fil_name_process(): If the recovery of a tablespace was deferred,
do invoke fil_ibd_load() even though the name in recv_spaces is
not changing. This allows us to recover from a situation where
there are many FILE_RENAME records, renaming a tablespace back
and forth, and a FILE_MODIFY record that had been written by
fil_names_clear().

Co-developed with: Thirunarayanan Balathandayuthapani

Fixed tpool timer implementation on POSIX.
Prior to this patch, under some specific rare circumstances (concurrency
related), timer callback execution might be skipped.

When attempting to recover a database with an incorrect encryption key,
the unencrypted page contents should be expected to differ from what
was written before recovery. Let us suppress some more messages.
This caused intermittent failures, depending on when the latest
log checkpoint was triggered.

Histogram_json_hb::range_selectivity() may return small negative
numbers due to rounding errors in the histogram.

Make sure the returned value is non-negative.
Add an assert to catch negative values that are not small.

(attempt #2)

trx_undo_rec_copy(): Return nullptr if the undo record is corrupted.

trx_undo_rec_get_undo_no(): Define inline with the declaration.

trx_purge_dummy_rec: Replaced with a -1 pointer.

row_undo_rec_get(), UndorecApplier::apply_undo_rec(): Check
if trx_undo_rec_copy() returned nullptr.

trx_purge_get_next_rec(): Return nullptr upon encountering any
corruption, to signal the end of purge.

On GNU/Linux, even though the C11 aligned_alloc() appeared in
GNU libc early on, some custom memory allocators did not
implement it until recently. For example, before
gperftools/gperftools@d406f2285390c402e824dd28e6992f7f890dcdf9
the free() in tcmalloc would fail to free memory that was
returned by aligned_alloc(), because the latter would map to the
built-in allocator of libc. The Linux specific memalign() has a
similar interface and is safer to use, because it has been
available for a longer time. For AddressSanitizer, we will use
aligned_alloc() so that the constraint on size can be enforced.

buf_tmp_reserve_compression_buf(): When HAVE_ALIGNED_ALLOC holds,
round up the size to be an integer multiple of the alignment.

pfs_malloc(): In the unit test stub, round up the size to be an
integer multiple of the alignment.

Table_cache_instance: Define the structure aligned at
the CPU cache line, and remove a pad[] data member.
Krunal Bauskar reported this to improve performance on ARMv8.

aligned_malloc(): Wrapper for the Microsoft _aligned_malloc()
and the ISO/IEC 9899:2011 <stdlib.h> aligned_alloc().
Note: The parameters are in the Microsoft order (size, alignment),
opposite of aligned_alloc(alignment, size).
Note: The standard defines that size must be an integer multiple
of alignment. It is enforced by AddressSanitizer but not by GNU libc
on Linux.

aligned_free(): Wrapper for the Microsoft _aligned_free() and
the standard free().

HAVE_ALIGNED_ALLOC: A new test. Unfortunately, support for
aligned_alloc() may still be missing on some platforms.
We will fall back to posix_memalign() for those cases.

HAVE_MEMALIGN: Remove, along with any use of the nonstandard memalign().

PFS_ALIGNEMENT (sic): Removed; we will use CPU_LEVEL1_DCACHE_LINESIZE.

PFS_ALIGNED: Defined using the C++11 keyword alignas.

buf_pool_t::page_hash_table::create(),
lock_sys_t::hash_table::create():
lock_sys_t::hash_table::resize(): Pad the allocation size to an
integer multiple of the alignment.

Reviewed by: Vladislav Vaintroub

There was a race condition between log_checkpoint_low() and
deleting or renaming data files. The scenario is as follows:

1. The buffer pool does not contain dirty pages.
2. A FILE_DELETE or FILE_RENAME record is written.
3. The checkpoint LSN will be moved ahead of the write of the record.
4. The server is killed before the file is actually renamed or deleted.

We will prevent this race condition by ensuring that a log checkpoint
cannot occur between the durable write and the file system operation:

1. Durably write the FILE_DELETE or FILE_RENAME record.
2. Perform the file system operation.
3. Allow any log checkpoint to proceed.

mtr_t::commit_file(): Implement the DELETE or RENAME logic.

fil_delete_tablespace(): Delegate some of the logic to
mtr_t::commit_file().

fil_space_t::rename(): Delegate some logic to mtr_t::commit_file().
Remove the debug injection point fil_rename_tablespace_failure_2
because we do test RENAME failures without any debug injection.

fil_name_write_rename_low(), fil_name_write_rename(): Remove.

Tested by Matthias Leich

buf_page_create_low(): Before retrying, release the exclusive page latch
in order to prevent an infinite loop in buf_pool_t::corrupted_evict().

recv_recover_page(): Correct a debug assertion to refer to recv_sys.lsn,
which may be ahead of log_sys.lsn during non-final recovery batches.
In commit 685d958e (MDEV-14425)
when some redundant LSN fields were removed,
log_sys.log.scanned_lsn had been replaced with a reference to
log_sys.lsn instead of the more appropriate recv_sys.lsn.

recv_scan_log(): Remove a redundant call to log_sys.set_recovered_lsn().
It suffices to adjust the log_sys.lsn after parsing (and before starting
to apply) records for the last batch.

Note: Normally, log_sys.lsn must be the latest log sequence number.
Before the final recovery batch, this may be safely violated, because
log_write_up_to() will be a no-op. That function will be invoked by the
buf_flush_page_cleaner thread to initiate writes of recovered pages.

Work around MDEV-28718 for now, but also optimize the interation
of information_schema.SYSTEM_VARIABLES.

Add test case to show that tzinfo data into bootstrap is
desired functionality.

Bug report thanks to Dan Lenski of AWS.

ha_innobase::prepare_inplace_alter_table(): If the ALTER TABLE
operation is no-op for InnoDB, do reset m_prebuilt->trx_id
so that ha_innobase::table_version() will always report either 0
or the identifier of the transaction that would commit changes
to the InnoDB data dictionary.

The failure scenario involved a completed DROP INDEX followed by
a no-op ALTER TABLE during which the server was killed.
An effort to create a reproducible test failed.

The bug was that build_notnull_conds_for_range_scans() did not take into
account the join_tab is not yet sorted with constant tables first.
Fixed the bug by testing explicitely if a table is a const table.

Since commit 0b47c126 (MDEV-13542)
we treat all-zero pages as corrupted ones.

During a stress test, a read-ahead of an all-zero page was triggered
and the page read was completed concurrently with buf_page_create_low().
This caused the assertion to fail, because buf_page_create_low() was
waiting for the page latch.

buf_page_get_low(): Only invoke buf_pool_t::corrupted_evict()
if the block was not already marked as corrupted.

buf_page_create_low(): On page identifier mismatch, retry the
buf_pool.page_hash lookup.

buf_pool_t::corrupted_evict(): Set the state of the block to FREED
so that a concurrent buf_page_get_low() will refuse to load the page.
Wait for the page latch to be vacant before proceeding to remove
the block from buf_pool.page_hash and buf_pool.LRU.

page_id_t::set_corrupted(), page_id_t::is_corrupted(): Accessors
for indicating a corrupted page identifier.

Tested by Matthias Leich

Avoid the loop with getting rid of back and forth jumping.

In commit c4c88307 (MDEV-28111) we disabled
the file system cache on the InnoDB write-ahead log file (ib_logfile0)
by default on Linux.

It turns out that especially with innodb_flush_trx_log_at_commit=2,
writing to the log via the file system cache typically improves throughput,
especially on slow storage or at a small number of concurrent transactions.
For other values of innodb_flush_log_at_trx_commit, direct writes were
observed to be mostly but not always faster. Whether it pays off to
disable the file system cache on the log may depend on the type of storage,
the workload, and the operating system kernel version.

On Linux and Microsoft Windows, we will introduce the settable Boolean
global variable innodb_log_file_buffering that indicates whether the
file system cache on the redo log file is enabled. The default value is
innodb_log_file_buffering=OFF. If the server is started up with
innodb_flush_log_at_trx_commit=2, the value will be changed to
innodb_log_file_buffering=ON.

When a persistent memory interface is being used for the log,
the value cannot be changed from innodb_log_file_buffering=OFF.
On Linux, when the physical block size cannot be determined
to be a power of 2 between 64 and 4096 bytes, the file system cache
cannot be disabled, and innodb_log_file_buffering=ON cannot be changed.

Server log messages will indicate whether the file system cache is
enabled for the redo log:

[Note] InnoDB: Buffered log writes (block size=512 bytes)
[Note] InnoDB: File system buffers for log disabled (block size=512 bytes)

After this change, the startup parameter innodb_flush_method will no
longer control whether O_DIRECT will be set on the redo log on Linux.

On other operating systems that support O_DIRECT, no interface has been
implemented for controlling the file system cache for the redo log.
The innodb_flush_method values O_DIRECT, O_DIRECT_NO_FSYNC, O_DSYNC
will enable O_DIRECT for data files, not the log.

Tested by: Matthias Leich, Axel Schwenke

trx_purge_free_segment(): Do mark that the block will be modified.

It seems possible that this regression was introduced by the
changes to the page-freeing logic
in commit 4179f93d (MDEV-18976).

Tested by: Matthias Leich

- innodb_fts.sync_block doesn't make sense after MDEV-25581's patch
because fts cache syncing is done as a part of insert operation
and it leads to completion of select over insert sometimes.
This test case is not relevant any more

In commit 73fee39e (MDEV-27985)
a regression was introduced that would cause bpage=nullptr to
be referenced.

buf_flush_LRU_list_batch(): Always terminate the loop upon
encountering a null pointer.

MDEV-26127 Assertion `err != DB_DUPLICATE_KEY' failed or InnoDB: Failing assertion: id != 0 on ALTER ... REBUILD PARTITION

During rebuild of partition, the partitioning engine calls
alter_close_table(), which does not unlock and close some table
instances of the target table.
Then, the engine fails to rename partitions because there are table
instances that are still locked.

Closing all the table instance of the target table fixes the bug.

innodb_drop_database(): Use explicit TO_BINARY casts on
SYS_TABLES.NAME, which for historical reasons uses the wrong collation
latin1_swedish_ci instead of BINARY.