/*

 * Copyright 1999-2007 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// Linux_OS defines the interface to Linux operating systems

/* pthread_getattr_np comes with LinuxThreads-0.9-7 on RedHat 7.1 */

typedef int (*pthread_getattr_func_type) (pthread_t, pthread_attr_t *);

class Linux {

  friend class os;

  // For signal-chaining

#define MAXSIGNUM 32

  static struct sigaction sigact[MAXSIGNUM]; // saved preinstalled sigactions

  static unsigned int sigs;             // mask of signals that have

                                        // preinstalled signal handlers

  static bool libjsig_is_loaded;        // libjsig that interposes sigaction(),

                                        // __sigaction(), signal() is loaded

  static struct sigaction *(*get_signal_action)(int);

  static struct sigaction *get_preinstalled_handler(int);

  static void save_preinstalled_handler(int, struct sigaction&);

  static void check_signal_handler(int sig);

  // For signal flags diagnostics

  static int sigflags[MAXSIGNUM];

  static int (*_clock_gettime)(clockid_t, struct timespec *);

  static int (*_pthread_getcpuclockid)(pthread_t, clockid_t *);

  static address   _initial_thread_stack_bottom;

  static uintptr_t _initial_thread_stack_size;

  static char *_glibc_version;

  static char *_libpthread_version;

  static bool _is_floating_stack;

  static bool _is_NPTL;

  static bool _supports_fast_thread_cpu_time;

 protected:

  static julong _physical_memory;

  static pthread_t _main_thread;

  static Mutex* _createThread_lock;

  static int _page_size;

  static julong available_memory();

  static julong physical_memory() { return _physical_memory; }

  static void initialize_system_info();

  static void set_glibc_version(char *s)      { _glibc_version = s; }

  static void set_libpthread_version(char *s) { _libpthread_version = s; }

  static bool supports_variable_stack_size();

  static void set_is_NPTL()                   { _is_NPTL = true;  }

  static void set_is_LinuxThreads()           { _is_NPTL = false; }

  static void set_is_floating_stack()         { _is_floating_stack = true; }

 public:

  static void init_thread_fpu_state();

  static int  get_fpu_control_word();

  static void set_fpu_control_word(int fpu_control);

  static pthread_t main_thread(void)                                { return _main_thread; }

  // returns kernel thread id (similar to LWP id on Solaris), which can be

  // used to access /proc

  static pid_t gettid();

  static void set_createThread_lock(Mutex* lk)                      { _createThread_lock = lk; }

  static Mutex* createThread_lock(void)                             { return _createThread_lock; }

  static void hotspot_sigmask(Thread* thread);

  static address   initial_thread_stack_bottom(void)                { return _initial_thread_stack_bottom; }

  static uintptr_t initial_thread_stack_size(void)                  { return _initial_thread_stack_size; }

  static bool is_initial_thread(void);

  static int page_size(void)                                        { return _page_size; }

  static void set_page_size(int val)                                { _page_size = val; }

  static address   ucontext_get_pc(ucontext_t* uc);

  static intptr_t* ucontext_get_sp(ucontext_t* uc);

  static intptr_t* ucontext_get_fp(ucontext_t* uc);

  // For Analyzer Forte AsyncGetCallTrace profiling support:

  //

  // This interface should be declared in os_linux_i486.hpp, but

  // that file provides extensions to the os class and not the

  // Linux class.

  static ExtendedPC fetch_frame_from_ucontext(Thread* thread, ucontext_t* uc,

    intptr_t** ret_sp, intptr_t** ret_fp);

  // This boolean allows users to forward their own non-matching signals

  // to JVM_handle_linux_signal, harmlessly.

  static bool signal_handlers_are_installed;

  static int get_our_sigflags(int);

  static void set_our_sigflags(int, int);

  static void signal_sets_init();

  static void install_signal_handlers();

  static void set_signal_handler(int, bool);

  static bool is_sig_ignored(int sig);

  static sigset_t* unblocked_signals();

  static sigset_t* vm_signals();

  static sigset_t* allowdebug_blocked_signals();

  // For signal-chaining

  static struct sigaction *get_chained_signal_action(int sig);

  static bool chained_handler(int sig, siginfo_t* siginfo, void* context);

  // GNU libc and libpthread version strings

  static char *glibc_version()                { return _glibc_version; }

  static char *libpthread_version()           { return _libpthread_version; }

  // NPTL or LinuxThreads?

  static bool is_LinuxThreads()               { return !_is_NPTL; }

  static bool is_NPTL()                       { return _is_NPTL;  }

  // NPTL is always floating stack. LinuxThreads could be using floating

  // stack or fixed stack.

  static bool is_floating_stack()             { return _is_floating_stack; }

  static void libpthread_init();

  // Minimum stack size a thread can be created with (allowing

  // the VM to completely create the thread and enter user code)

  static size_t min_stack_allowed;

  // Return default stack size or guard size for the specified thread type

  static size_t default_stack_size(os::ThreadType thr_type);

  static size_t default_guard_size(os::ThreadType thr_type);

  static void capture_initial_stack(size_t max_size);

  // Stack overflow handling

  static bool manually_expand_stack(JavaThread * t, address addr);

  static int max_register_window_saves_before_flushing();

  // Real-time clock functions

  static void clock_init(void);

  // fast POSIX clocks support

  static void fast_thread_clock_init(void);

  static bool supports_monotonic_clock() {

    return _clock_gettime != NULL;

  }

  static int clock_gettime(clockid_t clock_id, struct timespec *tp) {

    return _clock_gettime ? _clock_gettime(clock_id, tp) : -1;

  }

  static int pthread_getcpuclockid(pthread_t tid, clockid_t *clock_id) {

    return _pthread_getcpuclockid ? _pthread_getcpuclockid(tid, clock_id) : -1;

  }

  static bool supports_fast_thread_cpu_time() {

    return _supports_fast_thread_cpu_time;

  }

  static jlong fast_thread_cpu_time(clockid_t clockid);

  // Stack repair handling

  // none present

  // LinuxThreads work-around for 6292965

  static int safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime);

  // Linux suspend/resume support - this helper is a shadow of its former

  // self now that low-level suspension is barely used, and old workarounds

  // for LinuxThreads are no longer needed.

  class SuspendResume {

  private:

    volatile int _suspend_action;

    // values for suspend_action:

    #define SR_NONE               (0x00)

    #define SR_SUSPEND            (0x01)  // suspend request

    #define SR_CONTINUE           (0x02)  // resume request

    volatile jint _state;

    // values for _state: + SR_NONE

    #define SR_SUSPENDED          (0x20)

  public:

    SuspendResume() { _suspend_action = SR_NONE; _state = SR_NONE; }

    int suspend_action() const     { return _suspend_action; }

    void set_suspend_action(int x) { _suspend_action = x;    }

    // atomic updates for _state

    void set_suspended()           {

      jint temp, temp2;

      do {

        temp = _state;

        temp2 = Atomic::cmpxchg(temp | SR_SUSPENDED, &_state, temp);

      } while (temp2 != temp);

    }

    void clear_suspended()        {

      jint temp, temp2;

      do {

        temp = _state;

        temp2 = Atomic::cmpxchg(temp & ~SR_SUSPENDED, &_state, temp);

      } while (temp2 != temp);

    }

    bool is_suspended()            { return _state & SR_SUSPENDED;       }

    #undef SR_SUSPENDED

  };

};

class PlatformEvent : public CHeapObj {

  private:

    double CachePad [4] ;   // increase odds that _mutex is sole occupant of cache line

    volatile int _Event ;

    volatile int _nParked ;

    pthread_mutex_t _mutex  [1] ;

    pthread_cond_t  _cond   [1] ;

    double PostPad  [2] ;

    Thread * _Assoc ;

  public:       // TODO-FIXME: make dtor private

    ~PlatformEvent() { guarantee (0, "invariant") ; }

  public:

    PlatformEvent() {

      int status;

      status = pthread_cond_init (_cond, NULL);

      assert_status(status == 0, status, "cond_init");

      status = pthread_mutex_init (_mutex, NULL);

      assert_status(status == 0, status, "mutex_init");

      _Event   = 0 ;

      _nParked = 0 ;

      _Assoc   = NULL ;

    }

    // Use caution with reset() and fired() -- they may require MEMBARs

    void reset() { _Event = 0 ; }

    int  fired() { return _Event; }

    void park () ;

    void unpark () ;

    int  TryPark () ;

    int  park (jlong millis) ;

    void SetAssociation (Thread * a) { _Assoc = a ; }

} ;

class PlatformParker : public CHeapObj {

  protected:

    pthread_mutex_t _mutex [1] ;

    pthread_cond_t  _cond  [1] ;

  public:       // TODO-FIXME: make dtor private

    ~PlatformParker() { guarantee (0, "invariant") ; }

  public:

    PlatformParker() {

      int status;

      status = pthread_cond_init (_cond, NULL);

      assert_status(status == 0, status, "cond_init");

      status = pthread_mutex_init (_mutex, NULL);

      assert_status(status == 0, status, "mutex_init");

    }

} ;