busybox/procps/nmeter.c

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/*
* Licensed under GPLv2, see file LICENSE in this source tree.
*
* Based on nanotop.c from floppyfw project
*
* Contact me: vda.linux@googlemail.com
*/
//config:config NMETER
//config: bool "nmeter"
//config: default y
//config: help
//config: Prints selected system stats continuously, one line per update.
//applet:IF_NMETER(APPLET(nmeter, _BB_DIR_USR_BIN, _BB_SUID_DROP))
//kbuild:lib-$(CONFIG_NMETER) += nmeter.o
//usage:#define nmeter_trivial_usage
//usage: "[-d MSEC] FORMAT_STRING"
//usage:#define nmeter_full_usage "\n\n"
//usage: "Monitor system in real time"
//usage: "\n"
//usage: "\n -d MSEC Milliseconds between updates (default:1000)"
//usage: "\n"
//usage: "\nFormat specifiers:"
//usage: "\n %Nc or %[cN] Monitor CPU. N - bar size (default:10)"
//usage: "\n (displays: S:system U:user N:niced D:iowait I:irq i:softirq)"
//usage: "\n %[niface] Monitor network interface 'iface'"
//usage: "\n %m Monitor allocated memory"
//usage: "\n %[mf] Monitor free memory"
//usage: "\n %[mt] Monitor total memory"
//usage: "\n %s Monitor allocated swap"
//usage: "\n %f Monitor number of used file descriptors"
//usage: "\n %Ni Monitor total/specific IRQ rate"
//usage: "\n %x Monitor context switch rate"
//usage: "\n %p Monitor forks"
//usage: "\n %[pn] Monitor # of processes"
//usage: "\n %b Monitor block io"
//usage: "\n %Nt Show time (with N decimal points)"
//usage: "\n %r Print <cr> instead of <lf> at EOL"
//TODO:
// simplify code
// /proc/locks
// /proc/stat:
// disk_io: (3,0):(22272,17897,410702,4375,54750)
// btime 1059401962
//TODO: use sysinfo libc call/syscall, if appropriate
// (faster than open/read/close):
// sysinfo({uptime=15017, loads=[5728, 15040, 16480]
// totalram=2107416576, freeram=211525632, sharedram=0, bufferram=157204480}
// totalswap=134209536, freeswap=134209536, procs=157})
#include "libbb.h"
typedef unsigned long long ullong;
enum { /* Preferably use powers of 2 */
PROC_MIN_FILE_SIZE = 256,
PROC_MAX_FILE_SIZE = 16 * 1024,
};
typedef struct proc_file {
char *file;
int file_sz;
smallint last_gen;
} proc_file;
static const char *const proc_name[] = {
"stat", // Must match the order of proc_file's!
"loadavg",
"net/dev",
"meminfo",
"diskstats",
"sys/fs/file-nr"
};
struct globals {
// Sample generation flip-flop
smallint gen;
// Linux 2.6? (otherwise assumes 2.4)
smallint is26;
// 1 if sample delay is not an integer fraction of a second
smallint need_seconds;
char *cur_outbuf;
const char *final_str;
int delta;
int deltanz;
struct timeval tv;
#define first_proc_file proc_stat
proc_file proc_stat; // Must match the order of proc_name's!
proc_file proc_loadavg;
proc_file proc_net_dev;
proc_file proc_meminfo;
proc_file proc_diskstats;
proc_file proc_sys_fs_filenr;
};
#define G (*ptr_to_globals)
#define gen (G.gen )
#define is26 (G.is26 )
#define need_seconds (G.need_seconds )
#define cur_outbuf (G.cur_outbuf )
#define final_str (G.final_str )
#define delta (G.delta )
#define deltanz (G.deltanz )
#define tv (G.tv )
#define proc_stat (G.proc_stat )
#define proc_loadavg (G.proc_loadavg )
#define proc_net_dev (G.proc_net_dev )
#define proc_meminfo (G.proc_meminfo )
#define proc_diskstats (G.proc_diskstats )
#define proc_sys_fs_filenr (G.proc_sys_fs_filenr)
#define INIT_G() do { \
SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
cur_outbuf = outbuf; \
final_str = "\n"; \
deltanz = delta = 1000000; \
} while (0)
// We depend on this being a char[], not char* - we take sizeof() of it
#define outbuf bb_common_bufsiz1
static inline void reset_outbuf(void)
{
cur_outbuf = outbuf;
}
static inline int outbuf_count(void)
{
return cur_outbuf - outbuf;
}
static void print_outbuf(void)
{
int sz = cur_outbuf - outbuf;
if (sz > 0) {
xwrite(STDOUT_FILENO, outbuf, sz);
cur_outbuf = outbuf;
}
}
static void put(const char *s)
{
int sz = strlen(s);
if (sz > outbuf + sizeof(outbuf) - cur_outbuf)
sz = outbuf + sizeof(outbuf) - cur_outbuf;
memcpy(cur_outbuf, s, sz);
cur_outbuf += sz;
}
static void put_c(char c)
{
if (cur_outbuf < outbuf + sizeof(outbuf))
*cur_outbuf++ = c;
}
static void put_question_marks(int count)
{
while (count--)
put_c('?');
}
static void readfile_z(proc_file *pf, const char* fname)
{
// open_read_close() will do two reads in order to be sure we are at EOF,
// and we don't need/want that.
int fd;
int sz, rdsz;
char *buf;
sz = pf->file_sz;
buf = pf->file;
if (!buf) {
buf = xmalloc(PROC_MIN_FILE_SIZE);
sz = PROC_MIN_FILE_SIZE;
}
again:
fd = xopen(fname, O_RDONLY);
buf[0] = '\0';
rdsz = read(fd, buf, sz-1);
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close(fd);
if (rdsz > 0) {
if (rdsz == sz-1 && sz < PROC_MAX_FILE_SIZE) {
sz *= 2;
buf = xrealloc(buf, sz);
goto again;
}
buf[rdsz] = '\0';
}
pf->file_sz = sz;
pf->file = buf;
}
static const char* get_file(proc_file *pf)
{
if (pf->last_gen != gen) {
pf->last_gen = gen;
readfile_z(pf, proc_name[pf - &first_proc_file]);
}
return pf->file;
}
static ullong read_after_slash(const char *p)
{
p = strchr(p, '/');
if (!p) return 0;
return strtoull(p+1, NULL, 10);
}
enum conv_type { conv_decimal, conv_slash };
// Reads decimal values from line. Values start after key, for example:
// "cpu 649369 0 341297 4336769..." - key is "cpu" here.
// Values are stored in vec[]. arg_ptr has list of positions
// we are interested in: for example: 1,2,5 - we want 1st, 2nd and 5th value.
static int vrdval(const char* p, const char* key,
enum conv_type conv, ullong *vec, va_list arg_ptr)
{
int indexline;
int indexnext;
p = strstr(p, key);
if (!p) return 1;
p += strlen(key);
indexline = 1;
indexnext = va_arg(arg_ptr, int);
while (1) {
while (*p == ' ' || *p == '\t') p++;
if (*p == '\n' || *p == '\0') break;
if (indexline == indexnext) { // read this value
*vec++ = conv==conv_decimal ?
strtoull(p, NULL, 10) :
read_after_slash(p);
indexnext = va_arg(arg_ptr, int);
}
while (*p > ' ') p++; // skip over value
indexline++;
}
return 0;
}
// Parses files with lines like "cpu0 21727 0 15718 1813856 9461 10485 0 0":
// rdval(file_contents, "string_to_find", result_vector, value#, value#...)
// value# start with 1
static int rdval(const char* p, const char* key, ullong *vec, ...)
{
va_list arg_ptr;
int result;
va_start(arg_ptr, vec);
result = vrdval(p, key, conv_decimal, vec, arg_ptr);
va_end(arg_ptr);
return result;
}
// Parses files with lines like "... ... ... 3/148 ...."
static int rdval_loadavg(const char* p, ullong *vec, ...)
{
va_list arg_ptr;
int result;
va_start(arg_ptr, vec);
result = vrdval(p, "", conv_slash, vec, arg_ptr);
va_end(arg_ptr);
return result;
}
// Parses /proc/diskstats
// 1 2 3 4 5 6(rd) 7 8 9 10(wr) 11 12 13 14
// 3 0 hda 51292 14441 841783 926052 25717 79650 843256 3029804 0 148459 3956933
// 3 1 hda1 0 0 0 0 <- ignore if only 4 fields
static int rdval_diskstats(const char* p, ullong *vec)
{
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ullong rd = rd; // for compiler
int indexline = 0;
vec[0] = 0;
vec[1] = 0;
while (1) {
indexline++;
while (*p == ' ' || *p == '\t') p++;
if (*p == '\0') break;
if (*p == '\n') {
indexline = 0;
p++;
continue;
}
if (indexline == 6) {
rd = strtoull(p, NULL, 10);
} else if (indexline == 10) {
vec[0] += rd; // TODO: *sectorsize (don't know how to find out sectorsize)
vec[1] += strtoull(p, NULL, 10);
while (*p != '\n' && *p != '\0') p++;
continue;
}
while (*p > ' ') p++; // skip over value
}
return 0;
}
static void scale(ullong ul)
{
char buf[5];
/* see http://en.wikipedia.org/wiki/Tera */
smart_ulltoa4(ul, buf, " kmgtpezy");
buf[4] = '\0';
put(buf);
}
#define S_STAT(a) \
typedef struct a { \
struct s_stat *next; \
void (*collect)(struct a *s) FAST_FUNC; \
const char *label;
#define S_STAT_END(a) } a;
S_STAT(s_stat)
S_STAT_END(s_stat)
static void FAST_FUNC collect_literal(s_stat *s UNUSED_PARAM)
{
}
static s_stat* init_literal(void)
{
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s_stat *s = xzalloc(sizeof(*s));
s->collect = collect_literal;
return (s_stat*)s;
}
static s_stat* init_delay(const char *param)
{
delta = strtoul(param, NULL, 0) * 1000; /* param can be "" */
deltanz = delta > 0 ? delta : 1;
need_seconds = (1000000%deltanz) != 0;
return NULL;
}
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static s_stat* init_cr(const char *param UNUSED_PARAM)
{
final_str = "\r";
return (s_stat*)0;
}
// user nice system idle iowait irq softirq (last 3 only in 2.6)
//cpu 649369 0 341297 4336769 11640 7122 1183
//cpuN 649369 0 341297 4336769 11640 7122 1183
enum { CPU_FIELDCNT = 7 };
S_STAT(cpu_stat)
ullong old[CPU_FIELDCNT];
int bar_sz;
char *bar;
S_STAT_END(cpu_stat)
static void FAST_FUNC collect_cpu(cpu_stat *s)
{
ullong data[CPU_FIELDCNT] = { 0, 0, 0, 0, 0, 0, 0 };
unsigned frac[CPU_FIELDCNT] = { 0, 0, 0, 0, 0, 0, 0 };
ullong all = 0;
int norm_all = 0;
int bar_sz = s->bar_sz;
char *bar = s->bar;
int i;
if (rdval(get_file(&proc_stat), "cpu ", data, 1, 2, 3, 4, 5, 6, 7)) {
put_question_marks(bar_sz);
return;
}
for (i = 0; i < CPU_FIELDCNT; i++) {
ullong old = s->old[i];
if (data[i] < old) old = data[i]; //sanitize
s->old[i] = data[i];
all += (data[i] -= old);
}
if (all) {
for (i = 0; i < CPU_FIELDCNT; i++) {
ullong t = bar_sz * data[i];
norm_all += data[i] = t / all;
frac[i] = t % all;
}
while (norm_all < bar_sz) {
unsigned max = frac[0];
int pos = 0;
for (i = 1; i < CPU_FIELDCNT; i++) {
if (frac[i] > max) max = frac[i], pos = i;
}
frac[pos] = 0; //avoid bumping up same value twice
data[pos]++;
norm_all++;
}
memset(bar, '.', bar_sz);
memset(bar, 'S', data[2]); bar += data[2]; //sys
memset(bar, 'U', data[0]); bar += data[0]; //usr
memset(bar, 'N', data[1]); bar += data[1]; //nice
memset(bar, 'D', data[4]); bar += data[4]; //iowait
memset(bar, 'I', data[5]); bar += data[5]; //irq
memset(bar, 'i', data[6]); bar += data[6]; //softirq
} else {
memset(bar, '?', bar_sz);
}
put(s->bar);
}
static s_stat* init_cpu(const char *param)
{
int sz;
cpu_stat *s = xzalloc(sizeof(*s));
s->collect = collect_cpu;
sz = strtoul(param, NULL, 0); /* param can be "" */
if (sz < 10) sz = 10;
if (sz > 1000) sz = 1000;
s->bar = xzalloc(sz+1);
/*s->bar[sz] = '\0'; - xzalloc did it */
s->bar_sz = sz;
return (s_stat*)s;
}
S_STAT(int_stat)
ullong old;
int no;
S_STAT_END(int_stat)
static void FAST_FUNC collect_int(int_stat *s)
{
ullong data[1];
ullong old;
if (rdval(get_file(&proc_stat), "intr", data, s->no)) {
put_question_marks(4);
return;
}
old = s->old;
if (data[0] < old) old = data[0]; //sanitize
s->old = data[0];
scale(data[0] - old);
}
static s_stat* init_int(const char *param)
{
int_stat *s = xzalloc(sizeof(*s));
s->collect = collect_int;
if (param[0] == '\0') {
s->no = 1;
} else {
int n = xatoi_positive(param);
s->no = n + 2;
}
return (s_stat*)s;
}
S_STAT(ctx_stat)
ullong old;
S_STAT_END(ctx_stat)
static void FAST_FUNC collect_ctx(ctx_stat *s)
{
ullong data[1];
ullong old;
if (rdval(get_file(&proc_stat), "ctxt", data, 1)) {
put_question_marks(4);
return;
}
old = s->old;
if (data[0] < old) old = data[0]; //sanitize
s->old = data[0];
scale(data[0] - old);
}
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static s_stat* init_ctx(const char *param UNUSED_PARAM)
{
ctx_stat *s = xzalloc(sizeof(*s));
s->collect = collect_ctx;
return (s_stat*)s;
}
S_STAT(blk_stat)
const char* lookfor;
ullong old[2];
S_STAT_END(blk_stat)
static void FAST_FUNC collect_blk(blk_stat *s)
{
ullong data[2];
int i;
if (is26) {
i = rdval_diskstats(get_file(&proc_diskstats), data);
} else {
i = rdval(get_file(&proc_stat), s->lookfor, data, 1, 2);
// Linux 2.4 reports bio in Kbytes, convert to sectors:
data[0] *= 2;
data[1] *= 2;
}
if (i) {
put_question_marks(9);
return;
}
for (i=0; i<2; i++) {
ullong old = s->old[i];
if (data[i] < old) old = data[i]; //sanitize
s->old[i] = data[i];
data[i] -= old;
}
scale(data[0]*512); // TODO: *sectorsize
put_c(' ');
scale(data[1]*512);
}
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static s_stat* init_blk(const char *param UNUSED_PARAM)
{
blk_stat *s = xzalloc(sizeof(*s));
s->collect = collect_blk;
s->lookfor = "page";
return (s_stat*)s;
}
S_STAT(fork_stat)
ullong old;
S_STAT_END(fork_stat)
static void FAST_FUNC collect_thread_nr(fork_stat *s UNUSED_PARAM)
{
ullong data[1];
if (rdval_loadavg(get_file(&proc_loadavg), data, 4)) {
put_question_marks(4);
return;
}
scale(data[0]);
}
static void FAST_FUNC collect_fork(fork_stat *s)
{
ullong data[1];
ullong old;
if (rdval(get_file(&proc_stat), "processes", data, 1)) {
put_question_marks(4);
return;
}
old = s->old;
if (data[0] < old) old = data[0]; //sanitize
s->old = data[0];
scale(data[0] - old);
}
static s_stat* init_fork(const char *param)
{
fork_stat *s = xzalloc(sizeof(*s));
if (*param == 'n') {
s->collect = collect_thread_nr;
} else {
s->collect = collect_fork;
}
return (s_stat*)s;
}
S_STAT(if_stat)
ullong old[4];
const char *device;
char *device_colon;
S_STAT_END(if_stat)
static void FAST_FUNC collect_if(if_stat *s)
{
ullong data[4];
int i;
if (rdval(get_file(&proc_net_dev), s->device_colon, data, 1, 3, 9, 11)) {
put_question_marks(10);
return;
}
for (i=0; i<4; i++) {
ullong old = s->old[i];
if (data[i] < old) old = data[i]; //sanitize
s->old[i] = data[i];
data[i] -= old;
}
put_c(data[1] ? '*' : ' ');
scale(data[0]);
put_c(data[3] ? '*' : ' ');
scale(data[2]);
}
static s_stat* init_if(const char *device)
{
if_stat *s = xzalloc(sizeof(*s));
if (!device || !device[0])
bb_show_usage();
s->collect = collect_if;
s->device = device;
s->device_colon = xasprintf("%s:", device);
return (s_stat*)s;
}
S_STAT(mem_stat)
char opt;
S_STAT_END(mem_stat)
// "Memory" value should not include any caches.
// IOW: neither "ls -laR /" nor heavy read/write activity
// should affect it. We'd like to also include any
// long-term allocated kernel-side mem, but it is hard
// to figure out. For now, bufs, cached & slab are
// counted as "free" memory
//2.6.16:
//MemTotal: 773280 kB
//MemFree: 25912 kB - genuinely free
//Buffers: 320672 kB - cache
//Cached: 146396 kB - cache
//SwapCached: 0 kB
//Active: 183064 kB
//Inactive: 356892 kB
//HighTotal: 0 kB
//HighFree: 0 kB
//LowTotal: 773280 kB
//LowFree: 25912 kB
//SwapTotal: 131064 kB
//SwapFree: 131064 kB
//Dirty: 48 kB
//Writeback: 0 kB
//Mapped: 96620 kB
//Slab: 200668 kB - takes 7 Mb on my box fresh after boot,
// but includes dentries and inodes
// (== can take arbitrary amount of mem)
//CommitLimit: 517704 kB
//Committed_AS: 236776 kB
//PageTables: 1248 kB
//VmallocTotal: 516052 kB
//VmallocUsed: 3852 kB
//VmallocChunk: 512096 kB
//HugePages_Total: 0
//HugePages_Free: 0
//Hugepagesize: 4096 kB
static void FAST_FUNC collect_mem(mem_stat *s)
{
ullong m_total = 0;
ullong m_free = 0;
ullong m_bufs = 0;
ullong m_cached = 0;
ullong m_slab = 0;
if (rdval(get_file(&proc_meminfo), "MemTotal:", &m_total, 1)) {
put_question_marks(4);
return;
}
if (s->opt == 't') {
scale(m_total << 10);
return;
}
if (rdval(proc_meminfo.file, "MemFree:", &m_free , 1)
|| rdval(proc_meminfo.file, "Buffers:", &m_bufs , 1)
|| rdval(proc_meminfo.file, "Cached:", &m_cached, 1)
|| rdval(proc_meminfo.file, "Slab:", &m_slab , 1)
) {
put_question_marks(4);
return;
}
m_free += m_bufs + m_cached + m_slab;
switch (s->opt) {
case 'f':
scale(m_free << 10); break;
default:
scale((m_total - m_free) << 10); break;
}
}
static s_stat* init_mem(const char *param)
{
mem_stat *s = xzalloc(sizeof(*s));
s->collect = collect_mem;
s->opt = param[0];
return (s_stat*)s;
}
S_STAT(swp_stat)
S_STAT_END(swp_stat)
static void FAST_FUNC collect_swp(swp_stat *s UNUSED_PARAM)
{
ullong s_total[1];
ullong s_free[1];
if (rdval(get_file(&proc_meminfo), "SwapTotal:", s_total, 1)
|| rdval(proc_meminfo.file, "SwapFree:" , s_free, 1)
) {
put_question_marks(4);
return;
}
scale((s_total[0]-s_free[0]) << 10);
}
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static s_stat* init_swp(const char *param UNUSED_PARAM)
{
swp_stat *s = xzalloc(sizeof(*s));
s->collect = collect_swp;
return (s_stat*)s;
}
S_STAT(fd_stat)
S_STAT_END(fd_stat)
static void FAST_FUNC collect_fd(fd_stat *s UNUSED_PARAM)
{
ullong data[2];
if (rdval(get_file(&proc_sys_fs_filenr), "", data, 1, 2)) {
put_question_marks(4);
return;
}
scale(data[0] - data[1]);
}
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static s_stat* init_fd(const char *param UNUSED_PARAM)
{
fd_stat *s = xzalloc(sizeof(*s));
s->collect = collect_fd;
return (s_stat*)s;
}
S_STAT(time_stat)
int prec;
int scale;
S_STAT_END(time_stat)
static void FAST_FUNC collect_time(time_stat *s)
{
char buf[sizeof("12:34:56.123456")];
struct tm* tm;
int us = tv.tv_usec + s->scale/2;
time_t t = tv.tv_sec;
if (us >= 1000000) {
t++;
us -= 1000000;
}
tm = localtime(&t);
sprintf(buf, "%02d:%02d:%02d", tm->tm_hour, tm->tm_min, tm->tm_sec);
if (s->prec)
sprintf(buf+8, ".%0*d", s->prec, us / s->scale);
put(buf);
}
static s_stat* init_time(const char *param)
{
int prec;
time_stat *s = xzalloc(sizeof(*s));
s->collect = collect_time;
prec = param[0] - '0';
if (prec < 0) prec = 0;
else if (prec > 6) prec = 6;
s->prec = prec;
s->scale = 1;
while (prec++ < 6)
s->scale *= 10;
return (s_stat*)s;
}
static void FAST_FUNC collect_info(s_stat *s)
{
gen ^= 1;
while (s) {
put(s->label);
s->collect(s);
s = s->next;
}
}
typedef s_stat* init_func(const char *param);
// Deprecated %NNNd is to be removed, -d MSEC supersedes it
static const char options[] ALIGN1 = "ncmsfixptbdr";
static init_func *const init_functions[] = {
init_if,
init_cpu,
init_mem,
init_swp,
init_fd,
init_int,
init_ctx,
init_fork,
init_time,
init_blk,
init_delay,
init_cr
};
int nmeter_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nmeter_main(int argc UNUSED_PARAM, char **argv)
{
char buf[32];
s_stat *first = NULL;
s_stat *last = NULL;
s_stat *s;
char *opt_d;
char *cur, *prev;
INIT_G();
xchdir("/proc");
if (open_read_close("version", buf, sizeof(buf)-1) > 0) {
buf[sizeof(buf)-1] = '\0';
is26 = (strstr(buf, " 2.4.") == NULL);
}
if (getopt32(argv, "d:", &opt_d))
init_delay(opt_d);
argv += optind;
if (!argv[0])
bb_show_usage();
// Can use argv[0] directly, but this will mess up
// parameters as seen by e.g. ps. Making a copy...
cur = xstrdup(argv[0]);
while (1) {
char *param, *p;
prev = cur;
again:
cur = strchr(cur, '%');
if (!cur)
break;
if (cur[1] == '%') { // %%
overlapping_strcpy(cur, cur + 1);
cur++;
goto again;
}
*cur++ = '\0'; // overwrite %
if (cur[0] == '[') {
// format: %[foptstring]
cur++;
p = strchr(options, cur[0]);
param = cur+1;
while (cur[0] != ']') {
if (!cur[0])
bb_show_usage();
cur++;
}
*cur++ = '\0'; // overwrite [
} else {
// format: %NNNNNNf
param = cur;
while (cur[0] >= '0' && cur[0] <= '9')
cur++;
if (!cur[0])
bb_show_usage();
p = strchr(options, cur[0]);
*cur++ = '\0'; // overwrite format char
}
if (!p)
bb_show_usage();
s = init_functions[p-options](param);
if (s) {
s->label = prev;
/*s->next = NULL; - all initXXX funcs use xzalloc */
if (!first)
first = s;
else
last->next = s;
last = s;
} else {
// %NNNNd or %r option. remove it from string
strcpy(prev + strlen(prev), cur);
cur = prev;
}
}
if (prev[0]) {
s = init_literal();
s->label = prev;
/*s->next = NULL; - all initXXX funcs use xzalloc */
if (!first)
first = s;
else
last->next = s;
last = s;
}
// Generate first samples but do not print them, they're bogus
collect_info(first);
reset_outbuf();
if (delta >= 0) {
gettimeofday(&tv, NULL);
usleep(delta > 1000000 ? 1000000 : delta - tv.tv_usec%deltanz);
}
while (1) {
gettimeofday(&tv, NULL);
collect_info(first);
put(final_str);
print_outbuf();
// Negative delta -> no usleep at all
// This will hog the CPU but you can have REALLY GOOD
// time resolution ;)
// TODO: detect and avoid useless updates
// (like: nothing happens except time)
if (delta >= 0) {
int rem;
// can be commented out, will sacrifice sleep time precision a bit
gettimeofday(&tv, NULL);
if (need_seconds)
rem = delta - ((ullong)tv.tv_sec*1000000 + tv.tv_usec) % deltanz;
else
rem = delta - tv.tv_usec%deltanz;
// Sometimes kernel wakes us up just a tiny bit earlier than asked
// Do not go to very short sleep in this case
if (rem < delta/128) {
rem += delta;
}
usleep(rem);
}
}
/*return 0;*/
}