A new implementation of Node's Platform::GetMemory (in src/platform_linux.cc)

nodejs_rss_vsize.c

/* A new implementation of Node's Platform::GetMemory (in src/platform_linux.cc) */
/* Copyright (c) 2011 Olivier Mengué */

#include <stdlib.h>
#include <stdio.h>
#include <sys/param.h> // MAXPATHLEN

#include <fcntl.h>     // O_RDONLY

#include <sys/time.h>  // gettimeofday

typedef enum {
  false = 0,
  true = 1
} bool;
static char buf[MAXPATHLEN + 1];


// From NodeJs: src/platform_linux.cc
int GetMemory(size_t *rss, size_t *vsize) {
  FILE *f = fopen("/proc/self/stat", "r");
  if (!f) return -1;

  int itmp;
  char ctmp;
  size_t page_size = getpagesize();
  char *cbuf;
  bool foundExeEnd;

  /* PID */
  if (fscanf(f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Exec file */
  cbuf = buf;
  foundExeEnd = false;
  if (fscanf (f, "%c", cbuf++) == 0) goto error; // (
  while (1) {
    if (fscanf(f, "%c", cbuf) == 0) goto error;
    if (*cbuf == ')') {
      foundExeEnd = true;
    } else if (foundExeEnd && *cbuf == ' ') {
      *cbuf = 0;
      break;
    }

    cbuf++;
  }
  /* State */
  if (fscanf (f, "%c ", &ctmp) == 0) goto error; /* coverity[secure_coding] */
  /* Parent process */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Process group */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Session id */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* TTY */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* TTY owner process group */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Flags */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Minor faults (no memory page) */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Minor faults, children */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Major faults (memory page faults) */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Major faults, children */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* utime */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* stime */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* utime, children */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* stime, children */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* jiffies remaining in current time slice */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* 'nice' value */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* jiffies until next timeout */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* jiffies until next SIGALRM */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* start time (jiffies since system boot) */
  if (fscanf (f, "%d ", &itmp) == 0) goto error; /* coverity[secure_coding] */

  /* Virtual memory size */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  *vsize = (size_t) itmp;

  /* Resident set size */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  *rss = (size_t) itmp * page_size;

  /* rlim */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Start of text */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* End of text */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */
  /* Start of stack */
  if (fscanf (f, "%u ", &itmp) == 0) goto error; /* coverity[secure_coding] */

  fclose (f);

  return 0;

error:
  fclose (f);
  return -1;
}


int GetMemory2(size_t *rss, size_t *vsize) {
  // See proc(5) manual
  FILE *f = fopen("/proc/self/stat", "r");
  if (!f) return -1;

  int i;
  int c;

  // skip pid
  c = fgetc(f);
  if (c < '1' || c > '9') goto error;
  do {
      if ((c = fgetc(f)) == EOF) goto error;
  } while (c >= '0' && c <= '9');
  if (c != ' ') goto error;
  if ((c = fgetc(f)) == EOF || c != '(') goto error;

  // skip process name
  do {
    if ((c = fgetc(f)) == EOF) goto error;
  } while (c != ')');
  if ((c = fgetc(f)) == EOF || c != ' ') goto error;

  // skip 20 columns
  for(i=0; i<20; i++) {
    do {
      if ((c = fgetc(f)) == EOF) goto error;
      if (c == ')') goto error; // the process name breaks parsing
    } while (c != ' ');
  }

  // read vsize
  size_t value = 0;
  while (1) {
    if ((c = fgetc(f)) == EOF) goto error;
    if (c == ' ') break;
    if (c < '0' || c > '9') goto error;
    value = value * 10 + (c - '0');
  }
  *vsize = value;

  // read rss
  value = 0;
  while (1) {
    if ((c = fgetc(f)) == EOF) goto error;
    if (c == ' ') break;
    if (c < '0' || c > '9') goto error;
    value = value * 10 + (c - '0');
  }
  *rss = value * getpagesize();

  fclose(f);
  return 0;

error:
  *rss = *vsize = 0;
  fclose(f);
  return -1;
}



int GetMemory3(size_t *rss, size_t *vsize) {
  // See proc(5) manual
  int fd = open("/proc/self/stat", O_RDONLY);
  if (fd < 0) return -1;

  char buf[512];
  ssize_t len = read(fd, buf, sizeof(buf));
  close(fd);

  if (len == sizeof(buf))
    buf[sizeof(buf)-1] = '\n';
  if (len <= 0 || buf[len-1] != '\n') goto error;
  //if (len < 40) goto error;

  char *p = buf;

  if (*p < '1' || *p > '9') goto error;
  do {
      if (*++p == '\n') goto error;
  } while (*p >= '0' && *p <= '9');
  if (*p != ' ') goto error;
  if (*++p != '(') goto error;

  // skip process name
  do {
    if (*++p == '\n') goto error;
  } while (*p != ')');
  if (*++p != ' ') goto error;

  // skip 20 columns
  int i;
  for(i=0; i<20; i++) {
    do {
      if (*++p == '\n') goto error;
      if (*p == ')') goto error; // the process name breaks parsing
    } while (*p != ' ');
  }

  // read vsize
  size_t value = 0;
  int c;
  while (1) {
    c = *++p;
    if (c == ' ') break;
    if (c < '0' || c > '9') goto error;
    value = value * 10 + (c - '0');
  }
  *vsize = value;

  // read rss
  value = 0;
  while (1) {
    c = *++p;
    if (c == ' ') break;
    if (c < '0' || c > '9') goto error;
    value = value * 10 + (c - '0');
  }
  *rss = value * getpagesize();

  return 0;

error:
  *rss = *vsize = 0;
  return -1;
}



typedef int (*GetMemory_func)(size_t *rss, size_t *vsize);


void test(GetMemory_func func)
{
  struct timeval start, stop, diff;
  size_t rss = 0, vsize = 0;

  gettimeofday(&start, NULL);
  int res = GetMemory(&rss, &vsize);
      res = GetMemory(&rss, &vsize);
      res = GetMemory(&rss, &vsize);
  gettimeofday(&stop, NULL);

  time_t sec = stop.tv_sec  - start.tv_sec;
  int usec   = (int)stop.tv_usec - (int)start.tv_usec;
  if (usec < 0) {
    sec--;
    usec += 1000000;
  }

  printf("%ld.%06d res = %d, rss = %zd, vsize = %zd\n", sec, usec, res, rss, vsize);
}




int main() {

  FILE *f = fopen("/proc/self/stat", "r");
  char s[2048];
  fputs(fgets(s, sizeof(s), f), stdout);
  fclose(f);

  test(GetMemory);

  test(GetMemory);
  test(GetMemory2);
  test(GetMemory3);

  void * p = malloc(10*1024*1024);

  test(GetMemory);
  test(GetMemory2);
  test(GetMemory3);
}