Primitives for services to interact with the structured logger: functions pertaining to log_line and log_item data. More...

#include <log_builtins.h>

Public Attributes
int(*	wellknown_by_type )(log_item_type t)
	See whether a type is wellknown. More...

int(*	wellknown_by_name )(const char *key, size_t length)
	See whether a string is a wellknown field name. More...

log_item_type(*	wellknown_get_type )(uint idx)
	Accessor: from a record describing a wellknown key, get its type. More...

const char (	wellknown_get_name )(uint idx)
	Accessor: from a record describing a wellknown key, get its name. More...

int(*	item_inconsistent )(log_item *li)
	Sanity check an item. More...

bool(*	item_generic_type )(log_item_type t)
	Predicate used to determine whether a type is generic (generic string, generic float, generic integer) rather than a well-known type. More...

bool(*	item_string_class )(log_item_class c)
	Predicate used to determine whether a class is a string class (C-string or Lex-string). More...

bool(*	item_numeric_class )(log_item_class c)
	Predicate used to determine whether a class is a numeric class (integer or float). More...

bool(*	item_set_int )(log_item_data *lid, longlong i)
	Set an integer value on a log_item. More...

bool(*	item_set_float )(log_item_data *lid, double f)
	Set a floating point value on a log_item. More...

bool(*	item_set_lexstring )(log_item_data lid, const char s, size_t s_len)
	Set a string value on a log_item. More...

bool(*	item_set_cstring )(log_item_data lid, const char s)
	Set a string value on a log_item. More...

void(*	line_set_flag )(log_line *ll, log_line_flags_mask mask, log_line_flags_mask value)
	Set/reset one or more log line flags. More...

log_item_data (	item_set_with_key )(log_item li, log_item_type t, const char key, uint32 alloc)
	Create new log item with key name "key", and allocation flags of "alloc" (see enum_log_item_free). More...

log_item_data (	item_set )(log_item *li, log_item_type t)
	As log_item_set_with_key(), except that the key is automatically derived from the wellknown log_item_type t. More...

log_item_data (	line_item_set_with_key )(log_line ll, log_item_type t, const char key, uint32 alloc)
	Create new log item in log line "ll", with key name "key", and allocation flags of "alloc" (see enum_log_item_free). More...

log_item_data (	line_item_set )(log_line *ll, log_item_type t)
	Create a new log item of well-known type "t" in log line "ll". More...

log_line (	line_init )()
	Dynamically allocate and initialize a log_line. More...

void(*	line_exit )(log_line *ll)
	Release a log_line allocated with line_init() More...

int(*	line_item_count )(log_line *ll)
	How many items are currently set on the given log_line? More...

log_item_type_mask(*	line_item_types_seen )(log_line *ll, log_item_type_mask m)
	Test whether a given type is presumed present on the log line. More...

log_item (	line_get_output_buffer )(log_line *ll)
	Get log-line's output buffer. More...

log_item_iter (	line_item_iter_acquire )(log_line *ll)
	Get an iterator for the items in a log_line. More...

void(*	line_item_iter_release )(log_item_iter *it)
	Release an iterator for the items in a log_line. More...

log_item (	line_item_iter_first )(log_item_iter *it)
	Use the log_line iterator to get the first item from the set. More...

log_item (	line_item_iter_next )(log_item_iter *it)
	Use the log_line iterator to get the next item from the set. More...

log_item (	line_item_iter_current )(log_item_iter *it)
	Use the log_line iterator to get the current item from the set. More...

int(*	line_submit )(log_line *ll)
	Complete, filter, and write submitted log items. More...

int(*	message )(int log_type,...)
	Submit a log-message for log "log_type". More...

int(*	sanitize )(log_item *li)
	Escape \0 bytes, add \0 terminator. More...

const char (	errmsg_by_errcode )(int mysql_errcode)
	Return MySQL error message for a given error code. More...

longlong(*	errcode_by_errsymbol )(const char *sym)
	Return MySQL error code for a given error symbol. More...

const char (	label_from_prio )(int prio)
	Convenience function: Derive a log label ("error", "warning", "information") from a severity. More...

ulonglong(*	parse_iso8601_timestamp )(const char *timestamp, size_t len)
	Parse a ISO8601 timestamp and return the number of microseconds since the epoch. More...

log_service_error(*	open_errstream )(const char name_or_ext, void *my_errstream)
	open an error log file More...

log_service_error(*	write_errstream )(void my_errstream, const char buffer, size_t length)
	write to an error log file previously opened with open_errstream() More...

int(*	dedicated_errstream )(void *my_errstream)
	are we writing to a dedicated errstream, or are we sharing it? More...

log_service_error(*	close_errstream )(void **my_errstream)
	close an error log file previously opened with open_errstream() More...

log_service_error(*	reopen_errstream )(const char file, void *my_errstream)
	re-open an error log file (primarily to facilitate flush/log-rotation) More...

Detailed Description

Primitives for services to interact with the structured logger: functions pertaining to log_line and log_item data.

Member Data Documentation

◆ close_errstream

log_service_error(* s_mysql_log_builtins::close_errstream) (void **my_errstream)

close an error log file previously opened with open_errstream()

Parameters

my_stream a handle describing the log file

Returns: LOG_SERVICE_SUCCESS on success

◆ dedicated_errstream

int(* s_mysql_log_builtins::dedicated_errstream) (void *my_errstream)

are we writing to a dedicated errstream, or are we sharing it?

Parameters

my_errstream a handle describing the log file

Return values

0	not dedicated (multiplexed, stderr, ...)
1	dedicated

◆ errcode_by_errsymbol

longlong(* s_mysql_log_builtins::errcode_by_errsymbol) (const char *sym)

Return MySQL error code for a given error symbol.

Parameters

sym	the symbol to look up

Return values

-1	failure
>=0	the MySQL error code

◆ errmsg_by_errcode

const char *(* s_mysql_log_builtins::errmsg_by_errcode) (int mysql_errcode)

Return MySQL error message for a given error code.

Parameters

mysql_errcode the error code the message for which to look up

Return values

the	message (a printf-style format string)

◆ item_generic_type

bool(* s_mysql_log_builtins::item_generic_type) (log_item_type t)

Predicate used to determine whether a type is generic (generic string, generic float, generic integer) rather than a well-known type.

Parameters

t	log item type to examine

Return values

true	if generic type
false	if wellknown type

◆ item_inconsistent

int(* s_mysql_log_builtins::item_inconsistent) (log_item *li)

Sanity check an item.

Certain log sinks have very low requirements with regard to the data they receive; they write keys as strings, and then data according to the item's class (string, integer, or float), formatted to the sink's standards (e.g. JSON, XML, ...). Code that has higher requirements can use this check to see whether the given item is of a known type (whether generic or wellknown), whether the given type and class agree, and whether in case of a well-known type, the given key is correct for that type. If your code generates items that don't pass this check, you should probably go meditate on it.

Parameters

li	the log_item to check

Return values

LOG_ITEM_OK	no problems
LOG_ITEM_TYPE_NOT_FOUND	unknown item type
LOG_ITEM_CLASS_MISMATCH	item_class derived from type isn't what's set on the item
LOG_ITEM_KEY_MISMATCH	class not generic, so key should match wellknown
LOG_ITEM_STRING_NULL	class is string, pointer is nullptr
LOG_ITEM_KEY_NULL	no key set (this is legal e.g. on aux items of filter rules, but should not occur in a log_line, i.e., log_sinks are within their rights to discard such items)

◆ item_numeric_class

bool(* s_mysql_log_builtins::item_numeric_class) (log_item_class c)

Predicate used to determine whether a class is a numeric class (integer or float).

Parameters

c	log item class to examine

Return values

true	if of a numeric class
false	if not of a numeric class

◆ item_set

log_item_data *(* s_mysql_log_builtins::item_set) (log_item *li, log_item_type t)

As log_item_set_with_key(), except that the key is automatically derived from the wellknown log_item_type t.

Create new log item with type "t". Will return a pointer to the item's log_item_data struct for convenience. This is mostly interesting for filters and other services that create items that are not part of a log_line; sources etc. that intend to create an item for a log_line (the more common case) should usually use the below line_item_set_with_key() which creates an item (like this function does), but also correctly inserts it into a log_line.

The allocation of this item will be LOG_ITEM_FREE_NONE; specifically, any pre-existing value will be clobbered. It is therefore WRONG a) to use this on a log_item that already has a key; it should only be used on freshly init'd log_items; b) to use this on a log_item that already has a value (specifically, an allocated one); the correct order is to init a log_item, then set up type and key, and finally to set the value. If said value is an allocated string, the log_item's alloc should be bitwise or'd with LOG_ITEM_FREE_VALUE.

Parameters

li	the log_item to work on
t	the item-type

Return values

a	pointer to the log_item's log_data, for easy chaining: log_item_set_with_key(...)->data_integer= 1;

◆ item_set_cstring

bool(* s_mysql_log_builtins::item_set_cstring) (log_item_data *lid, const char *s)

Set a string value on a log_item.

Fails gracefully if no log_item_data is supplied, so it can safely wrap log_line_item_set[_with_key]().

Parameters

lid	log_item_data struct to set the value on
s	pointer to NTBS

Return values

true	lid was nullptr (possibly: OOM, could not set up log_item)
false	all's well

◆ item_set_float

bool(* s_mysql_log_builtins::item_set_float) (log_item_data *lid, double f)

Set a floating point value on a log_item.

Fails gracefully if no log_item_data is supplied, so it can safely wrap log_line_item_set[_with_key]().

Parameters

lid	log_item_data struct to set the value on
f	float to set

Return values

true	lid was nullptr (possibly: OOM, could not set up log_item)
false	all's well

◆ item_set_int

bool(* s_mysql_log_builtins::item_set_int) (log_item_data *lid, longlong i)

Set an integer value on a log_item.

Fails gracefully if no log_item_data is supplied, so it can safely wrap log_line_item_set[_with_key]().

Parameters

lid	log_item_data struct to set the value on
i	integer to set

Return values

true	lid was nullptr (possibly: OOM, could not set up log_item)
false	all's well

◆ item_set_lexstring

bool(* s_mysql_log_builtins::item_set_lexstring) (log_item_data *lid, const char *s, size_t s_len)

Set a string value on a log_item.

Fails gracefully if no log_item_data is supplied, so it can safely wrap log_line_item_set[_with_key]().

Parameters

lid	log_item_data struct to set the value on
s	pointer to string
s_len	length of string

Return values

true	lid was nullptr (possibly: OOM, could not set up log_item)
false	all's well

◆ item_set_with_key

log_item_data *(* s_mysql_log_builtins::item_set_with_key) (log_item *li, log_item_type t, const char *key, uint32 alloc)

Create new log item with key name "key", and allocation flags of "alloc" (see enum_log_item_free).

Will return a pointer to the item's log_item_data struct for convenience. This is mostly interesting for filters and other services that create items that are not part of a log_line; sources etc. that intend to create an item for a log_line (the more common case) should usually use the below line_item_set_with_key() which creates an item (like this function does), but also correctly inserts it into a log_line.

Parameters

li	the log_item to work on
t	the item-type
key	the key to set on the item. ignored for non-generic types (may pass nullptr for those) see alloc
alloc	LOG_ITEM_FREE_KEY if key was allocated by caller LOG_ITEM_FREE_NONE if key was not allocated Allocated keys will automatically free()d when the log_item is. The log_item's alloc flags will be set to the submitted value; specifically, any pre-existing value will be clobbered. It is therefore WRONG a) to use this on a log_item that already has a key; it should only be used on freshly init'd log_items; b) to use this on a log_item that already has a value (specifically, an allocated one); the correct order is to init a log_item, then set up type and key, and finally to set the value. If said value is an allocated string, the log_item's alloc should be bitwise or'd with LOG_ITEM_FREE_VALUE.

Return values

a	pointer to the log_item's log_data, for easy chaining: log_item_set_with_key(...)->data_integer= 1;

◆ item_string_class

bool(* s_mysql_log_builtins::item_string_class) (log_item_class c)

Predicate used to determine whether a class is a string class (C-string or Lex-string).

Parameters

c	log item class to examine

Return values

true	if of a string class
false	if not of a string class

◆ label_from_prio

const char *(* s_mysql_log_builtins::label_from_prio) (int prio)

Convenience function: Derive a log label ("error", "warning", "information") from a severity.

Parameters

prio	the severity/prio in question

Returns: a label corresponding to that priority.

Return values

System	for prio of SYSTEM_LEVEL
Error	for prio of ERROR_LEVEL
Warning	for prio of WARNING_LEVEL
Note	for prio of INFORMATION_LEVEL

◆ line_exit

void(* s_mysql_log_builtins::line_exit) (log_line *ll)

Release a log_line allocated with line_init()

Parameters

ll	a log_line previously allocated with line_init()

◆ line_get_output_buffer

log_item *(* s_mysql_log_builtins::line_get_output_buffer) (log_line *ll)

Get log-line's output buffer.

If the logger core provides this buffer, the log-service may use it to assemble its output therein and implicitly return it to the core. Participation is required for services that support populating performance_schema.error_log, and optional for all others.

Parameters

ll	the log_line to examine

Return values

nullptr	success, an output buffer is available
otherwise	failure, no output buffer is available

◆ line_init

log_line *(* s_mysql_log_builtins::line_init) ()

Dynamically allocate and initialize a log_line.

Return values

nullptr	could not set up buffer (too small?)
other	address of the newly initialized log_line

◆ line_item_count

int(* s_mysql_log_builtins::line_item_count) (log_line *ll)

How many items are currently set on the given log_line?

Parameters

ll	the log-line to examine

Return values

the	number of items set

◆ line_item_iter_acquire

log_item_iter *(* s_mysql_log_builtins::line_item_iter_acquire) (log_line *ll)

Get an iterator for the items in a log_line.

For now, only one iterator may exist per log_line.

Parameters

ll	the log_line to examine

Return values

a	log_iter_iter, or nullptr on failure

◆ line_item_iter_current

log_item *(* s_mysql_log_builtins::line_item_iter_current) (log_item_iter *it)

Use the log_line iterator to get the current item from the set.

Parameters

it	the iterator to use

Return values

pointer to the current log_item in the collection, or nullptr

◆ line_item_iter_first

log_item *(* s_mysql_log_builtins::line_item_iter_first) (log_item_iter *it)

Use the log_line iterator to get the first item from the set.

Parameters

it	the iterator to use

Return values

pointer to the first log_item in the collection, or nullptr

◆ line_item_iter_next

log_item *(* s_mysql_log_builtins::line_item_iter_next) (log_item_iter *it)

Use the log_line iterator to get the next item from the set.

Parameters

it	the iterator to use

Return values

pointer to the next log_item in the collection, or nullptr

◆ line_item_iter_release

void(* s_mysql_log_builtins::line_item_iter_release) (log_item_iter *it)

Release an iterator for the items in a log_line.

Parameters

it	the iterator to release

◆ line_item_set

log_item_data *(* s_mysql_log_builtins::line_item_set) (log_line *ll, log_item_type t)

Create a new log item of well-known type "t" in log line "ll".

On success, the number of registered items on the log line is increased, the item's type is added to the log_line's "seen" property, and a pointer to the item's log_item_data struct is returned for convenience.

The allocation of this item will be LOG_ITEM_FREE_NONE; specifically, any pre-existing value will be clobbered. It is therefore WRONG a) to use this on a log_item that already has a key; it should only be used on freshly init'd log_items; b) to use this on a log_item that already has a value (specifically, an allocated one); the correct order is to init a log_item, then set up type and key, and finally to set the value. If said value is an allocated string, the log_item's alloc should be bitwise or'd with LOG_ITEM_FREE_VALUE.

Parameters

ll	the log_line to work on
t	the item-type

Return values

a	pointer to the log_item's log_data, for easy chaining: log_line_item_set_with_key(...)->data_integer= 1;

◆ line_item_set_with_key

log_item_data *(* s_mysql_log_builtins::line_item_set_with_key) (log_line *ll, log_item_type t, const char *key, uint32 alloc)

Create new log item in log line "ll", with key name "key", and allocation flags of "alloc" (see enum_log_item_free).

On success, the number of registered items on the log line is increased, the item's type is added to the log_line's "seen" property, and a pointer to the item's log_item_data struct is returned for convenience.

Parameters

ll	the log_line to work on
t	the item-type
key	the key to set on the item. ignored for non-generic types (may pass nullptr for those) see alloc
alloc	LOG_ITEM_FREE_KEY if key was allocated by caller LOG_ITEM_FREE_NONE if key was not allocated Allocated keys will automatically free()d when the log_item is. The log_item's alloc flags will be set to the submitted value; specifically, any pre-existing value will be clobbered. It is therefore WRONG a) to use this on a log_item that already has a key; it should only be used on freshly init'd log_items; b) to use this on a log_item that already has a value (specifically, an allocated one); the correct order is to init a log_item, then set up type and key, and finally to set the value. If said value is an allocated string, the log_item's alloc should be bitwise or'd with LOG_ITEM_FREE_VALUE.

Return values

a	pointer to the log_item's log_data, for easy chaining: log_line_item_set_with_key(...)->data_integer= 1;

◆ line_item_types_seen

log_item_type_mask(* s_mysql_log_builtins::line_item_types_seen) (log_line *ll, log_item_type_mask m)

Test whether a given type is presumed present on the log line.

Parameters

ll	the log_line to examine
m	the log_type to test for

Return values

0	not present
!=0	present

◆ line_set_flag

void(* s_mysql_log_builtins::line_set_flag) (log_line *ll, log_line_flags_mask mask, log_line_flags_mask value)

Set/reset one or more log line flags.

Example to set the flag: log_line_set_flag(ll, LOG_LINE_EMIT_TELEMETRY, LOG_LINE_EMIT_TELEMETRY); to reset the flag: log_line_set_flag(ll, LOG_LINE_EMIT_TELEMETRY, 0);

◆ line_submit

int(* s_mysql_log_builtins::line_submit) (log_line *ll)

Complete, filter, and write submitted log items.

This expects a log_line collection of log-related key/value pairs, e.g. from log_message().

Where missing, timestamp, priority, thread-ID (if any) and so forth are added.

Log item source services, log item filters, and log item sinks are then called; then all applicable resources are freed.

This interface is intended to facilitate the building of submission interfaces other than the variadic message() one below. See the example fluent C++ LogEvent() wrapper for an example of how to leverage it.

Parameters

ll	key/value pairs describing info to log

Return values

int	number of fields in created log line

◆ message

int(* s_mysql_log_builtins::message) (int log_type,...)

Submit a log-message for log "log_type".

Variadic convenience function for logging.

This fills in the array that is used by the filter and log-writer services. Where missing, timestamp, priority, and thread-ID (if any) are added. Log item source services, log item filters, and log item writers are called.

The variadic list accepts a list of "assignments" of the form

log_item_type, value, for well-known types, and
log_item_type, key, value, for ad-hoc types (LOG_ITEM_GEN_*)

As its last item, the list should have

an element of type LOG_ITEM_LOG_MESSAGE, containing a printf-style format string, followed by all variables necessary to satisfy the substitutions in that string

OR
an element of type LOG_ITEM_LOG_LOOKUP, containing a MySQL error code, which will be looked up in the list or regular error messages, followed by all variables necessary to satisfy the substitutions in that string

OR
an element of type LOG_ITEM_LOG_VERBATIM, containing a string that will be used directly, with no % substitutions

see log_vmessage() for more information.

◆ open_errstream

log_service_error(* s_mysql_log_builtins::open_errstream) (const char *name_or_ext, void **my_errstream)

open an error log file

Parameters

name_or_ext if beginning with '.': @global.log_error, except with this extension otherwise: use this as file name in the same location as @global.log_error

Value not contain folder separators!

Parameters

[out] my_errstream an error log handle, or nullptr on failure

Returns: LOG_SERVICE_SUCCESS success; LOG_SERVICE_INVALID_ARGUMENT no my_errstream, or bad log name; LOG_SERVICE_OUT_OF_MEMORY could not allocate file handle; LOG_SERVICE_LOCK_ERROR couldn't lock lock; LOG_SERVICE_UNABLE_TO_WRITE couldn't write to given location; LOG_SERVICE_COULD_NOT_MAKE_LOG_NAME could not make log name

◆ parse_iso8601_timestamp

ulonglong(* s_mysql_log_builtins::parse_iso8601_timestamp) (const char *timestamp, size_t len)

Parse a ISO8601 timestamp and return the number of microseconds since the epoch.

Heeds +/- timezone info if present.

See also: make_iso8601_timestamp()

Parameters

timestamp	an ASCII string containing an ISO8601 timestamp
len	Length in bytes of the aforementioned string

Returns: microseconds since the epoch

◆ reopen_errstream

log_service_error(* s_mysql_log_builtins::reopen_errstream) (const char *file, void **my_errstream)

re-open an error log file (primarily to facilitate flush/log-rotation)

If the new file can be opened, update the my_errstream descriptor to use it and close the old file. Otherwise, keep using the old file.

Parameters

name_or_ext if beginning with '.': @global.log_error, except with this extension otherwise: use this as file name in the same location as @global.log_error

Value may not contain folder separators!

In the general case, the caller will be a log-writer, the log-writer will just pass its preferred file extension, and the resulting file name and path will therefore be the same as for the original log file.

Parameters

[in,out] my_errstream an error log handle

Returns: LOG_SERVICE_INVALID_ARGUMENT, or the result of open_errstream()

◆ sanitize

int(* s_mysql_log_builtins::sanitize) (log_item *li)

Escape \0 bytes, add \0 terminator.

For log-writers and other sinks that terminate in an API using C-strings.

Parameters

li	list_item to process

Return values

-1	out of memory
0	success

◆ wellknown_by_name

int(* s_mysql_log_builtins::wellknown_by_name) (const char *key, size_t length)

See whether a string is a wellknown field name.

Parameters

key	potential key starts here
length	length of the string to examine

Return values

LOG_ITEM_TYPE_RESERVED	reserved, but not "wellknown" key
LOG_ITEM_TYPE_NOT_FOUND	key not found
>0	index in array of wellknowns

◆ wellknown_by_type

int(* s_mysql_log_builtins::wellknown_by_type) (log_item_type t)

See whether a type is wellknown.

Parameters

t	log item type to examine

Return values

LOG_ITEM_TYPE_NOT_FOUND	key not found
>0	index in array of wellknowns

◆ wellknown_get_name

const char *(* s_mysql_log_builtins::wellknown_get_name) (uint idx)

Accessor: from a record describing a wellknown key, get its name.

Parameters

idx	index in array of wellknowns, see log_item_wellknown_by_...()

Return values

name (NTBS)

◆ wellknown_get_type

log_item_type(* s_mysql_log_builtins::wellknown_get_type) (uint idx)

Accessor: from a record describing a wellknown key, get its type.

Parameters

idx	index in array of wellknowns, see log_item_wellknown_by_...()

Return values

the	log item type for the wellknown key

◆ write_errstream

log_service_error(* s_mysql_log_builtins::write_errstream) (void *my_errstream, const char *buffer, size_t length)

write to an error log file previously opened with open_errstream()

Parameters

my_errstream	a handle describing the log file
buffer	pointer to the string to write
length	length of the string to write

Returns: LOG_SERVICE_SUCCESS success; otherwise failure

The documentation for this struct was generated from the following file:

include/mysql/components/services/log_builtins.h

Public Attributes

Detailed Description

Member Data Documentation

◆ close_errstream

◆ dedicated_errstream

◆ errcode_by_errsymbol

◆ errmsg_by_errcode

◆ item_generic_type

◆ item_inconsistent

◆ item_numeric_class

◆ item_set

◆ item_set_cstring

◆ item_set_float

◆ item_set_int

◆ item_set_lexstring

◆ item_set_with_key

◆ item_string_class

◆ label_from_prio

◆ line_exit

◆ line_get_output_buffer

◆ line_init

◆ line_item_count

◆ line_item_iter_acquire

◆ line_item_iter_current

◆ line_item_iter_first

◆ line_item_iter_next

◆ line_item_iter_release

◆ line_item_set

◆ line_item_set_with_key

◆ line_item_types_seen

◆ line_set_flag

◆ line_submit

◆ message

◆ open_errstream

◆ parse_iso8601_timestamp

◆ reopen_errstream

◆ sanitize

◆ wellknown_by_name

◆ wellknown_by_type

◆ wellknown_get_name

◆ wellknown_get_type

◆ write_errstream