Change watchdog_enabled to use Duration

Also return the value via the return value instead of via an out
parameter.

Author: tbu-

src/lib.rs

@@ -34,6 +34,7 @@ use std::os::unix::io::RawFd;
 use std::os::unix::net::UnixDatagram;
 use std::process;
 use std::str::FromStr;
+use std::time::Duration;
 
 use libc::CLOCK_MONOTONIC;
 
@@ -472,10 +473,13 @@ fn fd_cloexec(fd: u32) -> io::Result<()> {
 /// ```no_run
 /// # use sd_notify;
 /// #
-/// let mut usec = 0;
-/// let enabled = sd_notify::watchdog_enabled(&mut usec);
+/// if let Some(duration) = sd_notify::watchdog_enabled() {
+///     // watchdog enabled with `duration`
+/// } else {
+///     // watchdog disabled
+/// }
 /// ```
-pub fn watchdog_enabled(usec: &mut u64) -> bool {
+pub fn watchdog_enabled() -> Option<Duration> {
     let s = env::var(WATCHDOG_USEC)
         .ok()
         .and_then(|s| u64::from_str(&s).ok());
@@ -485,10 +489,9 @@ pub fn watchdog_enabled(usec: &mut u64) -> bool {
 
     match (s, p) {
         (Some(usec_val), Some(pid)) if pid == process::id() => {
-            *usec = usec_val;
-            true
+            Some(Duration::from_micros(usec_val))
         }
-        _ => false,
+        _ => None,
     }
 }
 
@@ -504,8 +507,8 @@ pub fn watchdog_enabled(usec: &mut u64) -> bool {
 /// preconditions. See its safety documentation for more details. It can only
 /// be safely called before threads are spawned, in particular before any
 /// `tokio` runtime initialization or `#[tokio::main]`.
-pub unsafe fn watchdog_enabled_and_unset_env(usec: &mut u64) -> bool {
-    let result = watchdog_enabled(usec);
+pub unsafe fn watchdog_enabled_and_unset_env() -> Option<Duration> {
+    let result = watchdog_enabled();
     unsafe {
         env::remove_var(WATCHDOG_USEC);
         env::remove_var(WATCHDOG_PID);

tests/watchdog_enabled.rs

@@ -3,6 +3,7 @@
 
 use std::env;
 use std::process;
+use std::time::Duration;
 
 #[test]
 fn watchdog_enabled() {
@@ -14,11 +15,9 @@ fn watchdog_enabled() {
         env::set_var("WATCHDOG_PID", "1");
     }
 
-    let mut usec = 0;
     unsafe {
-        assert!(!sd_notify::watchdog_enabled_and_unset_env(&mut usec));
+        assert_eq!(sd_notify::watchdog_enabled_and_unset_env(), None);
     }
-    assert_eq!(usec, 0);
 
     assert!(env::var_os("WATCHDOG_USEC").is_none());
     assert!(env::var_os("WATCHDOG_PID").is_none());
@@ -29,19 +28,15 @@ fn watchdog_enabled() {
         env::set_var("WATCHDOG_PID", process::id().to_string());
     }
 
-    let mut usec = 0;
     unsafe {
-        assert!(!sd_notify::watchdog_enabled_and_unset_env(&mut usec));
+        assert_eq!(sd_notify::watchdog_enabled_and_unset_env(), None);
     }
-    assert_eq!(usec, 0);
 
     assert!(env::var_os("WATCHDOG_USEC").is_none());
     assert!(env::var_os("WATCHDOG_PID").is_none());
 
     // no usec, no pip no unset env
-    let mut usec = 0;
-    assert!(!sd_notify::watchdog_enabled(&mut usec));
-    assert_eq!(usec, 0);
+    assert_eq!(sd_notify::watchdog_enabled(), None);
 
     assert!(env::var_os("WATCHDOG_USEC").is_none());
     assert!(env::var_os("WATCHDOG_PID").is_none());
@@ -52,9 +47,7 @@ fn watchdog_enabled() {
         env::set_var("WATCHDOG_PID", process::id().to_string());
     }
 
-    let mut usec = 0;
-    assert!(sd_notify::watchdog_enabled(&mut usec));
-    assert_eq!(usec, 5);
+    assert_eq!(sd_notify::watchdog_enabled(), Some(Duration::from_micros(5)));
     assert!(env::var_os("WATCHDOG_USEC").is_some());
     assert!(env::var_os("WATCHDOG_PID").is_some());
 }