From 435b54ebbef5bb9a907dd11998a9babdc9421c4b Mon Sep 17 00:00:00 2001
From: "Alexander A. Klimov" <alexander.klimov@icinga.com>
Date: Tue, 18 Feb 2020 17:27:07 +0100
Subject: [PATCH] Initialize Configuration#Concurrency from
 /sys/fs/cgroup/cpuset/cpuset.cpus

refs #7842
---
 icinga-app/icinga.cpp      |  2 +-
 lib/base/configuration.cpp | 78 ++++++++++++++++++++++++++++++++++++++
 lib/base/configuration.hpp |  1 +
 3 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/icinga-app/icinga.cpp b/icinga-app/icinga.cpp
index 1811c8e07..05b121054 100644
--- a/icinga-app/icinga.cpp
+++ b/icinga-app/icinga.cpp
@@ -440,7 +440,7 @@ static int Main()
 	Configuration::SetReadOnly(true);
 
 	if (!Configuration::ConcurrencyWasModified) {
-		Configuration::Concurrency = std::thread::hardware_concurrency();
+		Configuration::Concurrency = Configuration::GetDefaultConcurrency();
 	}
 
 	Application::GetTP().Restart();
diff --git a/lib/base/configuration.cpp b/lib/base/configuration.cpp
index 908c16183..37b2f4569 100644
--- a/lib/base/configuration.cpp
+++ b/lib/base/configuration.cpp
@@ -3,6 +3,21 @@
 #include "base/configuration.hpp"
 #include "base/configuration-ti.cpp"
 #include "base/exception.hpp"
+#include <boost/algorithm/string.hpp>
+#include <boost/asio.hpp>
+#include <boost/lexical_cast.hpp>
+#include <boost/system/error_code.hpp>
+#include <boost/system/system_error.hpp>
+#include <cstdint>
+#include <iostream>
+#include <set>
+#include <string>
+#include <vector>
+
+#ifdef __linux__
+#	include <fcntl.h>
+#	include <sys/errno.h>
+#endif /* __linux__ */
 
 using namespace icinga;
 
@@ -27,6 +42,69 @@ bool Configuration::AttachDebugger{false};
 String Configuration::CacheDir;
 int Configuration::Concurrency{1};
 bool Configuration::ConcurrencyWasModified{false};
+
+int Configuration::GetDefaultConcurrency()
+{
+#ifdef __linux__
+	{
+		using namespace boost::algorithm;
+		using namespace boost::asio;
+		using namespace boost::system;
+
+		int f = open("/sys/fs/cgroup/cpuset/cpuset.cpus", O_RDONLY);
+
+		if (f < 0) {
+			if (errno != ENOENT) {
+				throw system_error(error_code(errno, system_category()));
+			}
+		} else {
+			std::string rawCpus;
+
+			{
+				io_context io;
+				buffered_read_stream<posix::stream_descriptor> stream (io);
+
+				stream.next_layer() = posix::stream_descriptor(io, f);
+
+				try {
+					read(stream, dynamic_buffer(rawCpus));
+				} catch (const system_error& se) {
+					if (se.code() != error::make_error_code(error::eof)) {
+						throw;
+					}
+				}
+			}
+
+			rawCpus.erase(rawCpus.find_last_not_of('\n') + 1u);
+
+			std::vector<std::string> ranges;
+			boost::split(ranges, rawCpus, is_any_of(","));
+
+			std::set<uintmax_t> cpus;
+
+			for (auto& range : ranges) {
+				std::vector<std::string> rangeEnds;
+				boost::split(rangeEnds, range, is_any_of("-"));
+
+				if (rangeEnds.size() > 1u) {
+					auto to (boost::lexical_cast<uintmax_t>(rangeEnds.at(1)));
+
+					for (auto i (boost::lexical_cast<uintmax_t>(rangeEnds.at(0))); i <= to; ++i) {
+						cpus.emplace(i);
+					}
+				} else {
+					cpus.emplace(boost::lexical_cast<uintmax_t>(rangeEnds.at(0)));
+				}
+			}
+
+			return cpus.size();
+		}
+	}
+#endif /* __linux__ */
+
+	return std::thread::hardware_concurrency();
+}
+
 String Configuration::ConfigDir;
 String Configuration::DataDir;
 String Configuration::EventEngine;
diff --git a/lib/base/configuration.hpp b/lib/base/configuration.hpp
index a5aed01e8..de1280615 100644
--- a/lib/base/configuration.hpp
+++ b/lib/base/configuration.hpp
@@ -32,6 +32,7 @@ public:
 	void SetCacheDir(const String& value, bool suppress_events = false, const Value& cookie = Empty) override;
 
 	int GetConcurrency() const override;
+	static int GetDefaultConcurrency();
 	void SetConcurrency(int value, bool suppress_events = false, const Value& cookie = Empty) override;
 
 	String GetConfigDir() const override;