Reuse MySQL connections within requests

src/wasm/worker.cpp

@@ -804,6 +804,7 @@ public:
 	// never cache these opaque handles across requests.
 	std::vector<SQLite*> sqlite_handles;
 	std::vector<MySQL*> mysql_handles;
+	std::vector<MySQL*> mysql_request_pool;
 #endif
 	~WasmWorkspace()
 	{
@@ -820,7 +821,7 @@ public:
 		for(auto* db : sqlite_handles)
 			if(db)
 				delete db;   // ~SQLite disconnects
-		for(auto* db : mysql_handles)
+		for(auto* db : mysql_request_pool)
 			if(db)
 				delete db;   // ~MySQL disconnects
 #endif
@@ -2409,11 +2410,32 @@ private:
 						String op = request["op"].to_string();
 						if(op == "connect")
 						{
-							MySQL* db = new MySQL();
-							bool ok = db->connect(request["host"].to_string(), request["username"].to_string(), request["password"].to_string());
+							String host = request["host"].to_string();
+							String username = request["username"].to_string();
+							String password = request["password"].to_string();
+							MySQL* db = 0;
+							for(auto* pooled : self->mysql_request_pool)
+								if(pooled && pooled->connection && pooled->request_host == host && pooled->request_username == username && pooled->request_password == password)
+								{
+									db = pooled;
+									break;
+								}
+							bool ok = db != 0;
+							if(!db)
+							{
+								db = new MySQL();
+								db->request_pooled = true;
+								db->request_host = host;
+								db->request_username = username;
+								db->request_password = password;
+								ok = db->connect(host, username, password);
+								if(ok && db->connection)
+									self->mysql_request_pool.push_back(db);
+							}
 							u64 handle = 0;
 							if(ok && db->connection)
 							{
+								db->request_leases++;
 								self->mysql_handles.push_back(db);
 								handle = self->mysql_handles.size();
 							}
@@ -2443,7 +2465,8 @@ private:
 							}
 							else if(op == "disconnect" && db)
 							{
-								delete db;
+								if(db->request_leases > 0)
+									db->request_leases--;
 								self->mysql_handles[(size_t)handle - 1] = 0;
 							}
 						}