分割されたApacheのログをマージする（C版）。This program merge divided Apache log.

aplogmerge.c

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <limits.h>

typedef struct preread {
  FILE* file;
  char *line_buf;
  int dt;
} t_preread;
char* month_str[] = {
  "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
int MAX_OF_LINE_LEN = 8192;
int MONTH_NUM = -1;

int process(int sz, t_preread* prs[], int pickup);
int is_left(int sz, t_preread* prs[]);
int parse_dt(const char* line);
int get_min(int sz, t_preread* prs[]);
int month_num(char* s);

int main(int argc, char** argv) {
  int sz = argc - 1;
  t_preread* prereads[sz];
  for (int i=0; i<sz; i++) {
    prereads[i] = (t_preread *)malloc(sizeof(t_preread));
    prereads[i]->file = fopen(argv[i+1], "r");
    prereads[i]->line_buf = malloc(sizeof(char*)*MAX_OF_LINE_LEN);
    if (NULL == fgets(prereads[i]->line_buf, MAX_OF_LINE_LEN, prereads[i]->file)) {
      prereads[i]->line_buf[0] = 0;
      prereads[i]->file = NULL;
      break;
    }
    prereads[i]->dt = parse_dt(prereads[i]->line_buf);
    prereads[i]->dt = 0;
  }
  int pickup = 0;
  do {
    pickup = process(sz, prereads, pickup);
  } while (is_left(sz, prereads));

  return 0;
}

int process(int sz, t_preread* prs[], int pickup) {
  t_preread* pr = prs[pickup];
  if (NULL != pr && 0 == pr->line_buf[0]) {
    int dt = -1;
    do {
      if (NULL == fgets(pr->line_buf, MAX_OF_LINE_LEN, pr->file)) {
	pr->line_buf[0] = 0;
	pr->file = NULL;
	break;
      }
      dt = parse_dt(pr->line_buf);
    } while (dt < 0);
    pr->dt = dt;
  }
  int min_idx = get_min(sz, prs);
  t_preread* min_pr = prs[min_idx];
  printf("%s", min_pr->line_buf);
  min_pr->line_buf[0] = 0;
  if (NULL == min_pr->file) {
    prs[min_idx] = NULL;
    return 0;
  }
  return min_idx;
}

int is_left(int sz, t_preread* prs[]) {
  for (int i=0; i<sz; i++) {
    if (NULL != prs[i]) return 1;
  }
  return 0;
}

int get_min(int sz, t_preread* prs[]) {
  int min = INT_MAX;
  int idx = 0;
  for (int i=0; i<sz; i++) {
    if (NULL == prs[i]) continue;
    if (min > prs[i]->dt) {
      min = prs[i]->dt;
      idx = i;
    }
  }
  return idx;
}

int find_dt_parts(char** p, int idx) {
  char buf[5];
  int i = 0;
  for (i=0; i<4; i++) {
    if (!isalnum(**p)) break;
    buf[i] = **p;
    (*p)++;
  }
  (*p)++;
  buf[i] = 0;
  if ('0' <= buf[0] && buf[0] <= '9') {
    return atoi(buf);
  } else {
    if (MONTH_NUM < 0) MONTH_NUM = month_num(buf);
    return MONTH_NUM;
  }
  return -1;
}

int month_num(char* s) {
  for (int j=0; j<12; j++) {
    if (0 == memcmp(s, month_str[j], 3)) {
      return j;
    }
  }
  return -1;
}

int parse_dt(const char* line) {
  char* st = strchr(line, '[');
  char* ed = strchr(line, ' ');
  if (NULL == st || NULL == ed) return -1;
  char* c = NULL;
  int dt = 0;
  st++;
  int d = atoi(st); st += 3;
  if (MONTH_NUM < 0) MONTH_NUM = month_num(st); //インチキだけど、ちょっとでも速く…
  int m = MONTH_NUM; st += 4;
  int y = atoi(st)-2000; st += 5;
  int h = atoi(st); st += 3;
  int M = atoi(st); st += 3;
  int s = atoi(st);
  return (y*365 + m*31 + d)*86400 + h*3600 + M*60 + s;
}

10mの処理が7mと若干早くなるだけ（-ω-）
書きなおした意味ね〜