src/os/solaris/vm/os_solaris.cpp
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src/os/solaris/vm/os_solaris.cpp

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*** 3494,3524 **** // 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 PosixSemaphore 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() --- 3494,3551 ---- // Void return because it's a hint and can fail. void os::hint_no_preempt() { schedctl_start(schedctl_init()); } + //////////////////////////////////////////////////////////////////////////////// + // suspend/resume support + + // The low-level signal-based suspend/resume support is a remnant from the + // old VM-suspension that used to be for java-suspension, safepoints etc, + // within hotspot. Needed for fetch_frame_from_ucontext(), which is used by: + // - Forte Analyzer: AsyncGetCallTrace() + // - StackBanging: get_frame_at_stack_banging_point() + // - JFR: get_topframe()-->....-->get_valid_uc_in_signal_handler() + // + // The remaining code is greatly simplified from the more general suspension + // code that used to be used. + // + // The protocol is quite simple: + // - suspend: + // - sends a signal to the target thread + // - polls the suspend state of the osthread using a yield loop + // - target thread signal handler (SR_handler) sets suspend state + // and blocks in sigsuspend until continued + // - resume: + // - sets target osthread state to continue + // - sends signal to end the sigsuspend loop in the SR_handler + // + // Note that the SR_lock plays no role in this suspend/resume protocol, + // but is checked for NULL in SR_handler as a thread termination indicator. + // + 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 PosixSemaphore sr_semaphore; ! void os::Solaris::SR_handler(Thread* thread, ucontext_t* context) { // 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, context); // 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()
*** 3661,3709 **** 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((const 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"); - 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. void os::os_exception_wrapper(java_call_t f, JavaValue* value, const methodHandle& method, JavaCallArguments* args, Thread* thread) { --- 3688,3697 ----
src/os/solaris/vm/os_solaris.cpp
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