From ea2a2846790f2482f2127822bdfa2064df3cbed8 Mon Sep 17 00:00:00 2001
From: Adam Wegrzynek <adam.wegrzynek@cern.ch>
Date: Thu, 9 May 2019 15:03:50 +0200
Subject: [PATCH] Unique values in the buffer

---
 README.md                       |  6 ++++++
 include/Monitoring/Monitoring.h |  7 +++++++
 src/Monitoring.cxx              | 20 +++++++++++++++++++-
 test/testMonitoring.cxx         | 15 +++++++++++++++
 4 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 124287ee5..c464f53bd 100644
--- a/README.md
+++ b/README.md
@@ -124,6 +124,12 @@ monitoring->flushBuffer();
 
 See how it works in the example: [examples/10-Buffering.cxx](examples/10-Buffering.cxx).
 
+### Unique metric buffering
+In addition to above, you may want to keep only unique metrics (defined by metric name) within the buffer (only the last metric is kept).
+```cpp
+monitoring->enableUniqueBuffering(const std::size_t maxSize)
+```
+
 ### Calculating derived metrics
 The module can calculate derived metrics. To do so, use optional `DerivedMetricMode mode` parameter of `send` method:
 ```
diff --git a/include/Monitoring/Monitoring.h b/include/Monitoring/Monitoring.h
index 7aed192b0..d9b8eb569 100644
--- a/include/Monitoring/Monitoring.h
+++ b/include/Monitoring/Monitoring.h
@@ -82,6 +82,10 @@ class Monitoring
     /// Flushes metric buffer (this can also happen when buffer is full)
     void flushBuffer();
 
+    /// Enables unique metric buffering
+    /// There might be only unique metric name within a buffer
+    void enableUniqueBuffering(const std::size_t size = 128);
+
     /// Enables metric buffering
     /// \param size 		buffer size
     void enableBuffering(const std::size_t size = 128);
@@ -137,6 +141,9 @@ class Monitoring
     /// Metric buffer
     std::unordered_map<std::underlying_type<Verbosity>::type, std::vector<Metric>> mStorage;
 
+    /// Flag that states whether unique buffering is enabled
+    bool mUniqueBuffering;
+
     /// Flag stating whether metric buffering is enabled
     bool mBuffering;
 
diff --git a/src/Monitoring.cxx b/src/Monitoring.cxx
index 9d9facb9d..6f9af1c7f 100644
--- a/src/Monitoring.cxx
+++ b/src/Monitoring.cxx
@@ -37,12 +37,19 @@ Monitoring::Monitoring()
 {
   mProcessMonitor = std::make_unique<ProcessMonitor>();
   mDerivedHandler = std::make_unique<DerivedMetrics>();
+  mUniqueBuffering = false;
   mBuffering = false;
   mProcessMonitoringInterval = 0;
   mAutoPushInterval = 0;
   mMonitorRunning = false;
 }
 
+void Monitoring::enableUniqueBuffering(const std::size_t size)
+{
+  mUniqueBuffering = true;
+  enableBuffering(size);
+}
+
 void Monitoring::enableBuffering(const std::size_t size)
 {
   mBufferSize = size;
@@ -182,7 +189,18 @@ void Monitoring::transmit(Metric&& metric)
 {
   if (mBuffering) {
     auto index = static_cast<std::underlying_type<Verbosity>::type>(metric.getVerbosity());
-    mStorage[index].push_back(std::move(metric));
+    if (mUniqueBuffering) {
+      auto find = std::find_if(mStorage[index].begin(), mStorage[index].end(), [&metric](Metric const& m) {
+        return m.getName() == metric.getName();
+      });
+      if (find == std::end(mStorage[index])) {
+        mStorage[index].push_back(std::move(metric));
+      } else {
+        std::swap(*find, metric);
+      }
+    } else {
+      mStorage[index].push_back(std::move(metric));
+    }
     if (mStorage[index].size() >= mBufferSize) {
       flushBuffer(index);
     }
diff --git a/test/testMonitoring.cxx b/test/testMonitoring.cxx
index 998a16c6b..e99a6e3e4 100644
--- a/test/testMonitoring.cxx
+++ b/test/testMonitoring.cxx
@@ -68,6 +68,21 @@ BOOST_AUTO_TEST_CASE(testSymbols)
   BOOST_WARN_MESSAGE(BOOST_IS_DEFINED( O2_MONITORING_OS_MAC ), "Mac OS detected");
 }
 
+BOOST_AUTO_TEST_CASE(uniqueBuffering)
+{
+  auto monitoring = Monitoring::Get("stdout://");
+  monitoring->enableUniqueBuffering(4);
+  monitoring->send({10, "myMetricIntUnique"});
+  monitoring->send({11, "myMetricInt"});
+  monitoring->send({12, "myMetricInt"});
+  monitoring->send({13, "myMetricIntAnother"});
+  monitoring->send({14, "myMetricInt"});
+  monitoring->send({15, "myMetricInt"});
+  monitoring->send({16, "myMetricInt"});
+  monitoring->send({17, "myMetricIntFlush"});
+  monitoring->send({18, "myMetricInt"});
+}
+
 } // namespace Test
 } // namespace monitoring
 } // namespace o2