--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Core/MetricsRegistry.cpp	Tue Jan 29 15:15:48 2019 +0100
@@ -0,0 +1,321 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders of this
+ * program give permission to link the code of its release with the
+ * OpenSSL project's "OpenSSL" library (or with modified versions of it
+ * that use the same license as the "OpenSSL" library), and distribute
+ * the linked executables. You must obey the GNU General Public License
+ * in all respects for all of the code used other than "OpenSSL". If you
+ * modify file(s) with this exception, you may extend this exception to
+ * your version of the file(s), but you are not obligated to do so. If
+ * you do not wish to do so, delete this exception statement from your
+ * version. If you delete this exception statement from all source files
+ * in the program, then also delete it here.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "PrecompiledHeaders.h"
+#include "MetricsRegistry.h"
+
+#include "OrthancException.h"
+#include "ChunkedBuffer.h"
+
+namespace Orthanc
+{
+  static const boost::posix_time::ptime GetNow()
+  {
+    return boost::posix_time::second_clock::universal_time();
+  }
+
+
+  class MetricsRegistry::Item
+  {
+  private:
+    MetricsType               type_;
+    boost::posix_time::ptime  time_;
+    bool                      hasValue_;
+    float                     value_;
+    
+    void Touch(float value,
+               const boost::posix_time::ptime& now)
+    {
+      hasValue_ = true;
+      value_ = value;
+      time_ = now;
+    }
+
+    void Touch(float value)
+    {
+      Touch(value, GetNow());
+    }
+
+    void UpdateMax(float value,
+                   int duration)
+    {
+      if (hasValue_)
+      {
+        const boost::posix_time::ptime now = GetNow();
+
+        if (value > value_ ||
+            (now - time_).total_seconds() > duration)
+        {
+          Touch(value, now);
+        }
+      }
+      else
+      {
+        Touch(value);
+      }
+    }
+    
+    void UpdateMin(float value,
+                   int duration)
+    {
+      if (hasValue_)
+      {
+        const boost::posix_time::ptime now = GetNow();
+        
+        if (value < value_ ||
+            (now - time_).total_seconds() > duration)
+        {
+          Touch(value, now);
+        }
+      }
+      else
+      {
+        Touch(value);
+      }
+    }
+
+  public:
+    Item(MetricsType type) :
+    type_(type),
+    hasValue_(false)
+    {
+    }
+
+    MetricsType GetType() const
+    {
+      return type_;
+    }
+
+    void Update(float value)
+    {
+      switch (type_)
+      {
+        case MetricsType_Default:
+          Touch(value);
+          break;
+          
+        case MetricsType_MaxOver10Seconds:
+          UpdateMax(value, 10);
+          break;
+
+        case MetricsType_MaxOver1Minute:
+          UpdateMax(value, 60);
+          break;
+
+        case MetricsType_MinOver10Seconds:
+          UpdateMin(value, 10);
+          break;
+
+        case MetricsType_MinOver1Minute:
+          UpdateMin(value, 60);
+          break;
+
+        default:
+          throw OrthancException(ErrorCode_NotImplemented);
+      }
+    }
+
+    bool HasValue() const
+    {
+      return hasValue_;
+    }
+
+    const boost::posix_time::ptime& GetTime() const
+    {
+      if (hasValue_)
+      {
+        return time_;
+      }
+      else
+      {
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
+      }
+    }
+
+    float GetValue() const
+    {
+      if (hasValue_)
+      {
+        return value_;
+      }
+      else
+      {
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
+      }
+    }
+  };
+
+
+  MetricsRegistry::~MetricsRegistry()
+  {
+    for (Content::iterator it = content_.begin(); it != content_.end(); ++it)
+    {
+      assert(it->second != NULL);
+      delete it->second;
+    }
+  }
+
+
+  void MetricsRegistry::SetEnabled(bool enabled)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+    enabled_ = enabled;
+  }
+
+
+  void MetricsRegistry::Register(const std::string& name,
+                                 MetricsType type)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+
+    Content::iterator found = content_.find(name);
+
+    if (found == content_.end())
+    {
+      content_[name] = new Item(type);
+    }
+    else
+    {
+      assert(found->second != NULL);
+
+      // This metrics already exists: Only recreate it if there is a
+      // mismatch in the type of metrics
+      if (found->second->GetType() != type)
+      {
+        delete found->second;
+        found->second = new Item(type);
+      }
+    }    
+  }
+
+
+  void MetricsRegistry::SetValueInternal(const std::string& name,
+                                         float value,
+                                         MetricsType type)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+
+    Content::iterator found = content_.find(name);
+
+    if (found == content_.end())
+    {
+      std::auto_ptr<Item> item(new Item(type));
+      item->Update(value);
+      content_[name] = item.release();
+    }
+    else
+    {
+      assert(found->second != NULL);
+      found->second->Update(value);
+    }
+  }
+
+
+  MetricsType MetricsRegistry::GetMetricsType(const std::string& name)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+
+    Content::const_iterator found = content_.find(name);
+
+    if (found == content_.end())
+    {
+      throw OrthancException(ErrorCode_InexistentItem);
+    }
+    else
+    {
+      assert(found->second != NULL);
+      return found->second->GetType();
+    }
+  }
+
+
+  void MetricsRegistry::ExportPrometheusText(std::string& s)
+  {
+    // https://www.boost.org/doc/libs/1_69_0/doc/html/date_time/examples.html#date_time.examples.seconds_since_epoch
+    static const boost::posix_time::ptime EPOCH(boost::gregorian::date(1970, 1, 1));
+
+    boost::mutex::scoped_lock lock(mutex_);
+
+    s.clear();
+
+    if (!enabled_)
+    {
+      return;
+    }
+
+    ChunkedBuffer buffer;
+
+    for (Content::const_iterator it = content_.begin();
+         it != content_.end(); ++it)
+    {
+      assert(it->second != NULL);
+
+      if (it->second->HasValue())
+      {
+        boost::posix_time::time_duration diff = it->second->GetTime() - EPOCH;
+
+        std::string line = (it->first + " " +
+                            boost::lexical_cast<std::string>(it->second->GetValue()) + " " + 
+                            boost::lexical_cast<std::string>(diff.total_milliseconds()) + "\n");
+
+        buffer.AddChunk(line);
+      }
+    }
+
+    buffer.Flatten(s);
+  }
+
+
+  void  MetricsRegistry::Timer::Start()
+  {
+    if (registry_.IsEnabled())
+    {
+      active_ = true;
+      start_ = GetNow();
+    }
+    else
+    {
+      active_ = false;
+    }
+  }
+
+
+  MetricsRegistry::Timer::~Timer()
+  {
+    if (active_)
+    {   
+      boost::posix_time::time_duration diff = GetNow() - start_;
+      registry_.SetValue(name_, diff.total_milliseconds(), type_);
+    }
+  }
+}