/
debug_sync.cc
1838 lines (1514 loc) · 54.1 KB
/
debug_sync.cc
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/* Copyright (c) 2009, 2013, Oracle and/or its affiliates.
Copyright (c) 2009, 2022, MariaDB
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"
#include <cstring>
#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 */
bool clear_event; /* do not clear signal when waited
for if false. */
};
/* 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 set of of "signals".
2. Global condition variable for signaling and waiting.
3. Global mutex to synchronize access to the above.
*/
struct st_debug_sync_globals
{
Hash_set<LEX_CSTRING> ds_signal_set; /* A set of active signals */
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 */
st_debug_sync_globals() :
ds_signal_set(PSI_NOT_INSTRUMENTED, signal_key),
dsp_hits (0), dsp_executed(0), dsp_max_active(0) {};
~st_debug_sync_globals()
{
clear_set();
}
void clear_set()
{
Hash_set<LEX_CSTRING>::Iterator it{ds_signal_set};
LEX_CSTRING *s;
while ((s= it++))
my_free(s);
ds_signal_set.clear();
}
/* Hash key function for ds_signal_set. */
static uchar *signal_key(const LEX_CSTRING *str, size_t *klen, my_bool)
{
*klen= str->length;
return (uchar*) str->str;
}
/**
Return true if the signal is found in global signal list.
@param signal_name Signal name identifying the signal.
@note
If signal is found in the global signal set, it means that the
signal thread has signalled to the waiting thread. This method
must be called with the debug_sync_global.ds_mutex held.
@retval true if signal is found in the global signal list.
@retval false otherwise.
*/
inline bool is_signalled(const char *signal_name, size_t length)
{
return ds_signal_set.find(signal_name, length);
}
void clear_signal(const String &signal_name)
{
DBUG_ENTER("clear_signal");
LEX_CSTRING *record= ds_signal_set.find(signal_name.ptr(),
signal_name.length());
if (record)
{
ds_signal_set.remove(record);
my_free(record);
}
DBUG_VOID_RETURN;
}
bool set_signal(const char *signal_name, size_t length)
{
/* Need to check if the signal is already in the hash set, because
Hash_set doesn't differentiate between OOM and key already in. */
if (is_signalled(signal_name, length))
return FALSE;
/* LEX_CSTRING and the string allocated with only one malloc. */
LEX_CSTRING *s= (LEX_CSTRING *) my_malloc(PSI_NOT_INSTRUMENTED,
sizeof(LEX_CSTRING) + length + 1,
MYF(0));
char *str= (char *)(s + 1);
memcpy(str, signal_name, length);
str[length]= '\0';
s->length= length;
s->str= str;
if (ds_signal_set.insert(s))
return TRUE;
return FALSE;
}
};
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 (!debug_sync_global)
debug_sync_global= new st_debug_sync_globals();
if (opt_debug_sync_timeout)
{
int rc;
/* Initialize the global variables. */
debug_sync_global->clear_set();
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->clear_set();
mysql_cond_destroy(&debug_sync_global->ds_cond);
mysql_mutex_destroy(&debug_sync_global->ds_mutex);
/* Print statistics. */
{
sql_print_information("Debug sync points hit: %lld",
debug_sync_global->dsp_hits);
sql_print_information("Debug sync points executed: %lld",
debug_sync_global->dsp_executed);
sql_print_information("Debug sync points max active per thread: %lld",
debug_sync_global->dsp_max_active);
}
}
delete debug_sync_global;
/* Just to be safe */
debug_sync_global= NULL;
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;
}
/**
Returns an allocated buffer containing a comma-separated C string of all
active signals.
Buffer must be freed by the caller.
*/
static const char *get_signal_set_as_string()
{
mysql_mutex_assert_owner(&debug_sync_global->ds_mutex);
size_t req_size= 1; // In case of empty set for the end '\0' char.
for (size_t i= 0; i < debug_sync_global->ds_signal_set.size(); i++)
req_size+= debug_sync_global->ds_signal_set.at(i)->length + 1;
char *buf= (char *) my_malloc(PSI_NOT_INSTRUMENTED, req_size, MYF(0));
if (!buf)
return nullptr;
memset(buf, '\0', req_size);
char *cur_pos= buf;
for (size_t i= 0; i < debug_sync_global->ds_signal_set.size(); i++)
{
const LEX_CSTRING *signal= debug_sync_global->ds_signal_set.at(i);
memcpy(cur_pos, signal->str, signal->length);
if (i != debug_sync_global->ds_signal_set.size() - 1)
cur_pos[signal->length]= ',';
else
cur_pos[signal->length] = '\0';
cur_pos+= signal->length + 1;
}
return buf;
}
/**
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. */
/*
Protect access with debug_sync_global->ds_mutex only if
it had been initialized.
*/
if (debug_sync_C_callback_ptr)
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;
/*
Protect access with debug_sync_global->ds_mutex only if
it had been initialized.
*/
if (debug_sync_C_callback_ptr)
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);
}
#ifdef DBUG_TRACE
/**
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_TRACE) */
/**
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->clear_set();
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 */
}
class Debug_token: public Lex_ident_ci
{
public:
using Lex_ident_ci::Lex_ident_ci;
};
/**
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 Debug_token dsp_name(action->sync_point.to_lex_cstring());
#ifdef DBUG_TRACE
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'",
(int) dsp_name.length, dsp_name.str,
action->activation_count,
action->hit_limit, action->execute, action->timeout,
sig_emit, sig_wait));});
#endif
/* Check this before sorting the array. action may move. */
is_dsp_now= dsp_name.streq("now"_LEX_CSTRING);
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);
}
}
#ifdef DBUG_TRACE
DBUG_EXECUTE("debug_sync_list", debug_sync_print_actions(thd););
#endif
/* 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 strtoul().
To return the last token without copying it, we require the input
string to be nul terminated.
@description