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mariadb/storage/maria/ma_checkpoint.c
Monty f03fee06b0 Improve error messages from Aria 
- Error on commit now returns HA_ERR_COMMIT_ERROR instead of
  HA_ERR_INTERNAL_ERROR
- If checkpoint fails, it will now print out where it failed.
2021-09-15 19:27:34 +03:00

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/* Copyright (C) 2006,2007 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
/*
WL#3071 Maria checkpoint
First version written by Guilhem Bichot on 2006-04-27.
*/
/* Here is the implementation of this module */
/** @todo RECOVERY BUG this is unreviewed code */
/*
Summary:
checkpoints are done either by a background thread (checkpoint every Nth
second) or by a client.
In ha_maria, it's not made available to clients, and will soon be done by a
background thread (periodically taking checkpoints and flushing dirty
pages).
*/
#include "maria_def.h"
#include "ma_pagecache.h"
#include "ma_blockrec.h"
#include "ma_checkpoint.h"
#include "ma_loghandler_lsn.h"
#include "ma_servicethread.h"
#include "ma_crypt.h"
/** @brief type of checkpoint currently running */
static CHECKPOINT_LEVEL checkpoint_in_progress= CHECKPOINT_NONE;
/** @brief protects checkpoint_in_progress */
static mysql_mutex_t LOCK_checkpoint;
/** @brief for killing the background checkpoint thread */
static mysql_cond_t COND_checkpoint;
/** @brief control structure for checkpoint background thread */
static MA_SERVICE_THREAD_CONTROL checkpoint_control=
{0, FALSE, FALSE, &LOCK_checkpoint, &COND_checkpoint};
/* is ulong like pagecache->blocks_changed */
static uint pages_to_flush_before_next_checkpoint;
static PAGECACHE_FILE *dfiles, /**< data files to flush in background */
*dfiles_end; /**< list of data files ends here */
static PAGECACHE_FILE *kfiles, /**< index files to flush in background */
*kfiles_end; /**< list of index files ends here */
/* those two statistics below could serve in SHOW GLOBAL STATUS */
static uint checkpoints_total= 0, /**< all checkpoint requests made */
checkpoints_ok_total= 0; /**< all checkpoints which succeeded */
struct st_filter_param
{
LSN up_to_lsn; /**< only pages with rec_lsn < this LSN */
uint max_pages; /**< stop after flushing this number pages */
}; /**< information to determine which dirty pages should be flushed */
static enum pagecache_flush_filter_result
filter_flush_file_medium(enum pagecache_page_type type,
pgcache_page_no_t page,
LSN rec_lsn, void *arg);
static enum pagecache_flush_filter_result
filter_flush_file_full(enum pagecache_page_type type,
pgcache_page_no_t page,
LSN rec_lsn, void *arg);
static enum pagecache_flush_filter_result
filter_flush_file_evenly(enum pagecache_page_type type,
pgcache_page_no_t pageno,
LSN rec_lsn, void *arg);
static int really_execute_checkpoint(void);
pthread_handler_t ma_checkpoint_background(void *arg);
static int collect_tables(LEX_STRING *str, LSN checkpoint_start_log_horizon);
/**
@brief Does a checkpoint
@param level what level of checkpoint to do
@param no_wait if another checkpoint of same or stronger level
is already running, consider our job done
@note In ha_maria, there can never be two threads trying a checkpoint at
the same time.
@return Operation status
@retval 0 ok
@retval !=0 error
*/
int ma_checkpoint_execute(CHECKPOINT_LEVEL level, my_bool no_wait)
{
int result= 0;
DBUG_ENTER("ma_checkpoint_execute");
if (!checkpoint_control.inited)
{
/*
If ha_maria failed to start, maria_panic_hton is called, we come here.
*/
DBUG_RETURN(0);
}
DBUG_ASSERT(level > CHECKPOINT_NONE);
/* look for already running checkpoints */
mysql_mutex_lock(&LOCK_checkpoint);
while (checkpoint_in_progress != CHECKPOINT_NONE)
{
if (no_wait && (checkpoint_in_progress >= level))
{
/*
If we are the checkpoint background thread, we don't wait (it's
smarter to flush pages instead of waiting here while the other thread
finishes its checkpoint).
*/
mysql_mutex_unlock(&LOCK_checkpoint);
goto end;
}
mysql_cond_wait(&COND_checkpoint, &LOCK_checkpoint);
}
checkpoint_in_progress= level;
mysql_mutex_unlock(&LOCK_checkpoint);
/* from then on, we are sure to be and stay the only checkpointer */
result= really_execute_checkpoint();
DBUG_EXECUTE_IF("maria_crash_after_checkpoint",
{ DBUG_PRINT("maria_crash", ("now")); DBUG_SUICIDE(); });
mysql_cond_broadcast(&COND_checkpoint);
end:
DBUG_RETURN(result);
}
/**
@brief Does a checkpoint, really; expects no other checkpoints
running.
Checkpoint level requested is read from checkpoint_in_progress.
@return Operation status
@retval 0 ok
@retval !=0 error
*/
static int really_execute_checkpoint(void)
{
uint i, error= 0;
int error_errno= 0;
/** @brief checkpoint_start_log_horizon will be stored there */
char *ptr;
const char *error_place= 0;
LEX_STRING record_pieces[4]; /**< only malloc-ed pieces */
LSN min_page_rec_lsn, min_trn_rec_lsn, min_first_undo_lsn;
TRANSLOG_ADDRESS checkpoint_start_log_horizon;
char checkpoint_start_log_horizon_char[LSN_STORE_SIZE];
DBUG_ENTER("really_execute_checkpoint");
DBUG_PRINT("enter", ("level: %d", checkpoint_in_progress));
bzero(&record_pieces, sizeof(record_pieces));
/*
STEP 1: record current end-of-log position using log's lock. It is
critical for the correctness of Checkpoint (related to memory visibility
rules, the log's lock is a mutex).
"Horizon" is a lower bound of the LSN of the next log record.
*/
checkpoint_start_log_horizon= translog_get_horizon();
DBUG_PRINT("info",("checkpoint_start_log_horizon " LSN_FMT "",
LSN_IN_PARTS(checkpoint_start_log_horizon)));
lsn_store(checkpoint_start_log_horizon_char, checkpoint_start_log_horizon);
/*
STEP 2: fetch information about transactions.
We must fetch transactions before dirty pages. Indeed, a transaction
first sets its rec_lsn then sets the page's rec_lsn then sets its rec_lsn
to 0. If we fetched pages first, we may see no dirty page yet, then we
fetch transactions but the transaction has already reset its rec_lsn to 0
so we miss rec_lsn again.
For a similar reason (over-allocated bitmap pages) we have to fetch
transactions before flushing bitmap pages.
min_trn_rec_lsn will serve to lower the starting point of the REDO phase
(down from checkpoint_start_log_horizon).
*/
if (unlikely(trnman_collect_transactions(&record_pieces[0],
&record_pieces[1],
&min_trn_rec_lsn,
&min_first_undo_lsn)))
{
error_place= "trnman_collect_transaction";
goto err;
}
/* STEP 3: fetch information about table files */
if (unlikely(collect_tables(&record_pieces[2],
checkpoint_start_log_horizon)))
{
error_place= "collect_tables";
goto err;
}
/* STEP 4: fetch information about dirty pages */
/*
It's better to do it _after_ having flushed some data pages (which
collect_tables() may have done), because those are now non-dirty and so we
have a more up-to-date dirty pages list to put into the checkpoint record,
and thus we will have less work at Recovery.
*/
/* Using default pagecache for now */
if (unlikely(pagecache_collect_changed_blocks_with_lsn(maria_pagecache,
&record_pieces[3],
&min_page_rec_lsn)))
{
error_place= "collect_pages";
goto err;
}
/* LAST STEP: now write the checkpoint log record */
{
LSN lsn;
translog_size_t total_rec_length;
/*
the log handler is allowed to modify "str" and "length" (but not "*str")
of its argument, so we must not pass it record_pieces directly,
otherwise we would later not know what memory pieces to my_free().
*/
LEX_CUSTRING log_array[TRANSLOG_INTERNAL_PARTS + 5];
log_array[TRANSLOG_INTERNAL_PARTS + 0].str=
(uchar*) checkpoint_start_log_horizon_char;
log_array[TRANSLOG_INTERNAL_PARTS + 0].length= total_rec_length=
sizeof(checkpoint_start_log_horizon_char);
for (i= 0; i < (sizeof(record_pieces)/sizeof(record_pieces[0])); i++)
{
log_array[TRANSLOG_INTERNAL_PARTS + 1 + i].str= (uchar*)record_pieces[i].str;
log_array[TRANSLOG_INTERNAL_PARTS + 1 + i].length= record_pieces[i].length;
total_rec_length+= (translog_size_t) record_pieces[i].length;
}
if (unlikely(translog_write_record(&lsn, LOGREC_CHECKPOINT,
&dummy_transaction_object, NULL,
total_rec_length,
sizeof(log_array)/sizeof(log_array[0]),
log_array, NULL, NULL) ||
translog_flush(lsn)))
{
error_place= "translog_write_record";
goto err;
}
translog_lock();
/*
This cannot be done as a inwrite_rec_hook of LOGREC_CHECKPOINT, because
such hook would be called before translog_flush (and we must be sure
that log was flushed before we write to the control file).
*/
if (unlikely(ma_control_file_write_and_force(lsn, last_logno,
max_trid_in_control_file,
recovery_failures)))
{
error_place= "ma_control_file_write";
error_errno= my_errno;
translog_unlock();
goto err;
}
translog_unlock();
}
/*
Note that we should not alter memory structures until we have successfully
written the checkpoint record and control file.
*/
/* checkpoint succeeded */
ptr= record_pieces[3].str;
pages_to_flush_before_next_checkpoint= uint4korr(ptr);
DBUG_PRINT("checkpoint",("%u pages to flush before next checkpoint",
pages_to_flush_before_next_checkpoint));
/* compute log's low-water mark */
{
TRANSLOG_ADDRESS log_low_water_mark= min_page_rec_lsn;
set_if_smaller(log_low_water_mark, min_trn_rec_lsn);
set_if_smaller(log_low_water_mark, min_first_undo_lsn);
set_if_smaller(log_low_water_mark, checkpoint_start_log_horizon);
/**
Now purge unneeded logs.
As some systems have an unreliable fsync (drive lying), we could try to
be robust against that: remember a few previous checkpoints in the
control file, and not purge logs immediately... Think about it.
*/
if (translog_purge(log_low_water_mark))
ma_message_no_user(0, "log purging failed");
}
goto end;
err:
error= 1;
my_printf_error(HA_ERR_GENERIC, "Aria engine: checkpoint failed at %s with "
"error %d", MYF(ME_ERROR_LOG),
error_place, (error_errno ? error_errno : my_errno));
/* we were possibly not able to determine what pages to flush */
pages_to_flush_before_next_checkpoint= 0;
end:
for (i= 0; i < (sizeof(record_pieces)/sizeof(record_pieces[0])); i++)
my_free(record_pieces[i].str);
mysql_mutex_lock(&LOCK_checkpoint);
checkpoint_in_progress= CHECKPOINT_NONE;
checkpoints_total++;
checkpoints_ok_total+= !error;
mysql_mutex_unlock(&LOCK_checkpoint);
DBUG_RETURN(error);
}
/**
@brief Initializes the checkpoint module
@param interval If one wants the module to create a
thread which will periodically do
checkpoints, and flush dirty pages, in the
background, it should specify a non-zero
interval in seconds. The thread will then be
created and will take checkpoints separated by
approximately 'interval' second.
@note A checkpoint is taken only if there has been some significant
activity since the previous checkpoint. Between checkpoint N and N+1 the
thread flushes all dirty pages which were already dirty at the time of
checkpoint N.
@return Operation status
@retval 0 ok
@retval !=0 error
*/
int ma_checkpoint_init(ulong interval)
{
int res= 0;
DBUG_ENTER("ma_checkpoint_init");
if (ma_service_thread_control_init(&checkpoint_control))
res= 1;
else if (interval > 0)
{
size_t intv= interval;
compile_time_assert(sizeof(void *) >= sizeof(ulong));
if ((res= mysql_thread_create(key_thread_checkpoint,
&checkpoint_control.thread, NULL,
ma_checkpoint_background,
(void*) intv)))
checkpoint_control.killed= TRUE;
}
else
checkpoint_control.killed= TRUE;
DBUG_RETURN(res);
}
#ifndef DBUG_OFF
/**
Function used to test recovery: flush some table pieces and then caller
crashes.
@param what_to_flush 0: current bitmap and all data pages
1: state
2: all bitmap pages
*/
static void flush_all_tables(int what_to_flush)
{
int res= 0;
LIST *pos; /**< to iterate over open tables */
mysql_mutex_lock(&THR_LOCK_maria);
for (pos= maria_open_list; pos; pos= pos->next)
{
MARIA_HA *info= (MARIA_HA*)pos->data;
if (info->s->now_transactional)
{
switch (what_to_flush)
{
case 0:
res= _ma_flush_table_files(info, MARIA_FLUSH_DATA | MARIA_FLUSH_INDEX,
FLUSH_KEEP, FLUSH_KEEP);
break;
case 1:
res= _ma_state_info_write(info->s,
MA_STATE_INFO_WRITE_DONT_MOVE_OFFSET|
MA_STATE_INFO_WRITE_LOCK);
DBUG_PRINT("maria_flush_states",
("is_of_horizon: LSN " LSN_FMT,
LSN_IN_PARTS(info->s->state.is_of_horizon)));
break;
case 2:
res= _ma_bitmap_flush_all(info->s);
break;
}
}
DBUG_ASSERT(res == 0);
}
mysql_mutex_unlock(&THR_LOCK_maria);
}
#endif
/**
@brief Destroys the checkpoint module
*/
void ma_checkpoint_end(void)
{
DBUG_ENTER("ma_checkpoint_end");
/*
Some intentional crash methods, usually triggered by
SET MARIA_CHECKPOINT_INTERVAL=X
*/
DBUG_EXECUTE_IF("maria_flush_bitmap",
{
DBUG_PRINT("maria_flush_bitmap", ("now"));
flush_all_tables(2);
});
DBUG_EXECUTE_IF("maria_flush_whole_page_cache",
{
DBUG_PRINT("maria_flush_whole_page_cache", ("now"));
flush_all_tables(0);
});
DBUG_EXECUTE_IF("maria_flush_whole_log",
{
DBUG_PRINT("maria_flush_whole_log", ("now"));
translog_flush(translog_get_horizon());
});
/*
Note that for WAL reasons, maria_flush_states requires
maria_flush_whole_log.
*/
DBUG_EXECUTE_IF("maria_flush_states",
{
DBUG_PRINT("maria_flush_states", ("now"));
flush_all_tables(1);
});
DBUG_EXECUTE_IF("maria_crash",
{ DBUG_PRINT("maria_crash", ("now")); DBUG_SUICIDE(); });
if (checkpoint_control.inited)
{
ma_service_thread_control_end(&checkpoint_control);
my_free(dfiles);
my_free(kfiles);
dfiles= kfiles= NULL;
}
DBUG_VOID_RETURN;
}
/**
@brief dirty-page filtering criteria for MEDIUM checkpoint.
We flush data/index pages which have been dirty since the previous
checkpoint (this is the two-checkpoint rule: the REDO phase will not have
to start from earlier than the next-to-last checkpoint).
Bitmap pages are handled by _ma_bitmap_flush_all().
@param type Page's type
@param pageno Page's number
@param rec_lsn Page's rec_lsn
@param arg filter_param
*/
static enum pagecache_flush_filter_result
filter_flush_file_medium(enum pagecache_page_type type,
pgcache_page_no_t pageno __attribute__ ((unused)),
LSN rec_lsn, void *arg)
{
struct st_filter_param *param= (struct st_filter_param *)arg;
return (type == PAGECACHE_LSN_PAGE) &&
(cmp_translog_addr(rec_lsn, param->up_to_lsn) <= 0);
}
/**
@brief dirty-page filtering criteria for FULL checkpoint.
We flush all dirty data/index pages.
Bitmap pages are handled by _ma_bitmap_flush_all().
@param type Page's type
@param pageno Page's number
@param rec_lsn Page's rec_lsn
@param arg filter_param
*/
static enum pagecache_flush_filter_result
filter_flush_file_full(enum pagecache_page_type type,
pgcache_page_no_t pageno __attribute__ ((unused)),
LSN rec_lsn __attribute__ ((unused)),
void *arg __attribute__ ((unused)))
{
return (type == PAGECACHE_LSN_PAGE);
}
/**
@brief dirty-page filtering criteria for background flushing thread.
We flush data/index pages which have been dirty since the previous
checkpoint (this is the two-checkpoint rule: the REDO phase will not have
to start from earlier than the next-to-last checkpoint), and no
bitmap pages. But we flush no more than a certain number of pages (to have
an even flushing, no write burst).
The reason to not flush bitmap pages is that they may not be in a flushable
state at this moment and we don't want to wait for them.
@param type Page's type
@param pageno Page's number
@param rec_lsn Page's rec_lsn
@param arg filter_param
*/
static enum pagecache_flush_filter_result
filter_flush_file_evenly(enum pagecache_page_type type,
pgcache_page_no_t pageno __attribute__ ((unused)),
LSN rec_lsn, void *arg)
{
struct st_filter_param *param= (struct st_filter_param *)arg;
if (unlikely(param->max_pages == 0)) /* all flushed already */
return FLUSH_FILTER_SKIP_ALL;
if ((type == PAGECACHE_LSN_PAGE) &&
(cmp_translog_addr(rec_lsn, param->up_to_lsn) <= 0))
{
param->max_pages--;
return FLUSH_FILTER_OK;
}
return FLUSH_FILTER_SKIP_TRY_NEXT;
}
/**
@brief Background thread which does checkpoints and flushes periodically.
Takes a checkpoint. After this, all pages dirty at the time of that
checkpoint are flushed evenly until it is time to take another checkpoint.
This ensures that the REDO phase starts at earliest (in LSN time) at the
next-to-last checkpoint record ("two-checkpoint rule").
@note MikaelR questioned why the same thread does two different jobs, the
risk could be that while a checkpoint happens no LRD flushing happens.
*/
static ulong maria_checkpoint_min_cache_activity= 10*1024*1024;
/* Set in ha_maria.cc */
ulong maria_checkpoint_min_log_activity= 1*1024*1024;
pthread_handler_t ma_checkpoint_background(void *arg)
{
/** @brief At least this of log/page bytes written between checkpoints */
/*
If the interval could be changed by the user while we are in this thread,
it could be annoying: for example it could cause "case 2" to be executed
right after "case 0", thus having 'dfile' unset. So the thread cares only
about the interval's value when it started.
*/
const size_t interval= (size_t)arg;
size_t sleeps, sleep_time;
TRANSLOG_ADDRESS log_horizon_at_last_checkpoint=
translog_get_horizon();
ulonglong pagecache_flushes_at_last_checkpoint=
maria_pagecache->global_cache_write;
uint UNINIT_VAR(pages_bunch_size);
struct st_filter_param filter_param;
PAGECACHE_FILE *UNINIT_VAR(dfile); /**< data file currently being flushed */
PAGECACHE_FILE *UNINIT_VAR(kfile); /**< index file currently being flushed */
my_thread_init();
DBUG_PRINT("info",("Maria background checkpoint thread starts"));
DBUG_ASSERT(interval > 0);
PSI_CALL_set_thread_account(0,0,0,0);
/*
Recovery ended with all tables closed and a checkpoint: no need to take
one immediately.
*/
sleeps= 1;
pages_to_flush_before_next_checkpoint= 0;
for(;;) /* iterations of checkpoints and dirty page flushing */
{
#if 0 /* good for testing, to do a lot of checkpoints, finds a lot of bugs */
sleeps=0;
#endif
switch (sleeps % interval)
{
case 0:
{
/* If checkpoints are disabled, wait 1 second and try again */
if (maria_checkpoint_disabled)
{
sleep_time= 1;
break;
}
{
TRANSLOG_ADDRESS horizon= translog_get_horizon();
/*
With background flushing evenly distributed over the time
between two checkpoints, we should have only little flushing to do
in the checkpoint.
*/
/*
No checkpoint if little work of interest for recovery was done
since last checkpoint. Such work includes log writing (lengthens
recovery, checkpoint would shorten it), page flushing (checkpoint
would decrease the amount of read pages in recovery).
In case of one short statement per minute (very low load), we don't
want to checkpoint every minute, hence the positive
maria_checkpoint_min_activity.
*/
if ((ulonglong) (horizon - log_horizon_at_last_checkpoint) <=
maria_checkpoint_min_log_activity &&
((ulonglong) (maria_pagecache->global_cache_write -
pagecache_flushes_at_last_checkpoint) *
maria_pagecache->block_size) <=
maria_checkpoint_min_cache_activity)
{
/*
Not enough has happend since last checkpoint.
Sleep for a while and try again later
*/
sleep_time= interval;
break;
}
sleep_time= 1;
ma_checkpoint_execute(CHECKPOINT_MEDIUM, TRUE);
/*
Snapshot this kind of "state" of the engine. Note that the value
below is possibly greater than last_checkpoint_lsn.
*/
log_horizon_at_last_checkpoint= translog_get_horizon();
pagecache_flushes_at_last_checkpoint=
maria_pagecache->global_cache_write;
/*
If the checkpoint above succeeded it has set d|kfiles and
d|kfiles_end. If is has failed, it has set
pages_to_flush_before_next_checkpoint to 0 so we will skip flushing
and sleep until the next checkpoint.
*/
}
break;
}
case 1:
/* set up parameters for background page flushing */
filter_param.up_to_lsn= last_checkpoint_lsn;
pages_bunch_size= pages_to_flush_before_next_checkpoint / (uint)interval;
dfile= dfiles;
kfile= kfiles;
/* fall through */
default:
if (pages_bunch_size > 0)
{
DBUG_PRINT("checkpoint",
("Maria background checkpoint thread: %u pages",
pages_bunch_size));
/* flush a bunch of dirty pages */
filter_param.max_pages= pages_bunch_size;
while (dfile != dfiles_end)
{
/*
We use FLUSH_KEEP_LAZY: if a file is already in flush, it's
smarter to move to the next file than wait for this one to be
completely flushed, which may take long.
StaleFilePointersInFlush: notice how below we use "dfile" which
is an OS file descriptor plus some function and MARIA_SHARE
pointers; this data dates from a previous checkpoint; since then,
the table may have been closed (so MARIA_SHARE* became stale), and
the file descriptor reassigned to another table which does not
have the same CRC-read-set callbacks: it is thus important that
flush_pagecache_blocks_with_filter() does not use the pointers,
only the OS file descriptor.
*/
int res=
flush_pagecache_blocks_with_filter(maria_pagecache,
dfile, FLUSH_KEEP_LAZY,
filter_flush_file_evenly,
&filter_param);
if (unlikely(res & PCFLUSH_ERROR))
ma_message_no_user(0, "background data page flush failed");
if (filter_param.max_pages == 0) /* bunch all flushed, sleep */
break; /* and we will continue with the same file */
dfile++; /* otherwise all this file is flushed, move to next file */
/*
MikaelR noted that he observed that Linux's file cache may never
fsync to disk until this cache is full, at which point it decides
to empty the cache, making the machine very slow. A solution was
to fsync after writing 2 MB. So we might want to fsync() here if
we wrote enough pages.
*/
}
while (kfile != kfiles_end)
{
int res=
flush_pagecache_blocks_with_filter(maria_pagecache,
kfile, FLUSH_KEEP_LAZY,
filter_flush_file_evenly,
&filter_param);
if (unlikely(res & PCFLUSH_ERROR))
ma_message_no_user(0, "background index page flush failed");
if (filter_param.max_pages == 0) /* bunch all flushed, sleep */
break; /* and we will continue with the same file */
kfile++; /* otherwise all this file is flushed, move to next file */
}
sleep_time= 1;
}
else
{
/* Can directly sleep until the next checkpoint moment */
sleep_time= interval - (sleeps % interval);
}
}
if (my_service_thread_sleep(&checkpoint_control,
sleep_time * 1000000000ULL))
break;
sleeps+= sleep_time;
}
DBUG_PRINT("info",("Maria background checkpoint thread ends"));
{
CHECKPOINT_LEVEL level= CHECKPOINT_FULL;
/*
That's the final one, which guarantees that a clean shutdown always ends
with a checkpoint.
*/
DBUG_EXECUTE_IF("maria_checkpoint_indirect", level= CHECKPOINT_INDIRECT;);
ma_checkpoint_execute(level, FALSE);
}
my_thread_end();
return 0;
}
/**
@brief Allocates buffer and stores in it some info about open tables,
does some flushing on those.
Does the allocation because the caller cannot know the size itself.
Memory freeing is to be done by the caller (if the "str" member of the
LEX_STRING is not NULL).
The caller is taking a checkpoint.
@param[out] str pointer to where the allocated buffer,
and its size, will be put; buffer will be filled
with info about open tables
@param checkpoint_start_log_horizon Of the in-progress checkpoint
record.
@return Operation status
@retval 0 OK
@retval 1 Error
*/
static int collect_tables(LEX_STRING *str, LSN checkpoint_start_log_horizon)
{
MARIA_SHARE **distinct_shares= NULL;
char *ptr;
uint error= 1, sync_error= 0, nb, nb_stored, i;
my_bool unmark_tables= TRUE;
size_t total_names_length;
LIST *pos; /**< to iterate over open tables */
struct st_state_copy {
uint index;
MARIA_STATE_INFO state;
};
struct st_state_copy *state_copies= NULL, /**< fixed-size cache of states */
*state_copies_end, /**< cache ends here */
*state_copy; /**< iterator in cache */
TRANSLOG_ADDRESS UNINIT_VAR(state_copies_horizon); /**< horizon of states' _copies_ */
struct st_filter_param filter_param;
PAGECACHE_FLUSH_FILTER filter;
DBUG_ENTER("collect_tables");
/* let's make a list of distinct shares */
mysql_mutex_lock(&THR_LOCK_maria);
for (nb= 0, pos= maria_open_list; pos; pos= pos->next)
{
MARIA_HA *info= (MARIA_HA*)pos->data;
MARIA_SHARE *share= info->s;
/* the first three variables below can never change */
if (share->base.born_transactional && !share->temporary &&
share->mode != O_RDONLY &&
!(share->in_checkpoint & MARIA_CHECKPOINT_SEEN_IN_LOOP))
{
/*
Apart from us, only maria_close() reads/sets in_checkpoint but cannot
run now as we hold THR_LOCK_maria.
*/
/*
This table is relevant for checkpoint and not already seen. Mark it,
so that it is not seen again in the loop.
*/
nb++;
DBUG_ASSERT(share->in_checkpoint == 0);
/* This flag ensures that we count only _distinct_ shares. */
share->in_checkpoint= MARIA_CHECKPOINT_SEEN_IN_LOOP;
}
}
if (unlikely((distinct_shares=
(MARIA_SHARE **)my_malloc(PSI_INSTRUMENT_ME, nb * sizeof(MARIA_SHARE *),
MYF(MY_WME))) == NULL))
goto err;
for (total_names_length= 0, i= 0, pos= maria_open_list; pos; pos= pos->next)
{
MARIA_HA *info= (MARIA_HA*)pos->data;
MARIA_SHARE *share= info->s;
if (share->in_checkpoint & MARIA_CHECKPOINT_SEEN_IN_LOOP)
{
distinct_shares[i++]= share;
/*
With this we prevent the share from going away while we later flush
and force it without holding THR_LOCK_maria. For example if the share
could be my_free()d by maria_close() we would have a problem when we
access it to flush the table. We "pin" the share pointer.
And we also take down MARIA_CHECKPOINT_SEEN_IN_LOOP, so that it is
not seen again in the loop.
*/
share->in_checkpoint= MARIA_CHECKPOINT_LOOKS_AT_ME;
total_names_length+= share->open_file_name.length;
}
}
DBUG_ASSERT(i == nb);
mysql_mutex_unlock(&THR_LOCK_maria);
DBUG_PRINT("info",("found %u table shares", nb));
str->length=
4 + /* number of tables */
(2 + /* short id */
LSN_STORE_SIZE + /* first_log_write_at_lsn */
1 /* end-of-name 0 */
) * nb + total_names_length;
if (unlikely((str->str= my_malloc(PSI_INSTRUMENT_ME, str->length, MYF(MY_WME))) == NULL))
goto err;
ptr= str->str;
ptr+= 4; /* real number of stored tables is not yet know */
/* only possible checkpointer, so can do the read below without mutex */
filter_param.up_to_lsn= last_checkpoint_lsn;
switch(checkpoint_in_progress)
{
case CHECKPOINT_MEDIUM:
filter= &filter_flush_file_medium;
break;
case CHECKPOINT_FULL:
filter= &filter_flush_file_full;
break;
case CHECKPOINT_INDIRECT:
filter= NULL;
break;
default:
DBUG_ASSERT(0);
goto err;
}
/*
The principle of reading/writing the state below is explained in
ma_recovery.c, look for "Recovery of the state".
*/
#define STATE_COPIES 1024
state_copies= (struct st_state_copy *)
my_malloc(PSI_INSTRUMENT_ME, STATE_COPIES * sizeof(struct st_state_copy), MYF(MY_WME));
dfiles= (PAGECACHE_FILE *)my_realloc(PSI_INSTRUMENT_ME, (uchar *)dfiles,
/* avoid size of 0 for my_realloc */
MY_MAX(1, nb) * sizeof(PAGECACHE_FILE),
MYF(MY_WME | MY_ALLOW_ZERO_PTR));
kfiles= (PAGECACHE_FILE *)my_realloc(PSI_INSTRUMENT_ME, (uchar *)kfiles,
/* avoid size of 0 for my_realloc */
MY_MAX(1, nb) * sizeof(PAGECACHE_FILE),
MYF(MY_WME | MY_ALLOW_ZERO_PTR));
if (unlikely((state_copies == NULL) ||
(dfiles == NULL) || (kfiles == NULL)))
goto err;
state_copy= state_copies_end= NULL;
dfiles_end= dfiles;
kfiles_end= kfiles;
for (nb_stored= 0, i= 0; i < nb; i++)
{
MARIA_SHARE *share= distinct_shares[i];
PAGECACHE_FILE kfile, dfile;
my_bool ignore_share;
if (!(share->in_checkpoint & MARIA_CHECKPOINT_LOOKS_AT_ME))
{
/*
No need for a mutex to read the above, only us can write *this* bit of
the in_checkpoint bitmap
*/
continue;
}
/**
@todo We should not look at tables which didn't change since last
checkpoint.
*/
DBUG_PRINT("info",("looking at table '%s'", share->open_file_name.str));
if (state_copy == state_copies_end) /* we have no more cached states */
{
/*
Collect and cache a bunch of states. We do this for many states at a
time, to not lock/unlock the log's lock too often.
*/
uint j, bound= MY_MIN(nb, i + STATE_COPIES);
state_copy= state_copies;
/* part of the state is protected by log's lock */
translog_lock();
state_copies_horizon= translog_get_horizon_no_lock();
for (j= i; j < bound; j++)
{
MARIA_SHARE *share2= distinct_shares[j];
if (!(share2->in_checkpoint & MARIA_CHECKPOINT_LOOKS_AT_ME))
continue;
state_copy->index= j;
state_copy->state= share2->state; /* we copy the state */
state_copy++;
/*
data_file_length is not updated under log's lock by the bitmap
code, but writing a wrong data_file_length is ok: a next
maria_close() will correct it; if we crash before, Recovery will
set it to the true physical size.
*/
}
translog_unlock();
if (state_copy == state_copies)
break; /* Nothing to do */
/**
We are going to flush these states.
Before, all records describing how to undo such state must be
in the log (WAL). Usually this means UNDOs. In the special case of
data|key_file_length, recovery just needs to open the table to fix the
length, so any LOGREC_FILE_ID/REDO/UNDO allowing recovery to
understand it must open a table, is enough; so as long as
data|key_file_length is updated after writing any log record it's ok:
if we copied new value above, it means the record was before
state_copies_horizon and we flush such record below.
Apart from data|key_file_length which are easily recoverable from the
real file's size, all other state members must be updated only when
writing the UNDO; otherwise, if updated before, if their new value is
flushed by a checkpoint and there is a crash before UNDO is written,
their REDO group will be missing or at least incomplete and skipped
by recovery, so bad state value will stay. For example, setting
key_root before writing the UNDO: the table would have old index
pages (they were pinned at time of crash) and a new, thus wrong,
key_root.
@todo RECOVERY BUG check that all code honours that.
*/
if (translog_flush(state_copies_horizon))
goto err;
/* now we have cached states and they are WAL-safe*/
state_copies_end= state_copy-1;
state_copy= state_copies;
}
/* locate our state among these cached ones */
for ( ; state_copy->index != i; state_copy++)
DBUG_ASSERT(state_copy <= state_copies_end);
/* OS file descriptors are ints which we stored in 4 bytes */
compile_time_assert(sizeof(int) <= 4);
/*
Protect against maria_close() (which does some memory freeing in
MARIA_FILE_BITMAP) with close_lock. intern_lock is not
sufficient as we, as well as maria_close(), are going to unlock
intern_lock in the middle of manipulating the table. Serializing us and
maria_close() should help avoid problems.
*/
mysql_mutex_lock(&share->close_lock);
mysql_mutex_lock(&share->intern_lock);
/*
Tables in a normal state have their two file descriptors open.
In some rare cases like REPAIR, some descriptor may be closed or even
-1. If that happened, the _ma_state_info_write() may fail. This is
prevented by enclosing all all places which close/change kfile.file with
intern_lock.
*/
kfile= share->kfile;
dfile= share->bitmap.file;
/*
Ignore table which has no logged writes (all its future log records will
be found naturally by Recovery). Ignore obsolete shares (_before_
setting themselves to last_version=0 they already did all flush and
sync; if we flush their state now we may be flushing an obsolete state
onto a newer one (assuming the table has been reopened with a different
share but of course same physical index file).
*/
ignore_share= (share->id == 0) | (share->last_version == 0);
DBUG_PRINT("info", ("ignore_share: %d", ignore_share));
if (!ignore_share)
{
size_t open_file_name_len= share->open_file_name.length + 1;
/* remember the descriptors for background flush */
*(dfiles_end++)= dfile;
*(kfiles_end++)= kfile;
/* we will store this table in the record */
nb_stored++;
int2store(ptr, share->id);
ptr+= 2;
lsn_store(ptr, share->lsn_of_file_id);
ptr+= LSN_STORE_SIZE;
/*
first_bitmap_with_space is not updated under log's lock, and is
important. We would need the bitmap's lock to get it right. Recovery
of this is not clear, so we just play safe: write it out as
unknown: if crash, _ma_bitmap_init() at next open (for example in
Recovery) will convert it to 0 and thus the first insertion will
search for free space from the file's first bitmap (0) -
under-optimal but safe.
If no crash, maria_close() will write the exact value.
*/
state_copy->state.first_bitmap_with_space= ~(ulonglong)0;
memcpy(ptr, share->open_file_name.str, open_file_name_len);
ptr+= open_file_name_len;
if (cmp_translog_addr(share->state.is_of_horizon,
checkpoint_start_log_horizon) >= 0)
{
/*
State was flushed recently, it does not hold down the log's
low-water mark and will not give avoidable work to Recovery. So we
needn't flush it. Also, it is possible that while we copied the
state above (under log's lock, without intern_lock) it was being
modified in memory or flushed to disk (without log's lock, under
intern_lock, like in maria_extra()), so our copy may be incorrect
and we should not flush it.
It may also be a share which got last_version==0 since we checked
last_version; in this case, it flushed its state and the LSN test
above will catch it.
*/
}
else
{
/*
We could do the state flush only if share->changed, but it's
tricky.
Consider a maria_write() which has written REDO,UNDO, and before it
calls _ma_writeinfo() (setting share->changed=1), checkpoint
happens and sees share->changed=0, does not flush state. It is
possible that Recovery does not start from before the REDO and thus
the state is not recovered. A solution may be to set
share->changed=1 under log mutex when writing log records.
The current solution is to keep a copy the last saved state and
not write the state if it was same as last time. It's ok if
is_of_horizon would be different on disk if all other data is
the same.
*/
DBUG_ASSERT(share->last_version != 0);
state_copy->state.is_of_horizon= share->state.is_of_horizon=
share->checkpoint_state.is_of_horizon= state_copies_horizon;
if (kfile.file >= 0 && memcmp(&share->checkpoint_state,
&state_copy->state,
sizeof(state_copy->state)))
{
sync_error|=
_ma_state_info_write_sub(kfile.file, &state_copy->state,
MA_STATE_INFO_WRITE_DONT_MOVE_OFFSET);
memcpy(&share->checkpoint_state,
&state_copy->state, sizeof(state_copy->state));
}
/*
We don't set share->changed=0 because it may interfere with a
concurrent _ma_writeinfo() doing share->changed=1 (cancel its
effect). The sad consequence is that we will flush the same state at
each checkpoint if the table was once written and then not anymore.
*/
}
}
#ifdef EXTRA_DEBUG_BITMAP
else
{
DBUG_ASSERT(share->bitmap.changed == 0 &&
share->bitmap.changed_not_flushed == 0);
}
#endif
/*
_ma_bitmap_flush_all() may wait, so don't keep intern_lock as
otherwise this would deadlock with allocate_and_write_block_record()
calling _ma_set_share_data_file_length()
*/
mysql_mutex_unlock(&share->intern_lock);
if (!ignore_share)
{
/*
share->bitmap is valid because it's destroyed under close_lock which
we hold.
*/
if (_ma_bitmap_flush_all(share))
{
sync_error= 1;
/** @todo all write failures should mark table corrupted */
ma_message_no_user(0, "checkpoint bitmap page flush failed");
}
DBUG_ASSERT(share->pagecache == maria_pagecache);
}
/*
Clean up any unused states.
TODO: Only do this call if there has been # (10?) ended transactions
since last call.
We had to release intern_lock to respect lock order with LOCK_trn_list.
*/
_ma_remove_not_visible_states_with_lock(share, FALSE);
if (share->in_checkpoint & MARIA_CHECKPOINT_SHOULD_FREE_ME)
{
/*
maria_close() left us free the share. When it run it set share->id
to 0. As it run before we locked close_lock, we should have seen this
and so this assertion should be true:
*/
DBUG_ASSERT(ignore_share);
mysql_mutex_destroy(&share->intern_lock);
mysql_mutex_unlock(&share->close_lock);
mysql_mutex_destroy(&share->close_lock);
ma_crypt_free(share);
my_free(share);
}
else
{
/* share goes back to normal state */
share->in_checkpoint= 0;
mysql_mutex_unlock(&share->close_lock);
}
/*
We do the big disk writes out of intern_lock to not block other
users of this table (intern_lock is taken at the start and end of
every statement). This means that file descriptors may be invalid
(files may have been closed for example by HA_EXTRA_PREPARE_FOR_*
under Windows, or REPAIR). This should not be a problem as we use
MY_IGNORE_BADFD. Descriptors may even point to other files but then
the old blocks (of before the close) must have been flushed for sure,
so our flush will flush new blocks (of after the latest open) and that
should do no harm.
*/
/*
If CHECKPOINT_MEDIUM, this big flush below may result in a
serious write burst. Realize that all pages dirtied between the
last checkpoint and the one we are doing now, will be flushed at
next checkpoint, except those evicted by LRU eviction (depending on
the size of the page cache compared to the size of the working data
set, eviction may be rare or frequent).
We avoid that burst by anticipating: those pages are flushed
in bunches spanned regularly over the time interval between now and
the next checkpoint, by a background thread. Thus the next checkpoint
will have only little flushing to do (CHECKPOINT_MEDIUM should thus be
only a little slower than CHECKPOINT_INDIRECT).
*/
/*
PageCacheFlushConcurrencyBugs
Inside the page cache, calls to flush_pagecache_blocks_int() on the same
file are serialized. Examples of concurrency bugs which happened when we
didn't have this serialization:
- maria_chk_size() (via CHECK TABLE) happens concurrently with
Checkpoint: Checkpoint is flushing a page: it pins the page and is
pre-empted, maria_chk_size() wants to flush this page too so gets an
error because Checkpoint pinned this page. Such error makes
maria_chk_size() mark the table as corrupted.
- maria_close() happens concurrently with Checkpoint:
Checkpoint is flushing a page: it registers a request on the page, is
pre-empted ; maria_close() flushes this page too with FLUSH_RELEASE:
FLUSH_RELEASE will cause a free_block() which assumes the page is in the
LRU, but it is not (as Checkpoint registered a request). Crash.
- one thread is evicting a page of the file out of the LRU: it marks it
iPC_BLOCK_IN_SWITCH and is pre-empted. Then two other threads do flushes
of the same file concurrently (like above). Then one flusher sees the
page is in switch, removes it from changed_blocks[] and puts it in its
first_in_switch, so the other flusher will not see the page at all and
return too early. If it's maria_close() which returns too early, then
maria_close() may close the file descriptor, and the other flusher, and
the evicter will fail to write their page: corruption.
*/
if (!ignore_share)
{
if (filter != NULL)
{
if ((flush_pagecache_blocks_with_filter(maria_pagecache,
&dfile, FLUSH_KEEP_LAZY,
filter, &filter_param) &
PCFLUSH_ERROR))
ma_message_no_user(0, "checkpoint data page flush failed");
if ((flush_pagecache_blocks_with_filter(maria_pagecache,
&kfile, FLUSH_KEEP_LAZY,
filter, &filter_param) &
PCFLUSH_ERROR))
ma_message_no_user(0, "checkpoint index page flush failed");
}
/*
fsyncs the fd, that's the loooong operation (e.g. max 150 fsync
per second, so if you have touched 1000 files it's 7 seconds).
*/
sync_error|=
mysql_file_sync(dfile.file, MYF(MY_WME | MY_IGNORE_BADFD)) |
mysql_file_sync(kfile.file, MYF(MY_WME | MY_IGNORE_BADFD));
/*
in case of error, we continue because writing other tables to disk is
still useful.
*/
}
}
if (sync_error)
goto err;
/* We maybe over-estimated (due to share->id==0 or last_version==0) */
DBUG_ASSERT(str->length >= (uint)(ptr - str->str));
str->length= (uint)(ptr - str->str);
/*
As we support max 65k tables open at a time (2-byte short id), we
assume uint is enough for the cumulated length of table names; and
LEX_STRING::length is uint.
*/
int4store(str->str, nb_stored);
error= unmark_tables= 0;
err:
if (unlikely(unmark_tables))
{
/* maria_close() uses THR_LOCK_maria from start to end */
mysql_mutex_lock(&THR_LOCK_maria);
for (i= 0; i < nb; i++)
{
MARIA_SHARE *share= distinct_shares[i];
if (share->in_checkpoint & MARIA_CHECKPOINT_SHOULD_FREE_ME)
{
share->in_checkpoint&= ~MARIA_CHECKPOINT_SHOULD_FREE_ME;
/* maria_close() left us to free the share */
free_maria_share(share);
}
else
{
/* share goes back to normal state */
share->in_checkpoint= 0;
}
}
mysql_mutex_unlock(&THR_LOCK_maria);
}
my_free(distinct_shares);
my_free(state_copies);
DBUG_RETURN(error);
}
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