base/threading: restrict to set only current thread priority

base/threading/platform_thread_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-#if defined(OS_WIN)
+#if defined(OS_POSIX)
+#include <sys/types.h>
+#include <unistd.h>
+#elif defined(OS_WIN)
 #include <windows.h>
 #endif
 
 namespace base {
 
 // Trivial tests that thread runs and doesn't crash on create and join ---------
 
 class TrivialThread : public PlatformThread::Delegate {
  public:
   TrivialThread() : did_run_(false) {}
@@ skipping 141 matching lines @@
   for (size_t n = 0; n < arraysize(thread); n++)
     ASSERT_FALSE(thread[n].IsRunning());
 
   // Make sure that the thread ID is the same across calls.
   EXPECT_EQ(main_thread_id, PlatformThread::CurrentId());
 }
 
 namespace {
 
 const ThreadPriority kThreadPriorityTestValues[] = {
-// Disable non-normal priority toggling on POSIX as it appears to be broken
-// (http://crbug.com/468793). This is prefered to disabling the tests altogether
-// on POSIX as it at least provides coverage for running this code under
-// "normal" priority.
-#if !defined(OS_POSIX)
+// The order should be higher to lower to cover as much cases as possible on
+// Linux trybots running without CAP_SYS_NICE permission.
+#if !defined(OS_ANDROID)
+    // PlatformThread::GetCurrentThreadPriority() on Android does not support
+    // REALTIME_AUDIO case. See http://crbug.com/505474.
+    ThreadPriority::REALTIME_AUDIO,
+#endif
     ThreadPriority::DISPLAY,
-    ThreadPriority::REALTIME_AUDIO,
-    // Keep BACKGROUND second to last to test backgrounding from other
-    // priorities.
+    // This redundant BACKGROUND priority is to test backgrounding from other
+    // priorities, and unbackgrounding.
     ThreadPriority::BACKGROUND,
-#endif  // !defined(OS_POSIX)
-    // Keep NORMAL last to test unbackgrounding.
-    ThreadPriority::NORMAL
-};
+    ThreadPriority::NORMAL,
+    ThreadPriority::BACKGROUND};
+
+bool IsBumpingPriorityAllowed() {
+#if defined(OS_POSIX)
+  // Only root can raise thread priority on POSIX environment. On Linux, users
+  // who have CAP_SYS_NICE permission also can raise the thread priority, but
+  // libcap.so would be needed to check the capability.
+  return geteuid() == 0;
+#else
+  return true;
+#endif
+}
 
 }  // namespace
 
-// Test changing another thread's priority.
-// NOTE: This test is partially disabled on POSIX, see note above and
-// http://crbug.com/468793.
-TEST(PlatformThreadTest, ThreadPriorityOtherThread) {
-  PlatformThreadHandle current_handle(PlatformThread::CurrentHandle());
-
-  // Confirm that the current thread's priority is as expected.
-  EXPECT_EQ(ThreadPriority::NORMAL,
-            PlatformThread::GetThreadPriority(current_handle));
-
-  // Create a test thread.
-  FunctionTestThread thread;
-  PlatformThreadHandle handle;
-  ASSERT_TRUE(PlatformThread::Create(0, &thread, &handle));
-  thread.WaitForThreadStart();
-  EXPECT_NE(thread.thread_id(), kInvalidThreadId);
-  EXPECT_NE(thread.thread_id(), PlatformThread::CurrentId());
-
-  // New threads should get normal priority by default.
-  EXPECT_EQ(ThreadPriority::NORMAL, PlatformThread::GetThreadPriority(handle));
-
-  // Toggle each supported priority on the test thread and confirm it only
-  // affects it (and not the current thread).
-  for (size_t i = 0; i < arraysize(kThreadPriorityTestValues); ++i) {
-    SCOPED_TRACE(i);
-
-    // Alter and verify the test thread's priority.
-    PlatformThread::SetThreadPriority(handle, kThreadPriorityTestValues[i]);
-    EXPECT_EQ(kThreadPriorityTestValues[i],
-              PlatformThread::GetThreadPriority(handle));
-
-    // Make sure the current thread was otherwise unaffected.
-    EXPECT_EQ(ThreadPriority::NORMAL,
-              PlatformThread::GetThreadPriority(current_handle));
-  }
-
-  thread.MarkForTermination();
-  PlatformThread::Join(handle);
-}
+#if defined(OS_MACOSX)
+// PlatformThread::GetCurrentThreadPriority() is not implemented on OS X.
+#define MAYBE_ThreadPriorityCurrentThread DISABLED_ThreadPriorityCurrentThread
+#else
+#define MAYBE_ThreadPriorityCurrentThread ThreadPriorityCurrentThread
+#endif
 
 // Test changing the current thread's priority (which has different semantics on
 // some platforms).
-// NOTE: This test is partially disabled on POSIX, see note above and
-// http://crbug.com/468793.
-TEST(PlatformThreadTest, ThreadPriorityCurrentThread) {
-  PlatformThreadHandle current_handle(PlatformThread::CurrentHandle());
+TEST(PlatformThreadTest, MAYBE_ThreadPriorityCurrentThread) {
+  // Confirm that the current thread's priority is as expected.
+  EXPECT_EQ(ThreadPriority::NORMAL, PlatformThread::GetCurrentThreadPriority());
 
-  // Confirm that the current thread's priority is as expected.
-  EXPECT_EQ(ThreadPriority::NORMAL,
-            PlatformThread::GetThreadPriority(current_handle));
-
-  // Create a test thread for verification purposes only.
-  FunctionTestThread thread;
-  PlatformThreadHandle handle;
-  ASSERT_TRUE(PlatformThread::Create(0, &thread, &handle));
-  thread.WaitForThreadStart();
-  EXPECT_NE(thread.thread_id(), kInvalidThreadId);
-  EXPECT_NE(thread.thread_id(), PlatformThread::CurrentId());
-
-  // Confirm that the new thread's priority is as expected.
-  EXPECT_EQ(ThreadPriority::NORMAL, PlatformThread::GetThreadPriority(handle));
-
-  // Toggle each supported priority on the current thread and confirm it only
-  // affects it (and not the test thread).
+  // Toggle each supported priority on the current thread and confirm it
+  // affects it.
+  const bool bumping_priority_allowed = IsBumpingPriorityAllowed();
   for (size_t i = 0; i < arraysize(kThreadPriorityTestValues); ++i) {
     SCOPED_TRACE(i);
+    if (!bumping_priority_allowed &&
+        kThreadPriorityTestValues[i] >
+            PlatformThread::GetCurrentThreadPriority()) {
+      continue;
+    }
 
     // Alter and verify the current thread's priority.
-    PlatformThread::SetThreadPriority(current_handle,
-                                      kThreadPriorityTestValues[i]);
+    PlatformThread::SetCurrentThreadPriority(kThreadPriorityTestValues[i]);
     EXPECT_EQ(kThreadPriorityTestValues[i],
-              PlatformThread::GetThreadPriority(current_handle));
-
-    // Make sure the test thread was otherwise unaffected.
-    EXPECT_EQ(ThreadPriority::NORMAL,
-              PlatformThread::GetThreadPriority(handle));
+              PlatformThread::GetCurrentThreadPriority());
   }
 
   // Restore current thread priority for follow-up tests.
-  PlatformThread::SetThreadPriority(current_handle, ThreadPriority::NORMAL);
-
-  thread.MarkForTermination();
-  PlatformThread::Join(handle);
+  PlatformThread::SetCurrentThreadPriority(ThreadPriority::NORMAL);

[Nico, 2015/07/14 04:53:33]

Is this not a bump in practice? (From background to normal) According to the new
comment in platform_thread.h, will this not work on linux, and keep the test
thread in background priority for the remaining tests?

[Takashi Toyoshima, 2015/07/14 05:22:17]

That's true. If this could be a serious issue, I'll change this test to run in a
dedicated thread.

 }
 
 }  // namespace base