src/os/solaris/vm/os_solaris.cpp

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rev 4773 : 8005849: JEP 167: Event-Based JVM Tracing
Reviewed-by: acorn, coleenp, sla
Contributed-by: Karen Kinnear <karen.kinnear@oracle.com>, Bengt Rutisson <bengt.rutisson@oracle.com>, Calvin Cheung <calvin.cheung@oracle.com>, Erik Gahlin <erik.gahlin@oracle.com>, Erik Helin <erik.helin@oracle.com>, Jesper Wilhelmsson <jesper.wilhelmsson@oracle.com>, Keith McGuigan <keith.mcguigan@oracle.com>, Mattias Tobiasson <mattias.tobiasson@oracle.com>, Markus Gronlund <markus.gronlund@oracle.com>, Mikael Auno <mikael.auno@oracle.com>, Nils Eliasson <nils.eliasson@oracle.com>, Nils Loodin <nils.loodin@oracle.com>, Rickard Backman <rickard.backman@oracle.com>, Staffan Larsen <staffan.larsen@oracle.com>, Stefan Karlsson <stefan.karlsson@oracle.com>, Yekaterina Kantserova <yekaterina.kantserova@oracle.com>

@@ -238,10 +238,12 @@
 extern "C" {
   static int pthread_mutex_default_init(mutex_t *mx, int scope, void *arg) { memset(mx, 0, sizeof(mutex_t)); return 0; }
   static int pthread_cond_default_init(cond_t *cv, int scope, void *arg){ memset(cv, 0, sizeof(cond_t)); return 0; }
 }
 
+static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
+
 // Thread Local Storage
 // This is common to all Solaris platforms so it is defined here,
 // in this common file.
 // The declarations are in the os_cpu threadLS*.hpp files.
 //

@@ -2578,10 +2580,61 @@
 
 void* os::user_handler() {
   return CAST_FROM_FN_PTR(void*, UserHandler);
 }
 
+class Semaphore : public StackObj {
+  public:
+    Semaphore();
+    ~Semaphore();
+    void signal();
+    void wait();
+    bool trywait();
+    bool timedwait(unsigned int sec, int nsec);
+  private:
+    sema_t _semaphore;
+};
+
+
+Semaphore::Semaphore() {
+  sema_init(&_semaphore, 0, NULL, NULL);
+}
+
+Semaphore::~Semaphore() {
+  sema_destroy(&_semaphore);
+}
+
+void Semaphore::signal() {
+  sema_post(&_semaphore);
+}
+
+void Semaphore::wait() {
+  sema_wait(&_semaphore);
+}
+
+bool Semaphore::trywait() {
+  return sema_trywait(&_semaphore) == 0;
+}
+
+bool Semaphore::timedwait(unsigned int sec, int nsec) {
+  struct timespec ts;
+  unpackTime(&ts, false, (sec * NANOSECS_PER_SEC) + nsec);
+
+  while (1) {
+    int result = sema_timedwait(&_semaphore, &ts);
+    if (result == 0) {
+      return true;
+    } else if (errno == EINTR) {
+      continue;
+    } else if (errno == ETIME) {
+      return false;
+    } else {
+      return false;
+    }
+  }
+}
+
 extern "C" {
   typedef void (*sa_handler_t)(int);
   typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
 }
 

@@ -4162,10 +4215,72 @@
 // Void return because it's a hint and can fail.
 void os::hint_no_preempt() {
   schedctl_start(schedctl_init());
 }
 
+static void resume_clear_context(OSThread *osthread) {
+  osthread->set_ucontext(NULL);
+}
+
+static void suspend_save_context(OSThread *osthread, ucontext_t* context) {
+  osthread->set_ucontext(context);
+}
+
+static Semaphore sr_semaphore;
+
+void os::Solaris::SR_handler(Thread* thread, ucontext_t* uc) {
+  // Save and restore errno to avoid confusing native code with EINTR
+  // after sigsuspend.
+  int old_errno = errno;
+
+  OSThread* osthread = thread->osthread();
+  assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
+
+  os::SuspendResume::State current = osthread->sr.state();
+  if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
+    suspend_save_context(osthread, uc);
+
+    // attempt to switch the state, we assume we had a SUSPEND_REQUEST
+    os::SuspendResume::State state = osthread->sr.suspended();
+    if (state == os::SuspendResume::SR_SUSPENDED) {
+      sigset_t suspend_set;  // signals for sigsuspend()
+
+      // get current set of blocked signals and unblock resume signal
+      thr_sigsetmask(SIG_BLOCK, NULL, &suspend_set);
+      sigdelset(&suspend_set, os::Solaris::SIGasync());
+
+      sr_semaphore.signal();
+      // wait here until we are resumed
+      while (1) {
+        sigsuspend(&suspend_set);
+
+        os::SuspendResume::State result = osthread->sr.running();
+        if (result == os::SuspendResume::SR_RUNNING) {
+          sr_semaphore.signal();
+          break;
+        }
+      }
+
+    } else if (state == os::SuspendResume::SR_RUNNING) {
+      // request was cancelled, continue
+    } else {
+      ShouldNotReachHere();
+    }
+
+    resume_clear_context(osthread);
+  } else if (current == os::SuspendResume::SR_RUNNING) {
+    // request was cancelled, continue
+  } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
+    // ignore
+  } else {
+    // ignore
+  }
+
+  errno = old_errno;
+}
+
+
 void os::interrupt(Thread* thread) {
   assert(Thread::current() == thread || Threads_lock->owned_by_self(), "possibility of dangling Thread pointer");
 
   OSThread* osthread = thread->osthread();
 

@@ -4245,32 +4360,130 @@
   while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
 
   return buf[0] == 'y' || buf[0] == 'Y';
 }
 
+static int sr_notify(OSThread* osthread) {
+  int status = thr_kill(osthread->thread_id(), os::Solaris::SIGasync());
+  assert_status(status == 0, status, "thr_kill");
+  return status;
+}
+
+// "Randomly" selected value for how long we want to spin
+// before bailing out on suspending a thread, also how often
+// we send a signal to a thread we want to resume
+static const int RANDOMLY_LARGE_INTEGER = 1000000;
+static const int RANDOMLY_LARGE_INTEGER2 = 100;
+
+static bool do_suspend(OSThread* osthread) {
+  assert(osthread->sr.is_running(), "thread should be running");
+  assert(!sr_semaphore.trywait(), "semaphore has invalid state");
+
+  // mark as suspended and send signal
+  if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
+    // failed to switch, state wasn't running?
+    ShouldNotReachHere();
+    return false;
+  }
+
+  if (sr_notify(osthread) != 0) {
+    ShouldNotReachHere();
+  }
+
+  // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
+  while (true) {
+    if (sr_semaphore.timedwait(0, 2000 * NANOSECS_PER_MILLISEC)) {
+      break;
+    } else {
+      // timeout
+      os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
+      if (cancelled == os::SuspendResume::SR_RUNNING) {
+        return false;
+      } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
+        // make sure that we consume the signal on the semaphore as well
+        sr_semaphore.wait();
+        break;
+      } else {
+        ShouldNotReachHere();
+        return false;
+      }
+    }
+  }
+
+  guarantee(osthread->sr.is_suspended(), "Must be suspended");
+  return true;
+}
+
+static void do_resume(OSThread* osthread) {
+  assert(osthread->sr.is_suspended(), "thread should be suspended");
+  assert(!sr_semaphore.trywait(), "invalid semaphore state");
+
+  if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
+    // failed to switch to WAKEUP_REQUEST
+    ShouldNotReachHere();
+    return;
+  }
+
+  while (true) {
+    if (sr_notify(osthread) == 0) {
+      if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
+        if (osthread->sr.is_running()) {
+          return;
+        }
+      }
+    } else {
+      ShouldNotReachHere();
+    }
+  }
+
+  guarantee(osthread->sr.is_running(), "Must be running!");
+}
+
+void os::SuspendedThreadTask::internal_do_task() {
+  if (do_suspend(_thread->osthread())) {
+    SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
+    do_task(context);
+    do_resume(_thread->osthread());
+  }
+}
+
+class PcFetcher : public os::SuspendedThreadTask {
+public:
+  PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
+  ExtendedPC result();
+protected:
+  void do_task(const os::SuspendedThreadTaskContext& context);
+private:
+  ExtendedPC _epc;
+};
+
+ExtendedPC PcFetcher::result() {
+  guarantee(is_done(), "task is not done yet.");
+  return _epc;
+}
+
+void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
+  Thread* thread = context.thread();
+  OSThread* osthread = thread->osthread();
+  if (osthread->ucontext() != NULL) {
+    _epc = os::Solaris::ucontext_get_pc((ucontext_t *) context.ucontext());
+  } else {
+    // NULL context is unexpected, double-check this is the VMThread
+    guarantee(thread->is_VM_thread(), "can only be called for VMThread");
+  }
+}
+
 // A lightweight implementation that does not suspend the target thread and
 // thus returns only a hint. Used for profiling only!
 ExtendedPC os::get_thread_pc(Thread* thread) {
   // Make sure that it is called by the watcher and the Threads lock is owned.
   assert(Thread::current()->is_Watcher_thread(), "Must be watcher and own Threads_lock");
   // For now, is only used to profile the VM Thread
   assert(thread->is_VM_thread(), "Can only be called for VMThread");
-  ExtendedPC epc;
-
-  GetThreadPC_Callback  cb(ProfileVM_lock);
-  OSThread *osthread = thread->osthread();
-  const int time_to_wait = 400; // 400ms wait for initial response
-  int status = cb.interrupt(thread, time_to_wait);
-
-  if (cb.is_done() ) {
-    epc = cb.addr();
-  } else {
-    DEBUG_ONLY(tty->print_cr("Failed to get pc for thread: %d got %d status",
-                              osthread->thread_id(), status););
-    // epc is already NULL
-  }
-  return epc;
+  PcFetcher fetcher(thread);
+  fetcher.run();
+  return fetcher.result();
 }
 
 
 // This does not do anything on Solaris. This is basically a hook for being
 // able to use structured exception handling (thread-local exception filters) on, e.g., Win32.