[Support] Provide access to current thread name/thread id.

Applications often need the current thread id when making
system calls, and some operating systems provide the notion
of a thread name, which can be useful in enabling better
diagnostics when debugging or logging.

This patch adds an accessor for the thread id, and "best effort"
getters and setters for the thread name.  Since this is
non critical functionality, no error is returned to indicate
that a platform doesn't support thread names.

Differential Revision: https://reviews.llvm.org/D30526

llvm-svn: 296887

3 files changed, 311 insertions, 84 deletions

diff --git a/llvm/lib/Support/Threading.cpp b/llvm/lib/Support/Threading.cpp
index 760f9e2c388..a9ecf9b10bf 100644
--- a/llvm/lib/Support/Threading.cpp
+++ b/llvm/lib/Support/Threading.cpp
@@ -14,14 +14,21 @@
 
 #include "llvm/Support/Threading.h"
 #include "llvm/Config/config.h"
-#include "llvm/Support/Atomic.h"
 #include "llvm/Support/Host.h"
-#include "llvm/Support/Mutex.h"
 #include "llvm/Support/thread.h"
+
 #include <cassert>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
 
 using namespace llvm;
 
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code.
+//===----------------------------------------------------------------------===//
+
 bool llvm::llvm_is_multithreaded() {
 #if LLVM_ENABLE_THREADS != 0
   return true;
@@ -30,100 +37,38 @@ bool llvm::llvm_is_multithreaded() {
 #endif
 }
 
-#if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)
-#include <pthread.h>
-
-struct ThreadInfo {
-  void (*UserFn)(void *);
-  void *UserData;
-};
-static void *ExecuteOnThread_Dispatch(void *Arg) {
-  ThreadInfo *TI = reinterpret_cast<ThreadInfo*>(Arg);
-  TI->UserFn(TI->UserData);
-  return nullptr;
-}
-
-void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
+#if LLVM_ENABLE_THREADS == 0 ||                                                \
+    (!defined(LLVM_ON_WIN32) && !defined(HAVE_PTHREAD_H))
+// Support for non-Win32, non-pthread implementation.
+void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
                                   unsigned RequestedStackSize) {
-  ThreadInfo Info = { Fn, UserData };
-  pthread_attr_t Attr;
-  pthread_t Thread;
-
-  // Construct the attributes object.
-  if (::pthread_attr_init(&Attr) != 0)
-    return;
-
-  // Set the requested stack size, if given.
-  if (RequestedStackSize != 0) {
-    if (::pthread_attr_setstacksize(&Attr, RequestedStackSize) != 0)
-      goto error;
-  }
-
-  // Construct and execute the thread.
-  if (::pthread_create(&Thread, &Attr, ExecuteOnThread_Dispatch, &Info) != 0)
-    goto error;
-
-  // Wait for the thread and clean up.
-  ::pthread_join(Thread, nullptr);
-
- error:
-  ::pthread_attr_destroy(&Attr);
+  (void)RequestedStackSize;
+  Fn(UserData);
 }
-#elif LLVM_ENABLE_THREADS!=0 && defined(LLVM_ON_WIN32)
-#include "Windows/WindowsSupport.h"
-#include <process.h>
-
-// Windows will at times define MemoryFence.
-#ifdef MemoryFence
-#undef MemoryFence
-#endif
 
-struct ThreadInfo {
-  void (*func)(void*);
-  void *param;
-};
+unsigned llvm::heavyweight_hardware_concurrency() { return 1; }
 
-static unsigned __stdcall ThreadCallback(void *param) {
-  struct ThreadInfo *info = reinterpret_cast<struct ThreadInfo *>(param);
-  info->func(info->param);
+uint64_t llvm::get_threadid_np() { return 0; }
 
-  return 0;
-}
-
-void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
-                                  unsigned RequestedStackSize) {
-  struct ThreadInfo param = { Fn, UserData };
+void llvm::set_thread_name(const Twine &Name) {}
 
-  HANDLE hThread = (HANDLE)::_beginthreadex(NULL,
-                                            RequestedStackSize, ThreadCallback,
-                                            &param, 0, NULL);
+void llvm::get_thread_name(SmallVectorImpl<char> &Name) { Name.clear(); }
 
-  if (hThread) {
-    // We actually don't care whether the wait succeeds or fails, in
-    // the same way we don't care whether the pthread_join call succeeds
-    // or fails.  There's not much we could do if this were to fail. But
-    // on success, this call will wait until the thread finishes executing
-    // before returning.
-    (void)::WaitForSingleObject(hThread, INFINITE);
-    ::CloseHandle(hThread);
-  }
-}
 #else
-// Support for non-Win32, non-pthread implementation.
-void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
-                                  unsigned RequestedStackSize) {
-  (void) RequestedStackSize;
-  Fn(UserData);
-}
-
-#endif
 
 unsigned llvm::heavyweight_hardware_concurrency() {
-#if !LLVM_ENABLE_THREADS
-  return 1;
-#endif
   int NumPhysical = sys::getHostNumPhysicalCores();
   if (NumPhysical == -1)
     return thread::hardware_concurrency();
   return NumPhysical;
 }
+
+// Include the platform-specific parts of this class.
+#ifdef LLVM_ON_UNIX
+#include "Unix/Threading.inc"
+#endif
+#ifdef LLVM_ON_WIN32
+#include "Windows/Threading.inc"
+#endif
+
+#endif
diff --git a/llvm/lib/Support/Unix/Threading.inc b/llvm/lib/Support/Unix/Threading.inc
new file mode 100644
index 00000000000..d697f5b62bc
--- /dev/null
+++ b/llvm/lib/Support/Unix/Threading.inc
@@ -0,0 +1,181 @@
+//===- Unix/Threading.inc - Unix Threading Implementation ----- -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the Unix specific implementation of Threading functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/Twine.h"
+
+#if defined(__APPLE__)
+#include <mach/mach_init.h>
+#include <mach/mach_port.h>
+#endif
+
+#include <pthread.h>
+
+#if defined(__FreeBSD__)
+#include <pthread_np.h>
+#endif
+
+#if defined(__NetBSD__)
+#include <lwp.h>
+#endif
+
+#if defined(__linux__)
+#include <sys/syscall.h>
+#endif
+
+#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#endif
+
+namespace {
+  struct ThreadInfo {
+    void(*UserFn)(void *);
+    void *UserData;
+  };
+}
+
+static void *ExecuteOnThread_Dispatch(void *Arg) {
+  ThreadInfo *TI = reinterpret_cast<ThreadInfo*>(Arg);
+  TI->UserFn(TI->UserData);
+  return nullptr;
+}
+
+void llvm::llvm_execute_on_thread(void(*Fn)(void*), void *UserData,
+  unsigned RequestedStackSize) {
+  ThreadInfo Info = { Fn, UserData };
+  pthread_attr_t Attr;
+  pthread_t Thread;
+
+  // Construct the attributes object.
+  if (::pthread_attr_init(&Attr) != 0)
+    return;
+
+  // Set the requested stack size, if given.
+  if (RequestedStackSize != 0) {
+    if (::pthread_attr_setstacksize(&Attr, RequestedStackSize) != 0)
+      goto error;
+  }
+
+  // Construct and execute the thread.
+  if (::pthread_create(&Thread, &Attr, ExecuteOnThread_Dispatch, &Info) != 0)
+    goto error;
+
+  // Wait for the thread and clean up.
+  ::pthread_join(Thread, nullptr);
+
+error:
+  ::pthread_attr_destroy(&Attr);
+}
+
+
+uint64_t llvm::get_threadid() {
+#if defined(__APPLE__)
+  // Calling "mach_thread_self()" bumps the reference count on the thread
+  // port, so we need to deallocate it. mach_task_self() doesn't bump the ref
+  // count.
+  thread_port_t Self = mach_thread_self();
+  mach_port_deallocate(mach_task_self(), Self);
+  return Self;
+#elif defined(__FreeBSD__)
+  return uint64_t(pthread_getthreadid_np());
+#elif defined(__NetBSD__)
+  return uint64_t(_lwp_self());
+#elif defined(__ANDROID__)
+  return uint64_t(gettid());
+#elif defined(__linux__)
+  return uint64_t(syscall(SYS_gettid));
+#elif defined(LLVM_ON_WIN32)
+  return uint64_t(::GetCurrentThreadId());
+#else
+  return uint64_t(pthread_self());
+#endif
+}
+
+
+void llvm::set_thread_name(const Twine &Name) {
+  // Make sure the input is null terminated.
+  SmallString<64> Storage;
+  StringRef NameStr = Name.toNullTerminatedStringRef(Storage);
+#if defined(__linux__)
+#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
+  ::pthread_setname_np(::pthread_self(), NameStr.data());
+#endif
+#elif defined(__FreeBSD__)
+  ::pthread_set_name_np(::pthread_self(), NameStr.data());
+#elif defined(__NetBSD__)
+  ::pthread_setname_np(::pthread_self(), "%s",
+    const_cast<char *>(NameStr.data()));
+#elif defined(__APPLE__)
+  ::pthread_setname_np(NameStr.data());
+#endif
+}
+
+void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
+  Name.clear();
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#if defined(__FreeBSD_kernel__)
+  int pid = ::pthread_self();
+#else
+  int pid = ::getpid();
+#endif
+
+  int tid = ::pthread_getthreadid_np();
+
+  struct kinfo_proc *kp = nullptr, *nkp;
+  size_t len = 0;
+  int error;
+  int ctl[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID | KERN_PROC_INC_THREAD,
+    (int)pid };
+
+  while (1) {
+    error = sysctl(ctl, 4, kp, &len, nullptr, 0);
+    if (kp == nullptr || (error != 0 && errno == ENOMEM)) {
+      // Add extra space in case threads are added before next call.
+      len += sizeof(*kp) + len / 10;
+      nkp = (struct kinfo_proc *)realloc(kp, len);
+      if (nkp == nullptr) {
+        free(kp);
+        return;
+      }
+      kp = nkp;
+      continue;
+    }
+    if (error != 0)
+      len = 0;
+    break;
+  }
+
+  for (size_t i = 0; i < len / sizeof(*kp); i++) {
+    if (kp[i].ki_tid == (lwpid_t)tid) {
+      Name.append(kp[i].ki_tdname, kp[i].ki_tdname + strlen(kp[i].ki_tdname));
+      break;
+    }
+  }
+  free(kp);
+  return;
+#elif defined(__NetBSD__)
+  char buf[PTHREAD_MAX_NAMELEN_NP];
+  ::pthread_getname_np(::pthread_self(), buf, PTHREAD_MAX_NAMELEN_NP);
+
+  Name.append(buf, buf + strlen(buf));
+#elif defined(__linux__)
+#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
+  constexpr int MAXNAMELEN = 16;
+  char Buffer[MAXNAMELEN];
+  if (0 == ::pthread_getname_np(::pthread_self(), Buffer, MAXNAMELEN))
+    Name.append(Buffer, Buffer + strlen(Buffer));
+#endif
+#endif
+}
diff --git a/llvm/lib/Support/Windows/Threading.inc b/llvm/lib/Support/Windows/Threading.inc
new file mode 100644
index 00000000000..30086544ab2
--- /dev/null
+++ b/llvm/lib/Support/Windows/Threading.inc
@@ -0,0 +1,101 @@
+//===- Windows/Threading.inc - Win32 Threading Implementation - -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the Win32 specific implementation of Threading functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/Twine.h"
+
+#include "Windows/WindowsSupport.h"
+#include <process.h>
+
+// Windows will at times define MemoryFence.
+#ifdef MemoryFence
+#undef MemoryFence
+#endif
+
+namespace {
+  struct ThreadInfo {
+    void(*func)(void*);
+    void *param;
+  };
+}
+
+static unsigned __stdcall ThreadCallback(void *param) {
+  struct ThreadInfo *info = reinterpret_cast<struct ThreadInfo *>(param);
+  info->func(info->param);
+
+  return 0;
+}
+
+void llvm::llvm_execute_on_thread(void(*Fn)(void*), void *UserData,
+  unsigned RequestedStackSize) {
+  struct ThreadInfo param = { Fn, UserData };
+
+  HANDLE hThread = (HANDLE)::_beginthreadex(NULL,
+    RequestedStackSize, ThreadCallback,
+    &param, 0, NULL);
+
+  if (hThread) {
+    // We actually don't care whether the wait succeeds or fails, in
+    // the same way we don't care whether the pthread_join call succeeds
+    // or fails.  There's not much we could do if this were to fail. But
+    // on success, this call will wait until the thread finishes executing
+    // before returning.
+    (void)::WaitForSingleObject(hThread, INFINITE);
+    ::CloseHandle(hThread);
+  }
+}
+
+uint64_t llvm::get_threadid() {
+  return uint64_t(::GetCurrentThreadId());
+}
+
+void llvm::set_thread_name(const Twine &Name) {
+#if defined(_MSC_VER)
+  // Make sure the input is null terminated.
+  SmallString<64> Storage;
+  StringRef NameStr = Name.toNullTerminatedStringRef(Storage);
+  constexpr DWORD MS_VC_EXCEPTION = 0x406D1388;
+
+#pragma pack(push, 8)
+  struct THREADNAME_INFO {
+    DWORD dwType;     // Must be 0x1000.
+    LPCSTR szName;    // Pointer to thread name
+    DWORD dwThreadId; // Thread ID (-1 == current thread)
+    DWORD dwFlags;    // Reserved.  Do not use.
+  };
+#pragma pack(pop)
+
+  THREADNAME_INFO info;
+  info.dwType = 0x1000;
+  info.szName = NameStr.data();
+  info.dwThreadId = ::GetCurrentThreadId();
+  info.dwFlags = 0;
+
+  __try {
+    ::RaiseException(MS_VC_EXCEPTION, 0, sizeof(info) / sizeof(ULONG_PTR),
+      (ULONG_PTR *)&info);
+  }
+  __except (EXCEPTION_EXECUTE_HANDLER) {
+  }
+#endif
+}
+
+void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
+  // "Name" is not an inherent property of a thread on Windows.  In fact, when
+  // you "set" the name, you are only firing a one-time message to a debugger
+  // which it interprets as a program setting its threads' name.  We may be
+  // able to get fancy by creating a TLS entry when someone calls
+  // set_thread_name so that subsequent calls to get_thread_name return this
+  // value.
+  Name.clear();
+}