diff options
Diffstat (limited to 'sql/debug_sync.cc')
| -rw-r--r-- | sql/debug_sync.cc | 1631 |
1 files changed, 1631 insertions, 0 deletions
diff --git a/sql/debug_sync.cc b/sql/debug_sync.cc new file mode 100644 index 00000000..dde3ce5a --- /dev/null +++ b/sql/debug_sync.cc @@ -0,0 +1,1631 @@ +/* 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) */ |