diff options
Diffstat (limited to 'sql/debug_sync.cc')
| -rw-r--r-- | sql/debug_sync.cc | 230 |
1 files changed, 201 insertions, 29 deletions
diff --git a/sql/debug_sync.cc b/sql/debug_sync.cc index 55523a728f8..eac111d32d7 100644 --- a/sql/debug_sync.cc +++ b/sql/debug_sync.cc @@ -18,6 +18,7 @@ #include "mariadb.h" #include "debug_sync.h" +#include <cstring> #if defined(ENABLED_DEBUG_SYNC) @@ -48,6 +49,8 @@ struct st_debug_sync_action 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. */ @@ -67,21 +70,99 @@ struct st_debug_sync_control }; + + /** Definitions for the debug sync facility. - 1. Global string variable to hold a "signal" ("signal post", "flag mast"). + 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 { - String ds_signal; /* signal variable */ + 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) {}; + ~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 */ /** @@ -161,7 +242,7 @@ int debug_sync_init(void) int rc; /* Initialize the global variables. */ - debug_sync_global.ds_signal.length(0); + 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, @@ -195,7 +276,7 @@ void debug_sync_end(void) debug_sync_C_callback_ptr= NULL; /* Destroy the global variables. */ - debug_sync_global.ds_signal.free(); + debug_sync_global.clear_set(); mysql_cond_destroy(&debug_sync_global.ds_cond); mysql_mutex_destroy(&debug_sync_global.ds_mutex); @@ -272,6 +353,40 @@ void debug_sync_init_thread(THD *thd) /** + 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 @@ -554,7 +669,7 @@ static void debug_sync_reset(THD *thd) /* Clear the global signal. */ mysql_mutex_lock(&debug_sync_global.ds_mutex); - debug_sync_global.ds_signal.length(0); + debug_sync_global.clear_set(); mysql_mutex_unlock(&debug_sync_global.ds_mutex); DBUG_VOID_RETURN; @@ -1175,6 +1290,7 @@ static bool debug_sync_eval_action(THD *thd, char *action_str, char *action_end) /* Set default for EXECUTE and TIMEOUT options. */ action->execute= 1; action->timeout= opt_debug_sync_timeout; + action->clear_event= true; /* Get next token. If none follows, set action. */ if (!(ptr= debug_sync_token(&token, &token_length, ptr, action_end))) @@ -1226,6 +1342,16 @@ static bool debug_sync_eval_action(THD *thd, char *action_str, char *action_end) } /* + Try NO_CLEAR_EVENT. + */ + if (!my_strcasecmp(system_charset_info, token, "NO_CLEAR_EVENT")) + { + action->clear_event= false; + /* 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")) @@ -1325,13 +1451,19 @@ uchar *debug_sync_value_ptr(THD *thd) if (opt_debug_sync_timeout) { - static char on[]= "ON - current signal: '"; + static char on[]= "ON - current signals: '"; // 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 '\'' */); + size_t lgt= sizeof(on) + 1; /* +1 as we'll have to append ' at the end. */ + + for (size_t i= 0; i < debug_sync_global.ds_signal_set.size(); i++) + { + /* Assume each signal is separated by a comma, hence +1. */ + lgt+= debug_sync_global.ds_signal_set.at(i)->length + 1; + } + char *vend; char *vptr; @@ -1339,10 +1471,15 @@ uchar *debug_sync_value_ptr(THD *thd) { 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++)= '\''; + for (size_t i= 0; i < debug_sync_global.ds_signal_set.size(); i++) + { + const LEX_CSTRING *s= debug_sync_global.ds_signal_set.at(i); + vptr= debug_sync_bmove_len(vptr, vend, s->str, s->length); + if (i != debug_sync_global.ds_signal_set.size() - 1) + *(vptr++)= ','; + } + DBUG_ASSERT(vptr < vend); + *(vptr++)= '\''; *vptr= '\0'; /* We have one byte reserved for the worst case. */ } mysql_mutex_unlock(&debug_sync_global.ds_mutex); @@ -1358,6 +1495,9 @@ uchar *debug_sync_value_ptr(THD *thd) } + + + /** Execute requested action at a synchronization point. @@ -1413,12 +1553,28 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action) 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)) + int offset= 0, pos; + bool error= false; + + /* This loop covers all signals in the list except for the last one. + Split the signal string by commas and set a signal in the global + variable for each one. */ + while (!error && (pos= action->signal.strstr(",", 1, offset)) > 0) + { + error= debug_sync_global.set_signal(action->signal.ptr() + offset, + pos - offset); + offset= pos + 1; + } + + if (error || + /* The last signal in the list. */ + debug_sync_global.set_signal(action->signal.ptr() + offset, + action->signal.length() - offset)) { /* Error is reported by my_malloc(). @@ -1461,31 +1617,43 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action) 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. */ - DBUG_PRINT("debug_sync_exec", - ("wait for '%s' at: '%s' curr: '%s'", - sig_wait, dsp_name, - debug_sync_global.ds_signal.c_ptr()));); + DBUG_EXECUTE("debug_sync_exec", { + const char *signal_set= get_signal_set_as_string(); + if (!signal_set) + { + DBUG_PRINT("debug_sync_exec", + ("Out of memory when fetching signal set")); + } + else + { + /* Functions as DBUG_PRINT args can change keyword and line nr. */ + DBUG_PRINT("debug_sync_exec", + ("wait for '%s' at: '%s', curr: '%s'", + sig_wait, dsp_name, signal_set)); + my_free((void *)signal_set); + }}); + /* - Wait until global signal string matches the wait_for string. - Interrupt when thread or query is killed or facility disabled. + Wait until the signal set contains the wait_for string. + Interrupt when thread or query is killed or facility is 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 & KILL_HARD_BIT) && opt_debug_sync_timeout) + while (!debug_sync_global.is_signalled(action->wait_for.ptr(), + action->wait_for.length()) && + !(thd->killed & KILL_HARD_BIT) && + opt_debug_sync_timeout) { error= mysql_cond_timedwait(&debug_sync_global.ds_cond, &debug_sync_global.ds_mutex, &abstime); - DBUG_EXECUTE("debug_sync", + // TODO turn this into a for loop printing. + DBUG_EXECUTE("debug_sync", { /* Functions as DBUG_PRINT args can change keyword and line nr. */ DBUG_PRINT("debug_sync", - ("awoke from %s global: %s error: %d", - sig_wait, debug_sync_global.ds_signal.c_ptr(), - error));); + ("awoke from %s error: %d", + sig_wait, error));}); if (unlikely(error == ETIMEDOUT || error == ETIME)) { // We should not make the statement fail, even if in strict mode. @@ -1498,6 +1666,10 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action) } error= 0; } + + if (action->clear_event) + debug_sync_global.clear_signal(action->wait_for); + DBUG_EXECUTE("debug_sync_exec", if (thd->killed) DBUG_PRINT("debug_sync_exec", @@ -1571,10 +1743,10 @@ static void debug_sync(THD *thd, const char *sync_point_name, size_t name_len) st_debug_sync_control *ds_control= thd->debug_sync_control; st_debug_sync_action *action; DBUG_ENTER("debug_sync"); + DBUG_PRINT("debug_sync_point", ("hit: '%s'", sync_point_name)); 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++; |