From 7361b79da6f611478428ebac022ad41a22414c85 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Sun, 5 Feb 2023 00:44:21 +0100
Subject: Added number_of_threads()

---
 debian/changelog       |  6 ++++++
 process.cpp            | 43 ++++++++++++++++++++++++++++++++++---------
 process.h              |  2 ++
 tests/test-process.cpp | 12 +++++++++++-
 4 files changed, 53 insertions(+), 10 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index 2f91dac..8f473aa 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+libreichwein (1.4~pre1) UNRELEASED; urgency=medium
+
+  * Added number_of_threads()
+
+ -- Roland Reichwein <mail@reichwein.it>  Sun, 05 Feb 2023 00:25:04 +0100
+
 libreichwein (1.3) unstable; urgency=medium
 
   * Fixed upload in Makefile
diff --git a/process.cpp b/process.cpp
index 67cf1ce..c504330 100644
--- a/process.cpp
+++ b/process.cpp
@@ -16,23 +16,48 @@ namespace fs = std::filesystem;
 
 bool Reichwein::Process::is_running(pid_t pid)
 {
-  fs::path pid_file{"/proc/" + std::to_string(pid) + "/stat"};
-  if (!fs::exists(pid_file))
-   return false;
+ // 3rd position is status for pid
+ fs::path pid_file{"/proc/" + std::to_string(pid) + "/stat"};
+ if (!fs::exists(pid_file))
+  return false;
 
-  std::string s{Reichwein::File::getFile(pid_file)};
+ std::string s{Reichwein::File::getFile(pid_file)};
 
-  auto pos0{s.find(' ', 0)};
+ auto pos0{s.find(' ', 0)};
+ pos0 = s.find(' ', pos0 + 1);
+ pos0++;
+
+ auto pos1{s.find(' ', pos0 + 1)};
+
+ std::string state{s.substr(pos0, pos1 - pos0)};
+
+ return state == "R" || state == "S";
+}
+
+int Reichwein::Process::number_of_threads(pid_t pid)
+{
+ // 20th position is the number of threads for pid
+ fs::path pid_file{"/proc/" + std::to_string(pid) + "/stat"};
+ if (!fs::exists(pid_file))
+  return false;
+
+ std::string s{Reichwein::File::getFile(pid_file)};
+
+ size_t pos0{};
+ for (int i = 0; i < 19; i++) {
   pos0 = s.find(' ', pos0 + 1);
-  pos0++;
+  if (pos0 == std::string::npos)
+   throw std::runtime_error("Bad format in /proc/" + std::to_string(pid) + "/stat");
+ }
 
-  auto pos1{s.find(' ', pos0 + 1)};
+ size_t pos1{s.find(' ', pos0 + 1)};
 
-  std::string state{s.substr(pos0, pos1 - pos0)};
+ std::string number_of_threads_s{s.substr(pos0, pos1 - pos0)};
 
-  return state == "R" || state == "S";
+ return std::stoi(number_of_threads_s);
 }
 
+
 // tcp: tcp or tcp6
 bool Reichwein::Process::tcp_is_pid_listening_on(const std::string& tcp, pid_t pid, int port)
 {
diff --git a/process.h b/process.h
index fb24017..b01778c 100644
--- a/process.h
+++ b/process.h
@@ -10,6 +10,8 @@ namespace Reichwein::Process {
 
 EXPORT bool is_running(pid_t pid);
 
+EXPORT int number_of_threads(pid_t pid);
+
 EXPORT bool unix_is_pid_listening_on(pid_t pid, const std::string& path);
 EXPORT void wait_for_pid_listening_on(pid_t pid, const std::string& path);
 
diff --git a/tests/test-process.cpp b/tests/test-process.cpp
index dfee83f..9855546 100644
--- a/tests/test-process.cpp
+++ b/tests/test-process.cpp
@@ -1,5 +1,7 @@
 #include <gtest/gtest.h>
 
+#include <thread>
+
 #include "process.h"
 
 #include <unistd.h>
@@ -23,7 +25,7 @@ protected:
 
 };
 
-TEST_F(ProcessTest,is_running) {
+TEST_F(ProcessTest, is_running) {
  auto pid{::getpid()};
 
  EXPECT_NE(pid, -1);
@@ -32,3 +34,11 @@ TEST_F(ProcessTest,is_running) {
 
  EXPECT_EQ(Reichwein::Process::is_running(999999999), false);
 }
+
+TEST_F(ProcessTest, number_of_threads) {
+ EXPECT_EQ(Reichwein::Process::number_of_threads(::getpid()), 1);
+ std::thread t1{[](){std::this_thread::sleep_for(std::chrono::milliseconds(50));}};
+ EXPECT_EQ(Reichwein::Process::number_of_threads(::getpid()), 2);
+ t1.join();
+ EXPECT_EQ(Reichwein::Process::number_of_threads(::getpid()), 1);
+}
-- 
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