Initial commit of Admission Control xAPP and E2AP/X2AP definitions

[ric-app/admin.git] / src / protector-plugin / sliding_window.cc

diff --git a/src/protector-plugin/sliding_window.cc b/src/protector-plugin/sliding_window.cc
new file mode 100644 (file)
index 0000000..71eefe8
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+++ b/src/protector-plugin/sliding_window.cc
@@ -0,0 +1,141 @@
+/*
+==================================================================================
+
+        Copyright (c) 2018-2019 AT&T Intellectual Property.
+
+   Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+
+   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.
+==================================================================================
+*/
+
+#include "sliding_window.hpp"
+
+
+sliding_window::sliding_window(unsigned int window_size){
+
+  if (window_size < MIN_WINDOW_SIZE){
+    std::stringstream ss;
+    ss << "Error ::" << __FILE__ << ","<< __LINE__ << " window size must be >= " << MIN_WINDOW_SIZE << " Specified = " << window_size << std::endl;
+    error_string = ss.str();
+    throw std::logic_error(error_string);
+  }
+
+  if (window_size > MAX_WINDOW_SIZE){
+    std::stringstream ss;
+    ss << "Error ::" << __FILE__ << ","<< __LINE__ << " window size must be <= " << MAX_WINDOW_SIZE << " Specified = " << window_size << std::endl;
+    std::string error_string = ss.str();
+    throw std::logic_error(error_string);
+  }
+
+  window_size_ = window_size;
+  sliding_window_.resize(window_size_);
+  
+  head = window_size_ -1;
+  tail = 0;
+  net_events = 0;
+  leading_edge_ = std::chrono::steady_clock::now();
+}
+
+// expect to be called very frequently ....
+bool  sliding_window::update_window(unsigned int events){
+  // get current time
+  auto current_edge = std::chrono::steady_clock::now();
+  
+  int shift = std::chrono::duration_cast<std::chrono::seconds>(current_edge - leading_edge_).count();
+
+  if (shift < 0){
+    // we do not update any events if they happened in the past
+    // by more than unit of window .. (1 second currently)
+    return false;
+  }
+
+  // Advance window if shift >= 1
+  if (shift >= 1){
+    leading_edge_ = current_edge;
+  }
+  
+  if (shift >= window_size_){
+    // gap between current time and leading edge
+    // exceeds window size. Clear everything ...
+    tail = 0;
+    head = window_size_ -1;
+    std::fill(sliding_window_.begin(), sliding_window_.end(), 0);
+    sliding_window_[head] = events ;
+    net_events = events;
+    return true;
+  }
+  
+  for(int i = 0; i < shift; i++){
+    // Advance tail & head by requisite amount, reducing net event rate ..
+    net_events -= sliding_window_[tail];
+    sliding_window_[tail] = 0;
+    tail += 1;
+    if (tail >= window_size_){
+      tail = 0;
+    }
+    
+    head += 1;
+    if (head >= window_size_){
+      head = 0;
+    }
+  }
+
+  sliding_window_[head] += events;
+  net_events += events;
+
+  //std::cout <<net_events << "," << window_size_ << "," << shift << std::endl;  
+  return true;
+}
+
+// modifies window size. resets all parameters 
+bool sliding_window::resize_window(unsigned int window_size){
+  if (window_size < MIN_WINDOW_SIZE || window_size > MAX_WINDOW_SIZE){
+    std::stringstream ss;
+    ss << "Error ::" << __FILE__ << ","<< __LINE__ << " window size must be in [ " << MIN_WINDOW_SIZE << "," << MAX_WINDOW_SIZE << "]"  << std::endl;
+    error_string = ss.str();
+    return false;
+  }
+  
+  window_size_ = window_size;
+  sliding_window_.clear();
+  sliding_window_.resize(window_size_);
+  net_events = 0;
+  head = window_size_ -1;
+  tail = 0;
+  leading_edge_ = std::chrono::steady_clock::now();
+  return true;
+}
+
+std::string  sliding_window::display_window(void){
+  std::stringstream ss;
+  for(unsigned int i = 0; i < sliding_window_.size(); i++){
+    if (i == head){
+      ss <<"[H] ";
+    }
+    if (i == tail){
+      ss <<"[T] ";
+    }
+    
+    ss <<sliding_window_[i] <<",";
+  }
+  ss <<" [Events] = " << net_events << std::endl;
+
+  return ss.str();
+}
+
+void sliding_window::clear(void){
+  
+  resize_window(window_size_);
+}
+
+  
+