// processinfo_linux2.cpp


/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program 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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kControl

#include "mongo/platform/basic.h"

#include "processinfo.h"

#include <iostream>
#include <malloc.h>
#include <sched.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/utsname.h>
#include <unistd.h>
#ifdef __BIONIC__
#include <android/api-level.h>
#elif __UCLIBC__
#include <features.h>
#else
#include <gnu/libc-version.h>
#endif

#include <boost/filesystem.hpp>
#include <boost/none.hpp>
#include <boost/optional.hpp>

#include "mongo/util/file.h"
#include "mongo/util/log.h"

using namespace std;

#define KLONG long
#define KLF "l"

namespace mongo {

class LinuxProc {
public:
    LinuxProc(ProcessId pid) {
        char name[128];
        sprintf(name, "/proc/%d/stat", pid.asUInt32());

        FILE* f = fopen(name, "r");
        if (!f) {
            stringstream ss;
            ss << "couldn't open [" << name << "] " << errnoWithDescription();
            string s = ss.str();
            msgasserted(13538, s.c_str());
        }
        int found = fscanf(f,
                           "%d %127s %c "
                           "%d %d %d %d %d "
                           "%lu %lu %lu %lu %lu "
                           "%lu %lu %ld %ld " /* utime stime cutime cstime */
                           "%ld %ld "
                           "%ld "
                           "%ld "
                           "%lu " /* start_time */
                           "%lu "
                           "%ld "  // rss
                           "%lu %" KLF "u %" KLF "u %" KLF "u %" KLF "u %" KLF "u "
                           /*
                             "%*s %*s %*s %*s "
                             "%"KLF"u %*lu %*lu "
                             "%d %d "
                             "%lu %lu"
                           */

                           ,

                           &_pid,
                           _comm,
                           &_state,
                           &_ppid,
                           &_pgrp,
                           &_session,
                           &_tty,
                           &_tpgid,
                           &_flags,
                           &_min_flt,
                           &_cmin_flt,
                           &_maj_flt,
                           &_cmaj_flt,
                           &_utime,
                           &_stime,
                           &_cutime,
                           &_cstime,
                           &_priority,
                           &_nice,
                           &_nlwp,
                           &_alarm,
                           &_start_time,
                           &_vsize,
                           &_rss,
                           &_rss_rlim,
                           &_start_code,
                           &_end_code,
                           &_start_stack,
                           &_kstk_esp,
                           &_kstk_eip

                           /*
                             &_wchan,
                             &_exit_signal, &_processor,
                             &_rtprio, &_sched
                           */
                           );
        if (found == 0) {
            cout << "system error: reading proc info" << endl;
        }
        fclose(f);
    }

    unsigned long getVirtualMemorySize() {
        return _vsize;
    }

    unsigned long getResidentSizeInPages() {
        return (unsigned long)_rss;
    }

    int _pid;
    // The process ID.

    char _comm[128];
    // The filename of the executable, in parentheses.  This is visible whether or not the
    // executable is swapped out.

    char _state;
    // 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.

    int _ppid;
    // The PID of the parent.

    int _pgrp;
    // The process group ID of the process.

    int _session;
    // The session ID of the process.

    int _tty;
    // The tty the process uses.

    int _tpgid;
    // The process group ID of the process which currently owns the tty that the process is
    // connected to.

    unsigned long _flags;  // %lu
    // The  kernel flags word of the process. For bit meanings, see the PF_* defines in
    // <linux/sched.h>.  Details depend on the kernel version.

    unsigned long _min_flt;  // %lu
    // The number of minor faults the process has made which have not required loading a memory page
    // from disk.

    unsigned long _cmin_flt;  // %lu
    // The number of minor faults that the process

    unsigned long _maj_flt;  // %lu
    // The number of major faults the process has made which have required loading a memory page
    // from disk.

    unsigned long _cmaj_flt;  // %lu
    // The number of major faults that the process

    unsigned long _utime;  // %lu
    // The number of jiffies that this process has been scheduled in user mode.

    unsigned long _stime;  //  %lu
    // The number of jiffies that this process has been scheduled in kernel mode.

    long _cutime;  // %ld
    // The number of jiffies that this removed field.

    long _cstime;  // %ld

    long _priority;
    long _nice;

    long _nlwp;  // %ld
    // number of threads

    unsigned long _alarm;
    // The time in jiffies before the next SIGALRM is sent to the process due to an interval timer.
    // (unused since 2.6.17)

    unsigned long _start_time;  // %lu
    // The time in jiffies the process started after system boot.

    unsigned long _vsize;  // %lu
    // Virtual memory size in bytes.

    long _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

    unsigned long _rss_rlim;  // %lu
    // Current limit in bytes on the rss of the process (usually 4294967295 on i386).

    unsigned long _start_code;  // %lu
    // The address above which program text can run.

    unsigned long _end_code;  // %lu
    // The address below which program text can run.

    unsigned long _start_stack;  // %lu
    // The address of the start of the stack.

    unsigned long _kstk_esp;  // %lu
    // The current value of esp (stack pointer), as found in the kernel stack page for the process.

    unsigned long _kstk_eip;  // %lu
    // The current EIP (instruction pointer).
};


class LinuxSysHelper {
public:
    /**
    * Read the first 1023 bytes from a file
    */
    static string readLineFromFile(const char* fname) {
        FILE* f;
        char fstr[1024] = {0};

        f = fopen(fname, "r");
        if (f != NULL) {
            if (fgets(fstr, 1023, f) != NULL)
                fstr[strlen(fstr) < 1 ? 0 : strlen(fstr) - 1] = '\0';
            fclose(f);
        }
        return fstr;
    }

    /**
    * Get some details about the CPU
    */
    static void getCpuInfo(int& procCount, string& freq, string& features) {
        FILE* f;
        char fstr[1024] = {0};
        procCount = 0;

        f = fopen("/proc/cpuinfo", "r");
        if (f == NULL)
            return;

        while (fgets(fstr, 1023, f) != NULL && !feof(f)) {
            // until the end of the file
            fstr[strlen(fstr) < 1 ? 0 : strlen(fstr) - 1] = '\0';
            if (strncmp(fstr, "processor ", 10) == 0 || strncmp(fstr, "processor\t:", 11) == 0)
                ++procCount;
            if (strncmp(fstr, "cpu MHz\t\t:", 10) == 0)
                freq = fstr + 11;
            if (strncmp(fstr, "flags\t\t:", 8) == 0)
                features = fstr + 9;
        }

        fclose(f);
    }

    /**
    * Determine linux distro and version
    */
    static void getLinuxDistro(string& name, string& version) {
        char buf[4096] = {0};

        // try lsb file first
        if (boost::filesystem::exists("/etc/lsb-release")) {
            File f;
            f.open("/etc/lsb-release", true);
            if (!f.is_open() || f.bad())
                return;
            f.read(0, buf, f.len() > 4095 ? 4095 : f.len());

            // find the distribution name and version in the contents.
            // format:  KEY=VAL\n
            string contents = buf;
            unsigned lineCnt = 0;
            try {
                while (lineCnt < contents.length() - 1 &&
                       contents.substr(lineCnt).find('\n') != string::npos) {
                    // until we hit the last newline or eof
                    string line = contents.substr(lineCnt, contents.substr(lineCnt).find('\n'));
                    lineCnt += contents.substr(lineCnt).find('\n') + 1;
                    size_t delim = line.find('=');
                    string key = line.substr(0, delim);
                    string val = line.substr(delim + 1);  // 0-based offset of delim
                    if (key.compare("DISTRIB_ID") == 0)
                        name = val;
                    if (string(key).compare("DISTRIB_RELEASE") == 0)
                        version = val;
                }
            } catch (const std::out_of_range& e) {
                // attempted to get invalid substr
            }
            // return with lsb-release data if we found both the name and version
            if (!name.empty() && !version.empty()) {
                return;
            }
        }

        // try known flat-text file locations
        // format: Slackware-x86_64 13.0, Red Hat Enterprise Linux Server release 5.6 (Tikanga),
        // etc.
        typedef vector<string> pathvec;
        pathvec paths;
        pathvec::const_iterator i;
        bool found = false;
        paths.push_back("/etc/system-release");
        paths.push_back("/etc/redhat-release");
        paths.push_back("/etc/gentoo-release");
        paths.push_back("/etc/novell-release");
        paths.push_back("/etc/gentoo-release");
        paths.push_back("/etc/SuSE-release");
        paths.push_back("/etc/SUSE-release");
        paths.push_back("/etc/sles-release");
        paths.push_back("/etc/debian_release");
        paths.push_back("/etc/slackware-version");
        paths.push_back("/etc/centos-release");
        paths.push_back("/etc/os-release");

        for (i = paths.begin(); i != paths.end(); ++i) {
            // for each path
            if (boost::filesystem::exists(*i)) {
                // if the file exists, break
                found = true;
                break;
            }
        }

        if (found) {
            // found a file
            File f;
            f.open(i->c_str(), true);
            if (!f.is_open() || f.bad())
                // file exists but can't be opened
                return;

            // read up to 512 bytes
            int len = f.len() > 512 ? 512 : f.len();
            f.read(0, buf, len);
            buf[len] = '\0';
            name = buf;
            size_t nl = 0;
            if ((nl = name.find('\n', nl)) != string::npos)
                // stop at first newline
                name.erase(nl);
        } else {
            name = "unknown";
        }

        // There is no standard format for name and version so use the kernel version.
        version = "Kernel ";
        version += LinuxSysHelper::readLineFromFile("/proc/sys/kernel/osrelease");
    }

    /**
    * Get system memory total
    */
    static unsigned long long getSystemMemorySize() {
        string meminfo = readLineFromFile("/proc/meminfo");
        size_t lineOff = 0;
        if (!meminfo.empty() && (lineOff = meminfo.find("MemTotal")) != string::npos) {
            // found MemTotal line.  capture everything between 'MemTotal:' and ' kB'.
            lineOff = meminfo.substr(lineOff).find(':') + 1;
            meminfo = meminfo.substr(lineOff, meminfo.substr(lineOff).find("kB") - 1);
            lineOff = 0;

            // trim whitespace and append 000 to replace kB.
            while (isspace(meminfo.at(lineOff)))
                lineOff++;
            meminfo = meminfo.substr(lineOff);

            unsigned long long systemMem = 0;
            if (mongo::parseNumberFromString(meminfo, &systemMem).isOK()) {
                return systemMem * 1024;  // convert from kB to bytes
            } else
                log() << "Unable to collect system memory information";
        }
        return 0;
    }
};


ProcessInfo::ProcessInfo(ProcessId pid) : _pid(pid) {}

ProcessInfo::~ProcessInfo() {}

bool ProcessInfo::supported() {
    return true;
}

// get the number of CPUs available to the current process
boost::optional<unsigned long> ProcessInfo::getNumCoresForProcess() {
    cpu_set_t set;

    if (sched_getaffinity(0, sizeof(cpu_set_t), &set) == 0) {
#ifdef CPU_COUNT  // glibc >= 2.6 has CPU_COUNT defined
        return CPU_COUNT(&set);
#else
        unsigned long count = 0;
        for (size_t i = 0; i < CPU_SETSIZE; i++)
            if (CPU_ISSET(i, &set))
                count++;
        if (count > 0)
            return count;
#endif
    }

    return boost::none;
}

int ProcessInfo::getVirtualMemorySize() {
    LinuxProc p(_pid);
    return (int)(p.getVirtualMemorySize() / (1024.0 * 1024));
}

int ProcessInfo::getResidentSize() {
    LinuxProc p(_pid);
    return (int)((p.getResidentSizeInPages() * getPageSize()) / (1024.0 * 1024));
}

double ProcessInfo::getSystemMemoryPressurePercentage() {
    return 0.0;
}

void ProcessInfo::getExtraInfo(BSONObjBuilder& info) {
    struct rusage ru;
    getrusage(RUSAGE_SELF, &ru);
    if (ru.ru_majflt <= std::numeric_limits<long long>::max())
        info.appendNumber("page_faults", static_cast<long long>(ru.ru_majflt));
    else
        info.appendNumber("page_faults", static_cast<double>(ru.ru_majflt));
}

/**
* Save a BSON obj representing the host system's details
*/
void ProcessInfo::SystemInfo::collectSystemInfo() {
    utsname unameData;
    string distroName, distroVersion;
    string cpuFreq, cpuFeatures;
    int cpuCount;

    string verSig = LinuxSysHelper::readLineFromFile("/proc/version_signature");
    LinuxSysHelper::getCpuInfo(cpuCount, cpuFreq, cpuFeatures);
    LinuxSysHelper::getLinuxDistro(distroName, distroVersion);

    if (uname(&unameData) == -1) {
        log() << "Unable to collect detailed system information: " << strerror(errno);
    }

    osType = "Linux";
    osName = distroName;
    osVersion = distroVersion;
    memSize = LinuxSysHelper::getSystemMemorySize();
    addrSize = sizeof(void*) * CHAR_BIT;
    numCores = cpuCount;
    pageSize = static_cast<unsigned long long>(sysconf(_SC_PAGESIZE));
    cpuArch = unameData.machine;
    hasNuma = checkNumaEnabled();

    BSONObjBuilder bExtra;
    bExtra.append("versionString", LinuxSysHelper::readLineFromFile("/proc/version"));
#ifdef __BIONIC__
    stringstream ss;
    ss << "bionic (android api " << __ANDROID_API__ << ")";
    bExtra.append("libcVersion", ss.str());
#elif __UCLIBC__
    stringstream ss;
    ss << "uClibc-" << __UCLIBC_MAJOR__ << "." << __UCLIBC_MINOR__ << "." << __UCLIBC_SUBLEVEL__;
    bExtra.append("libcVersion", ss.str());
#else
    bExtra.append("libcVersion", gnu_get_libc_version());
#endif
    if (!verSig.empty())
        // optional
        bExtra.append("versionSignature", verSig);

    bExtra.append("kernelVersion", unameData.release);
    bExtra.append("cpuFrequencyMHz", cpuFreq);
    bExtra.append("cpuFeatures", cpuFeatures);
    bExtra.append("pageSize", static_cast<long long>(pageSize));
    bExtra.append("numPages", static_cast<int>(sysconf(_SC_PHYS_PAGES)));
    bExtra.append("maxOpenFiles", static_cast<int>(sysconf(_SC_OPEN_MAX)));

    _extraStats = bExtra.obj();
}

/**
* Determine if the process is running with (cc)NUMA
*/
bool ProcessInfo::checkNumaEnabled() {
    bool hasMultipleNodes = false;
    bool hasNumaMaps = false;

    try {
        hasMultipleNodes = boost::filesystem::exists("/sys/devices/system/node/node1");
        hasNumaMaps = boost::filesystem::exists("/proc/self/numa_maps");
    } catch (boost::filesystem::filesystem_error& e) {
        log() << "WARNING: Cannot detect if NUMA interleaving is enabled. "
              << "Failed to probe \"" << e.path1().string() << "\": " << e.code().message();
        return false;
    }

    if (hasMultipleNodes && hasNumaMaps) {
        // proc is populated with numa entries

        // read the second column of first line to determine numa state
        // ('default' = enabled, 'interleave' = disabled).  Logic from version.cpp's warnings.
        string line = LinuxSysHelper::readLineFromFile("/proc/self/numa_maps").append(" \0");
        size_t pos = line.find(' ');
        if (pos != string::npos && line.substr(pos + 1, 10).find("interleave") == string::npos)
            // interleave not found;
            return true;
    }
    return false;
}

bool ProcessInfo::blockCheckSupported() {
    return true;
}

bool ProcessInfo::blockInMemory(const void* start) {
    unsigned char x = 0;
    if (mincore(const_cast<void*>(alignToStartOfPage(start)), getPageSize(), &x)) {
        log() << "mincore failed: " << errnoWithDescription();
        return 1;
    }
    return x & 0x1;
}

bool ProcessInfo::pagesInMemory(const void* start, size_t numPages, vector<char>* out) {
    out->resize(numPages);
    if (mincore(const_cast<void*>(alignToStartOfPage(start)),
                numPages * getPageSize(),
                reinterpret_cast<unsigned char*>(&out->front()))) {
        log() << "mincore failed: " << errnoWithDescription();
        return false;
    }
    for (size_t i = 0; i < numPages; ++i) {
        (*out)[i] &= 0x1;
    }
    return true;
}
}