config_generic pointers */
extern struct config_generic *find_option(const char *name,
                                          bool create_placeholders,
                                          bool skip_errors,
                                          int elevel);
extern struct config_generic **get_explain_guc_options(int *num);
 
/* get string value of variable */
extern char *ShowGUCOption(const struct config_generic *record, bool use_units);
 
/* get whether or not the GUC variable is visible to current user */
extern bool ConfigOptionIsVisible(const struct config_generic *conf);
 
/* get the current set of variables */
extern struct config_generic **get_guc_variables(int *num_vars);
 
extern void build_guc_variables(void);
 
/* search in enum options */
extern const char *config_enum_lookup_by_value(const struct config_generic *record, int val);
extern bool config_enum_lookup_by_name(const struct config_enum *record,
                                       const char *value, int *retval);
extern char *config_enum_get_options(const struct config_enum *record,
                                     const char *prefix,
                                     const char *suffix,
                                     const char *separator);
 
#endif                          /* GUC_TABLES_H */