Bug fix for #1333

Prepared statements counters are now computed at runtime instead of on-demand.
Now MySQL_STMT_Manager_v14::get_metrics() doesn't depend anymore from the
number of prepared stataments cached.
The old code (slow code) is still present in the DEBUG version, and used to
validate the new counters. That also means that DEBUG versions are way slower
than non debug versions.

include/MySQL_PreparedStatement.h

@@ -224,10 +224,19 @@ class MySQL_STMT_Manager_v14 {
 	private:
 	uint64_t next_statement_id;
 	uint64_t num_stmt_with_ref_client_count_zero;
+	uint64_t num_stmt_with_ref_server_count_zero;
 	pthread_rwlock_t rwlock_;
 	std::map<uint64_t, MySQL_STMT_Global_info *> map_stmt_id_to_info;	// map using statement id
 	std::map<uint64_t, MySQL_STMT_Global_info *> map_stmt_hash_to_info;	// map using hashes
 	std::stack<uint64_t> free_stmt_ids;
+	struct {
+		uint64_t c_unique;
+		uint64_t c_total;
+		uint64_t stmt_max_stmt_id;
+		uint64_t cached;
+		uint64_t s_unique;
+		uint64_t s_total;
+	} statuses;
 	public:
 	MySQL_STMT_Manager_v14();
 	~MySQL_STMT_Manager_v14();

lib/MySQL_PreparedStatement.cpp

@@ -487,6 +487,13 @@ MySQL_STMT_Manager_v14::MySQL_STMT_Manager_v14() {
 	next_statement_id =
 	    1;  // we initialize this as 1 because we 0 is not allowed
 	num_stmt_with_ref_client_count_zero = 0;
+	num_stmt_with_ref_server_count_zero = 0;
+	statuses.c_unique = 0;
+	statuses.c_total = 0;
+	statuses.stmt_max_stmt_id = 0;
+	statuses.cached = 0;
+	statuses.s_unique = 0;
+	statuses.s_total = 0;
 }
 
 MySQL_STMT_Manager_v14::~MySQL_STMT_Manager_v14() {
@@ -497,6 +504,7 @@ void MySQL_STMT_Manager_v14::ref_count_client(uint64_t _stmt_id ,int _v, bool lo
 		pthread_rwlock_wrlock(&rwlock_);
 	auto s = map_stmt_id_to_info.find(_stmt_id);
 	if (s != map_stmt_id_to_info.end()) {
+		statuses.c_total += _v;
 		MySQL_STMT_Global_info *stmt_info = s->second;
 		if (stmt_info->ref_count_client == 0 && _v == 1) {
 			__sync_sub_and_fetch(&num_stmt_with_ref_client_count_zero,1);
@@ -527,6 +535,9 @@ void MySQL_STMT_Manager_v14::ref_count_client(uint64_t _stmt_id ,int _v, bool lo
 							map_stmt_hash_to_info.erase(s2);
 						}
 						__sync_sub_and_fetch(&num_stmt_with_ref_client_count_zero,1);
+						if (a->ref_count_server == 0) {
+							//__sync_sub_and_fetch(&num_stmt_with_ref_server_count_zero,1);
+						}
 						// m.erase(it);
 						// delete a;
 						i++;
@@ -538,9 +549,11 @@ void MySQL_STMT_Manager_v14::ref_count_client(uint64_t _stmt_id ,int _v, bool lo
 					auto s3 = map_stmt_id_to_info.find(id);
 					MySQL_STMT_Global_info *a = s3->second;
 					if (a->ref_count_server == 0) {
+						__sync_sub_and_fetch(&num_stmt_with_ref_server_count_zero,1);
 						free_stmt_ids.push(id);
 					}
 					map_stmt_id_to_info.erase(s3);
+					statuses.s_total -= a->ref_count_server;
 					delete a;
 					i--;
 				}
@@ -557,7 +570,15 @@ void MySQL_STMT_Manager_v14::ref_count_server(uint64_t _stmt_id ,int _v, bool lo
 	std::map<uint64_t, MySQL_STMT_Global_info *>::iterator s;
 	s = map_stmt_id_to_info.find(_stmt_id);
 	if (s != map_stmt_id_to_info.end()) {
+		statuses.s_total += _v;
 		MySQL_STMT_Global_info *stmt_info = s->second;
+		if (stmt_info->ref_count_server == 0 && _v == 1) {
+			__sync_sub_and_fetch(&num_stmt_with_ref_server_count_zero,1);
+		} else {
+			if (stmt_info->ref_count_server == 1 && _v == -1) {
+				__sync_add_and_fetch(&num_stmt_with_ref_server_count_zero,1);
+			}
+		}
 		stmt_info->ref_count_server += _v;
 	}
 	if (lock)
@@ -760,8 +781,13 @@ MySQL_STMT_Global_info *MySQL_STMT_Manager_v14::add_prepared_statement(
 //		                     1);  // increase reference count
 //		*is_new = true;
 		__sync_add_and_fetch(&num_stmt_with_ref_client_count_zero,1);
+		__sync_add_and_fetch(&num_stmt_with_ref_server_count_zero,1);
+	}
+	if (ret->ref_count_server == 0) {
+		__sync_sub_and_fetch(&num_stmt_with_ref_server_count_zero,1);
 	}
 	ret->ref_count_server++;
+	statuses.s_total++;
 //	__sync_fetch_and_add(&add_prepared_statement_calls, 1);
 //	__sync_fetch_and_add(&ret->ref_count_server,
 //	                     1);  // increase reference count
@@ -781,6 +807,10 @@ void MySQL_STMT_Manager_v14::get_metrics(uint64_t *c_unique, uint64_t *c_total,
 	uint64_t s_u = 0;
 	uint64_t s_t = 0;
 	pthread_rwlock_wrlock(&rwlock_);
+	statuses.cached = map_stmt_id_to_info.size();
+	statuses.c_unique = statuses.cached - num_stmt_with_ref_client_count_zero;
+	statuses.s_unique = statuses.cached - num_stmt_with_ref_server_count_zero;
+#ifdef DEBUG
 	for (std::map<uint64_t, MySQL_STMT_Global_info *>::iterator it = map_stmt_id_to_info.begin();
 	     it != map_stmt_id_to_info.end(); ++it) {
 		MySQL_STMT_Global_info *a = it->second;
@@ -797,13 +827,20 @@ void MySQL_STMT_Manager_v14::get_metrics(uint64_t *c_unique, uint64_t *c_total,
 			m = it->first;
 		}
 	}
-	pthread_rwlock_unlock(&rwlock_);
-	*c_unique = c_u;
-	*c_total = c_t;
+	assert (c_u == statuses.c_unique);
+	assert (c_t == statuses.c_total);
+	assert (c == statuses.cached);
+	assert (s_t == statuses.s_total);
+	assert (s_u == statuses.s_unique);
 	*stmt_max_stmt_id = m;
-	*cached = c;
-	*s_unique = s_u;
-	*s_total = s_t;
+#endif
+	*stmt_max_stmt_id = next_statement_id; // this is max stmt_id, no matter if in used or not
+	*c_unique = statuses.c_unique;
+	*c_total = statuses.c_total;
+	*cached = statuses.cached;
+	*s_total = statuses.s_total;
+	*s_unique = statuses.s_unique;
+	pthread_rwlock_unlock(&rwlock_);
 }