Thread barrier implementation

This commit introduces dynamic_barrier_t. Its a thread barrier that counts joins
but allows callback to be specified later. See std::barrier for a basic barrier
description.

common/utils/barrier/barrier.h

@@ -0,0 +1,53 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#ifndef _BARRIER_H_
+#define _BARRIER_H_
+#include <stdint.h>
+#include <pthread.h>
+
+typedef void (*callback_t)(void*);
+
+/// @brief This thread barrier allows modifying the maximum joins after it is initialized
+typedef struct dynamic_barrier_t {
+  pthread_mutex_t barrier_lock;
+  int completed_jobs;
+  int max_joins;
+  callback_t callback;
+  void* callback_arg;
+} dynamic_barrier_t;
+
+/// @brief Initialize the barrier
+/// @param barrier
+void dynamic_barrier_init(dynamic_barrier_t* barrier);
+
+/// @brief Perform join on the barrier. May run callback if it is already set
+/// @param barrier
+void dynamic_barrier_join(dynamic_barrier_t* barrier);
+
+/// @brief Set callback and max_joins. May run callback if the number of joins is already equal to max_joins
+/// @param barrier
+/// @param max_joins maximum number of joins before barrier triggers
+/// @param callback callback function
+/// @param arg callback function argument
+void dynamic_barrier_update(dynamic_barrier_t* barrier, int max_joins, callback_t callback, void* arg);
+
+#endif