Zhangxian Xu added a comment - 2021-02-18 15:08 Hi, I'm Zhangxian Xu, a student pursuing master's degree in Computer Science. It's a nice issue and I want to complete it as my Gsoc 2021 project . Hope to get some guidence on this issue. Thanks!

Oleksandr Byelkin added a comment - 2022-04-11 10:49 a draft diff --git a/include/my_alloc.h b/include/my_alloc.h index 52c04fe1b7d..4e67f4a1ee3 100644 --- a/include/my_alloc.h +++ b/include/my_alloc.h @@ -49,6 +49,9 @@ typedef struct st_mem_root MAX_BLOCK_USAGE_BEFORE_DROP block will be dropped in 'used' list) */ unsigned int first_block_usage; +#ifndef DBUG_OFF + my_bool read_only; +#endif void (*error_handler)(void); } MEM_ROOT; diff --git a/include/mysql.h.pp b/include/mysql.h.pp index 73b9f9f588b..4eea704165f 100644 --- a/include/mysql.h.pp +++ b/include/mysql.h.pp @@ -238,6 +238,7 @@ typedef struct st_mem_root size_t block_size; unsigned int block_num; unsigned int first_block_usage; + my_bool read_only; void (*error_handler)(void); } MEM_ROOT; typedef struct st_typelib { diff --git a/mysys/my_alloc.c b/mysys/my_alloc.c index d67b8be9bb8..8c09e4bab68 100644 --- a/mysys/my_alloc.c +++ b/mysys/my_alloc.c @@ -71,6 +71,9 @@ void init_alloc_root(MEM_ROOT *mem_root, size_t block_size, mem_root->error_handler= 0; mem_root->block_num= 4; /* We shift this with >>2 */ mem_root->first_block_usage= 0; +#ifndef DBUG_OFF + mem_root->read_only= 0; +#endif #if !(defined(HAVE_valgrind) && defined(EXTRA_DEBUG)) if (pre_alloc_size) @@ -177,6 +180,8 @@ void *alloc_root(MEM_ROOT *mem_root, size_t length) DBUG_ASSERT(alloc_root_inited(mem_root)); + DBUG_ASSERT(mem_root->read_only == 0); + DBUG_EXECUTE_IF("simulate_out_of_memory", { if (mem_root->error_handler) @@ -210,6 +215,8 @@ void *alloc_root(MEM_ROOT *mem_root, size_t length) DBUG_PRINT("enter",("root: %p", mem_root)); DBUG_ASSERT(alloc_root_inited(mem_root)); + DBUG_ASSERT(mem_root->read_only == 0); + DBUG_EXECUTE_IF("simulate_out_of_memory", { /* Avoid reusing an already allocated block */ diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc index 64e4cd30561..726e1634904 100644 --- a/sql/sql_prepare.cc +++ b/sql/sql_prepare.cc @@ -167,6 +167,9 @@ class Prepared_statement: public Statement Server_side_cursor *cursor; uchar *packet; uchar *packet_end; +#ifndef DBUG_OFF + ulong executed_counter; +#endif uint param_count; uint last_errno; uint flags; @@ -3996,6 +3999,9 @@ Prepared_statement::Prepared_statement(THD *thd_arg) cursor(0), packet(0), packet_end(0), +#ifndef DBUG_OFF + executed_counter(0), +#endif param_count(0), last_errno(0), flags((uint) IS_IN_USE), @@ -4069,8 +4075,8 @@ void Prepared_statement::setup_set_params() Prepared_statement::~Prepared_statement() { DBUG_ENTER("Prepared_statement::~Prepared_statement"); - DBUG_PRINT("enter",("stmt: %p cursor: %p", - this, cursor)); + DBUG_PRINT("enter",("stmt: %p cursor: %p, executed: %lu", + this, cursor, executed_counter)); delete cursor; /* We have to call free on the items even if cleanup is called as some items, @@ -4228,6 +4234,9 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len) init_param_array(this); lex->set_trg_event_type_for_tables(); +#ifndef DBUG_OFF + executed_counter= 0; +#endif /* While doing context analysis of the query (in check_prepared_statement) @@ -4525,6 +4534,16 @@ Prepared_statement::execute_loop(String *expanded_query, goto reexecute; } reset_stmt_params(this); +#ifndef DBUG_OFF + if (!error) + { + if (++executed_counter >= 2) + { + mem_root->read_only= 1; + } + DBUG_PRINT("XXX", ("execute counter: %lu", executed_counter)); + } +#endif return error; }