log_t::append_prepare_wait(): Do not attempt to read log_sys.write_lsn
because it is not protected by log_sys.latch but by write_lock, which
we cannot hold here. The assertion could fail if log_t::write_buf()
is executing concurrently, and it has not yet executed log_write_buf()
or updated log_sys.write_lsn.
Fixes up commit acd071f599 (MDEV-21923)
The parameter innodb_log_spin_wait_delay will be deprecated and
ignored, because there is no spin loop anymore.
Thanks to commit 685d958e38
and commit a635c40648
multiple mtr_t::commit() can concurrently copy their slice of
mtr_t::m_log to the shared log_sys.buf. Each writer would allocate
their own log sequence number by invoking log_t::append_prepare()
while holding a shared log_sys.latch. This function was too heavy,
because it would invoke a minimum of 4 atomic read-modify-write
operations as well as system calls in the supposedly fast code path.
It turns out that with a simpler data structure, instead of having
several data fields that needed to be kept consistent with each other,
we only need one Atomic_relaxed<uint64_t> write_lsn_offset, on which
we can operate using fetch_add(), fetch_sub() as well as a single-bit
fetch_or(), which reasonably modern compilers (GCC 7, Clang 15 or later)
can translate into loop-free code on AMD64.
Before anything can be written to the log, log_sys.clear_mmap()
must be invoked.
log_t::base_lsn: The LSN of the last write_buf() or persist().
This is a rough approximation of log_sys.lsn, which will be removed.
log_t::write_lsn_offset: An Atomic_relaxed<uint64_t> that buffers
updates of write_to_buf and base_lsn.
log_t::buf_free, log_t::max_buf_free, log_t::lsn. Remove.
Replaced by base_lsn and write_lsn_offset.
log_t::buf_size: Always reflects the usable size in append_prepare().
log_t::lsn_lock: Remove. For the memory-mapped log in resize_write(),
there will be a resize_wrap_mutex.
log_t::get_lsn_approx(): Return a lower bound of get_lsn().
This should be exact unless append_prepare_wait() is pending.
log_get_lsn(): A wrapper for log_sys.get_lsn(), which must be invoked
while holding an exclusive log_sys.latch.
recv_recovery_from_checkpoint_start(): Do not invoke fil_names_clear();
it would seem to be unnecessary.
In many places, references to log_sys.get_lsn() are replaced with
log_sys.get_flushed_lsn(), which remains a simple std::atomic::load().
Reviewed by: Debarun Banerjee
We deprecate and ignore the parameter innodb_buffer_pool_chunk_size
and let the buffer pool size to be changed in arbitrary 1-megabyte
increments.
innodb_buffer_pool_size_max: A new read-only startup parameter
that specifies the maximum innodb_buffer_pool_size. If 0 or
unspecified, it will default to the specified innodb_buffer_pool_size
rounded up to the allocation unit (2 MiB or 8 MiB). The maximum value
is 4GiB-2MiB on 32-bit systems and 16EiB-8MiB on 64-bit systems.
This maximum is very likely to be limited further by the operating system.
The status variable Innodb_buffer_pool_resize_status will reflect
the status of shrinking the buffer pool. When no shrinking is in
progress, the string will be empty.
Unlike before, the execution of SET GLOBAL innodb_buffer_pool_size
will block until the requested buffer pool size change has been
implemented, or the execution is interrupted by a KILL statement
a client disconnect, or server shutdown. If the
buf_flush_page_cleaner() thread notices that we are running out of
memory, the operation may fail with ER_WRONG_USAGE.
SET GLOBAL innodb_buffer_pool_size will be refused
if the server was started with --large-pages (even if
no HugeTLB pages were successfully allocated). This functionality
is somewhat exercised by the test main.large_pages, which now runs
also on Microsoft Windows. On Linux, explicit HugeTLB mappings are
apparently excluded from the reported Redident Set Size (RSS), and
apparently unshrinkable between mmap(2) and munmap(2).
The buffer pool will be mapped to a contiguous virtual memory area
that will be aligned and partitioned into extents of 8 MiB on
64-bit systems and 2 MiB on 32-bit systems.
Within an extent, the first few innodb_page_size blocks contain
buf_block_t objects that will cover the page frames in the rest
of the extent. The number of such frames is precomputed in the
array first_page_in_extent[] for each innodb_page_size.
In this way, there is a trivial mapping between
page frames and block descriptors and we do not need any
lookup tables like buf_pool.zip_hash or buf_pool_t::chunk_t::map.
We will always allocate the same number of block descriptors for
an extent, even if we do not need all the buf_block_t in the last
extent in case the innodb_buffer_pool_size is not an integer multiple
of the of extents size.
The minimum innodb_buffer_pool_size is 256*5/4 pages. At the default
innodb_page_size=16k this corresponds to 5 MiB. However, now that the
innodb_buffer_pool_size includes the memory allocated for the block
descriptors, the minimum would be innodb_buffer_pool_size=6m.
my_large_virtual_alloc(): A new function, similar to my_large_malloc().
my_virtual_mem_reserve(), my_virtual_mem_commit(),
my_virtual_mem_decommit(), my_virtual_mem_release():
New interface mostly by Vladislav Vaintroub, to separately
reserve and release virtual address space, as well as to
commit and decommit memory within it.
After my_virtual_mem_decommit(), the virtual memory range will be
read-only or unaccessible, depending on whether the build option
cmake -DHAVE_UNACCESSIBLE_AFTER_MEM_DECOMMIT=1
has been specified. This option is hard-coded on Microsoft Windows,
where VirtualMemory(MEM_DECOMMIT) will make the memory unaccessible.
On IBM AIX, Linux, Illumos and possibly Apple macOS, the virtual memory
will be zeroed out immediately. On other POSIX-like systems,
madvise(MADV_FREE) will be used if available, to give the operating
system kernel a permission to zero out the virtual memory range.
We prefer immediate freeing so that the reported
resident set size (RSS) of the process will reflect the current
innodb_buffer_pool_size. Shrinking the buffer pool is a rarely
executed resource intensive operation, and the immediate configuration
of the MMU mappings should not incur significant additional penalty.
opt_super_large_pages: Declare only on Solaris. Actually, this is
specific to the SPARC implementation of Solaris, but because we
lack access to a Solaris development environment, we will not revise
this for other MMU and ISA.
buf_pool_t::chunk_t::create(): Remove.
buf_pool_t::create(): Initialize all n_blocks of the buf_pool.free list.
buf_pool_t::allocate(): Renamed from buf_LRU_get_free_only().
buf_pool_t::LRU_warned: Changed to Atomic_relaxed<bool>,
only to be modified by the buf_flush_page_cleaner() thread.
buf_pool_t::shrink(): Attempt to shrink the buffer pool.
There are 3 possible outcomes: SHRINK_DONE (success),
SHRINK_IN_PROGRESS (the caller may keep trying),
and SHRINK_ABORT (we seem to be running out of buffer pool).
While traversing buf_pool.LRU, release the contended
buf_pool.mutex once in every 32 iterations in order to
reduce starvation. Use lru_scan_itr for efficient traversal,
similar to buf_LRU_free_from_common_LRU_list().
buf_pool_t::shrunk(): Update the reduced size of the buffer pool
in a way that is compatible with buf_pool_t::page_guess(),
and invoke my_virtual_mem_decommit().
buf_pool_t::resize(): Before invoking shrink(), run one batch of
buf_flush_page_cleaner() in order to prevent LRU_warn().
Abort if shrink() recommends it, or no blocks were withdrawn in
the past 15 seconds, or the execution of the statement
SET GLOBAL innodb_buffer_pool_size was interrupted.
buf_pool_t::first_to_withdraw: The first block descriptor that is
out of the bounds of the shrunk buffer pool.
buf_pool_t::withdrawn: The list of withdrawn blocks.
If buf_pool_t::resize() is aborted before shrink() completes,
we must be able to resurrect the withdrawn blocks in the free list.
buf_pool_t::contains_zip(): Added a parameter for the
number of least significant pointer bits to disregard,
so that we can find any pointers to within a block
that is supposed to be free.
buf_pool_t::is_shrinking(): Return the total number or blocks that
were withdrawn or are to be withdrawn.
buf_pool_t::to_withdraw(): Return the number of blocks that will need to
be withdrawn.
buf_pool_t::usable_size(): Number of usable pages, considering possible
in-progress attempt at shrinking the buffer pool.
buf_pool_t::page_guess(): Try to buffer-fix a guessed block pointer.
If HAVE_UNACCESSIBLE_AFTER_MEM_DECOMMIT is set, the pointer will
be validated before being dereferenced.
buf_pool_t::get_info(): Replaces buf_stats_get_pool_info().
innodb_init_param(): Refactored. We must first compute
srv_page_size_shift and then determine the valid bounds of
innodb_buffer_pool_size.
buf_buddy_shrink(): Replaces buf_buddy_realloc().
Part of the work is deferred to buf_buddy_condense_free(),
which is being executed when we are not holding any
buf_pool.page_hash latch.
buf_buddy_condense_free(): Do not relocate blocks.
buf_buddy_free_low(): Do not care about buffer pool shrinking.
This will be handled by buf_buddy_shrink() and
buf_buddy_condense_free().
buf_buddy_alloc_zip(): Assert !buf_pool.contains_zip()
when we are allocating from the binary buddy system.
Previously we were asserting this on multiple recursion levels.
buf_buddy_block_free(), buf_buddy_free_low():
Assert !buf_pool.contains_zip().
buf_buddy_alloc_from(): Remove the redundant parameter j.
buf_flush_LRU_list_batch(): Add the parameter to_withdraw
to keep track of buf_pool.n_blocks_to_withdraw.
buf_do_LRU_batch(): Skip buf_free_from_unzip_LRU_list_batch()
if we are shrinking the buffer pool. In that case, we want
to minimize the page relocations and just finish as quickly
as possible.
trx_purge_attach_undo_recs(): Limit purge_sys.n_pages_handled()
in every iteration, in case the buffer pool is being shrunk
in the middle of a purge batch.
Reviewed by: Debarun Banerjee
trx_t::autoinc_locks: Use small_vector<lock_t*,4> in order to avoid any
dynamic memory allocation in the most common case (a statement is
holding AUTO_INCREMENT locks on at most 4 tables or partitions).
lock_cancel_waiting_and_release(): Instead of removing elements from
the middle, simply assign nullptr, like lock_table_remove_autoinc_lock().
The added test innodb.auto_increment_lock_mode covers the dynamic memory
allocation as well as nondeterministically (occasionally) covers
the out-of-order lock release in lock_table_remove_autoinc_lock().
Reviewed by: Debarun Banerjee
innodb_log_file_mmap: Use a constant documentation string that
refers to persistent memory also when it is not available in the build.
HAVE_INNODB_MMAP: Remove, and unconditionally enable this code.
log_mmap(): On 32-bit systems, ensure that the size fits in 32 bits.
log_t::resize_start(), log_t::resize_abort(): Only handle memory-mapping
if HAVE_PMEM is defined. The generic memory-mapped interface is only for
reading the log in recovery. Writable memory mappings are only for
persistent memory, that is, Linux file systems with mount -o dax.
Reviewed by: Debarun Banerjee, Otto Kekäläinen
Most InnoDB functions do not throw any exceptions, not even indirectly
std::bad_alloc, which could be thrown by a C++ memory allocation function.
Let us annotate many functions with noexcept in order to reduce the code
footprint related to exception handling.
Reviewed by: Thirunarayanan Balathandayuthapani
fil_space_t::create(): Instead of invoking the default fil_space_t
constructor on a zero-filled buffer, allocate an uninitialized buffer
and invoke an explicitly defined constructor on it. Also, specify
initializer expressions for all constant data members, so that all of them
will be initialized in the constructor.
fil_space_t::being_imported: Replaces part of fil_space_t::purpose.
fil_space_t::is_being_imported(), fil_space_t::is_temporary():
Replaces fil_space_t::purpose.
fil_space_t:🆔 Changed the type from ulint to uint32_t to reduce
incompatibility with later branches that include
commit ca501ffb04 (MDEV-26195).
fil_space_t::try_to_close(): Do not attempt to close files that are
in an I/O bound phase of ALTER TABLE…IMPORT TABLESPACE.
log_file_op, first_page_init: recv_spaces_t:
Use uint32_t for the tablespace id.
Reviewed by: Debarun Banerjee
In some places, there were redundant comparisons against TRX_SYS_SPACE
or SRV_TMP_SPACE_ID. The temporary tablespace is never the subject of
log-based recovery.
Also, consistently check for SRV_SPACE_ID_UPPER_BOUND.
Reviewed by: Debarun Barerjee
When using the default innodb_log_buffer_size=2m, mariadb-backup --backup
would spend a lot of time re-reading and re-parsing the log. For reads,
it would be beneficial to memory-map the entire ib_logfile0 to the
address space (typically 48 bits or 256 TiB) and read it from there,
both during --backup and --prepare.
We will introduce the Boolean read-only parameter innodb_log_file_mmap
that will be OFF by default on most platforms, to avoid aggressive
read-ahead of the entire ib_logfile0 in when only a tiny portion would be
accessed. On Linux and FreeBSD the default is innodb_log_file_mmap=ON,
because those platforms define a specific mmap(2) option for enabling
such read-ahead and therefore it can be assumed that the default would
be on-demand paging. This parameter will only have impact on the initial
InnoDB startup and recovery. Any writes to the log will use regular I/O,
except when the ib_logfile0 is stored in a specially configured file system
that is backed by persistent memory (Linux "mount -o dax").
We also experimented with allowing writes of the ib_logfile0 via a
memory mapping and decided against it. A fundamental problem would be
unnecessary read-before-write in case of a major page fault, that is,
when a new, not yet cached, virtual memory page in the circular
ib_logfile0 is being written to. There appears to be no way to tell
the operating system that we do not care about the previous contents of
the page, or that the page fault handler should just zero it out.
Many references to HAVE_PMEM have been replaced with references to
HAVE_INNODB_MMAP.
The predicate log_sys.is_pmem() has been replaced with
log_sys.is_mmap() && !log_sys.is_opened().
Memory-mapped regular files differ from MAP_SYNC (PMEM) mappings in the
way that an open file handle to ib_logfile0 will be retained. In both
code paths, log_sys.is_mmap() will hold. Holding a file handle open will
allow log_t::clear_mmap() to disable the interface with fewer operations.
It should be noted that ever since
commit 685d958e38 (MDEV-14425)
most 64-bit Linux platforms on our CI platforms
(s390x a.k.a. IBM System Z being a notable exception) read and write
/dev/shm/*/ib_logfile0 via a memory mapping, pretending that it is
persistent memory (mount -o dax). So, the memory mapping based log
parsing that this change is enabling by default on Linux and FreeBSD
has already been extensively tested on Linux.
::log_mmap(): If a log cannot be opened as PMEM and the desired access
is read-only, try to open a read-only memory mapping.
xtrabackup_copy_mmap_snippet(), xtrabackup_copy_mmap_logfile():
Copy the InnoDB log in mariadb-backup --backup from a memory
mapped file.
log_t::resize_write(): Advance log_sys.resize_lsn and reset
the resize_log offset to START_OFFSET whenever the memory-mapped buffer
would wrap around.
Previously, in case the initial target offset would be beyond the
requested innodb_log_file_size, we only adjusted the offset but
not the LSN. An incorrect LSN would cause log_sys.buf_free to be out
of bounds when the log resizing completes.
The log_sys.lsn_lock will cover the entire duration of replicating
memory-mapped log for resizing. We just need a mutex that is compatible
with the caller holding log_sys.latch. While the choice of mtr_t::finisher
(for normal log writes) depends on mtr_t::spin_wait_delay,
replicating the log during resizing is a rare operation where we can
afford possible additional context switching overhead.
The recent commit 4ca355d863 (MDEV-33894)
caused a serious regression for online InnoDB ib_logfile0 resizing,
breaking crash-safety unless the memory-mapped log file interface is
being used. However, the log resizing was broken also before this.
To prevent such regressions in the future, we extend the test
innodb.log_file_size_online with a kill and restart of the server
and with some writes running concurrently with the log size change.
When run enough many times, this test revealed all the bugs that
are being fixed by the code changes.
log_t::resize_start(): Do not allow the resized log to start before
the current log sequence number. In this way, there is no need to
copy anything to the first block of resize_buf. The previous logic
regarding that was incorrect in two ways. First, we would have to
copy from the last written buffer (buf or flush_buf). Second, we failed
to ensure that the mini-transaction end marker bytes would be 1
in the buffer. If the source ib_logfile0 had wrapped around an odd number
of times, the end marker would be 0. This was occasionally observed
when running the test innodb.log_file_size_online.
log_t::resize_write_buf(): To adjust for the resize_start() change,
do not write anything that would be before the resize_lsn.
Take the buffer (resize_buf or resize_flush_buf) as a parameter.
Starting with commit 4ca355d863
we no longer swap buffers when rewriting the last log block.
log_t::append(): Define as a static function; only some debug
assertions need to refer to the log_sys object.
innodb_log_file_size_update(): Wake up the buf_flush_page_cleaner()
if needed, and wait for it to complete a batch while waiting for
the log resizing to be completed. If the current LSN is behind the
resize target LSN, we will write redundant FILE_CHECKPOINT records to
ensure that the log resizing completes. If the buf_pool.flush_list is
empty or the buf_flush_page_cleaner() is stuck for some reason, our wait
will time out in 5 seconds, so that we can periodically check if the
execution of SET GLOBAL innodb_log_file_size was aborted. Previously,
we could get into a busy loop here while the buf_flush_page_cleaner()
would remain idle.
Issue: During mtr_t:commit, if there is not enough space available in
redo log buffer, we flush the buffer. During flush, the LSN lock is
released allowing other concurrent mtr to commit. After flush we
reacquire the lock but use the old LSN obtained before check. It could
lead to redo log corruption. As the LSN moves backwards with the
possibility of data loss and unrecoverable server if the server aborts
for any reason or if server is shutdown with innodb_fast_shutdown=2.
With normal shutdown, recovery fails to map the checkpoint LSN to
correct offset.
In debug mode it hits log0log.cc:863: lsn_t log_t::write_buf()
Assertion `new_buf_free == ((lsn - first_lsn) & write_size_1)' failed.
In release mode, after normal shutdown, restart fails.
[ERROR] InnoDB: Missing FILE_CHECKPOINT(8416546) at 8416546
[ERROR] InnoDB: Log scan aborted at LSN 8416546
Backup fails reading the corrupt redo log.
[00] 2024-07-31 20:59:10 Retrying read of log at LSN=7334851
[00] FATAL ERROR: 2024-07-31 20:59:11 Was only able to copy log from
7334851 to 7334851, not 8416446; try increasing innodb_log_file_size
Unless a backup is tried or the server is shutdown or killed
immediately, the corrupt redo part is eventually truncated and there
may not be any visible issues seen in release mode.
This issue was introduced by the following commit.
commit a635c40648
MDEV-27774 Reduce scalability bottlenecks in mtr_t::commit()
Fix: If we need to release latch and flush redo before writing mtr
logs, make sure to get the latest system LSN after reacquiring the
redo system latch.
This bug was found related to MDEV-34212.
Some InnoDB tests, most notably innodb.table_flags,64k would occasionally
fail. I am able to reproduce this locally on a MemorySanitizer build,
sporadically.
The following is a minimal .test file for reproducing this:
--source include/have_innodb.inc
SELECT @@innodb_page_size;
and the .opt file:
--innodb-undo-tablespaces=0 --innodb-page-size=64k
--innodb-buffer-pool-size=20m
This bug was revealed due to the recent
commit 466ae1cf81
which set innodb_fast_shutdown=0 during server bootstrap
in our regression test driver.
Due to the bug, a write of undo page 50 in the system tablespace
was discarded in buf_page_t::flush(). A subsequent InnoDB startup
failed because an old version of that page would point to a
freed undo log page 300.
mtr_t::commit_shrink(): Only invoke fil_space_t::set_create_lsn()
on undo tablespaces, which will be fully reinitialized or created
from the scratch. On the system tablespace, we must only adjust
the file size, to avoid writing pages that are beyond the end
of the tablespace. Thanks to Thirunarayanan Balathandayuthapani
for providing this fix.
mtr_t::commit_shrink(): Do not assert that some previously clean pages
will be flagged as modified by this mini-transaction. It could be the
case that there had been no recent write-back of any of the undo
tablespace pages that we are modifying when truncating the tablespace.
It suffices to assert that some pages were modified again:
ut_ad(m_modifications).
This fixes up commit f5fddae3cb
In so-called optimistic buffer pool lookups, we must not
dereference a block descriptor before we have made sure that
it is accessible. While buf_pool_t::resize() is running,
block descriptors could become invalid.
The buf::Block_hint class was essentially duplicating
a buf_pool.page_hash lookup that was executed in
buf_page_optimistic_get() anyway. For better locality of
reference, we had better execute that lookup only once.
buf_page_optimistic_fix(): Prepare for buf_page_optimistic_get().
This basically is a simpler version of Buf::Block_hint.
buf_page_optimistic_get(): Assume that buf_page_optimistic_fix()
has been called and the page identifier verified. Should the block
be evicted, the block->modify_clock will be invalidated; we do not
need to check the block->page.id() again. It suffices to check
the block->modify_clock after acquiring the page latch.
btr_pcur_t::old_page_id: Store the expected page identifier
for buf_page_optimistic_fix().
btr_pcur_t::block_when_stored: Remove. This was duplicating
page_cur_t::block.
btr_pcur_optimistic_latch_leaves(): Remove redundant parameters.
First, invoke buf_page_optimistic_fix() on the requested page.
If needed, acquire a latch on the left page. Finally, acquire
a latch on the target page and recheck the block->modify_clock.
If the page had been freed while we were not holding a page latch,
fall back to the slow path. Validate the FIL_PAGE_PREV after
acquiring a latch on the current page. The block->modify_clock
is only being incremented when records are deleted or pages
reorganized or evicted; it does not guard against concurrent
page splits.
Reviewed by: Debarun Banerjee
log_t: Define buf_size, max_buf_free as 32-bit and next_checkpoint_no
as byte (we only need a bit) and rearrange some data members,
so that on AMD64 we can fit log_sys.latch and log_sys.log in
the same 64-byte cache line.
mtr_t::commit_log(), mtr_t::commit_logger: A part of mtr_t::commit()
split into a separate function, so that we will not unnecessarily invoke
log_sys.get_write_target() when running on a memory-mapped log file,
or log_sys.is_pmem().
Reviewed by: Vladislav Vaintroub
Tested by: Matthias Leich
Some fixes related to commit f838b2d799 and
Rows_log_event::do_apply_event() and Update_rows_log_event::do_exec_row()
for system-versioned tables were provided by Nikita Malyavin.
This was required by test versioning.rpl,trx_id,row.
innodb_log_spin_wait_delay_update(): Always acquire log_sys.latch
to protect the change of mtr_t::spin_wait_delay.
log_t::lock_lsn(): In the general case, actually use
mtr_t::spin_wait_delay as it was intended. In the x86 specific
log_t::lock_lsn_bts() we used mtr_t::spin_wait_delay.
The log_sys.lsn_lock is a very contended resource with a small
critical section in log_sys.append_prepare(). On many processor
microarchitectures, replacing the system call based log_sys.lsn_lock
with a pure spin lock would fare worse during high concurrency workloads,
wasting a significant amount of CPU cycles in the spin loop.
On other microarchitectures, we would see a significant amount of time
being spent in native_queued_spin_lock_slowpath() in the Linux kernel,
plus context switching between user and kernel address space. This was
pointed out by Steve Shaw from Intel Corporation.
Depending on the workload and the hardware implementation, it may be
useful to use a pure spin lock in log_sys.append_prepare().
We will introduce a parameter. The statement
SET GLOBAL INNODB_LOG_SPIN_WAIT_DELAY=50;
would enable a spin lock that will execute that many MY_RELAX_CPU()
operations (such as the x86 PAUSE instruction) between successive
attempts of acquiring the spin lock. The use of a system call based
log_sys.lsn_lock (which is the default setting) can be enabled by
SET GLOBAL INNODB_LOG_SPIN_WAIT_DELAY=0;
This patch will also introduce #ifdef LOG_LATCH_DEBUG
(part of cmake -DWITH_INNODB_EXTRA_DEBUG=ON) for more accurate
tracking of log_sys.latch ownership and reorganize the fields of
log_sys to improve the locality of reference and to reduce the
chances of false sharing.
When a spin lock is being used, it will be maintained in the
most significant bit of log_sys.buf_free. This is useful, because that is
one of the fields that is covered by the lock. For IA-32 or AMD64, we
implement the spin lock specially via log_t::lsn_lock_bts(), employing the
i386 LOCK BTS instruction. A straightforward std::atomic::fetch_or() would
translate into an inefficient loop around LOCK CMPXCHG.
mtr_t::spin_wait_delay: The value of innodb_log_spin_wait_delay.
mtr_t::finisher: Pointer to the currently used mtr_t::finish_write()
implementation. This allows to avoid introducing conditional branches.
We no longer invoke log_sys.is_pmem() at the mini-transaction level,
but we would do that in log_write_up_to().
mtr_t::finisher_update(): Update finisher when spin_wait_delay is
changed from or to 0 (the spin lock is changed to log_sys.lsn_lock or
vice versa).
Problem:
========
During upgrade, InnoDB does write the redo log for adjusting
the tablespace size or tablespace flags even before the log
has upgraded to configured format. This could lead to data
inconsistent if any crash happened during upgrade process.
Fix:
===
srv_start(): Write the tablespace flags adjustment, increased
tablespace size redo log only after redo log upgradation.
log_write_low(), log_reserve_and_write_fast(): Check whether
the redo log is in physical format.
This regression is introduced in MDEV-28708 where the MTR_LOG_NO_REDO
mtrs are assigned last_checkpoint_lsn as the LSN. It causes a race with
checkpoint in pending state. The concurrent checkpoint writes a
checkpoint LSN of larger value after pages with older checkpoint LSN is
inserted into the flush list. The next checkpoint sees the reversal in
checkpoint sequence and asserts if the pages are not yet flushed.
There could be several ways to solve this issue. Ideally the unlogged
mtr should take the latest LSN as opposed to going behind and use the
previous checkpoint LSN. It has been the older design and seems good.
Also, other than the critical race, using the old checkpoint LSN adds
the pages to other end of flush list overriding all existing dirty
pages and looks counter intuitive.
