mirror/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-01-16 12:02:42 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions
mariadb/sql/debug_sync.cc
Marko Mäkelä 5ff7e68c7e Merge 10.4 into 10.5
2020-09-04 18:44:44 +03:00

1631 lines
49 KiB
C++
Raw Blame History

/* Copyright (c) 2009, 2013, Oracle and/or its affiliates.
Copyright (c) 2009, 2020, MariaDB Corporation.
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,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
/* see include/mysql/service_debug_sync.h for debug sync documentation */
#include "mariadb.h"
#include "debug_sync.h"
#if defined(ENABLED_DEBUG_SYNC)
/*
Due to weaknesses in our include files, we need to include
sql_priv.h here. To have THD declared, we need to include
sql_class.h. This includes log_event.h, which in turn requires
declarations from sql_priv.h (e.g. OPTION_AUTO_IS_NULL).
sql_priv.h includes almost everything, so is sufficient here.
*/
#include "sql_priv.h"
#include "sql_parse.h"
/*
Action to perform at a synchronization point.
NOTE: This structure is moved around in memory by realloc(), qsort(),
and memmove(). Do not add objects with non-trivial constructors
or destructors, which might prevent moving of this structure
with these functions.
*/
struct st_debug_sync_action
{
ulong activation_count; /* MY_MAX(hit_limit, execute) */
ulong hit_limit; /* hits before kill query */
ulong execute; /* executes before self-clear */
ulong timeout; /* wait_for timeout */
String signal; /* signal to emit */
String wait_for; /* signal to wait for */
String sync_point; /* sync point name */
bool need_sort; /* if new action, array needs sort */
};
/* Debug sync control. Referenced by THD. */
struct st_debug_sync_control
{
st_debug_sync_action *ds_action; /* array of actions */
uint ds_active; /* # active actions */
uint ds_allocated; /* # allocated actions */
ulonglong dsp_hits; /* statistics */
ulonglong dsp_executed; /* statistics */
ulonglong dsp_max_active; /* statistics */
/*
thd->proc_info points at unsynchronized memory.
It must not go away as long as the thread exists.
*/
char ds_proc_info[80]; /* proc_info string */
};
/**
Definitions for the debug sync facility.
1. Global string variable to hold a "signal" ("signal post", "flag mast").
2. Global condition variable for signaling and waiting.
3. Global mutex to synchronize access to the above.
*/
struct st_debug_sync_globals
{
String ds_signal; /* signal variable */
mysql_cond_t ds_cond; /* condition variable */
mysql_mutex_t ds_mutex; /* mutex variable */
ulonglong dsp_hits; /* statistics */
ulonglong dsp_executed; /* statistics */
ulonglong dsp_max_active; /* statistics */
};
static st_debug_sync_globals debug_sync_global; /* All globals in one object */
/**
Callbacks from C files.
*/
C_MODE_START
static void debug_sync(THD *thd, const char *sync_point_name, size_t name_len);
static int debug_sync_qsort_cmp(const void *, const void *);
C_MODE_END
#ifdef HAVE_PSI_INTERFACE
static PSI_mutex_key key_debug_sync_globals_ds_mutex;
static PSI_mutex_info all_debug_sync_mutexes[]=
{
{ &key_debug_sync_globals_ds_mutex, "DEBUG_SYNC::mutex", PSI_FLAG_GLOBAL}
};
static PSI_cond_key key_debug_sync_globals_ds_cond;
static PSI_cond_info all_debug_sync_conds[]=
{
{ &key_debug_sync_globals_ds_cond, "DEBUG_SYNC::cond", PSI_FLAG_GLOBAL}
};
static void init_debug_sync_psi_keys(void)
{
const char* category= "sql";
int count;
count= array_elements(all_debug_sync_mutexes);
mysql_mutex_register(category, all_debug_sync_mutexes, count);
count= array_elements(all_debug_sync_conds);
mysql_cond_register(category, all_debug_sync_conds, count);
}
#endif /* HAVE_PSI_INTERFACE */
/**
Set the THD::proc_info without instrumentation.
This method is private to DEBUG_SYNC,
and on purpose avoid any use of:
- the SHOW PROFILE instrumentation
- the PERFORMANCE_SCHEMA instrumentation
so that using DEBUG_SYNC() in the server code
does not cause the instrumentations to record
spurious data.
*/
static const char*
debug_sync_thd_proc_info(THD *thd, const char* info)
{
const char* old_proc_info= thd->proc_info;
thd->proc_info= info;
return old_proc_info;
}
/**
Initialize the debug sync facility at server start.
@return status
@retval 0 ok
@retval != 0 error
*/
int debug_sync_init(void)
{
DBUG_ENTER("debug_sync_init");
#ifdef HAVE_PSI_INTERFACE
init_debug_sync_psi_keys();
#endif
if (opt_debug_sync_timeout)
{
int rc;
/* Initialize the global variables. */
debug_sync_global.ds_signal.length(0);
if ((rc= mysql_cond_init(key_debug_sync_globals_ds_cond,
&debug_sync_global.ds_cond, NULL)) ||
(rc= mysql_mutex_init(key_debug_sync_globals_ds_mutex,
&debug_sync_global.ds_mutex,
MY_MUTEX_INIT_FAST)))
DBUG_RETURN(rc); /* purecov: inspected */
/* Set the call back pointer in C files. */
debug_sync_C_callback_ptr= debug_sync;
}
DBUG_RETURN(0);
}
/**
End the debug sync facility.
@description
This is called at server shutdown or after a thread initialization error.
*/
void debug_sync_end(void)
{
DBUG_ENTER("debug_sync_end");
/* End the facility only if it had been initialized. */
if (debug_sync_C_callback_ptr)
{
/* Clear the call back pointer in C files. */
debug_sync_C_callback_ptr= NULL;
/* Destroy the global variables. */
debug_sync_global.ds_signal.free();
mysql_cond_destroy(&debug_sync_global.ds_cond);
mysql_mutex_destroy(&debug_sync_global.ds_mutex);
/* Print statistics. */
{
char llbuff[22];
sql_print_information("Debug sync points hit: %22s",
llstr(debug_sync_global.dsp_hits, llbuff));
sql_print_information("Debug sync points executed: %22s",
llstr(debug_sync_global.dsp_executed, llbuff));
sql_print_information("Debug sync points max active per thread: %22s",
llstr(debug_sync_global.dsp_max_active, llbuff));
}
}
DBUG_VOID_RETURN;
}
/* purecov: begin tested */
/**
Disable the facility after lack of memory if no error can be returned.
@note
Do not end the facility here because the global variables can
be in use by other threads.
*/
static void debug_sync_emergency_disable(void)
{
DBUG_ENTER("debug_sync_emergency_disable");
opt_debug_sync_timeout= 0;
DBUG_PRINT("debug_sync",
("Debug Sync Facility disabled due to lack of memory."));
sql_print_error("Debug Sync Facility disabled due to lack of memory.");
DBUG_VOID_RETURN;
}
/* purecov: end */
/**
Initialize the debug sync facility at thread start.
@param[in] thd thread handle
*/
void debug_sync_init_thread(THD *thd)
{
DBUG_ENTER("debug_sync_init_thread");
DBUG_ASSERT(thd);
if (opt_debug_sync_timeout)
{
thd->debug_sync_control= (st_debug_sync_control*)
my_malloc(PSI_NOT_INSTRUMENTED,
sizeof(st_debug_sync_control),
MYF(MY_WME | MY_ZEROFILL | MY_THREAD_SPECIFIC));
if (!thd->debug_sync_control)
{
/*
Error is reported by my_malloc().
We must disable the facility. We have no way to return an error.
*/
debug_sync_emergency_disable(); /* purecov: tested */
}
}
DBUG_VOID_RETURN;
}
/**
End the debug sync facility at thread end.
@param[in] thd thread handle
*/
void debug_sync_end_thread(THD *thd)
{
DBUG_ENTER("debug_sync_end_thread");
DBUG_ASSERT(thd);
if (thd->debug_sync_control)
{
st_debug_sync_control *ds_control= thd->debug_sync_control;
if (ds_control->ds_action)
{
st_debug_sync_action *action= ds_control->ds_action;
st_debug_sync_action *action_end= action + ds_control->ds_allocated;
for (; action < action_end; action++)
{
action->signal.free();
action->wait_for.free();
action->sync_point.free();
}
my_free(ds_control->ds_action);
}
/* Statistics. */
mysql_mutex_lock(&debug_sync_global.ds_mutex);
debug_sync_global.dsp_hits+= ds_control->dsp_hits;
debug_sync_global.dsp_executed+= ds_control->dsp_executed;
if (debug_sync_global.dsp_max_active < ds_control->dsp_max_active)
debug_sync_global.dsp_max_active= ds_control->dsp_max_active;
mysql_mutex_unlock(&debug_sync_global.ds_mutex);
my_free(ds_control);
thd->debug_sync_control= NULL;
}
DBUG_VOID_RETURN;
}
void debug_sync_reset_thread(THD *thd)
{
if (thd->debug_sync_control)
{
/*
This synchronization point can be used to synchronize on thread end.
This is the latest point in a THD's life, where this can be done.
*/
DEBUG_SYNC(thd, "thread_end");
thd->debug_sync_control->ds_active= 0;
}
}
/**
Move a string by length.
@param[out] to buffer for the resulting string
@param[in] to_end end of buffer
@param[in] from source string
@param[in] length number of bytes to copy
@return pointer to end of copied string
*/
static char *debug_sync_bmove_len(char *to, char *to_end,
const char *from, size_t length)
{
DBUG_ASSERT(to);
DBUG_ASSERT(to_end);
DBUG_ASSERT(!length || from);
set_if_smaller(length, (size_t) (to_end - to));
if (length)
memcpy(to, from, length);
return (to + length);
}
#if !defined(DBUG_OFF)
/**
Create a string that describes an action.
@param[out] result buffer for the resulting string
@param[in] size size of result buffer
@param[in] action action to describe
*/
static void debug_sync_action_string(char *result, uint size,
st_debug_sync_action *action)
{
char *wtxt= result;
char *wend= wtxt + size - 1; /* Allow emergency '\0'. */
DBUG_ASSERT(result);
DBUG_ASSERT(action);
/* If an execute count is present, signal or wait_for are needed too. */
DBUG_ASSERT(!action->execute ||
action->signal.length() || action->wait_for.length());
if (action->execute)
{
if (action->signal.length())
{
wtxt= debug_sync_bmove_len(wtxt, wend, STRING_WITH_LEN("SIGNAL "));
wtxt= debug_sync_bmove_len(wtxt, wend, action->signal.ptr(),
action->signal.length());
}
if (action->wait_for.length())
{
if ((wtxt == result) && (wtxt < wend))
*(wtxt++)= ' ';
wtxt= debug_sync_bmove_len(wtxt, wend, STRING_WITH_LEN(" WAIT_FOR "));
wtxt= debug_sync_bmove_len(wtxt, wend, action->wait_for.ptr(),
action->wait_for.length());
if (action->timeout != opt_debug_sync_timeout)
{
wtxt+= my_snprintf(wtxt, wend - wtxt, " TIMEOUT %lu", action->timeout);
}
}
if (action->execute != 1)
{
wtxt+= my_snprintf(wtxt, wend - wtxt, " EXECUTE %lu", action->execute);
}
}
if (action->hit_limit)
{
wtxt+= my_snprintf(wtxt, wend - wtxt, "%sHIT_LIMIT %lu",
(wtxt == result) ? "" : " ", action->hit_limit);
}
/*
If (wtxt == wend) string may not be terminated.
There is one byte left for an emergency termination.
*/
*wtxt= '\0';
}
/**
Print actions.
@param[in] thd thread handle
*/
static void debug_sync_print_actions(THD *thd)
{
st_debug_sync_control *ds_control= thd->debug_sync_control;
uint idx;
DBUG_ENTER("debug_sync_print_actions");
DBUG_ASSERT(thd);
if (!ds_control)
DBUG_VOID_RETURN;
for (idx= 0; idx < ds_control->ds_active; idx++)
{
const char *dsp_name= ds_control->ds_action[idx].sync_point.c_ptr();
char action_string[256];
debug_sync_action_string(action_string, sizeof(action_string),
ds_control->ds_action + idx);
DBUG_PRINT("debug_sync_list", ("%s %s", dsp_name, action_string));
}
DBUG_VOID_RETURN;
}
#endif /* !defined(DBUG_OFF) */
/**
Compare two actions by sync point name length, string.
@param[in] arg1 reference to action1
@param[in] arg2 reference to action2
@return difference
@retval == 0 length1/string1 is same as length2/string2
@retval < 0 length1/string1 is smaller
@retval > 0 length1/string1 is bigger
*/
static int debug_sync_qsort_cmp(const void* arg1, const void* arg2)
{
st_debug_sync_action *action1= (st_debug_sync_action*) arg1;
st_debug_sync_action *action2= (st_debug_sync_action*) arg2;
int diff;
DBUG_ASSERT(action1);
DBUG_ASSERT(action2);
if (!(diff= action1->sync_point.length() - action2->sync_point.length()))
diff= memcmp(action1->sync_point.ptr(), action2->sync_point.ptr(),
action1->sync_point.length());
return diff;
}
/**
Find a debug sync action.
@param[in] actionarr array of debug sync actions
@param[in] quantity number of actions in array
@param[in] dsp_name name of debug sync point to find
@param[in] name_len length of name of debug sync point
@return action
@retval != NULL found sync point in array
@retval NULL not found
@description
Binary search. Array needs to be sorted by length, sync point name.
*/
static st_debug_sync_action *debug_sync_find(st_debug_sync_action *actionarr,
int quantity,
const char *dsp_name,
size_t name_len)
{
st_debug_sync_action *action;
int low ;
int high ;
int mid ;
ssize_t diff ;
DBUG_ASSERT(actionarr);
DBUG_ASSERT(dsp_name);
DBUG_ASSERT(name_len);
low= 0;
high= quantity;
while (low < high)
{
mid= (low + high) / 2;
action= actionarr + mid;
if (!(diff= name_len - action->sync_point.length()) &&
!(diff= memcmp(dsp_name, action->sync_point.ptr(), name_len)))
return action;
if (diff > 0)
low= mid + 1;
else
high= mid - 1;
}
if (low < quantity)
{
action= actionarr + low;
if ((name_len == action->sync_point.length()) &&
!memcmp(dsp_name, action->sync_point.ptr(), name_len))
return action;
}
return NULL;
}
/**
Reset the debug sync facility.
@param[in] thd thread handle
@description
Remove all actions of this thread.
Clear the global signal.
*/
static void debug_sync_reset(THD *thd)
{
st_debug_sync_control *ds_control= thd->debug_sync_control;
DBUG_ENTER("debug_sync_reset");
DBUG_ASSERT(thd);
DBUG_ASSERT(ds_control);
/* Remove all actions of this thread. */
ds_control->ds_active= 0;
/* Clear the global signal. */
mysql_mutex_lock(&debug_sync_global.ds_mutex);
debug_sync_global.ds_signal.length(0);
mysql_mutex_unlock(&debug_sync_global.ds_mutex);
DBUG_VOID_RETURN;
}
/**
Remove a debug sync action.
@param[in] ds_control control object
@param[in] action action to be removed
@description
Removing an action mainly means to decrement the ds_active counter.
But if the action is between other active action in the array, then
the array needs to be shrunk. The active actions above the one to
be removed have to be moved down by one slot.
*/
static void debug_sync_remove_action(st_debug_sync_control *ds_control,
st_debug_sync_action *action)
{
uint dsp_idx= (uint)(action - ds_control->ds_action);
DBUG_ENTER("debug_sync_remove_action");
DBUG_ASSERT(ds_control);
DBUG_ASSERT(ds_control == current_thd->debug_sync_control);
DBUG_ASSERT(action);
DBUG_ASSERT(dsp_idx < ds_control->ds_active);
/* Decrement the number of currently active actions. */
ds_control->ds_active--;
/*
If this was not the last active action in the array, we need to
shift remaining active actions down to keep the array gap-free.
Otherwise binary search might fail or take longer than necessary at
least. Also new actions are always put to the end of the array.
*/
if (ds_control->ds_active > dsp_idx)
{
/*
Do not make save_action an object of class st_debug_sync_action.
Its destructor would tamper with the String pointers.
*/
uchar save_action[sizeof(st_debug_sync_action)];
/*
Copy the to-be-removed action object to temporary storage before
the shift copies the string pointers over. Do not use assignment
because it would use assignment operator methods for the Strings.
This would copy the strings. The shift below overwrite the string
pointers without freeing them first. By using memmove() we save
the pointers, which are overwritten by the shift.
*/
memmove(save_action, action, sizeof(st_debug_sync_action));
/* Move actions down. */
memmove((void*)(ds_control->ds_action + dsp_idx),
ds_control->ds_action + dsp_idx + 1,
(ds_control->ds_active - dsp_idx) *
sizeof(st_debug_sync_action));
/*
Copy back the saved action object to the now free array slot. This
replaces the double references of String pointers that have been
produced by the shift. Again do not use an assignment operator to
avoid string allocation/copy.
*/
memmove((void*)(ds_control->ds_action + ds_control->ds_active),
save_action, sizeof(st_debug_sync_action));
}
DBUG_VOID_RETURN;
}
/**
Get a debug sync action.
@param[in] thd thread handle
@param[in] dsp_name debug sync point name
@param[in] name_len length of sync point name
@return action
@retval != NULL ok
@retval NULL error
@description
Find the debug sync action for a debug sync point or make a new one.
*/
static st_debug_sync_action *debug_sync_get_action(THD *thd,
const char *dsp_name,
uint name_len)
{
st_debug_sync_control *ds_control= thd->debug_sync_control;
st_debug_sync_action *action;
DBUG_ENTER("debug_sync_get_action");
DBUG_ASSERT(thd);
DBUG_ASSERT(dsp_name);
DBUG_ASSERT(name_len);
DBUG_ASSERT(ds_control);
DBUG_PRINT("debug_sync", ("sync_point: '%.*s'", (int) name_len, dsp_name));
DBUG_PRINT("debug_sync", ("active: %u allocated: %u",
ds_control->ds_active, ds_control->ds_allocated));
/* There cannot be more active actions than allocated. */
DBUG_ASSERT(ds_control->ds_active <= ds_control->ds_allocated);
/* If there are active actions, the action array must be present. */
DBUG_ASSERT(!ds_control->ds_active || ds_control->ds_action);
/* Try to reuse existing action if there is one for this sync point. */
if (ds_control->ds_active &&
(action= debug_sync_find(ds_control->ds_action, ds_control->ds_active,
dsp_name, name_len)))
{
/* Reuse an already active sync point action. */
DBUG_ASSERT((uint)(action - ds_control->ds_action) < ds_control->ds_active);
DBUG_PRINT("debug_sync", ("reuse action idx: %ld",
(long) (action - ds_control->ds_action)));
}
else
{
/* Create a new action. */
int dsp_idx= ds_control->ds_active++;
set_if_bigger(ds_control->dsp_max_active, ds_control->ds_active);
if (ds_control->ds_active > ds_control->ds_allocated)
{
uint new_alloc= ds_control->ds_active + 3;
void *new_action= my_realloc(PSI_NOT_INSTRUMENTED, ds_control->ds_action,
new_alloc * sizeof(st_debug_sync_action),
MYF(MY_WME | MY_ALLOW_ZERO_PTR));
if (!new_action)
{
/* Error is reported by my_malloc(). */
goto err; /* purecov: tested */
}
ds_control->ds_action= (st_debug_sync_action*) new_action;
ds_control->ds_allocated= new_alloc;
/* Clear memory as we do not run string constructors here. */
bzero((uchar*) (ds_control->ds_action + dsp_idx),
(new_alloc - dsp_idx) * sizeof(st_debug_sync_action));
}
DBUG_PRINT("debug_sync", ("added action idx: %u", dsp_idx));
action= ds_control->ds_action + dsp_idx;
if (action->sync_point.copy(dsp_name, name_len, system_charset_info))
{
/* Error is reported by my_malloc(). */
goto err; /* purecov: tested */
}
action->need_sort= TRUE;
}
DBUG_ASSERT(action >= ds_control->ds_action);
DBUG_ASSERT(action < ds_control->ds_action + ds_control->ds_active);
DBUG_PRINT("debug_sync", ("action: %p array: %p count: %u",
action, ds_control->ds_action,
ds_control->ds_active));
DBUG_RETURN(action);
/* purecov: begin tested */
err:
DBUG_RETURN(NULL);
/* purecov: end */
}
/**
Set a debug sync action.
@param[in] thd thread handle
@param[in] action synchronization action
@return status
@retval FALSE ok
@retval TRUE error
@description
This is called from the debug sync parser. It arms the action for
the requested sync point. If the action parsed into an empty action,
it is removed instead.
Setting an action for a sync point means to make the sync point
active. When it is hit it will execute this action.
Before parsing, we "get" an action object. This is placed at the
end of the thread's action array unless the requested sync point
has an action already.
Then the parser fills the action object from the request string.
Finally the action is "set" for the sync point. If it was parsed
to be empty, it is removed from the array. If it did belong to a
sync point before, the sync point becomes inactive. If the action
became non-empty and it did not belong to a sync point before (it
was added at the end of the action array), the action array needs
to be sorted by sync point.
If the sync point name is "now", it is executed immediately.
*/
static bool debug_sync_set_action(THD *thd, st_debug_sync_action *action)
{
st_debug_sync_control *ds_control= thd->debug_sync_control;
bool is_dsp_now= FALSE;
DBUG_ENTER("debug_sync_set_action");
DBUG_ASSERT(thd);
DBUG_ASSERT(action);
DBUG_ASSERT(ds_control);
action->activation_count= MY_MAX(action->hit_limit, action->execute);
if (!action->activation_count)
{
debug_sync_remove_action(ds_control, action);
DBUG_PRINT("debug_sync", ("action cleared"));
}
else
{
const char *dsp_name= action->sync_point.c_ptr();
DBUG_EXECUTE("debug_sync", {
/* Functions as DBUG_PRINT args can change keyword and line nr. */
const char *sig_emit= action->signal.c_ptr();
const char *sig_wait= action->wait_for.c_ptr();
DBUG_PRINT("debug_sync",
("sync_point: '%s' activation_count: %lu hit_limit: %lu "
"execute: %lu timeout: %lu signal: '%s' wait_for: '%s'",
dsp_name, action->activation_count,
action->hit_limit, action->execute, action->timeout,
sig_emit, sig_wait));});
/* Check this before sorting the array. action may move. */
is_dsp_now= !my_strcasecmp(system_charset_info, dsp_name, "now");
if (action->need_sort)
{
action->need_sort= FALSE;
/* Sort actions by (name_len, name). */
my_qsort(ds_control->ds_action, ds_control->ds_active,
sizeof(st_debug_sync_action), debug_sync_qsort_cmp);
}
}
DBUG_EXECUTE("debug_sync_list", debug_sync_print_actions(thd););
/* Execute the special sync point 'now' if activated above. */
if (is_dsp_now)
{
DEBUG_SYNC(thd, "now");
/*
If HIT_LIMIT for sync point "now" was 1, the execution of the sync
point decremented it to 0. In this case the following happened:
- an error message was reported with my_error() and
- the statement was killed with thd->killed= THD::KILL_QUERY.
If a statement reports an error, it must not call send_ok().
The calling functions will not call send_ok(), if we return TRUE
from this function.
thd->killed is also set if the wait is interrupted from a
KILL or KILL QUERY statement. In this case, no error is reported
and shall not be reported as a result of SET DEBUG_SYNC.
Hence, we check for the first condition above.
*/
if (unlikely(thd->is_error()))
DBUG_RETURN(TRUE);
}
DBUG_RETURN(FALSE);
}
/**
Extract a token from a string.
@param[out] token_p returns start of token
@param[out] token_length_p returns length of token
@param[in,out] ptr current string pointer, adds '\0' terminators
@return string pointer or NULL
@retval != NULL ptr behind token terminator or at string end
@retval NULL no token found in remainder of string
@note
This function assumes that the string is in system_charset_info,
that this charset is single byte for ASCII NUL ('\0'), that no
character except of ASCII NUL ('\0') contains a byte with value 0,
and that ASCII NUL ('\0') is used as the string terminator.
This function needs to return tokens that are terminated with ASCII
NUL ('\0'). The tokens are used in my_strcasecmp(). Unfortunately
there is no my_strncasecmp().
To return the last token without copying it, we require the input
string to be nul terminated.
@description
This function skips space characters at string begin.
It returns a pointer to the first non-space character in *token_p.
If no non-space character is found before the string terminator
ASCII NUL ('\0'), the function returns NULL. *token_p and
*token_length_p remain unchanged in this case (they are not set).
The function takes a space character or an ASCII NUL ('\0') as a
terminator of the token. The space character could be multi-byte.
It returns the length of the token in bytes, excluding the
terminator, in *token_length_p.
If the terminator of the token is ASCII NUL ('\0'), it returns a
pointer to the terminator (string end).
If the terminator is a space character, it replaces the the first
byte of the terminator character by ASCII NUL ('\0'), skips the (now
corrupted) terminator character, and skips all following space
characters. It returns a pointer to the next non-space character or
to the string terminator ASCII NUL ('\0').
*/
static char *debug_sync_token(char **token_p, uint *token_length_p,
char *ptr, char *ptrend)
{
DBUG_ASSERT(token_p);
DBUG_ASSERT(token_length_p);
DBUG_ASSERT(ptr);
/* Skip leading space */
ptr+= system_charset_info->scan(ptr, ptrend, MY_SEQ_SPACES);
if (!*ptr)
{
ptr= NULL;
goto end;
}
/* Get token start. */
*token_p= ptr;
/* Find token end. */
ptr+= system_charset_info->scan(ptr, ptrend, MY_SEQ_NONSPACES);
/* Get token length. */
*token_length_p= (uint)(ptr - *token_p);
/* If necessary, terminate token. */
if (*ptr)
{
DBUG_ASSERT(ptr < ptrend);
/* Get terminator character length. */
uint mbspacelen= system_charset_info->charlen_fix(ptr, ptrend);
/* Terminate token. */
*ptr= '\0';
/* Skip the terminator. */
ptr+= mbspacelen;
/* Skip trailing space */
ptr+= system_charset_info->scan(ptr, ptrend, MY_SEQ_SPACES);
}
end:
return ptr;
}
/**
Extract a number from a string.
@param[out] number_p returns number
@param[in] actstrptr current pointer in action string
@return string pointer or NULL
@retval != NULL ptr behind token terminator or at string end
@retval NULL no token found or token is not valid number
@note
The same assumptions about charset apply as for debug_sync_token().
@description
This function fetches a token from the string and converts it
into a number.
If there is no token left in the string, or the token is not a valid
decimal number, NULL is returned. The result in *number_p is
undefined in this case.
*/
static char *debug_sync_number(ulong *number_p, char *actstrptr,
char *actstrend)
{
char *ptr;
char *ept;
char *token;
uint token_length;
DBUG_ASSERT(number_p);
DBUG_ASSERT(actstrptr);
/* Get token from string. */
if (!(ptr= debug_sync_token(&token, &token_length, actstrptr, actstrend)))
goto end;
*number_p= strtoul(token, &ept, 10);
if (*ept)
ptr= NULL;
end:
return ptr;
}
/**
Evaluate a debug sync action string.
@param[in] thd thread handle
@param[in,out] action_str action string to receive '\0' terminators
@return status
@retval FALSE ok
@retval TRUE error
@description
This is called when the DEBUG_SYNC system variable is set.
Parse action string, build a debug sync action, activate it.
Before parsing, we "get" an action object. This is placed at the
end of the thread's action array unless the requested sync point
has an action already.
Then the parser fills the action object from the request string.
Finally the action is "set" for the sync point. This means that the
sync point becomes active or inactive, depending on the action
values.
@note
The input string needs to be ASCII NUL ('\0') terminated. We split
nul-terminated tokens in it without copy.
@see the function comment of debug_sync_token() for more constraints
for the string.
*/
static bool debug_sync_eval_action(THD *thd, char *action_str, char *action_end)
{
st_debug_sync_action *action= NULL;
const char *errmsg;
char *ptr;
char *token;
uint token_length= 0;
DBUG_ENTER("debug_sync_eval_action");
DBUG_ASSERT(thd);
DBUG_ASSERT(action_str);
DBUG_PRINT("debug_sync", ("action_str: '%s'", action_str));
/*
Get debug sync point name. Or a special command.
*/
if (!(ptr= debug_sync_token(&token, &token_length, action_str, action_end)))
{
errmsg= "Missing synchronization point name";
goto err;
}
/*
If there is a second token, the first one is the sync point name.
*/
if (*ptr)
{
/* Get an action object to collect the requested action parameters. */
action= debug_sync_get_action(thd, token, token_length);
if (!action)
{
/* Error message is sent. */
DBUG_RETURN(TRUE); /* purecov: tested */
}
}
/*
Get kind of action to be taken at sync point.
*/
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
{
/* No action present. Try special commands. Token unchanged. */
/*
Try RESET.
*/
if (!my_strcasecmp(system_charset_info, token, "RESET"))
{
/* It is RESET. Reset all actions and global signal. */
debug_sync_reset(thd);
goto end;
}
/* Token unchanged. It still contains sync point name. */
errmsg= "Missing action after synchronization point name '%.*s'";
goto err;
}
/*
Check for pseudo actions first. Start with actions that work on
an existing action.
*/
DBUG_ASSERT(action);
/*
Try TEST.
*/
if (!my_strcasecmp(system_charset_info, token, "TEST"))
{
/* It is TEST. Nothing must follow it. */
if (*ptr)
{
errmsg= "Nothing must follow action TEST";
goto err;
}
/* Execute sync point. */
debug_sync(thd, action->sync_point.ptr(), action->sync_point.length());
/* Fix statistics. This was not a real hit of the sync point. */
thd->debug_sync_control->dsp_hits--;
goto end;
}
/*
Now check for actions that define a new action.
Initialize action. Do not use bzero(). Strings may have malloced.
*/
action->activation_count= 0;
action->hit_limit= 0;
action->execute= 0;
action->timeout= 0;
action->signal.length(0);
action->wait_for.length(0);
/*
Try CLEAR.
*/
if (!my_strcasecmp(system_charset_info, token, "CLEAR"))
{
/* It is CLEAR. Nothing must follow it. */
if (*ptr)
{
errmsg= "Nothing must follow action CLEAR";
goto err;
}
/* Set (clear/remove) action. */
goto set_action;
}
/*
Now check for real sync point actions.
*/
/*
Try SIGNAL.
*/
if (!my_strcasecmp(system_charset_info, token, "SIGNAL"))
{
/* It is SIGNAL. Signal name must follow. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
{
errmsg= "Missing signal name after action SIGNAL";
goto err;
}
if (action->signal.copy(token, token_length, system_charset_info))
{
/* Error is reported by my_malloc(). */
/* purecov: begin tested */
errmsg= NULL;
goto err;
/* purecov: end */
}
/* Set default for EXECUTE option. */
action->execute= 1;
/* Get next token. If none follows, set action. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
goto set_action;
}
/*
Try WAIT_FOR.
*/
if (!my_strcasecmp(system_charset_info, token, "WAIT_FOR"))
{
/* It is WAIT_FOR. Wait_for signal name must follow. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
{
errmsg= "Missing signal name after action WAIT_FOR";
goto err;
}
if (action->wait_for.copy(token, token_length, system_charset_info))
{
/* Error is reported by my_malloc(). */
/* purecov: begin tested */
errmsg= NULL;
goto err;
/* purecov: end */
}
/* Set default for EXECUTE and TIMEOUT options. */
action->execute= 1;
action->timeout= opt_debug_sync_timeout;
/* Get next token. If none follows, set action. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
goto set_action;
/*
Try TIMEOUT.
*/
if (!my_strcasecmp(system_charset_info, token, "TIMEOUT"))
{
/* It is TIMEOUT. Number must follow. */
if (!(ptr= debug_sync_number(&action->timeout, ptr, action_end)))
{
errmsg= "Missing valid number after TIMEOUT";
goto err;
}
/* Get next token. If none follows, set action. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
goto set_action;
}
}
/*
Try EXECUTE.
*/
if (!my_strcasecmp(system_charset_info, token, "EXECUTE"))
{
/*
EXECUTE requires either SIGNAL and/or WAIT_FOR to be present.
In this case action->execute has been preset to 1.
*/
if (!action->execute)
{
errmsg= "Missing action before EXECUTE";
goto err;
}
/* Number must follow. */
if (!(ptr= debug_sync_number(&action->execute, ptr, action_end)))
{
errmsg= "Missing valid number after EXECUTE";
goto err;
}
/* Get next token. If none follows, set action. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
goto set_action;
}
/*
Try HIT_LIMIT.
*/
if (!my_strcasecmp(system_charset_info, token, "HIT_LIMIT"))
{
/* Number must follow. */
if (!(ptr= debug_sync_number(&action->hit_limit, ptr, action_end)))
{
errmsg= "Missing valid number after HIT_LIMIT";
goto err;
}
/* Get next token. If none follows, set action. */
if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end)))
goto set_action;
}
errmsg= "Illegal or out of order stuff: '%.*s'";
err:
if (errmsg)
{
/*
NOTE: errmsg must either have %.*s or none % at all.
It can be NULL if an error message is already reported
(e.g. by my_malloc()).
*/
set_if_smaller(token_length, 64); /* Limit error message length. */
my_printf_error(ER_PARSE_ERROR, errmsg, MYF(0), token_length, token);
}
if (action)
debug_sync_remove_action(thd->debug_sync_control, action);
DBUG_RETURN(TRUE);
set_action:
DBUG_RETURN(debug_sync_set_action(thd, action));
end:
DBUG_RETURN(FALSE);
}
/**
Set the system variable 'debug_sync'.
@param[in] thd thread handle
@param[in] var set variable request
@return status
@retval FALSE ok, variable is set
@retval TRUE error, variable could not be set
@note
"Setting" of the system variable 'debug_sync' does not mean to
assign a value to it as usual. Instead a debug sync action is parsed
from the input string and stored apart from the variable value.
@note
For efficiency reasons, the action string parser places '\0'
terminators in the string. So we need to take a copy here.
*/
bool debug_sync_update(THD *thd, char *val_str, size_t len)
{
DBUG_ENTER("debug_sync_update");
DBUG_PRINT("debug_sync", ("set action: '%s'", val_str));
/*
debug_sync_eval_action() places '\0' in the string, which itself
must be '\0' terminated.
*/
DBUG_ASSERT(val_str[len] == '\0');
DBUG_RETURN(opt_debug_sync_timeout ?
debug_sync_eval_action(thd, val_str, val_str + len) :
FALSE);
}
/**
Retrieve the value of the system variable 'debug_sync'.
@param[in] thd thread handle
@return string
@retval != NULL ok, string pointer
@retval NULL memory allocation error
@note
The value of the system variable 'debug_sync' reflects if
the facility is enabled ("ON") or disabled (default, "OFF").
When "ON", the current signal is added.
*/
uchar *debug_sync_value_ptr(THD *thd)
{
char *value;
DBUG_ENTER("debug_sync_value_ptr");
if (opt_debug_sync_timeout)
{
static char on[]= "ON - current signal: '";
// Ensure exclusive access to debug_sync_global.ds_signal
mysql_mutex_lock(&debug_sync_global.ds_mutex);
size_t lgt= (sizeof(on) /* includes '\0' */ +
debug_sync_global.ds_signal.length() + 1 /* for '\'' */);
char *vend;
char *vptr;
if ((value= (char*) alloc_root(thd->mem_root, lgt)))
{
vend= value + lgt - 1; /* reserve space for '\0'. */
vptr= debug_sync_bmove_len(value, vend, STRING_WITH_LEN(on));
vptr= debug_sync_bmove_len(vptr, vend, debug_sync_global.ds_signal.ptr(),
debug_sync_global.ds_signal.length());
if (vptr < vend)
*(vptr++)= '\'';
*vptr= '\0'; /* We have one byte reserved for the worst case. */
}
mysql_mutex_unlock(&debug_sync_global.ds_mutex);
}
else
{
/* purecov: begin tested */
value= const_cast<char*>("OFF");
/* purecov: end */
}
DBUG_RETURN((uchar*) value);
}
/**
Execute requested action at a synchronization point.
@param[in] thd thread handle
@param[in] action action to be executed
@note
This is to be called only if activation count > 0.
*/
static void debug_sync_execute(THD *thd, st_debug_sync_action *action)
{
#ifndef DBUG_OFF
const char *dsp_name= action->sync_point.c_ptr();
const char *sig_emit= action->signal.c_ptr();
const char *sig_wait= action->wait_for.c_ptr();
#endif
DBUG_ENTER("debug_sync_execute");
DBUG_ASSERT(thd);
DBUG_ASSERT(action);
DBUG_PRINT("debug_sync",
("sync_point: '%s' activation_count: %lu hit_limit: %lu "
"execute: %lu timeout: %lu signal: '%s' wait_for: '%s'",
dsp_name, action->activation_count, action->hit_limit,
action->execute, action->timeout, sig_emit, sig_wait));
DBUG_ASSERT(action->activation_count);
action->activation_count--;
if (action->execute)
{
const char *UNINIT_VAR(old_proc_info);
action->execute--;
/*
If we will be going to wait, set proc_info for the PROCESSLIST table.
Do this before emitting the signal, so other threads can see it
if they awake before we enter_cond() below.
*/
if (action->wait_for.length())
{
st_debug_sync_control *ds_control= thd->debug_sync_control;
strxnmov(ds_control->ds_proc_info, sizeof(ds_control->ds_proc_info)-1,
"debug sync point: ", action->sync_point.c_ptr(), NullS);
old_proc_info= thd->proc_info;
debug_sync_thd_proc_info(thd, ds_control->ds_proc_info);
}
/*
Take mutex to ensure that only one thread access
debug_sync_global.ds_signal at a time. Need to take mutex for
read access too, to create a memory barrier in order to avoid that
threads just reads an old cached version of the signal.
*/
mysql_mutex_lock(&debug_sync_global.ds_mutex);
if (action->signal.length())
{
/* Copy the signal to the global variable. */
if (debug_sync_global.ds_signal.copy(action->signal))
{
/*
Error is reported by my_malloc().
We must disable the facility. We have no way to return an error.
*/
debug_sync_emergency_disable(); /* purecov: tested */
}
/* Wake threads waiting in a sync point. */
mysql_cond_broadcast(&debug_sync_global.ds_cond);
DBUG_PRINT("debug_sync_exec", ("signal '%s' at: '%s'",
sig_emit, dsp_name));
} /* end if (action->signal.length()) */
if (action->wait_for.length())
{
mysql_mutex_t *old_mutex= NULL;
mysql_cond_t *old_cond= NULL;
bool restore_current_mutex;
int error= 0;
struct timespec abstime;
/*
We don't use enter_cond()/exit_cond(). They do not save old
mutex and cond. This would prohibit the use of DEBUG_SYNC
between other places of enter_cond() and exit_cond().
We need to check for existence of thd->mysys_var to also make
it possible to use DEBUG_SYNC framework in scheduler when this
variable has been set to NULL.
*/
if (thd->mysys_var)
{
old_mutex= thd->mysys_var->current_mutex;
old_cond= thd->mysys_var->current_cond;
restore_current_mutex = true;
thd->mysys_var->current_mutex= &debug_sync_global.ds_mutex;
thd->mysys_var->current_cond= &debug_sync_global.ds_cond;
}
else
restore_current_mutex = false;
set_timespec(abstime, action->timeout);
DBUG_EXECUTE("debug_sync_exec", {
/* Functions as DBUG_PRINT args can change keyword and line nr. */
const char *sig_glob= debug_sync_global.ds_signal.c_ptr();
DBUG_PRINT("debug_sync_exec",
("wait for '%s' at: '%s' curr: '%s'",
sig_wait, dsp_name, sig_glob));});
/*
Wait until global signal string matches the wait_for string.
Interrupt when thread or query is killed or facility disabled.
The facility can become disabled when some thread cannot get
the required dynamic memory allocated.
*/
while (stringcmp(&debug_sync_global.ds_signal, &action->wait_for) &&
!thd->killed && opt_debug_sync_timeout)
{
error= mysql_cond_timedwait(&debug_sync_global.ds_cond,
&debug_sync_global.ds_mutex,
&abstime);
DBUG_EXECUTE("debug_sync", {
/* Functions as DBUG_PRINT args can change keyword and line nr. */
const char *sig_glob= debug_sync_global.ds_signal.c_ptr();
DBUG_PRINT("debug_sync",
("awoke from %s global: %s error: %d",
sig_wait, sig_glob, error));});
if (unlikely(error == ETIMEDOUT || error == ETIME))
{
// We should not make the statement fail, even if in strict mode.
Abort_on_warning_instant_set aws(thd, false);
push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
ER_DEBUG_SYNC_TIMEOUT,
ER_THD(thd, ER_DEBUG_SYNC_TIMEOUT));
DBUG_EXECUTE_IF("debug_sync_abort_on_timeout", DBUG_ASSERT(0););
break;
}
error= 0;
}
DBUG_EXECUTE("debug_sync_exec",
if (thd->killed)
DBUG_PRINT("debug_sync_exec",
("killed %d from '%s' at: '%s'",
thd->killed, sig_wait, dsp_name));
else
DBUG_PRINT("debug_sync_exec",
("%s from '%s' at: '%s'",
error ? "timeout" : "resume",
sig_wait, dsp_name)););
/*
We don't use enter_cond()/exit_cond(). They do not save old
mutex and cond. This would prohibit the use of DEBUG_SYNC
between other places of enter_cond() and exit_cond(). The
protected mutex must always unlocked _before_ mysys_var->mutex
is locked. (See comment in THD::exit_cond().)
*/
mysql_mutex_unlock(&debug_sync_global.ds_mutex);
if (restore_current_mutex)
{
mysql_mutex_lock(&thd->mysys_var->mutex);
thd->mysys_var->current_mutex= old_mutex;
thd->mysys_var->current_cond= old_cond;
debug_sync_thd_proc_info(thd, old_proc_info);
mysql_mutex_unlock(&thd->mysys_var->mutex);
}
else
debug_sync_thd_proc_info(thd, old_proc_info);
}
else
{
/* In case we don't wait, we just release the mutex. */
mysql_mutex_unlock(&debug_sync_global.ds_mutex);
} /* end if (action->wait_for.length()) */
} /* end if (action->execute) */
/* hit_limit is zero for infinite. Don't decrement unconditionally. */
if (action->hit_limit)
{
if (!--action->hit_limit)
{
thd->set_killed(KILL_QUERY);
my_error(ER_DEBUG_SYNC_HIT_LIMIT, MYF(0));
}
DBUG_PRINT("debug_sync_exec", ("hit_limit: %lu at: '%s'",
action->hit_limit, dsp_name));
}
DBUG_VOID_RETURN;
}
/**
Execute requested action at a synchronization point.
@param[in] thd thread handle
@param[in] sync_point_name name of synchronization point
@param[in] name_len length of sync point name
*/
static void debug_sync(THD *thd, const char *sync_point_name, size_t name_len)
{
if (!thd)
{
if (!(thd= current_thd))
return;
}
st_debug_sync_control *ds_control= thd->debug_sync_control;
st_debug_sync_action *action;
DBUG_ENTER("debug_sync");
DBUG_ASSERT(sync_point_name);
DBUG_ASSERT(name_len);
DBUG_ASSERT(ds_control);
DBUG_PRINT("debug_sync_point", ("hit: '%s'", sync_point_name));
/* Statistics. */
ds_control->dsp_hits++;
if (ds_control->ds_active &&
(action= debug_sync_find(ds_control->ds_action, ds_control->ds_active,
sync_point_name, name_len)) &&
action->activation_count)
{
/* Sync point is active (action exists). */
debug_sync_execute(thd, action);
/* Statistics. */
ds_control->dsp_executed++;
/* If action became inactive, remove it to shrink the search array. */
if (!action->activation_count)
debug_sync_remove_action(ds_control, action);
}
DBUG_VOID_RETURN;
}
/**
Define debug sync action.
@param[in] thd thread handle
@param[in] action_str action string
@return status
@retval FALSE ok
@retval TRUE error
@description
The function is similar to @c debug_sync_eval_action but is
to be called immediately from the server code rather than
to be triggered by setting a value to DEBUG_SYNC system variable.
@note
The input string is copied prior to be fed to
@c debug_sync_eval_action to let the latter modify it.
Caution.
The function allocates in THD::mem_root and therefore
is not recommended to be deployed inside big loops.
*/
bool debug_sync_set_action(THD *thd, const char *action_str, size_t len)
{
bool rc;
char *value;
DBUG_ENTER("debug_sync_set_action");
DBUG_ASSERT(thd);
DBUG_ASSERT(action_str);
value= strmake_root(thd->mem_root, action_str, len);
rc= debug_sync_eval_action(thd, value, value + len);
DBUG_RETURN(rc);
}
#else /* defined(ENABLED_DEBUG_SYNC) */
/* prevent linker/lib warning about file without public symbols */
int debug_sync_dummy;
#endif /* defined(ENABLED_DEBUG_SYNC) */
Reference in a new issue View git blame Copy permalink