/*

 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "jvm.h"

#include "memory/allocation.inline.hpp"

#include "os_linux.inline.hpp"

#include "runtime/os.hpp"

#include "runtime/os_perf.hpp"

#include CPU_HEADER(vm_version_ext)

#include <stdio.h>

#include <stdarg.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/resource.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <dirent.h>

#include <stdlib.h>

#include <dlfcn.h>

#include <pthread.h>

#include <limits.h>

/**

   /proc/[number]/stat

              Status information about the process.  This is used by ps(1).  It is defined in /usr/src/linux/fs/proc/array.c.

              The fields, in order, with their proper scanf(3) format specifiers, are:

              1. pid %d The process id.

              2. comm %s

                     The filename of the executable, in parentheses.  This is visible whether or not the executable is swapped out.

              3. state %c

                     One  character  from  the  string "RSDZTW" where R is running, S is sleeping in an interruptible wait, D is waiting in uninterruptible disk

                     sleep, Z is zombie, T is traced or stopped (on a signal), and W is paging.

              4. ppid %d

                     The PID of the parent.

              5. pgrp %d

                     The process group ID of the process.

              6. session %d

                     The session ID of the process.

              7. tty_nr %d

                     The tty the process uses.

              8. tpgid %d

                     The process group ID of the process which currently owns the tty that the process is connected to.

              9. flags %lu

                     The flags of the process.  The math bit is decimal 4, and the traced bit is decimal 10.

              10. minflt %lu

                     The number of minor faults the process has made which have not required loading a memory page from disk.

              11. cminflt %lu

                     The number of minor faults that the process's waited-for children have made.

              12. majflt %lu

                     The number of major faults the process has made which have required loading a memory page from disk.

              13. cmajflt %lu

                     The number of major faults that the process's waited-for children have made.

              14. utime %lu

                     The number of jiffies that this process has been scheduled in user mode.

              15. stime %lu

                     The number of jiffies that this process has been scheduled in kernel mode.

              16. cutime %ld

                     The number of jiffies that this process's waited-for children have been scheduled in user mode. (See also times(2).)

              17. cstime %ld

                     The number of jiffies that this process' waited-for children have been scheduled in kernel mode.

              18. priority %ld

                     The standard nice value, plus fifteen.  The value is never negative in the kernel.

              19. nice %ld

                     The nice value ranges from 19 (nicest) to -19 (not nice to others).

              20. 0 %ld  This value is hard coded to 0 as a placeholder for a removed field.

              21. itrealvalue %ld

                     The time in jiffies before the next SIGALRM is sent to the process due to an interval timer.

              22. starttime %lu

                     The time in jiffies the process started after system boot.

              23. vsize %lu

                     Virtual memory size in bytes.

              24. rss %ld

                     Resident Set Size: number of pages the process has in real memory, minus 3 for administrative purposes. This is just the pages which  count

                     towards text, data, or stack space.  This does not include pages which have not been demand-loaded in, or which are swapped out.

              25. rlim %lu

                     Current limit in bytes on the rss of the process (usually 4294967295 on i386).

              26. startcode %lu

                     The address above which program text can run.

              27. endcode %lu

                     The address below which program text can run.

              28. startstack %lu

                     The address of the start of the stack.

              29. kstkesp %lu

                     The current value of esp (stack pointer), as found in the kernel stack page for the process.

              30. kstkeip %lu

                     The current EIP (instruction pointer).

              31. signal %lu

                     The bitmap of pending signals (usually 0).

              32. blocked %lu

                     The bitmap of blocked signals (usually 0, 2 for shells).

              33. sigignore %lu

                     The bitmap of ignored signals.

              34. sigcatch %lu

                     The bitmap of catched signals.

              35. wchan %lu

                     This  is the "channel" in which the process is waiting.  It is the address of a system call, and can be looked up in a namelist if you need

                     a textual name.  (If you have an up-to-date /etc/psdatabase, then try ps -l to see the WCHAN field in action.)

              36. nswap %lu

                     Number of pages swapped - not maintained.

              37. cnswap %lu

                     Cumulative nswap for child processes.

              38. exit_signal %d

                     Signal to be sent to parent when we die.

              39. processor %d

                     CPU number last executed on.

 ///// SSCANF FORMAT STRING. Copy and use.

field:        1  2  3  4  5  6  7  8  9   10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38 39

format:       %d %s %c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld %lu %lu %ld %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %d %d

*/

/**

 * For platforms that have them, when declaring

 * a printf-style function,

 *   formatSpec is the parameter number (starting at 1)

 *       that is the format argument ("%d pid %s")

 *   params is the parameter number where the actual args to

 *       the format starts. If the args are in a va_list, this

 *       should be 0.

 */

#ifndef PRINTF_ARGS

#  define PRINTF_ARGS(formatSpec,  params) ATTRIBUTE_PRINTF(formatSpec, params)

#endif

#ifndef SCANF_ARGS

#  define SCANF_ARGS(formatSpec,   params) ATTRIBUTE_SCANF(formatSpec, params)

#endif

#ifndef _PRINTFMT_

#  define _PRINTFMT_

#endif

#ifndef _SCANFMT_

#  define _SCANFMT_

#endif

struct CPUPerfTicks {

  uint64_t  used;

  uint64_t  usedKernel;

  uint64_t  total;

};

typedef enum {

  CPU_LOAD_VM_ONLY,

  CPU_LOAD_GLOBAL,

} CpuLoadTarget;

enum {

  UNDETECTED,

  UNDETECTABLE,

  LINUX26_NPTL,

  BAREMETAL

};

struct CPUPerfCounters {

  int   nProcs;

  CPUPerfTicks jvmTicks;

  CPUPerfTicks* cpus;

};

static double get_cpu_load(int which_logical_cpu, CPUPerfCounters* counters, double* pkernelLoad, CpuLoadTarget target);

/** reads /proc/<pid>/stat data, with some checks and some skips.

 *  Ensure that 'fmt' does _NOT_ contain the first two "%d %s"

 */

static int SCANF_ARGS(2, 0) vread_statdata(const char* procfile, _SCANFMT_ const char* fmt, va_list args) {

  FILE*f;

  int n;

  char buf[2048];

  if ((f = fopen(procfile, "r")) == NULL) {

    return -1;

  }

  if ((n = fread(buf, 1, sizeof(buf), f)) != -1) {

    char *tmp;

    buf[n-1] = '\0';

    /** skip through pid and exec name. */

    if ((tmp = strrchr(buf, ')')) != NULL) {

      // skip the ')' and the following space

      // but check that buffer is long enough

      tmp += 2;

      if (tmp < buf + n) {

        n = vsscanf(tmp, fmt, args);

      }

    }

  }

  fclose(f);

  return n;

}

static int SCANF_ARGS(2, 3) read_statdata(const char* procfile, _SCANFMT_ const char* fmt, ...) {

  int   n;

  va_list args;

  va_start(args, fmt);

  n = vread_statdata(procfile, fmt, args);

  va_end(args);

  return n;

}

static FILE* open_statfile(void) {

  FILE *f;

  if ((f = fopen("/proc/stat", "r")) == NULL) {

    static int haveWarned = 0;

    if (!haveWarned) {

      haveWarned = 1;

    }

  }

  return f;

}

static void

next_line(FILE *f) {

  int c;

  do {

    c = fgetc(f);

  } while (c != '\n' && c != EOF);

}

/**

 * Return the total number of ticks since the system was booted.

 * If the usedTicks parameter is not NULL, it will be filled with

 * the number of ticks spent on actual processes (user, system or

 * nice processes) since system boot. Note that this is the total number

 * of "executed" ticks on _all_ CPU:s, that is on a n-way system it is

 * n times the number of ticks that has passed in clock time.

 *

 * Returns a negative value if the reading of the ticks failed.

 */

static OSReturn get_total_ticks(int which_logical_cpu, CPUPerfTicks* pticks) {

  FILE*         fh;

  uint64_t      userTicks, niceTicks, systemTicks, idleTicks;

  uint64_t      iowTicks = 0, irqTicks = 0, sirqTicks= 0;

  int           logical_cpu = -1;

  const int     expected_assign_count = (-1 == which_logical_cpu) ? 4 : 5;

  int           n;

  if ((fh = open_statfile()) == NULL) {

    return OS_ERR;

  }

  if (-1 == which_logical_cpu) {

    n = fscanf(fh, "cpu " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "

            UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT,

            &userTicks, &niceTicks, &systemTicks, &idleTicks,

            &iowTicks, &irqTicks, &sirqTicks);

  } else {

    // Move to next line

    next_line(fh);

    // find the line for requested cpu faster to just iterate linefeeds?

    for (int i = 0; i < which_logical_cpu; i++) {

      next_line(fh);

    }

    n = fscanf(fh, "cpu%u " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "

               UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT,

               &logical_cpu, &userTicks, &niceTicks,

               &systemTicks, &idleTicks, &iowTicks, &irqTicks, &sirqTicks);

  }

  fclose(fh);

  if (n < expected_assign_count || logical_cpu != which_logical_cpu) {

#ifdef DEBUG_LINUX_PROC_STAT

    vm_fprintf(stderr, "[stat] read failed");

#endif

    return OS_ERR;

  }

#ifdef DEBUG_LINUX_PROC_STAT

  vm_fprintf(stderr, "[stat] read "

          UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "

          UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " \n",

          userTicks, niceTicks, systemTicks, idleTicks,

          iowTicks, irqTicks, sirqTicks);

#endif

  pticks->used       = userTicks + niceTicks;

  pticks->usedKernel = systemTicks + irqTicks + sirqTicks;

  pticks->total      = userTicks + niceTicks + systemTicks + idleTicks +

                       iowTicks + irqTicks + sirqTicks;

  return OS_OK;

}

static int get_systemtype(void) {

  static int procEntriesType = UNDETECTED;

  DIR *taskDir;

  if (procEntriesType != UNDETECTED) {

    return procEntriesType;

  }

  // Check whether we have a task subdirectory

  if ((taskDir = opendir("/proc/self/task")) == NULL) {

    procEntriesType = UNDETECTABLE;

  } else {

    // The task subdirectory exists; we're on a Linux >= 2.6 system

    closedir(taskDir);

    procEntriesType = LINUX26_NPTL;

  }

  return procEntriesType;

}

/** read user and system ticks from a named procfile, assumed to be in 'stat' format then. */

static int read_ticks(const char* procfile, uint64_t* userTicks, uint64_t* systemTicks) {

  return read_statdata(procfile, "%*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u " UINT64_FORMAT " " UINT64_FORMAT,

    userTicks, systemTicks);

}

/**

 * Return the number of ticks spent in any of the processes belonging

 * to the JVM on any CPU.

 */

static OSReturn get_jvm_ticks(CPUPerfTicks* pticks) {

  uint64_t userTicks;

  uint64_t systemTicks;

  if (get_systemtype() != LINUX26_NPTL) {

    return OS_ERR;

  }

  if (read_ticks("/proc/self/stat", &userTicks, &systemTicks) != 2) {

    return OS_ERR;

  }

  // get the total

  if (get_total_ticks(-1, pticks) != OS_OK) {

    return OS_ERR;

  }

  pticks->used       = userTicks;

  pticks->usedKernel = systemTicks;

  return OS_OK;

}

/**

 * Return the load of the CPU as a double. 1.0 means the CPU process uses all

 * available time for user or system processes, 0.0 means the CPU uses all time

 * being idle.

 *

 * Returns a negative value if there is a problem in determining the CPU load.

 */

static double get_cpu_load(int which_logical_cpu, CPUPerfCounters* counters, double* pkernelLoad, CpuLoadTarget target) {

  uint64_t udiff, kdiff, tdiff;

  CPUPerfTicks* pticks;

  CPUPerfTicks  tmp;

  double user_load;

  *pkernelLoad = 0.0;

  if (target == CPU_LOAD_VM_ONLY) {

    pticks = &counters->jvmTicks;

  } else if (-1 == which_logical_cpu) {

    pticks = &counters->cpus[counters->nProcs];

  } else {

    pticks = &counters->cpus[which_logical_cpu];

  }

  tmp = *pticks;

  if (target == CPU_LOAD_VM_ONLY) {

    if (get_jvm_ticks(pticks) != OS_OK) {

      return -1.0;

    }

  } else if (get_total_ticks(which_logical_cpu, pticks) != OS_OK) {

    return -1.0;

  }

  // seems like we sometimes end up with less kernel ticks when

  // reading /proc/self/stat a second time, timing issue between cpus?

  if (pticks->usedKernel < tmp.usedKernel) {

    kdiff = 0;

  } else {

    kdiff = pticks->usedKernel - tmp.usedKernel;

  }

  tdiff = pticks->total - tmp.total;

  udiff = pticks->used - tmp.used;

  if (tdiff == 0) {

    return 0.0;

  } else if (tdiff < (udiff + kdiff)) {

    tdiff = udiff + kdiff;

  }

  *pkernelLoad = (kdiff / (double)tdiff);

  // BUG9044876, normalize return values to sane values

  *pkernelLoad = MAX2<double>(*pkernelLoad, 0.0);

  *pkernelLoad = MIN2<double>(*pkernelLoad, 1.0);

  user_load = (udiff / (double)tdiff);

  user_load = MAX2<double>(user_load, 0.0);

  user_load = MIN2<double>(user_load, 1.0);

  return user_load;

}

static int SCANF_ARGS(1, 2) parse_stat(_SCANFMT_ const char* fmt, ...) {

  FILE *f;

  va_list args;

  va_start(args, fmt);

  if ((f = open_statfile()) == NULL) {

    va_end(args);

    return OS_ERR;

  }

  for (;;) {

    char line[80];

    if (fgets(line, sizeof(line), f) != NULL) {

      if (vsscanf(line, fmt, args) == 1) {

        fclose(f);

        va_end(args);

        return OS_OK;

      }

    } else {

        fclose(f);

        va_end(args);

        return OS_ERR;

    }

  }

}

static int get_noof_context_switches(uint64_t* switches) {

  return parse_stat("ctxt " UINT64_FORMAT "\n", switches);

}

/** returns boot time in _seconds_ since epoch */

static int get_boot_time(uint64_t* time) {

  return parse_stat("btime " UINT64_FORMAT "\n", time);

}

static int perf_context_switch_rate(double* rate) {

  static pthread_mutex_t contextSwitchLock = PTHREAD_MUTEX_INITIALIZER;

  static uint64_t      lastTime;

  static uint64_t      lastSwitches;

  static double        lastRate;

  uint64_t lt = 0;

  int res = 0;

  if (lastTime == 0) {

    uint64_t tmp;

    if (get_boot_time(&tmp) < 0) {

      return OS_ERR;

    }

    lt = tmp * 1000;

  }

  res = OS_OK;