test crashing after any_db assinged nonzero lenght fixed.

test crashing after any_db assinged nonzero lenght fixed.

Table_function_json_table::m_dep_tables attempts to cache the value of
m_json->used_tables(), poorly. Remove the cache and use the value
directly.

The query used a subquery of this form:

SELECT ...
WHERE
   EXISTS( SELECT ...
           FROM JSON_TABLE(outer_ref, ..) as JT
           WHERE trivial_correlation_cond)

EXISTS-to-IN conversion code was unable to see that the subquery will
still be correlated after the trivial_correlation is removed, which
eventually caused a crash due to inability to construct a query plan.

Fixed by making Item_subselect::walk() also walk arguments of Table
Functions.

Use a function instead of lambda

(TODO: squash this with previous patch for MDEV-25346)

add_table_to_list - remove the table_function argument.

mysql_derived_prepare() sets Name_resolution_context::outer_context=NULL
for the WHERE clause's context.
Do the same for all ON expressions, too.

Add testcase

Followup: also handle NATURAL JOIN, extend the new approach with
Name_resolution_context::ignored_tables

tests updated.

- Address review input. No functional changes.

Post-rebase fix, JSON_TABLE touched the parser.

(Also fixes MDEV-25254).
Re-work Name Resolution for the argument of JSON_TABLE(json_doc, ....)
function. The json_doc argument can refer to other tables, but it can
only refer to the tables that precede[*] the JSON_TABLE(...) call.

[*] - For queries with RIGHT JOINs, the "preceding" is determined after
the query is normalized by converting RIGHT JOIN into left one.

The implementation is as follows:
- Table function arguments use their own Name_resolution_context.

- The Name_resolution_context now has a bitmap of tables that should be
  ignored when searching for a field.

- get_disallowed_table_deps() walks the TABLE_LIST::nested_join tree
  and computes a bitmap of tables that do not "precede" the given
  JSON_TABLE(...) invocation  (according the above definition of
  "preceding").

should not abort on field::set().

More informative messages added.
Do not issue additional messages if already handled.

feature_json variable incremented.

Field reset added.

syntax fixed.

calling members of NULL object crashes on some platforms.

No plugin for the JSON_TABLE so get the storage type name directly.

MDEV-25230 JSON_TABLE: CREATE VIEW with 2nd level NESTED PATH ends up with invalid frm, Assertion `m_status == DA_ERROR || m_status == DA_OK || m_status == DA_OK_BULK' failed.

Handle multiple NESTED paths.

JSON_TABLE shojldn't be counted in the query_cache.

MDEV-25189 SON_TABLE: Assertion `l_offset >= 0 && table->s->rec_buff_length - l_offset > 0' failed upon CREATE .. SELECT.

fixed already, so just the testcase.

MDEV-25188 JSON_TABLE: ASAN use-after-poison in Field_long::reset / Table_function_json_table::setup or malloc(): invalid size.

                                                                                                         MDEV-25192 JSON_TABLE: ASAN use-after-poison in field_conv_memcpy / Create_tmp_table::finalize upon query with derived table.

MDEV-25186 JSON_TABLE: ASAN global-buffer-overflow in my_strnncoll_binary upon inserting query with join into query cache.

MDEV-25178 JSON_TABLE: ASAN use-after-poison in my_fill_8bit Json_table_column::On_response::respond.

table record buffer size was smaller than required when the charset
changes.

Wrong comma was added after the single column.

Field length can increase after the change_charset(), so need to
set field->ptr properly.

also sensitive parts of the test moved to json_not_embedded.test.

access rights checking fixed.

should return some error code from ha_json_table::rnd_pos() not just 1.

- Don't touch simplify_joins()
- All dependencies caused by JSON_TABLE(...) are now added by
  add_table_function_dependencies().

Fix for for the problem with
- Cross-outer-join dependency
- dead-end join prefix
- join order pruning

See the comments in the patch for detailed description

The specific table handler for the table functions was introduced,
and used to implement JSON_TABLE.

Also increase user name up to 128.

The work was started by Rucha Deodhar <rucha.deodhar@mariadb.com>,
contains audit plugin fixes by Alexey Botchkov <holyfoot@askmonty.org>.

Having both readers and writers use a single lock word in
futex system calls caused performance regression compared to
SRW_LOCK_DUMMY (mutex and 2 condition variables).
A contributing factor is that we did not accurately keep
track of the number of waiting threads and thus had to invoke
system calls to wake up any waiting threads.

SUX_LOCK_GENERIC: Renamed from SRW_LOCK_DUMMY. This is the
original implementation, with rw_lock (std::atomic<uint32_t>),
a mutex and two condition variables. Using a separate writer
mutex (as described below) is not possible, because the mutex ownership
in a buf_block_t::lock must be able to transfer from a write submitter
thread to an I/O completion thread, and pthread_mutex_lock() may assume
that the submitter thread is recursively acquiring the mutex that it
already holds, while in reality the I/O completion thread is the real
owner. POSIX does not define an interface for requesting a mutex to
be non-recursive.

On Microsoft Windows, srw_lock_low will remain a simple wrapper of
SRWLOCK. On 32-bit Microsoft Windows, sizeof(SRWLOCK)=4 while
sizeof(srw_lock_low)=8.

On other platforms, srw_lock_low is an alias of ssux_lock_low,
the Simple (non-recursive) Shared/Update/eXclusive lock.

In the futex-based implementation of ssux_lock_low (Linux, OpenBSD,
Microsoft Windows), we shall use a dedicated mutex for exclusive
requests (writer), and have a WRITER flag in the 'readers' lock word
to inform that a writer is holding the lock or waiting for the lock to
be granted. When the WRITER flag is set, all lock requests must acquire
the writer mutex. Normally, shared (S) lock requests simply perform a
compare-and-swap on the 'readers' word.

Update locks are implemented as a combination of writer mutex
and a normal counter in the 'readers' lock word. The conflict between
U and X locks is guaranteed by the writer mutex.
Unlike SUX_LOCK_GENERIC, wr_u_downgrade() will not wake up any pending
rd_lock() waits. They will wait until u_unlock() releases the writer mutex.

The ssux_lock_low is always wrapped by sux_lock (with a recursion count
of U and X locks), used for dict_index_t::lock and buf_block_t::lock.
Their memory footprint for the futex-based implementation will increase
by sizeof(srw_mutex), or 4 bytes.

This change addresses a performance regression in read-only benchmarks,
such as sysbench oltp_read_only. Also write performance was improved.

On 32-bit Linux and OpenBSD, lock_sys_t::hash_table will allocate
two hash table elements for each srw_lock (14 instead of 15 hash
table cells per 64-byte cache line on IA-32). On Microsoft Windows,
sizeof(SRWLOCK)==sizeof(void*) and there is no change.

Reviewed by: Vladislav Vaintroub
Tested by: Axel Schwenke and Vladislav Vaintroub

On Linux, OpenBSD and Microsoft Windows, srw_mutex was an alias for a
rw-lock while we only need mutex functionality. Let us implement a
futex-based mutex with one bit for HOLDER and 31 bits for counting
waiting requests.

srw_lock::wr_unlock() can avoid waking up a waiter when no waiting
requests exist. (Previously, we only had 1-bit rw_lock::WRITER_WAITING
flag that could be wrongly cleared if multiple waiting wr_lock() exist.
Now we have no problem with up to 2,147,483,648 conflicting threads.)

On 64-bit Microsoft Windows, the advantage is that
sizeof(srw_mutex) is 4, while sizeof(SRWLOCK) would be 8.

Reviewed by: Vladislav Vaintroub

This also means SKIP LOCKED is compatible with the NOWAIT/
WAIT n syntax consisten with the MySQL-8.0 implementation.