Synchronize deck only if necessary

Look at the modification time of the deck, and synchronize if it has
been modified after the last deck read.

1 files changed, 25 insertions, 3 deletions

diff --git a/src/util/time.rs b/src/util/time.rs
index f88955d..d9a9f72 100644
--- a/src/util/time.rs
+++ b/src/util/time.rs
@@ -1,9 +1,14 @@
 use anyhow::Result;
+use std::thread;
 use std::time::SystemTime;
 
-pub fn now() -> Result<u64> {
-    Ok(SystemTime::now()
-        .duration_since(SystemTime::UNIX_EPOCH)?
+pub fn seconds_since_unix_epoch() -> Result<u64> {
+    Ok(seconds_since_unix_epoch_of(SystemTime::now())?)
+}
+
+pub fn seconds_since_unix_epoch_of(time: SystemTime) -> Result<u64> {
+    Ok(time
+        .duration_since(std::time::SystemTime::UNIX_EPOCH)?
         .as_secs())
 }
 
@@ -31,3 +36,20 @@ fn plural(n: u64, str: &str) -> String {
         format!("{} {}s", n, str)
     }
 }
+
+/// Call the function, then sleep if necessary.
+///
+/// Calling this will at least take the duration asked for in parameters.
+pub fn wait_at_least<F>(f: F, d: std::time::Duration) -> Result<()>
+where
+    F: Fn() -> Result<()>,
+{
+    let t1 = SystemTime::now();
+    f()?;
+    let t2 = SystemTime::now();
+    let elapsed = t2.duration_since(t1)?;
+    if elapsed < d {
+        thread::sleep(d - elapsed);
+    }
+    Ok(())
+}