From 9386a58bf2f9537fcaa527308727b8cb4cc59a4c Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gunnar.beutner@netways.de>
Date: Sun, 16 Nov 2014 13:14:42 +0100
Subject: [PATCH] Implement an experimental variable to limit the number of
 threads

---
 icinga-app/icinga.cpp    |  1 +
 lib/base/application.cpp | 22 ++++++++++++++++++++++
 lib/base/application.hpp |  3 +++
 lib/base/threadpool.cpp  |  3 ++-
 lib/base/workqueue.cpp   |  3 ++-
 5 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/icinga-app/icinga.cpp b/icinga-app/icinga.cpp
index 14925ec08..38525fc65 100644
--- a/icinga-app/icinga.cpp
+++ b/icinga-app/icinga.cpp
@@ -156,6 +156,7 @@ int Main(void)
 	Application::DeclareApplicationType("icinga/IcingaApplication");
 	Application::DeclareRunAsUser(ICINGA_USER);
 	Application::DeclareRunAsGroup(ICINGA_GROUP);
+	Application::DeclareConcurrency(boost::thread::hardware_concurrency());
 
 	LogSeverity logLevel = Logger::GetConsoleLogSeverity();
 	Logger::SetConsoleLogSeverity(LogWarning);
diff --git a/lib/base/application.cpp b/lib/base/application.cpp
index d5085bfd7..6e489d3ef 100644
--- a/lib/base/application.cpp
+++ b/lib/base/application.cpp
@@ -1093,6 +1093,7 @@ void Application::DeclareRunAsUser(const String& user)
 {
 	ScriptVariable::Set("RunAsUser", user, false);
 }
+
 /**
  * Retrieves the name of the group.
  *
@@ -1103,6 +1104,27 @@ String Application::GetRunAsGroup(void)
 	return ScriptVariable::Get("RunAsGroup");
 }
 
+/**
+ * Sets the concurrency level.
+ *
+ * @param path The new concurrency level.
+ */
+void Application::DeclareConcurrency(int ncpus)
+{
+	ScriptVariable::Set("Concurrency", ncpus, false);
+}
+
+/**
+ * Retrieves the concurrency level.
+ *
+ * @returns The concurrency level.
+ */
+int Application::GetConcurrency(void)
+{
+	Value defaultConcurrency = boost::thread::hardware_concurrency();
+	return ScriptVariable::Get("Concurrency", &defaultConcurrency);
+}
+
 /**
  * Sets the name of the group.
  *
diff --git a/lib/base/application.hpp b/lib/base/application.hpp
index 42db85696..be662297e 100644
--- a/lib/base/application.hpp
+++ b/lib/base/application.hpp
@@ -122,6 +122,9 @@ public:
 	static String GetRunAsGroup(void);
 	static void DeclareRunAsGroup(const String& group);
 
+	static int GetConcurrency(void);
+	static void DeclareConcurrency(int ncpus);
+
 	static void MakeVariablesConstant(void);
 
 	static ThreadPool& GetTP(void);
diff --git a/lib/base/threadpool.cpp b/lib/base/threadpool.cpp
index b9771c406..2b2682860 100644
--- a/lib/base/threadpool.cpp
+++ b/lib/base/threadpool.cpp
@@ -22,6 +22,7 @@
 #include "base/debug.hpp"
 #include "base/utility.hpp"
 #include "base/exception.hpp"
+#include "base/application.hpp"
 #include <boost/bind.hpp>
 #include <iostream>
 
@@ -260,7 +261,7 @@ void ThreadPool::ManagerThreadProc(void)
 				int tthreads = wthreads - alive;
 
 				/* Make sure there is at least one thread per CPU */
-				int ncput = std::max(boost::thread::hardware_concurrency() / QUEUECOUNT, 4U);
+				int ncput = std::max(static_cast<unsigned int>(Application::GetConcurrency()) / QUEUECOUNT, 4U);
 				if (alive + tthreads < ncput)
 					tthreads = ncput - alive;
 
diff --git a/lib/base/workqueue.cpp b/lib/base/workqueue.cpp
index 1d0256329..0450493b5 100644
--- a/lib/base/workqueue.cpp
+++ b/lib/base/workqueue.cpp
@@ -21,6 +21,7 @@
 #include "base/utility.hpp"
 #include "base/logger.hpp"
 #include "base/convert.hpp"
+#include "base/application.hpp"
 #include <boost/bind.hpp>
 #include <boost/foreach.hpp>
 
@@ -177,7 +178,7 @@ void WorkQueue::WorkerThreadProc(void)
 }
 
 ParallelWorkQueue::ParallelWorkQueue(void)
-	: m_QueueCount(boost::thread::hardware_concurrency()),
+	: m_QueueCount(Application::GetConcurrency()),
 	  m_Queues(new WorkQueue[m_QueueCount]),
 	  m_Index(0)
 { }