Auto merge fix for Bug#49020

2 files changed, 27 insertions, 80 deletions

diff --git a/plugin/semisync/semisync_master.cc b/plugin/semisync/semisync_master.cc
index cc83978ad4e..526797a3c4a 100644
--- a/plugin/semisync/semisync_master.cc
+++ b/plugin/semisync/semisync_master.cc
@@ -63,29 +63,14 @@ static int gettimeofday(struct timeval *tv, void *tz)
  *
  ******************************************************************************/
 
-ActiveTranx::ActiveTranx(int max_connections,
-			 pthread_mutex_t *lock,
+ActiveTranx::ActiveTranx(pthread_mutex_t *lock,
 			 unsigned long trace_level)
-  : Trace(trace_level), num_transactions_(max_connections),
-    num_entries_(max_connections << 1),
+  : Trace(trace_level),
+    num_entries_(max_connections << 1), /* Transaction hash table size
+                                         * is set to double the size
+                                         * of max_connections */
     lock_(lock)
 {
-  /* Allocate the memory for the array */
-  node_array_ = new TranxNode[num_transactions_];
-  for (int idx = 0; idx < num_transactions_; ++idx)
-  {
-    node_array_[idx].log_pos_     = 0;
-    node_array_[idx].hash_next_   = NULL;
-    node_array_[idx].next_        = node_array_ + idx + 1;
-
-    node_array_[idx].log_name_    = new char[FN_REFLEN];
-    node_array_[idx].log_name_[0] = '\x0';
-  }
-  node_array_[num_transactions_-1].next_ = NULL;
-
-  /* All nodes in the array go to the pool initially. */
-  free_pool_ = node_array_;
-
   /* No transactions are in the list initially. */
   trx_front_ = NULL;
   trx_rear_  = NULL;
@@ -95,24 +80,13 @@ ActiveTranx::ActiveTranx(int max_connections,
   for (int idx = 0; idx < num_entries_; ++idx)
     trx_htb_[idx] = NULL;
 
-  sql_print_information("Semi-sync replication initialized for %d "
-                        "transactions.", num_transactions_);
+  sql_print_information("Semi-sync replication initialized for transactions.");
 }
 
 ActiveTranx::~ActiveTranx()
 {
-  for (int idx = 0; idx < num_transactions_; ++idx)
-  {
-    delete [] node_array_[idx].log_name_;
-    node_array_[idx].log_name_ = NULL;
-  }
-
-  delete [] node_array_;
   delete [] trx_htb_;
-
-  node_array_       = NULL;
   trx_htb_          = NULL;
-  num_transactions_ = 0;
   num_entries_      = 0;
 }
 
@@ -143,26 +117,21 @@ unsigned int ActiveTranx::get_hash_value(const char *log_file_name,
 
 ActiveTranx::TranxNode* ActiveTranx::alloc_tranx_node()
 {
-  TranxNode *ptr = free_pool_;
-
-  if (free_pool_)
-  {
-    free_pool_ = free_pool_->next_;
-    ptr->next_ = NULL;
-    ptr->hash_next_ = NULL;
-  }
-  else
+  MYSQL_THD thd= (MYSQL_THD)current_thd;
+  /* The memory allocated for TranxNode will be automatically freed at
+     the end of the command of current THD. And because
+     ha_autocommit_or_rollback() will always be called before that, so
+     we are sure that the node will be removed from the active list
+     before it get freed. */
+  TranxNode *trx_node = (TranxNode *)thd_alloc(thd, sizeof(TranxNode));
+  if (trx_node)
   {
-    /*
-      free_pool should never be NULL here, because we have
-      max_connections number of pre-allocated nodes.
-    */
-    sql_print_error("You have encountered a semi-sync bug (free_pool == NULL), "
-                    "please report to http://bugs.mysql.com");
-    assert(free_pool_);
+    trx_node->log_name_[0] = '\0';
+    trx_node->log_pos_= 0;
+    trx_node->next_= 0;
+    trx_node->hash_next_= 0;
   }
-
-  return ptr;
+  return trx_node;
 }
 
 int ActiveTranx::compare(const char *log_file_name1, my_off_t log_file_pos1,
@@ -306,8 +275,6 @@ int ActiveTranx::clear_active_tranx_nodes(const char *log_file_name,
     /* Clear the active transaction list. */
     if (trx_front_ != NULL)
     {
-      trx_rear_->next_ = free_pool_;
-      free_pool_ = trx_front_;
       trx_front_ = NULL;
       trx_rear_  = NULL;
     }
@@ -326,11 +293,6 @@ int ActiveTranx::clear_active_tranx_nodes(const char *log_file_name,
     {
       next_node = curr_node->next_;
 
-      /* Put the node in the memory pool. */
-      curr_node->next_ = free_pool_;
-      free_pool_       = curr_node;
-      n_frees++;
-
       /* Remove the node from the hash table. */
       unsigned int hash_val = get_hash_value(curr_node->log_name_, curr_node->log_pos_);
       TranxNode **hash_ptr = &(trx_htb_[hash_val]);
@@ -391,8 +353,7 @@ ReplSemiSyncMaster::ReplSemiSyncMaster()
     wait_file_pos_(0),
     master_enabled_(false),
     wait_timeout_(0L),
-    state_(0),
-    max_transactions_(0L)
+    state_(0)
 {
   strcpy(reply_file_name_, "");
   strcpy(wait_file_name_, "");
@@ -413,7 +374,6 @@ int ReplSemiSyncMaster::initObject()
   /* References to the parameter works after set_options(). */
   setWaitTimeout(rpl_semi_sync_master_timeout);
   setTraceLevel(rpl_semi_sync_master_trace_level);
-  max_transactions_ = (int)max_connections;
 
   /* Mutex initialization can only be done after MY_INIT(). */
   pthread_mutex_init(&LOCK_binlog_, MY_MUTEX_INIT_FAST);
@@ -436,9 +396,7 @@ int ReplSemiSyncMaster::enableMaster()
 
   if (!getMasterEnabled())
   {
-    active_tranxs_ = new ActiveTranx(max_connections,
-				     &LOCK_binlog_,
-				     trace_level_);
+    active_tranxs_ = new ActiveTranx(&LOCK_binlog_, trace_level_);
     if (active_tranxs_ != NULL)
     {
       commit_file_name_inited_ = false;
diff --git a/plugin/semisync/semisync_master.h b/plugin/semisync/semisync_master.h
index d2b87745600..bfb1cb74cd0 100644
--- a/plugin/semisync/semisync_master.h
+++ b/plugin/semisync/semisync_master.h
@@ -23,31 +23,26 @@
 /**
    This class manages memory for active transaction list.
 
-   We record each active transaction with a TranxNode.  Because each
-   session can only have only one open transaction, the total active
-   transaction nodes can not exceed the maximum sessions.  Currently
-   in MySQL, sessions are the same as connections.
+   We record each active transaction with a TranxNode, each session
+   can have only one open transaction. Because of EVENT, the total
+   active transaction nodes can exceed the maximum allowed
+   connections.
 */
 class ActiveTranx
   :public Trace {
 private:
   struct TranxNode {
-    char             *log_name_;
+    char             log_name_[FN_REFLEN];
     my_off_t          log_pos_;
     struct TranxNode *next_;            /* the next node in the sorted list */
     struct TranxNode *hash_next_;    /* the next node during hash collision */
   };
 
-  /* The following data structure maintains an active transaction list. */
-  TranxNode       *node_array_;
-  TranxNode       *free_pool_;
-
   /* These two record the active transaction list in sort order. */
   TranxNode       *trx_front_, *trx_rear_;
 
   TranxNode      **trx_htb_;        /* A hash table on active transactions. */
 
-  int              num_transactions_;               /* maximum transactions */
   int              num_entries_;              /* maximum hash table entries */
   pthread_mutex_t *lock_;                                     /* mutex lock */
 
@@ -74,8 +69,7 @@ private:
   }
 
 public:
-  ActiveTranx(int max_connections, pthread_mutex_t *lock,
-	      unsigned long trace_level);
+  ActiveTranx(pthread_mutex_t *lock, unsigned long trace_level);
   ~ActiveTranx();
 
   /* Insert an active transaction node with the specified position.
@@ -177,11 +171,6 @@ class ReplSemiSyncMaster
 
   bool            state_;                    /* whether semi-sync is switched */
 
-  /* The number of maximum active transactions.  This should be the same as
-   * maximum connections because MySQL does not do connection sharing now.
-   */
-  int             max_transactions_;
-
   void lock();
   void unlock();
   void cond_broadcast();