From 9ee09fed2fcd57093fc83dc8e53301270e7227c9 Mon Sep 17 00:00:00 2001
From: "kosak@google.com"
 <kosak@google.com@861a406c-534a-0410-8894-cb66d6ee9925>
Date: Fri, 17 Jul 2015 22:53:00 +0000
Subject: Implement GetThreadCount for Linux.

git-svn-id: http://googletest.googlecode.com/svn/trunk@726 861a406c-534a-0410-8894-cb66d6ee9925
---
 src/gtest-port.cc       | 30 ++++++++++++++++++++++++++----
 test/gtest-port_test.cc | 49 +++++++++++++++++++++----------------------------
 2 files changed, 47 insertions(+), 32 deletions(-)

diff --git a/src/gtest-port.cc b/src/gtest-port.cc
index 448a807..19fa028 100644
--- a/src/gtest-port.cc
+++ b/src/gtest-port.cc
@@ -35,6 +35,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <fstream>
 
 #if GTEST_OS_WINDOWS
 # include <windows.h>
@@ -83,10 +84,31 @@ const int kStdOutFileno = STDOUT_FILENO;
 const int kStdErrFileno = STDERR_FILENO;
 #endif  // _MSC_VER
 
-#if GTEST_OS_MAC
+#if GTEST_OS_LINUX
+
+namespace {
+template <typename T>
+T ReadProcFileField(const string& filename, int field) {
+  std::string dummy;
+  std::ifstream file(filename.c_str());
+  while (field-- > 0) {
+    file >> dummy;
+  }
+  T output = 0;
+  file >> output;
+  return output;
+}
+}  // namespace
+
+// Returns the number of active threads, or 0 when there is an error.
+size_t GetThreadCount() {
+  const string filename =
+      (Message() << "/proc/" << getpid() << "/stat").GetString();
+  return ReadProcFileField<int>(filename, 19);
+}
+
+#elif GTEST_OS_MAC
 
-// Returns the number of threads running in the process, or 0 to indicate that
-// we cannot detect it.
 size_t GetThreadCount() {
   const task_t task = mach_task_self();
   mach_msg_type_number_t thread_count;
@@ -132,7 +154,7 @@ size_t GetThreadCount() {
   return 0;
 }
 
-#endif  // GTEST_OS_MAC
+#endif  // GTEST_OS_LINUX
 
 #if GTEST_IS_THREADSAFE && GTEST_OS_WINDOWS
 
diff --git a/test/gtest-port_test.cc b/test/gtest-port_test.cc
index c904f1e..7647859 100644
--- a/test/gtest-port_test.cc
+++ b/test/gtest-port_test.cc
@@ -304,58 +304,51 @@ TEST(FormatCompilerIndependentFileLocationTest, FormatsUknownFileAndLine) {
   EXPECT_EQ("unknown file", FormatCompilerIndependentFileLocation(NULL, -1));
 }
 
-#if GTEST_OS_MAC || GTEST_OS_QNX
+#if GTEST_OS_LINUX || GTEST_OS_MAC || GTEST_OS_QNX
 void* ThreadFunc(void* data) {
-  pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data);
-  pthread_mutex_lock(mutex);
-  pthread_mutex_unlock(mutex);
+  internal::Mutex* mutex = static_cast<internal::Mutex*>(data);
+  mutex->Lock();
+  mutex->Unlock();
   return NULL;
 }
 
 TEST(GetThreadCountTest, ReturnsCorrectValue) {
-  EXPECT_EQ(1U, GetThreadCount());
-  pthread_mutex_t mutex;
-  pthread_attr_t  attr;
+  const size_t starting_count = GetThreadCount();
   pthread_t       thread_id;
 
-  // TODO(vladl@google.com): turn mutex into internal::Mutex for automatic
-  // destruction.
-  pthread_mutex_init(&mutex, NULL);
-  pthread_mutex_lock(&mutex);
-  ASSERT_EQ(0, pthread_attr_init(&attr));
-  ASSERT_EQ(0, pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE));
-
-  const int status = pthread_create(&thread_id, &attr, &ThreadFunc, &mutex);
-  ASSERT_EQ(0, pthread_attr_destroy(&attr));
-  ASSERT_EQ(0, status);
-  EXPECT_EQ(2U, GetThreadCount());
-  pthread_mutex_unlock(&mutex);
+  internal::Mutex mutex;
+  {
+    internal::MutexLock lock(&mutex);
+    pthread_attr_t  attr;
+    ASSERT_EQ(0, pthread_attr_init(&attr));
+    ASSERT_EQ(0, pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE));
+
+    const int status = pthread_create(&thread_id, &attr, &ThreadFunc, &mutex);
+    ASSERT_EQ(0, pthread_attr_destroy(&attr));
+    ASSERT_EQ(0, status);
+    EXPECT_EQ(starting_count + 1, GetThreadCount());
+  }
 
   void* dummy;
   ASSERT_EQ(0, pthread_join(thread_id, &dummy));
 
-# if GTEST_OS_MAC
-
-  // MacOS X may not immediately report the updated thread count after
+  // The OS may not immediately report the updated thread count after
   // joining a thread, causing flakiness in this test. To counter that, we
   // wait for up to .5 seconds for the OS to report the correct value.
   for (int i = 0; i < 5; ++i) {
-    if (GetThreadCount() == 1)
+    if (GetThreadCount() == starting_count)
       break;
 
     SleepMilliseconds(100);
   }
 
-# endif  // GTEST_OS_MAC
-
-  EXPECT_EQ(1U, GetThreadCount());
-  pthread_mutex_destroy(&mutex);
+  EXPECT_EQ(starting_count, GetThreadCount());
 }
 #else
 TEST(GetThreadCountTest, ReturnsZeroWhenUnableToCountThreads) {
   EXPECT_EQ(0U, GetThreadCount());
 }
-#endif  // GTEST_OS_MAC || GTEST_OS_QNX
+#endif  // GTEST_OS_LINUX || GTEST_OS_MAC || GTEST_OS_QNX
 
 TEST(GtestCheckDeathTest, DiesWithCorrectOutputOnFailure) {
   const bool a_false_condition = false;
-- 
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