From ff305e63b6ae7c20a3b423c5d7ca00816ff4db02 Mon Sep 17 00:00:00 2001
From: Vinnie Falco <vinnie.falco@gmail.com>
Date: Fri, 4 Oct 2013 10:56:19 -0700
Subject: [PATCH] Add CPUMeter and ScopedTimeInterval

---
 Builds/VisualStudio2012/beast.vcxproj         |   5 +-
 Builds/VisualStudio2012/beast.vcxproj.filters |  15 +-
 beast/Chrono.h                                |   3 +-
 beast/chrono/CPUMeter.h                       | 159 ++++++++++++++++++
 beast/chrono/Chrono.cpp                       |   2 +-
 .../{CPUUsage.h => ScopedTimeInterval.h}      |  38 +++--
 .../impl/{CPUUsage.cpp => CPUMeter.cpp}       |   2 +-
 7 files changed, 203 insertions(+), 21 deletions(-)
 create mode 100644 beast/chrono/CPUMeter.h
 rename beast/chrono/{CPUUsage.h => ScopedTimeInterval.h} (56%)
 rename beast/chrono/impl/{CPUUsage.cpp => CPUMeter.cpp} (97%)

diff --git a/Builds/VisualStudio2012/beast.vcxproj b/Builds/VisualStudio2012/beast.vcxproj
index e4b8bfebf..657a854f9 100644
--- a/Builds/VisualStudio2012/beast.vcxproj
+++ b/Builds/VisualStudio2012/beast.vcxproj
@@ -84,8 +84,9 @@
     <ClInclude Include="..\..\beast\Arithmetic.h" />
     <ClInclude Include="..\..\beast\Atomic.h" />
     <ClInclude Include="..\..\beast\ByteOrder.h" />
-    <ClInclude Include="..\..\beast\chrono\CPUUsage.h" />
+    <ClInclude Include="..\..\beast\chrono\CPUMeter.h" />
     <ClInclude Include="..\..\beast\chrono\RelativeTime.h" />
+    <ClInclude Include="..\..\beast\chrono\ScopedTimeInterval.h" />
     <ClInclude Include="..\..\beast\Config.h" />
     <ClInclude Include="..\..\beast\config\CompilerConfig.h" />
     <ClInclude Include="..\..\beast\config\compiler\Clang.h" />
@@ -398,7 +399,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\beast\chrono\Chrono.cpp" />
-    <ClCompile Include="..\..\beast\chrono\impl\CPUUsage.cpp">
+    <ClCompile Include="..\..\beast\chrono\impl\CPUMeter.cpp">
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">true</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">true</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">true</ExcludedFromBuild>
diff --git a/Builds/VisualStudio2012/beast.vcxproj.filters b/Builds/VisualStudio2012/beast.vcxproj.filters
index cfc1e9cca..6d8a46ed8 100644
--- a/Builds/VisualStudio2012/beast.vcxproj.filters
+++ b/Builds/VisualStudio2012/beast.vcxproj.filters
@@ -1224,9 +1224,6 @@
     <ClInclude Include="..\..\modules\beast_asio\http\HTTPResponseParser.h">
       <Filter>beast_asio\http</Filter>
     </ClInclude>
-    <ClInclude Include="..\..\beast\chrono\CPUUsage.h">
-      <Filter>beast\chrono</Filter>
-    </ClInclude>
     <ClInclude Include="..\..\beast\thread\RecursiveMutex.h">
       <Filter>beast\thread</Filter>
     </ClInclude>
@@ -1236,6 +1233,12 @@
     <ClInclude Include="..\..\beast\thread\TryLockGuard.h">
       <Filter>beast\thread</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\beast\chrono\ScopedTimeInterval.h">
+      <Filter>beast\chrono</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\beast\chrono\CPUMeter.h">
+      <Filter>beast\chrono</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\modules\beast_core\containers\AbstractFifo.cpp">
@@ -1775,15 +1778,15 @@
     <ClCompile Include="..\..\modules\beast_asio\http\HTTPResponseParser.cpp">
       <Filter>beast_asio\http</Filter>
     </ClCompile>
-    <ClCompile Include="..\..\beast\chrono\impl\CPUUsage.cpp">
-      <Filter>beast\chrono\impl</Filter>
-    </ClCompile>
     <ClCompile Include="..\..\beast\thread\impl\RecursiveMutex.cpp">
       <Filter>beast\thread\impl</Filter>
     </ClCompile>
     <ClCompile Include="..\..\beast\thread\Thread.cpp">
       <Filter>beast\thread</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\beast\chrono\impl\CPUMeter.cpp">
+      <Filter>beast\chrono\impl</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <Text Include="..\..\TODO.txt">
diff --git a/beast/Chrono.h b/beast/Chrono.h
index 728baa1f8..027b1f5f3 100644
--- a/beast/Chrono.h
+++ b/beast/Chrono.h
@@ -20,7 +20,8 @@
 #ifndef BEAST_CHRONO_H_INCLUDED
 #define BEAST_CHRONO_H_INCLUDED
 
-#include "chrono/CPUUsage.h"
+#include "chrono/CPUMeter.h"
 #include "chrono/RelativeTime.h"
+#include "chrono/ScopedTimeInterval.h"
 
 #endif
diff --git a/beast/chrono/CPUMeter.h b/beast/chrono/CPUMeter.h
new file mode 100644
index 000000000..8a02b591c
--- /dev/null
+++ b/beast/chrono/CPUMeter.h
@@ -0,0 +1,159 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of Beast: https://github.com/vinniefalco/Beast
+    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef BEAST_CHRONO_CPUMETER_H_INCLUDED
+#define BEAST_CHRONO_CPUMETER_H_INCLUDED
+
+#include "RelativeTime.h"
+#include "SCopedTimeInterval.h"
+#include "../thread/SharedData.h"
+#include "../Atomic.h"
+
+namespace beast {
+
+/** Measurements of CPU utilization. */
+class CPUMeter
+{
+private:
+    struct MeasureIdle
+    {
+        explicit MeasureIdle (CPUMeter& meter)
+            : m_meter (&meter)
+            { }
+        void operator() (RelativeTime const& interval) const
+            { m_meter->addIdleTime (interval); }
+        CPUMeter* m_meter;
+    };
+
+    struct MeasureActive
+    {
+        explicit MeasureActive (CPUMeter& meter)
+            : m_meter (&meter)
+            { }
+        void operator() (RelativeTime const& interval) const
+            { m_meter->addActiveTime (interval); }
+        CPUMeter* m_meter;
+    };
+
+public:
+    /** The type of container that measures idle time. */
+    typedef ScopedTimeInterval <MeasureIdle>    ScopedIdleTime;
+    typedef ScopedTimeInterval <MeasureActive>  ScopedActiveTime;
+
+    /** Returns the fraction of time that the CPU is being used. */
+    double getCpuUsage () const
+    {
+        SharedState::ConstAccess state (m_state);
+        double const seconds (state->usage.seconds());
+        if (seconds > 0)
+            return (state->usage.active.inSeconds() / seconds);
+        return 0;
+    }
+
+private:
+    enum
+    {
+        // The amount of time an aggregate must accrue before a swap
+        secondsPerAggregate     = 3
+
+        // The number of aggregates in the rolling history buffer
+        ,numberOfAggregates     = 20
+    };
+
+    // Aggregated sample data
+    struct Aggregate
+    {
+        RelativeTime idle;
+        RelativeTime active;
+
+        // Returns the total number of seconds in the aggregate
+        double seconds () const
+            { return idle.inSeconds() + active.inSeconds(); }
+
+        // Reset the accumulated times
+        void clear ()
+            { idle = RelativeTime (0); active = RelativeTime (0); }
+
+        Aggregate& operator+= (Aggregate const& other)
+            { idle += other.idle; active += other.active; return *this; }
+
+        Aggregate& operator-= (Aggregate const& other)
+            { idle -= other.idle; active -= other.active; return *this; }
+    };
+
+    struct State
+    {
+        State () : index (0)
+        {
+        }
+
+        // Returns a reference to the current aggregate
+        Aggregate& front ()
+        {
+            return history [index];
+        }
+
+        // Checks the current aggregate to see if we should advance
+        void update()
+        {
+            if (front().seconds() >= secondsPerAggregate)
+                advance();
+        }
+
+        // Advance the index in the rolling history
+        void advance ()
+        {
+            usage += history [index];
+            index = (++index) % numberOfAggregates;
+            usage -= history [index];
+            history [index].clear ();
+        }
+
+        // Index of the current aggregate we are accumulating
+        int index;
+
+        // Delta summed usage over the entire history buffer
+        Aggregate usage;
+
+        // The rolling history buffer
+        Aggregate history [numberOfAggregates];
+    };
+
+    typedef SharedData <State> SharedState;
+
+    SharedState m_state;
+
+    void addIdleTime (RelativeTime const& interval)
+    {
+        SharedState::Access state (m_state);
+        state->front().idle += interval;
+        state->update();
+    }
+
+    void addActiveTime (RelativeTime const& interval)
+    {
+        SharedState::Access state (m_state);
+        state->front().active += interval;
+        state->update();
+    }
+};
+
+}
+
+#endif
diff --git a/beast/chrono/Chrono.cpp b/beast/chrono/Chrono.cpp
index a3030761f..5ce5772e6 100644
--- a/beast/chrono/Chrono.cpp
+++ b/beast/chrono/Chrono.cpp
@@ -19,5 +19,5 @@
 
 #include "BeastConfig.h"
 
-#include "impl/CPUUsage.cpp"
+#include "impl/CPUMeter.cpp"
 #include "impl/RelativeTime.cpp"
diff --git a/beast/chrono/CPUUsage.h b/beast/chrono/ScopedTimeInterval.h
similarity index 56%
rename from beast/chrono/CPUUsage.h
rename to beast/chrono/ScopedTimeInterval.h
index 049c779ed..af3672870 100644
--- a/beast/chrono/CPUUsage.h
+++ b/beast/chrono/ScopedTimeInterval.h
@@ -17,27 +17,45 @@
 */
 //==============================================================================
 
-#ifndef BEAST_CHRONO_CPUUSAGE_H_INCLUDED
-#define BEAST_CHRONO_CPUUSAGE_H_INCLUDED
+#ifndef BEAST_CHRONO_SCOPEDTIMEINTERVAL_H_INCLUDED
+#define BEAST_CHRONO_SCOPEDTIMEINTERVAL_H_INCLUDED
 
+#include "../Uncopyable.h"
 #include "RelativeTime.h"
 
 namespace beast {
 
-/** Measurements of CPU utilization. */
-
-#if 0
-/** Scoped lifetime measurement. */
-class ScopedTimeInterval
+/** Time measurement using scoped RAII container. 
+    UnaryFunction will be called with this signature:
+        void (RelativeTime const& interval);
+*/
+template <class UnaryFunction>
+class ScopedTimeInterval : public Uncopyable
 {
 public:
-    ScopedTimeInterval ();
-    ~ScopedTimeInterval ();
+    /** Create the measurement with a default-constructed UnaryFunction. */
+    ScopedTimeInterval ()
+        : m_start (RelativeTime::fromStartup())
+    {
+    }
+
+    /** Create the measurement with UnaryFunction constructed from one argument. */
+    template <typename Arg>
+    explicit ScopedTimeInterval (Arg arg)
+        : m_func (arg)
+        , m_start (RelativeTime::fromStartup ())
+    {
+    }
+
+    ~ScopedTimeInterval ()
+    {
+        m_func (RelativeTime::fromStartup() - m_start);
+    }
 
 private:
+    UnaryFunction m_func;
     RelativeTime m_start;
 };
-#endif
 
 }
 
diff --git a/beast/chrono/impl/CPUUsage.cpp b/beast/chrono/impl/CPUMeter.cpp
similarity index 97%
rename from beast/chrono/impl/CPUUsage.cpp
rename to beast/chrono/impl/CPUMeter.cpp
index a27bcd4e0..b5a67f4d1 100644
--- a/beast/chrono/impl/CPUUsage.cpp
+++ b/beast/chrono/impl/CPUMeter.cpp
@@ -17,5 +17,5 @@
 */
 //==============================================================================
 
-#include "../CPUUsage.h"
+#include "../CPUMeter.h"