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sys: change PidStat API
Rather than standalone functions, `PidStat` now provides a `read_for_pid` and `parse` method. Both are public. One side effect is that the documentation of PidStat's contents are on the same page as the ways to retrieve it. Additionally, we deprecate `read_proc_starttime` as it was reading the entire contents to then filter out one value, in order to promote caching. The standalone `read_proc_pid_stat` method is now also deprecated. Once we add pid-fds the API will feel cleaner this way. Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
This commit is contained in:
Wolfgang Bumiller
parent
e3b41dc815
commit
42a155668e
@ -26,6 +26,7 @@ lazy_static! {
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static ref CLOCK_TICKS: f64 = sysconf(libc::_SC_CLK_TCK) as f64;
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}
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/// Selected contents of the `/proc/PID/stat` file.
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pub struct PidStat {
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pub pid: Pid,
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pub ppid: Pid,
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@ -38,84 +39,94 @@ pub struct PidStat {
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pub rss: i64,
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}
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pub fn read_proc_pid_stat(pid: libc::pid_t) -> Result<PidStat, Error> {
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let stat = parse_proc_pid_stat(std::str::from_utf8(&std::fs::read(format!(
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"/proc/{}/stat",
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pid
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))?)?)?;
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if stat.pid.as_raw() != pid {
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bail!(
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"unexpected pid for process: found pid {} in /proc/{}/stat",
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stat.pid.as_raw(),
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impl PidStat {
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/// Retrieve the `stat` file contents of a process.
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pub fn read_for_pid(pid: Pid) -> Result<Self, Error> {
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let stat = Self::parse(std::str::from_utf8(&std::fs::read(format!(
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"/proc/{}/stat",
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pid
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);
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))?)?)?;
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if stat.pid != pid {
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bail!(
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"unexpected pid for process: found pid {} in /proc/{}/stat",
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stat.pid.as_raw(),
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pid
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);
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}
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Ok(stat)
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}
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/// Parse the contents of a `/proc/PID/stat` file.
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pub fn parse(statstr: &str) -> Result<PidStat, Error> {
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// It starts with the pid followed by a '('.
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let cmdbeg = statstr
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.find('(')
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.ok_or_else(|| format_err!("missing '(' in /proc/PID/stat"))?;
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if !statstr[..=cmdbeg].ends_with(" (") {
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bail!("bad /proc/PID/stat line before the '('");
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}
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let pid: u32 = statstr[..(cmdbeg - 1)]
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.parse()
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.map_err(|e| format_err!("bad pid in /proc/PID/stat: {}", e))?;
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let pid = Pid::from_raw(pid as i32);
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// After the '(' we have an arbitrary command name, then ')' and the remaining values
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let cmdend = statstr
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.rfind(')')
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.ok_or_else(|| format_err!("missing ')' in /proc/PID/stat"))?;
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let mut parts = statstr[cmdend + 1..].trim_start().split_ascii_whitespace();
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// helpers:
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fn required<'a>(value: Option<&'a str>, what: &'static str) -> Result<&'a str, Error> {
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value.ok_or_else(|| format_err!("missing '{}' in /proc/PID/stat", what))
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}
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fn req_num<T>(value: Option<&str>, what: &'static str) -> Result<T, Error>
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where
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T: FromStr,
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<T as FromStr>::Err: Into<Error>,
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{
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required(value, what)?.parse::<T>().map_err(|e| e.into())
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}
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fn req_byte(value: Option<&str>, what: &'static str) -> Result<u8, Error> {
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let value = required(value, what)?;
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if value.len() != 1 {
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bail!("invalid '{}' in /proc/PID/stat", what);
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}
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Ok(value.as_bytes()[0])
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}
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let out = PidStat {
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pid,
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status: req_byte(parts.next(), "status")?,
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ppid: Pid::from_raw(req_num::<u32>(parts.next(), "ppid")? as i32),
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utime: req_num::<u64>(parts.nth(9), "utime")?,
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stime: req_num::<u64>(parts.next(), "stime")?,
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num_threads: req_num::<u64>(parts.nth(4), "num_threads")?,
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starttime: req_num::<u64>(parts.nth(1), "start_time")?,
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vsize: req_num::<u64>(parts.next(), "vsize")?,
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rss: req_num::<i64>(parts.next(), "rss")? * 4096,
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};
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let _ = req_num::<u64>(parts.next(), "it_real_value")?;
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// and more...
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Ok(out)
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}
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Ok(stat)
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}
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fn parse_proc_pid_stat(statstr: &str) -> Result<PidStat, Error> {
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// It starts with the pid followed by a '('.
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let cmdbeg = statstr
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.find('(')
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.ok_or_else(|| format_err!("missing '(' in /proc/PID/stat"))?;
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if !statstr[..=cmdbeg].ends_with(" (") {
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bail!("bad /proc/PID/stat line before the '('");
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}
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let pid: u32 = statstr[..(cmdbeg - 1)]
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.parse()
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.map_err(|e| format_err!("bad pid in /proc/PID/stat: {}", e))?;
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let pid = Pid::from_raw(pid as i32);
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// After the '(' we have an arbitrary command name, then ')' and the remaining values
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let cmdend = statstr
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.rfind(')')
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.ok_or_else(|| format_err!("missing ')' in /proc/PID/stat"))?;
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let mut parts = statstr[cmdend + 1..].trim_start().split_ascii_whitespace();
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// helpers:
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fn required<'a>(value: Option<&'a str>, what: &'static str) -> Result<&'a str, Error> {
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value.ok_or_else(|| format_err!("missing '{}' in /proc/PID/stat", what))
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}
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fn req_num<T>(value: Option<&str>, what: &'static str) -> Result<T, Error>
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where
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T: FromStr,
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<T as FromStr>::Err: Into<Error>,
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{
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required(value, what)?.parse::<T>().map_err(|e| e.into())
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}
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fn req_byte(value: Option<&str>, what: &'static str) -> Result<u8, Error> {
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let value = required(value, what)?;
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if value.len() != 1 {
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bail!("invalid '{}' in /proc/PID/stat", what);
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}
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Ok(value.as_bytes()[0])
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}
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let out = PidStat {
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pid,
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status: req_byte(parts.next(), "status")?,
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ppid: Pid::from_raw(req_num::<u32>(parts.next(), "ppid")? as i32),
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utime: req_num::<u64>(parts.nth(9), "utime")?,
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stime: req_num::<u64>(parts.next(), "stime")?,
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num_threads: req_num::<u64>(parts.nth(4), "num_threads")?,
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starttime: req_num::<u64>(parts.nth(1), "start_time")?,
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vsize: req_num::<u64>(parts.next(), "vsize")?,
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rss: req_num::<i64>(parts.next(), "rss")? * 4096,
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};
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let _ = req_num::<u64>(parts.next(), "it_real_value")?;
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// and more...
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Ok(out)
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/// Read `/proc/PID/stat` for a pid.
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#[deprecated(note = "use `PidStat::read_for_pid`")]
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pub fn read_proc_pid_stat(pid: libc::pid_t) -> Result<PidStat, Error> {
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PidStat::read_for_pid(Pid::from_raw(pid))
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}
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#[test]
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fn test_read_proc_pid_stat() {
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let stat = parse_proc_pid_stat(
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let stat = PidStat::parse(
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"28900 (zsh) S 22489 28900 28900 34826 10252 4194304 6851 5946551 0 2344 6 3 25205 1413 \
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20 0 1 0 287592 12496896 1910 18446744073709551615 93999319244800 93999319938061 \
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140722897984224 0 0 0 2 3686404 134295555 1 0 0 17 10 0 0 0 0 0 93999320079088 \
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@ -134,19 +145,15 @@ fn test_read_proc_pid_stat() {
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assert_eq!(stat.rss, 1910 * 4096);
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}
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#[deprecated(note = "use `PidStat`")]
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pub fn read_proc_starttime(pid: libc::pid_t) -> Result<u64, Error> {
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let info = read_proc_pid_stat(pid)?;
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Ok(info.starttime)
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PidStat::read_for_pid(Pid::from_raw(pid)).map(|stat| stat.starttime)
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}
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pub fn check_process_running(pid: libc::pid_t) -> Option<PidStat> {
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if let Ok(info) = read_proc_pid_stat(pid) {
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if info.status != b'Z' {
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return Some(info);
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}
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}
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None
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PidStat::read_for_pid(Pid::from_raw(pid))
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.ok()
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.filter(|stat| stat.status != b'Z')
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}
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pub fn check_process_running_pstart(pid: libc::pid_t, pstart: u64) -> Option<PidStat> {
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