1//===- Unix/Threading.inc - Unix Threading Implementation ----- -*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides the Unix specific implementation of Threading functions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "Unix.h"
14#include "llvm/ADT/ScopeExit.h"
15#include "llvm/ADT/SmallString.h"
16#include "llvm/ADT/Twine.h"
17
18#if defined(__APPLE__)
19#include <mach/mach_init.h>
20#include <mach/mach_port.h>
21#endif
22
23#include <pthread.h>
24
25#if defined(__FreeBSD__) || defined(__OpenBSD__)
26#include <pthread_np.h> // For pthread_getthreadid_np() / pthread_set_name_np()
27#endif
28
29#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
30#include <errno.h>
31#include <sys/cpuset.h>
32#include <sys/sysctl.h>
33#include <sys/user.h>
34#include <unistd.h>
35#endif
36
37#if defined(__NetBSD__)
38#include <lwp.h> // For _lwp_self()
39#endif
40
41#if defined(__OpenBSD__)
42#include <unistd.h> // For getthrid()
43#endif
44
45#if defined(__linux__)
46#include <sched.h>       // For sched_getaffinity
47#include <sys/syscall.h> // For syscall codes
48#include <unistd.h>      // For syscall()
49#endif
50
51namespace llvm {
52pthread_t
53llvm_execute_on_thread_impl(void *(*ThreadFunc)(void *), void *Arg,
54                            llvm::Optional<unsigned> StackSizeInBytes) {
55  int errnum;
56
57  // Construct the attributes object.
58  pthread_attr_t Attr;
59  if ((errnum = ::pthread_attr_init(&Attr)) != 0) {
60    ReportErrnumFatal("pthread_attr_init failed", errnum);
61  }
62
63  auto AttrGuard = llvm::make_scope_exit([&] {
64    if ((errnum = ::pthread_attr_destroy(&Attr)) != 0) {
65      ReportErrnumFatal("pthread_attr_destroy failed", errnum);
66    }
67  });
68
69  // Set the requested stack size, if given.
70  if (StackSizeInBytes) {
71    if ((errnum = ::pthread_attr_setstacksize(&Attr, *StackSizeInBytes)) != 0) {
72      ReportErrnumFatal("pthread_attr_setstacksize failed", errnum);
73    }
74  }
75
76  // Construct and execute the thread.
77  pthread_t Thread;
78  if ((errnum = ::pthread_create(&Thread, &Attr, ThreadFunc, Arg)) != 0)
79    ReportErrnumFatal("pthread_create failed", errnum);
80
81  return Thread;
82}
83
84void llvm_thread_detach_impl(pthread_t Thread) {
85  int errnum;
86
87  if ((errnum = ::pthread_detach(Thread)) != 0) {
88    ReportErrnumFatal("pthread_detach failed", errnum);
89  }
90}
91
92void llvm_thread_join_impl(pthread_t Thread) {
93  int errnum;
94
95  if ((errnum = ::pthread_join(Thread, nullptr)) != 0) {
96    ReportErrnumFatal("pthread_join failed", errnum);
97  }
98}
99
100pthread_t llvm_thread_get_id_impl(pthread_t Thread) {
101  return Thread;
102}
103
104pthread_t llvm_thread_get_current_id_impl() {
105  return ::pthread_self();
106}
107
108} // namespace llvm
109
110uint64_t llvm::get_threadid() {
111#if defined(__APPLE__)
112  // Calling "mach_thread_self()" bumps the reference count on the thread
113  // port, so we need to deallocate it. mach_task_self() doesn't bump the ref
114  // count.
115  thread_port_t Self = mach_thread_self();
116  mach_port_deallocate(mach_task_self(), Self);
117  return Self;
118#elif defined(__FreeBSD__)
119  return uint64_t(pthread_getthreadid_np());
120#elif defined(__NetBSD__)
121  return uint64_t(_lwp_self());
122#elif defined(__OpenBSD__)
123  return uint64_t(getthrid());
124#elif defined(__ANDROID__)
125  return uint64_t(gettid());
126#elif defined(__linux__)
127  return uint64_t(syscall(SYS_gettid));
128#else
129  return uint64_t(pthread_self());
130#endif
131}
132
133
134static constexpr uint32_t get_max_thread_name_length_impl() {
135#if defined(__NetBSD__)
136  return PTHREAD_MAX_NAMELEN_NP;
137#elif defined(__APPLE__)
138  return 64;
139#elif defined(__linux__)
140#if HAVE_PTHREAD_SETNAME_NP
141  return 16;
142#else
143  return 0;
144#endif
145#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
146  return 16;
147#elif defined(__OpenBSD__)
148  return 32;
149#else
150  return 0;
151#endif
152}
153
154uint32_t llvm::get_max_thread_name_length() {
155  return get_max_thread_name_length_impl();
156}
157
158void llvm::set_thread_name(const Twine &Name) {
159  // Make sure the input is null terminated.
160  SmallString<64> Storage;
161  StringRef NameStr = Name.toNullTerminatedStringRef(Storage);
162
163  // Truncate from the beginning, not the end, if the specified name is too
164  // long.  For one, this ensures that the resulting string is still null
165  // terminated, but additionally the end of a long thread name will usually
166  // be more unique than the beginning, since a common pattern is for similar
167  // threads to share a common prefix.
168  // Note that the name length includes the null terminator.
169  if (get_max_thread_name_length() > 0)
170    NameStr = NameStr.take_back(get_max_thread_name_length() - 1);
171  (void)NameStr;
172#if defined(__linux__)
173#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
174#if HAVE_PTHREAD_SETNAME_NP
175  ::pthread_setname_np(::pthread_self(), NameStr.data());
176#endif
177#endif
178#elif defined(__FreeBSD__) || defined(__OpenBSD__)
179  ::pthread_set_name_np(::pthread_self(), NameStr.data());
180#elif defined(__NetBSD__)
181  ::pthread_setname_np(::pthread_self(), "%s",
182    const_cast<char *>(NameStr.data()));
183#elif defined(__APPLE__)
184  ::pthread_setname_np(NameStr.data());
185#endif
186}
187
188void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
189  Name.clear();
190
191#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
192  int pid = ::getpid();
193  uint64_t tid = get_threadid();
194
195  struct kinfo_proc *kp = nullptr, *nkp;
196  size_t len = 0;
197  int error;
198  int ctl[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID | KERN_PROC_INC_THREAD,
199    (int)pid };
200
201  while (1) {
202    error = sysctl(ctl, 4, kp, &len, nullptr, 0);
203    if (kp == nullptr || (error != 0 && errno == ENOMEM)) {
204      // Add extra space in case threads are added before next call.
205      len += sizeof(*kp) + len / 10;
206      nkp = (struct kinfo_proc *)::realloc(kp, len);
207      if (nkp == nullptr) {
208        free(kp);
209        return;
210      }
211      kp = nkp;
212      continue;
213    }
214    if (error != 0)
215      len = 0;
216    break;
217  }
218
219  for (size_t i = 0; i < len / sizeof(*kp); i++) {
220    if (kp[i].ki_tid == (lwpid_t)tid) {
221      Name.append(kp[i].ki_tdname, kp[i].ki_tdname + strlen(kp[i].ki_tdname));
222      break;
223    }
224  }
225  free(kp);
226  return;
227#elif defined(__NetBSD__)
228  constexpr uint32_t len = get_max_thread_name_length_impl();
229  char buf[len];
230  ::pthread_getname_np(::pthread_self(), buf, len);
231
232  Name.append(buf, buf + strlen(buf));
233#elif defined(__OpenBSD__)
234  constexpr uint32_t len = get_max_thread_name_length_impl();
235  char buf[len];
236  ::pthread_get_name_np(::pthread_self(), buf, len);
237
238  Name.append(buf, buf + strlen(buf));
239#elif defined(__linux__)
240#if HAVE_PTHREAD_GETNAME_NP
241  constexpr uint32_t len = get_max_thread_name_length_impl();
242  char Buffer[len] = {'\0'};  // FIXME: working around MSan false positive.
243  if (0 == ::pthread_getname_np(::pthread_self(), Buffer, len))
244    Name.append(Buffer, Buffer + strlen(Buffer));
245#endif
246#endif
247}
248
249SetThreadPriorityResult llvm::set_thread_priority(ThreadPriority Priority) {
250#if defined(__linux__) && defined(SCHED_IDLE)
251  // Some *really* old glibcs are missing SCHED_IDLE.
252  // http://man7.org/linux/man-pages/man3/pthread_setschedparam.3.html
253  // http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html
254  sched_param priority;
255  // For each of the above policies, param->sched_priority must be 0.
256  priority.sched_priority = 0;
257  // SCHED_IDLE    for running very low priority background jobs.
258  // SCHED_OTHER   the standard round-robin time-sharing policy;
259  return !pthread_setschedparam(
260             pthread_self(),
261             Priority == ThreadPriority::Background ? SCHED_IDLE : SCHED_OTHER,
262             &priority)
263             ? SetThreadPriorityResult::SUCCESS
264             : SetThreadPriorityResult::FAILURE;
265#elif defined(__APPLE__)
266  // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getpriority.2.html
267  // When setting a thread into background state the scheduling priority is set
268  // to lowest value, disk and network IO are throttled. Network IO will be
269  // throttled for any sockets the thread opens after going into background
270  // state. Any previously opened sockets are not affected.
271
272  // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/getiopolicy_np.3.html
273  // I/Os with THROTTLE policy are called THROTTLE I/Os. If a THROTTLE I/O
274  // request occurs within a small time window (usually a fraction of a second)
275  // of another NORMAL I/O request, the thread that issues the THROTTLE I/O is
276  // forced to sleep for a certain interval. This slows down the thread that
277  // issues the THROTTLE I/O so that NORMAL I/Os can utilize most of the disk
278  // I/O bandwidth.
279  return !setpriority(PRIO_DARWIN_THREAD, 0,
280                      Priority == ThreadPriority::Background ? PRIO_DARWIN_BG
281                                                             : 0)
282             ? SetThreadPriorityResult::SUCCESS
283             : SetThreadPriorityResult::FAILURE;
284#endif
285  return SetThreadPriorityResult::FAILURE;
286}
287
288#include <thread>
289
290int computeHostNumHardwareThreads() {
291#if defined(__FreeBSD__)
292  cpuset_t mask;
293  CPU_ZERO(&mask);
294  if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(mask),
295                         &mask) == 0)
296    return CPU_COUNT(&mask);
297#elif defined(__linux__)
298  cpu_set_t Set;
299  if (sched_getaffinity(0, sizeof(Set), &Set) == 0)
300    return CPU_COUNT(&Set);
301#endif
302  // Guard against std::thread::hardware_concurrency() returning 0.
303  if (unsigned Val = std::thread::hardware_concurrency())
304    return Val;
305  return 1;
306}
307
308void llvm::ThreadPoolStrategy::apply_thread_strategy(
309    unsigned ThreadPoolNum) const {}
310
311llvm::BitVector llvm::get_thread_affinity_mask() {
312  // FIXME: Implement
313  llvm_unreachable("Not implemented!");
314}
315
316unsigned llvm::get_cpus() { return 1; }
317