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/CMakeLists.txt

@@ -19,3 +19,4 @@ target_link_libraries(utils PRIVATE ${T_LIB})
 if (ENABLE_TESTS)
   add_subdirectory(hashtable/tests)
 endif()
+add_subdirectory(barrier)

common/utils/barrier/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_library(barrier barrier.c)
+target_include_directories(barrier PUBLIC ./)
+target_link_libraries(barrier PUBLIC pthread)
+
+if (ENABLE_TESTS)
+  add_subdirectory(tests)
+endif()

common/utils/barrier/barrier.c

@@ -0,0 +1,65 @@
+/*
+ * 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
+ */
+
+#include "barrier.h"
+#include "assertions.h"
+
+void dynamic_barrier_init(dynamic_barrier_t* barrier)
+{
+  int ret = pthread_mutex_init(&barrier->barrier_lock, NULL);
+  AssertFatal(ret == 0, "Mutex error %d", ret);
+  barrier->callback = NULL;
+  barrier->callback_arg = NULL;
+  barrier->completed_jobs = 0;
+}
+
+void dynamic_barrier_join(dynamic_barrier_t* barrier)
+{
+  int ret = pthread_mutex_lock(&barrier->barrier_lock);
+  AssertFatal(ret == 0, "Mutex error %d", ret);
+  barrier->completed_jobs++;
+  if (barrier->callback) {
+    if (barrier->completed_jobs == barrier->max_joins) {
+      barrier->completed_jobs = 0;
+      barrier->callback(barrier->callback_arg);
+      barrier->callback = NULL;
+      barrier->callback_arg = NULL;
+    }
+  }
+  ret = pthread_mutex_unlock(&barrier->barrier_lock);
+  AssertFatal(ret == 0, "Mutex error %d", ret);
+}
+
+void dynamic_barrier_update(dynamic_barrier_t* barrier, int max_joins, callback_t callback, void* arg)
+{
+  int ret = pthread_mutex_lock(&barrier->barrier_lock);
+  AssertFatal(ret == 0, "Mutex error %d", ret);
+  if (barrier->completed_jobs == max_joins) {
+    barrier->completed_jobs = 0;
+    callback(arg);
+  } else {
+    barrier->max_joins = max_joins;
+    barrier->callback = callback;
+    barrier->callback_arg = arg;
+  }
+  ret = pthread_mutex_unlock(&barrier->barrier_lock);
+  AssertFatal(ret == 0, "Mutex error %d", ret);
+}

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

common/utils/barrier/tests/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_executable(test_barrier test_barrier.cpp)
+target_link_libraries(test_barrier PRIVATE barrier GTest::gtest)
+add_dependencies(tests test_barrier)
+add_test(NAME test_barrier
+  COMMAND ./test_barrier)

common/utils/barrier/tests/test_barrier.cpp

@@ -0,0 +1,118 @@
+/*
+ * 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
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include <threads.h>
+#include <stdlib.h>
+#include <gtest/gtest.h>
+
+extern "C" {
+#include "barrier.h"
+void exit_function(const char *file, const char *function, const int line, const char *s, const int assert)
+{
+  if (assert) {
+    abort();
+  } else {
+    exit(EXIT_SUCCESS);
+  }
+}
+}
+
+static int trigger_count = 0;
+static int triggered = 0;
+void f(void *arg)
+{
+  triggered = 1;
+  trigger_count++;
+}
+
+TEST(dynamic_barrier, trigger_once)
+{
+  dynamic_barrier_t barrier;
+  triggered = 0;
+  dynamic_barrier_init(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_update(&barrier, 4, f, NULL);
+  EXPECT_EQ(triggered, 1);
+}
+
+TEST(dynamic_barrier, trigger_twice)
+{
+  dynamic_barrier_t barrier;
+  triggered = 0;
+  dynamic_barrier_init(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_update(&barrier, 4, f, NULL);
+  EXPECT_EQ(triggered, 1);
+  triggered = 0;
+  dynamic_barrier_init(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_join(&barrier);
+  dynamic_barrier_update(&barrier, 4, f, NULL);
+  EXPECT_EQ(triggered, 1);
+}
+
+int dynamic_barrier_thread(void *thr_data)
+{
+  dynamic_barrier_t *barrier = (dynamic_barrier_t *)thr_data;
+  dynamic_barrier_join(barrier);
+  return 0;
+}
+
+int dynamic_barrier_update_thread(void *thr_data)
+{
+  dynamic_barrier_t *barrier = (dynamic_barrier_t *)thr_data;
+  dynamic_barrier_update(barrier, 3, f, NULL);
+  return 0;
+}
+
+TEST(dynamic_barrier, multithreaded)
+{
+  thrd_t thr[3];
+  dynamic_barrier_t barrier;
+  trigger_count = 0;
+  for (int i = 0; i < 300; i++) {
+    dynamic_barrier_init(&barrier);
+    thrd_t update_thread;
+    thrd_create(&update_thread, dynamic_barrier_update_thread, &barrier);
+    for (int n = 0; n < 3; ++n)
+      thrd_create(&thr[n], dynamic_barrier_thread, &barrier);
+    for (int n = 0; n < 3; ++n)
+      thrd_join(thr[n], NULL);
+    thrd_join(update_thread, NULL);
+  }
+  assert(trigger_count == 300);
+}
+
+int main(int argc, char **argv)
+{
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}