Table of WiredTiger extension methods. More...

Public Attributes
int(*	err_printf )(WT_EXTENSION_API wt_api, WT_SESSION session, const char *fmt,...)
	Insert an error message into the WiredTiger error stream. More...

int(*	msg_printf )(WT_EXTENSION_API , WT_SESSION session, const char *fmt,...)
	Insert a message into the WiredTiger message stream. More...

const char (	strerror )(WT_EXTENSION_API , WT_SESSION session, int error)
	Return information about an error as a string. More...

int(*	map_windows_error )(WT_EXTENSION_API wt_api, WT_SESSION session, uint32_t windows_error)
	Map a Windows system error code to a POSIX 1003.1/ANSI C error. More...

void (	scr_alloc )(WT_EXTENSION_API wt_api, WT_SESSION session, size_t bytes)
	Allocate short-term use scratch memory. More...

void(*	scr_free )(WT_EXTENSION_API , WT_SESSION session, void *ref)
	Free short-term use scratch memory. More...

int(*	collator_config )(WT_EXTENSION_API wt_api, WT_SESSION session, const char uri, WT_CONFIG_ARG config, WT_COLLATOR *collatorp, int ownp)
	Configure the extension collator method. More...

int(*	collate )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_COLLATOR collator, WT_ITEM first, WT_ITEM second, int cmp)
	The extension collator method. More...

int(*	config_get )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_CONFIG_ARG config, const char key, WT_CONFIG_ITEM *value)
	Return the value of a configuration key. More...

int(*	config_get_string )(WT_EXTENSION_API wt_api, WT_SESSION session, const char config, const char key, WT_CONFIG_ITEM *value)
	Return the value of a configuration key from a string. More...

int(*	config_parser_open )(WT_EXTENSION_API wt_api, WT_SESSION session, const char config, size_t len, WT_CONFIG_PARSER *config_parserp)
	Create a handle that can be used to parse or create configuration strings compatible with WiredTiger APIs. More...

int(*	config_parser_open_arg )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_CONFIG_ARG config, WT_CONFIG_PARSER *config_parserp)
	Create a handle that can be used to parse or create configuration strings compatible with WiredTiger APIs. More...

int(*	file_system_get )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_FILE_SYSTEM **file_system)
	Get the file system abstraction used by WiredTiger. More...

int(*	metadata_insert )(WT_EXTENSION_API wt_api, WT_SESSION session, const char key, const char value)
	Insert a row into the metadata if it does not already exist. More...

int(*	metadata_remove )(WT_EXTENSION_API wt_api, WT_SESSION session, const char *key)
	Remove a row from the metadata. More...

int(*	metadata_search )(WT_EXTENSION_API wt_api, WT_SESSION session, const char key, char *valuep)
	Return a row from the metadata. More...

int(*	metadata_update )(WT_EXTENSION_API wt_api, WT_SESSION session, const char key, const char value)
	Update a row in the metadata by either inserting a new record or updating an existing record. More...

int(*	struct_pack )(WT_EXTENSION_API wt_api, WT_SESSION session, void buffer, size_t size, const char format,...)
	Pack a structure into a buffer. More...

int(*	struct_size )(WT_EXTENSION_API wt_api, WT_SESSION session, size_t sizep, const char format,...)
	Calculate the size required to pack a structure. More...

int(*	struct_unpack )(WT_EXTENSION_API wt_api, WT_SESSION session, const void buffer, size_t size, const char format,...)
	Unpack a structure from a buffer. More...

int(*	pack_start )(WT_EXTENSION_API wt_api, WT_SESSION session, const char format, void buffer, size_t size, WT_PACK_STREAM **psp)
	Start a packing operation into a buffer. More...

int(*	unpack_start )(WT_EXTENSION_API wt_api, WT_SESSION session, const char format, const void buffer, size_t size, WT_PACK_STREAM **psp)
	Start an unpacking operation from a buffer. More...

int(*	pack_close )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, size_t *usedp)
	Close a packing stream. More...

int(*	pack_item )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, WT_ITEM *item)
	Pack an item into a packing stream. More...

int(*	pack_int )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, int64_t i)
	Pack a signed integer into a packing stream. More...

int(*	pack_str )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, const char *s)
	Pack a string into a packing stream. More...

int(*	pack_uint )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, uint64_t u)
	Pack an unsigned integer into a packing stream. More...

int(*	unpack_item )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, WT_ITEM *item)
	Unpack an item from a packing stream. More...

int(*	unpack_int )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, int64_t *ip)
	Unpack a signed integer from a packing stream. More...

int(*	unpack_str )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, const char **sp)
	Unpack a string from a packing stream. More...

int(*	unpack_uint )(WT_EXTENSION_API wt_api, WT_PACK_STREAM ps, uint64_t *up)
	Unpack an unsigned integer from a packing stream. More...

uint64_t(*	transaction_id )(WT_EXTENSION_API wt_api, WT_SESSION session)
	Return the current transaction ID. More...

int(*	transaction_isolation_level )(WT_EXTENSION_API wt_api, WT_SESSION session)
	Return the current transaction's isolation level; returns one of WT_TXN_ISO_READ_COMMITTED, WT_TXN_ISO_READ_UNCOMMITTED, or WT_TXN_ISO_SNAPSHOT. More...

int(*	transaction_notify )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_TXN_NOTIFY *notify)
	Request notification of transaction resolution by specifying a function to be called when the session's current transaction is either committed or rolled back. More...

uint64_t(*	transaction_oldest )(WT_EXTENSION_API *wt_api)
	Return the oldest transaction ID not yet visible to a running transaction. More...

int(*	transaction_visible )(WT_EXTENSION_API wt_api, WT_SESSION session, uint64_t transaction_id)
	Return if the current transaction can see the given transaction ID. More...

const char (	version )(int majorp, int minorp, int *patchp)
	Get version information. More...

int(*	spin_init )(WT_EXTENSION_API wt_api, WT_EXTENSION_SPINLOCK spinlock, const char *name)
	Initialize a spinlock. More...

void(*	spin_destroy )(WT_EXTENSION_API wt_api, WT_EXTENSION_SPINLOCK spinlock)
	Destroy a spinlock. More...

void(*	spin_lock )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_EXTENSION_SPINLOCK *spinlock)
	Spin until the lock is acquired. More...

void(*	spin_unlock )(WT_EXTENSION_API wt_api, WT_SESSION session, WT_EXTENSION_SPINLOCK *spinlock)
	Release the spinlock. More...

Detailed Description

Table of WiredTiger extension methods.

This structure is used to provide a set of WiredTiger methods to extension modules without needing to link the modules with the WiredTiger library.

The extension methods may be used both by modules that are linked with the WiredTiger library (for example, a data source configured using the WT_CONNECTION::add_data_source method), and by modules not linked with the WiredTiger library (for example, a compression module configured using the WT_CONNECTION::add_compressor method).

To use these functions:

include the wiredtiger_ext.h header file,
declare a variable which references a WT_EXTENSION_API structure, and
initialize the variable using WT_CONNECTION::get_extension_api method.

#include <wiredtiger_ext.h>
 
static WT_EXTENSION_API *wt_api;
 
static void
my_data_source_init(WT_CONNECTION *connection)
{
    wt_api = connection->get_extension_api(connection);
}

The following code is from the sample compression module, where compression extension functions are configured in the extension's entry point:

/* Local compressor structure. */
typedef struct {
    WT_COMPRESSOR compressor; /* Must come first */
 
    WT_EXTENSION_API *wt_api; /* Extension API */
 
    unsigned long nop_calls; /* Count of calls */
 
} NOP_COMPRESSOR;

/*
 * wiredtiger_extension_init --
 *     A simple shared library compression example.
 */
int
wiredtiger_extension_init(WT_CONNECTION *connection, WT_CONFIG_ARG *config)
{
    NOP_COMPRESSOR *nop_compressor;
    int ret;
 
    (void)config; /* Unused parameters */
 
    if ((nop_compressor = calloc(1, sizeof(NOP_COMPRESSOR))) == NULL)
        return (errno);
 
    /*
     * Allocate a local compressor structure, with a WT_COMPRESSOR structure as the first field,
     * allowing us to treat references to either type of structure as a reference to the other type.
     *
     * Heap memory (not static), because it can support multiple databases.
     */
    nop_compressor->compressor.compress = nop_compress;
    nop_compressor->compressor.decompress = nop_decompress;
    nop_compressor->compressor.pre_size = nop_pre_size;
    nop_compressor->compressor.terminate = nop_terminate;
 
    nop_compressor->wt_api = connection->get_extension_api(connection);
 
    /* Load the compressor */
    if ((ret = connection->add_compressor(
           connection, "nop", (WT_COMPRESSOR *)nop_compressor, NULL)) == 0)
        return (0);
 
    free(nop_compressor);
    return (ret);
}

Examples: ex_encrypt.c, ex_file_system.c, nop_encrypt.c, rotn_encrypt.c, and sodium_encrypt.c.

Member Data Documentation

◆ collate

int(* WT_EXTENSION_API::collate) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_COLLATOR *collator, WT_ITEM *first, WT_ITEM *second, int *cmp)

The extension collator method.

Parameters

	wt_api	the extension handle
	session	the session handle (or NULL if none available)
	collator	the collator (or NULL if none available)
	first	first item
	second	second item
[out]	cmp	set less than 0 if `first` collates less than `second`, set equal to 0 if `first` collates equally to `second`, set greater than 0 if `first` collates greater than `second`

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

        WT_ITEM first, second;
        int cmp;
 
        first.data = key1;
        first.size = key1_len;
        second.data = key2;
        second.size = key2_len;
 
        error_check(wt_api->collate(wt_api, session, collator, &first, &second, &cmp));
        if (cmp == 0)
            printf("key1 collates identically to key2\n");
        else if (cmp < 0)
            printf("key1 collates less than key2\n");
        else
            printf("key1 collates greater than key2\n");

◆ collator_config

int(* WT_EXTENSION_API::collator_config) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *uri, WT_CONFIG_ARG *config, WT_COLLATOR **collatorp, int *ownp)

Configure the extension collator method.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
uri	the URI of the handle being configured
config	the configuration information passed to an application
collatorp	the selector collator, if any
ownp	set if the collator terminate method should be called when no longer needed

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            WT_COLLATOR *collator;
            int collator_owned;
            /*
             * Configure the appropriate collator.
             */
            error_check(wt_api->collator_config(
              wt_api, session, "dsrc:", config, &collator, &collator_owned));

◆ config_get

int(* WT_EXTENSION_API::config_get) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_CONFIG_ARG *config, const char *key, WT_CONFIG_ITEM *value)

Return the value of a configuration key.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
config	the configuration information passed to an application
key	configuration key string
value	the returned value

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            WT_CONFIG_ITEM v;
            const char *my_data_source_key;
 
            /*
             * Retrieve the value of the string type configuration string "key_format".
             */
            error_check(wt_api->config_get(wt_api, session, config, "key_format", &v));
 
            /*
             * Values returned from WT_EXTENSION_API::config in the str field are not
             * nul-terminated; the associated length must be used instead.
             */
            if (v.len == 1 && v.str[0] == 'r')
                my_data_source_key = "recno";
            else
                my_data_source_key = "bytestring";

Examples: ex_encrypt.c, nop_encrypt.c, rotn_encrypt.c, and sodium_encrypt.c.

◆ config_get_string

int(* WT_EXTENSION_API::config_get_string) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *config, const char *key, WT_CONFIG_ITEM *value)

Return the value of a configuration key from a string.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
config	the configuration string
key	configuration key string
value	the returned value

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            WT_CONFIG_ITEM v;
            const char *my_data_source_key;
 
            /*
             * Retrieve the value of the string type configuration string "key_format".
             */
            error_check(wt_api->config_get(wt_api, session, config, "key_format", &v));
 
            /*
             * Values returned from WT_EXTENSION_API::config in the str field are not
             * nul-terminated; the associated length must be used instead.
             */
            if (v.len == 1 && v.str[0] == 'r')
                my_data_source_key = "recno";
            else
                my_data_source_key = "bytestring";

◆ config_parser_open

int(* WT_EXTENSION_API::config_parser_open) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *config, size_t len, WT_CONFIG_PARSER **config_parserp)

Create a handle that can be used to parse or create configuration strings compatible with WiredTiger APIs.

This API is outside the scope of a WiredTiger connection handle, since applications may need to generate configuration strings prior to calling wiredtiger_open.

Parameters

	session	the session handle to be used for error reporting (if NULL, error messages will be written to stderr).
	config	the configuration string being parsed. The string must remain valid for the lifetime of the parser handle.
	len	the number of valid bytes in `config`
[out]	config_parserp	A pointer to the newly opened handle

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

        WT_CONFIG_ITEM k, v;
        WT_CONFIG_PARSER *parser;
        const char *config_string =
          "path=/dev/loop,page_size=1024,log=(archive=true,file_max=20MB)";
 
        error_check(
          wiredtiger_config_parser_open(NULL, config_string, strlen(config_string), &parser));
        error_check(parser->close(parser));

◆ config_parser_open_arg

int(* WT_EXTENSION_API::config_parser_open_arg) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_CONFIG_ARG *config, WT_CONFIG_PARSER **config_parserp)

Create a handle that can be used to parse or create configuration strings compatible with WiredTiger APIs.

This API is outside the scope of a WiredTiger connection handle, since applications may need to generate configuration strings prior to calling wiredtiger_open.

Parameters

	session	the session handle to be used for error reporting (if NULL, error messages will be written to stderr).
	config	the configuration string being parsed. The string must remain valid for the lifetime of the parser handle.
	len	the number of valid bytes in `config`
[out]	config_parserp	A pointer to the newly opened handle

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

        WT_CONFIG_ITEM k, v;
        WT_CONFIG_PARSER *parser;
        const char *config_string =
          "path=/dev/loop,page_size=1024,log=(archive=true,file_max=20MB)";
 
        error_check(
          wiredtiger_config_parser_open(NULL, config_string, strlen(config_string), &parser));
        error_check(parser->close(parser));

Examples: ex_file_system.c.

◆ err_printf

int(* WT_EXTENSION_API::err_printf) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *fmt,...)

Insert an error message into the WiredTiger error stream.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
fmt	a printf-like format specification

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

(void)wt_api->err_printf(wt_api, session, "extension error message: %s", msg);

Examples: ex_file_system.c, nop_encrypt.c, rotn_encrypt.c, and sodium_encrypt.c.

◆ file_system_get

int(* WT_EXTENSION_API::file_system_get) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_FILE_SYSTEM **file_system)

Get the file system abstraction used by WiredTiger.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
file_system	the returned file system handle.

Returns: zero on success and a non-zero error code on failure. See Error handling for details. If called from an extension's initialization routine, this may return WT_NOTFOUND if the file system has not yet been established.

            /*
             * Insert a new WiredTiger metadata record.
             */
            const char *key = "datasource_uri";
            const char *value = "data source uri's record";
 
            error_check(wt_api->metadata_insert(wt_api, session, key, value));

◆ map_windows_error

int(* WT_EXTENSION_API::map_windows_error) (WT_EXTENSION_API *wt_api, WT_SESSION *session, uint32_t windows_error)

Map a Windows system error code to a POSIX 1003.1/ANSI C error.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
windows_error	a Windows system error code

Returns: a string representation of the error

int posix_error = wt_api->map_windows_error(wt_api, session, ERROR_BAD_COMMAND);

◆ metadata_insert

int(* WT_EXTENSION_API::metadata_insert) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *key, const char *value)

Insert a row into the metadata if it does not already exist.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
key	row key
value	row value

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            /*
             * Insert a new WiredTiger metadata record.
             */
            const char *key = "datasource_uri";
            const char *value = "data source uri's record";
 
            error_check(wt_api->metadata_insert(wt_api, session, key, value));

◆ metadata_remove

int(* WT_EXTENSION_API::metadata_remove) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *key)

Remove a row from the metadata.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
key	row key

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            /*
             * Remove a WiredTiger metadata record.
             */
            const char *key = "datasource_uri";
 
            error_check(wt_api->metadata_remove(wt_api, session, key));

◆ metadata_search

int(* WT_EXTENSION_API::metadata_search) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *key, char **valuep)

Return a row from the metadata.

Parameters

	wt_api	the extension handle
	session	the session handle (or NULL if none available)
	key	row key
[out]	valuep	the row value

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            /*
             * Search for a WiredTiger metadata record.
             */
            const char *key = "datasource_uri";
            char *value;
 
            error_check(wt_api->metadata_search(wt_api, session, key, &value));
            printf("metadata: %s has a value of %s\n", key, value);

◆ metadata_update

int(* WT_EXTENSION_API::metadata_update) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *key, const char *value)

Update a row in the metadata by either inserting a new record or updating an existing record.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
key	row key
value	row value

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

            /*
             * Update a WiredTiger metadata record (insert it if it does not yet exist, update it if
             * it does).
             */
            const char *key = "datasource_uri";
            const char *value = "data source uri's record";
 
            error_check(wt_api->metadata_update(wt_api, session, key, value));

◆ msg_printf

int(* WT_EXTENSION_API::msg_printf) (WT_EXTENSION_API *, WT_SESSION *session, const char *fmt,...)

Insert a message into the WiredTiger message stream.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
fmt	a printf-like format specification

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

(void)wt_api->msg_printf(wt_api, session, "extension message: %s", msg);

◆ pack_close

int(* WT_EXTENSION_API::pack_close) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, size_t *usedp)

Close a packing stream.

Parameters

	ps	the packing stream handle
[out]	usedp	the number of bytes in the buffer used by the stream

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ pack_int

int(* WT_EXTENSION_API::pack_int) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, int64_t i)

Pack a signed integer into a packing stream.

Parameters

ps	the packing stream handle
i	a signed integer to pack

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ pack_item

int(* WT_EXTENSION_API::pack_item) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, WT_ITEM *item)

Pack an item into a packing stream.

Parameters

ps	the packing stream handle
item	an item to pack

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ pack_start

int(* WT_EXTENSION_API::pack_start) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *format, void *buffer, size_t size, WT_PACK_STREAM **psp)

Start a packing operation into a buffer.

See wiredtiger_pack_start for details.

Parameters

	session	the session handle
	format	the data format, see Packing and Unpacking Data
	buffer	a pointer to memory to hold the packed data
	size	the size of the buffer
[out]	psp	the new packing stream handle

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ pack_str

int(* WT_EXTENSION_API::pack_str) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, const char *s)

Pack a string into a packing stream.

Parameters

ps	the packing stream handle
s	a string to pack

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ pack_uint

int(* WT_EXTENSION_API::pack_uint) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, uint64_t u)

Pack an unsigned integer into a packing stream.

Parameters

ps	the packing stream handle
u	an unsigned integer to pack

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ scr_alloc

void*(* WT_EXTENSION_API::scr_alloc) (WT_EXTENSION_API *wt_api, WT_SESSION *session, size_t bytes)

Allocate short-term use scratch memory.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
bytes	the number of bytes of memory needed

Returns: A valid memory reference on success or NULL on error

        void *buffer;
        if ((buffer = wt_api->scr_alloc(wt_api, session, 512)) == NULL) {
            (void)wt_api->err_printf(
              wt_api, session, "buffer allocation: %s", session->strerror(session, ENOMEM));
            return (ENOMEM);
        }

◆ scr_free

void(* WT_EXTENSION_API::scr_free) (WT_EXTENSION_API *, WT_SESSION *session, void *ref)

Free short-term use scratch memory.

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
ref	a memory reference returned by WT_EXTENSION_API::scr_alloc

wt_api->scr_free(wt_api, session, buffer);

◆ spin_destroy

void(* WT_EXTENSION_API::spin_destroy) (WT_EXTENSION_API *wt_api, WT_EXTENSION_SPINLOCK *spinlock)

Destroy a spinlock.

Parameters

wt_api	the extension handle
session	the session handle
spinlock	the extension spinlock

◆ spin_init

int(* WT_EXTENSION_API::spin_init) (WT_EXTENSION_API *wt_api, WT_EXTENSION_SPINLOCK *spinlock, const char *name)

Initialize a spinlock.

Parameters

wt_api	the extension handle
session	the session handle
spinlock	the extension spinlock
name	the name for the spinlock

◆ spin_lock

void(* WT_EXTENSION_API::spin_lock) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_EXTENSION_SPINLOCK *spinlock)

Spin until the lock is acquired.

Parameters

wt_api	the extension handle
session	the session handle
spinlock	the extension spinlock

◆ spin_unlock

void(* WT_EXTENSION_API::spin_unlock) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_EXTENSION_SPINLOCK *spinlock)

Release the spinlock.

Parameters

wt_api	the extension handle
session	the session handle
spinlock	the extension spinlock

◆ strerror

const char*(* WT_EXTENSION_API::strerror) (WT_EXTENSION_API *, WT_SESSION *session, int error)

Return information about an error as a string.

(void)wt_api->err_printf(

wt_api, session, "WiredTiger error return: %s", wt_api->strerror(wt_api, session, ret));

Parameters

wt_api	the extension handle
session	the session handle (or NULL if none available)
error	a return value from a WiredTiger function

Returns: a string representation of the error

Examples: ex_file_system.c, nop_encrypt.c, rotn_encrypt.c, and sodium_encrypt.c.

◆ struct_pack

int(* WT_EXTENSION_API::struct_pack) (WT_EXTENSION_API *wt_api, WT_SESSION *session, void *buffer, size_t size, const char *format,...)

Pack a structure into a buffer.

Deprecated in favor of stream based pack and unpack API. See WT_EXTENSION_API::pack_start for details.

Parameters

wt_api	the extension handle
session	the session handle
buffer	a pointer to a packed byte array
size	the number of valid bytes in the buffer
format	the data format, see Packing and Unpacking Data

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ struct_size

int(* WT_EXTENSION_API::struct_size) (WT_EXTENSION_API *wt_api, WT_SESSION *session, size_t *sizep, const char *format,...)

Calculate the size required to pack a structure.

Deprecated in favor of stream based pack and unpack API.

Parameters

wt_api	the extension handle
session	the session handle
sizep	a location where the number of bytes needed for the matching call to WT_EXTENSION_API::struct_pack is returned
format	the data format, see Packing and Unpacking Data

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ struct_unpack

int(* WT_EXTENSION_API::struct_unpack) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const void *buffer, size_t size, const char *format,...)

Unpack a structure from a buffer.

Deprecated in favor of stream based pack and unpack API. See WT_EXTENSION_API::unpack_start for details.

Parameters

wt_api	the extension handle
session	the session handle
buffer	a pointer to a packed byte array
size	the number of valid bytes in the buffer
format	the data format, see Packing and Unpacking Data

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ transaction_id

uint64_t(* WT_EXTENSION_API::transaction_id) (WT_EXTENSION_API *wt_api, WT_SESSION *session)

Return the current transaction ID.

Parameters

wt_api	the extension handle
session	the session handle

Returns: the current transaction ID.

        uint64_t transaction_id;
 
        transaction_id = wt_api->transaction_id(wt_api, session);

◆ transaction_isolation_level

int(* WT_EXTENSION_API::transaction_isolation_level) (WT_EXTENSION_API *wt_api, WT_SESSION *session)

Return the current transaction's isolation level; returns one of WT_TXN_ISO_READ_COMMITTED, WT_TXN_ISO_READ_UNCOMMITTED, or WT_TXN_ISO_SNAPSHOT.

Parameters

wt_api	the extension handle
session	the session handle

Returns: the current transaction's isolation level.

        isolation_level = wt_api->transaction_isolation_level(wt_api, session);
        if (isolation_level == WT_TXN_ISO_SNAPSHOT)
            is_snapshot_isolation = 1;
        else
            is_snapshot_isolation = 0;

◆ transaction_notify

int(* WT_EXTENSION_API::transaction_notify) (WT_EXTENSION_API *wt_api, WT_SESSION *session, WT_TXN_NOTIFY *notify)

Request notification of transaction resolution by specifying a function to be called when the session's current transaction is either committed or rolled back.

If the transaction is being committed, but the notification function returns an error, the transaction will be rolled back.

Parameters

wt_api	the extension handle
session	the session handle
notify	a handler for commit or rollback events

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

        WT_TXN_NOTIFY handler;
        handler.notify = data_source_notify;
        error_check(wt_api->transaction_notify(wt_api, session, &handler));

◆ transaction_oldest

uint64_t(* WT_EXTENSION_API::transaction_oldest) (WT_EXTENSION_API *wt_api)

Return the oldest transaction ID not yet visible to a running transaction.

Parameters

wt_api	the extension handle
session	the session handle

Returns: the oldest transaction ID not yet visible to a running transaction.

        uint64_t transaction_oldest;
 
        transaction_oldest = wt_api->transaction_oldest(wt_api);

◆ transaction_visible

int(* WT_EXTENSION_API::transaction_visible) (WT_EXTENSION_API *wt_api, WT_SESSION *session, uint64_t transaction_id)

Return if the current transaction can see the given transaction ID.

Parameters

wt_api	the extension handle
session	the session handle
transaction_id	the transaction ID

Returns: true (non-zero) if the transaction ID is visible to the current transaction.

is_visible = wt_api->transaction_visible(wt_api, session, transaction_id);

◆ unpack_int

int(* WT_EXTENSION_API::unpack_int) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, int64_t *ip)

Unpack a signed integer from a packing stream.

Parameters

	ps	the packing stream handle
[out]	ip	the unpacked signed integer

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ unpack_item

int(* WT_EXTENSION_API::unpack_item) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, WT_ITEM *item)

Unpack an item from a packing stream.

Parameters

ps	the packing stream handle
item	an item to unpack

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ unpack_start

int(* WT_EXTENSION_API::unpack_start) (WT_EXTENSION_API *wt_api, WT_SESSION *session, const char *format, const void *buffer, size_t size, WT_PACK_STREAM **psp)

Start an unpacking operation from a buffer.

See wiredtiger_unpack_start for details.

Parameters

	session	the session handle
	format	the data format, see Packing and Unpacking Data
	buffer	a pointer to memory holding the packed data
	size	the size of the buffer
[out]	psp	the new packing stream handle

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ unpack_str

int(* WT_EXTENSION_API::unpack_str) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, const char **sp)

Unpack a string from a packing stream.

Parameters

	ps	the packing stream handle
[out]	sp	the unpacked string

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ unpack_uint

int(* WT_EXTENSION_API::unpack_uint) (WT_EXTENSION_API *wt_api, WT_PACK_STREAM *ps, uint64_t *up)

Unpack an unsigned integer from a packing stream.

Parameters

	ps	the packing stream handle
[out]	up	the unpacked unsigned integer

Returns: zero on success and a non-zero error code on failure. See Error handling for details.

◆ version

const char*(* WT_EXTENSION_API::version) (int *majorp, int *minorp, int *patchp)

Get version information.

printf("WiredTiger version %s\n", wiredtiger_version(NULL, NULL, NULL));

        int major_v, minor_v, patch;
        (void)wiredtiger_version(&major_v, &minor_v, &patch);
        printf("WiredTiger version is %d, %d (patch %d)\n", major_v, minor_v, patch);

Parameters

majorp	a location where the major version number is returned
minorp	a location where the minor version number is returned
patchp	a location where the patch version number is returned

Returns: a string representation of the version

Public Attributes

Detailed Description

Member Data Documentation

◆ collate

◆ collator_config

◆ config_get

◆ config_get_string

◆ config_parser_open

◆ config_parser_open_arg

◆ err_printf

◆ file_system_get

◆ map_windows_error

◆ metadata_insert

◆ metadata_remove

◆ metadata_search

◆ metadata_update

◆ msg_printf

◆ pack_close

◆ pack_int

◆ pack_item

◆ pack_start

◆ pack_str

◆ pack_uint

◆ scr_alloc

◆ scr_free

◆ spin_destroy

◆ spin_init

◆ spin_lock

◆ spin_unlock

◆ strerror

◆ struct_pack

◆ struct_size

◆ struct_unpack

◆ transaction_id

◆ transaction_isolation_level

◆ transaction_notify

◆ transaction_oldest

◆ transaction_visible

◆ unpack_int

◆ unpack_item

◆ unpack_start

◆ unpack_str

◆ unpack_uint

◆ version