From ecf78a4264b7c46a1624f0a0e69e1864a7e0c0bb Mon Sep 17 00:00:00 2001
From: Artemis Tosini <me@artem.ist>
Date: Tue, 12 Dec 2023 20:40:27 +0000
Subject: [PATCH] Might handle leap seconds better

---
 flake.nix                | 1 +
 src/tiles/local_time.rs  | 8 +++++---
 src/tiles/system_time.rs | 8 +++++---
 src/tiles/utc_time.rs    | 8 +++++---
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/flake.nix b/flake.nix
index e3e8fb6..2f32738 100644
--- a/flake.nix
+++ b/flake.nix
@@ -51,6 +51,7 @@
             packages = [
               pkg-config
               dbus
+              libfaketime
               toolchain.cargo
               toolchain.rustc
               toolchain.rustfmt
diff --git a/src/tiles/local_time.rs b/src/tiles/local_time.rs
index 64b8e3f..45d8333 100644
--- a/src/tiles/local_time.rs
+++ b/src/tiles/local_time.rs
@@ -106,9 +106,11 @@ pub async fn local_time_stream(config: LocalTimeConfig) {
                 ..Default::default()
             };
         }
-        let utc_next = utc_now.trunc_subsecs(0) + chrono::Duration::seconds(1);
-        let difference = utc_next - utc_now;
+        // It would take more resources to get time again, and we want to err on the side of
+        // "wait a few µs too long" rather than too short.
+        // Use a mod here in case someone handles leap seconds this way
+        let difference = 1_000_000_000 - (utc_now.timestamp_subsec_nanos() % 1_000_000_000);
 
-        sleep(difference.to_std().unwrap()).await;
+        sleep(std::time::Duration::from_nanos(difference.into())).await;
     }
 }
diff --git a/src/tiles/system_time.rs b/src/tiles/system_time.rs
index d4de7fc..5ec89f5 100644
--- a/src/tiles/system_time.rs
+++ b/src/tiles/system_time.rs
@@ -16,9 +16,11 @@ pub async fn system_time_stream(config: SystemTimeConfig) {
             ..Default::default()
         });
 
-        let next = now.trunc_subsecs(0) + chrono::Duration::seconds(1);
-        let difference = next - now;
+        // It would take more resources to get time again, and we want to err on the side of
+        // "wait a few µs too long" rather than too short.
+        // Use a mod here in case someone handles leap seconds this way
+        let difference = 1_000_000_000 - (now.timestamp_subsec_nanos() % 1_000_000_000);
 
-        sleep(difference.to_std().unwrap()).await;
+        sleep(std::time::Duration::from_nanos(difference.into())).await;
     }
 }
diff --git a/src/tiles/utc_time.rs b/src/tiles/utc_time.rs
index 5e1e619..70a1456 100644
--- a/src/tiles/utc_time.rs
+++ b/src/tiles/utc_time.rs
@@ -16,9 +16,11 @@ pub async fn utc_time_stream(config: UtcTimeConfig) {
             ..Default::default()
         });
 
-        let next = now.trunc_subsecs(0) + chrono::Duration::seconds(1);
-        let difference = next - now;
+        // It would take more resources to get time again, and we want to err on the side of
+        // "wait a few µs too long" rather than too short.
+        // Use a mod here in case someone handles leap seconds this way
+        let difference = 1_000_000_000 - (now.timestamp_subsec_nanos() % 1_000_000_000);
 
-        sleep(difference.to_std().unwrap()).await;
+        sleep(std::time::Duration::from_nanos(difference.into())).await;
     }
 }