[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

1 files changed, 181 insertions, 0 deletions

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
+}