From 15ec790a40d7d549545d4da80c98af4832c77edf Mon Sep 17 00:00:00 2001
From: Dominik Csapak <d.csapak@proxmox.com>
Date: Fri, 4 Sep 2020 14:33:27 +0200
Subject: [PATCH] tools/systemd/time: convert the resulting timestamp into an
 option

we want to use dates for the calendarspec, and with that there are some
impossible combinations that cannot be detected during parsing
(e.g. some datetimes do not exist in some timezones, and the timezone
can change after setting the schedule)

so finding no timestamp is not an error anymore but a valid result

we omit logging in that case (since it is not an error anymore)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
 src/api2/admin/sync.rs          |  3 ++-
 src/bin/proxmox-backup-proxy.rs |  9 ++++++---
 src/tools/systemd/time.rs       | 16 ++++++++++------
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/api2/admin/sync.rs b/src/api2/admin/sync.rs
index ff1e5ebf..bea52a0a 100644
--- a/src/api2/admin/sync.rs
+++ b/src/api2/admin/sync.rs
@@ -57,7 +57,8 @@ pub fn list_sync_jobs(
         job.next_run = (|| -> Option<i64> {
             let schedule = job.schedule.as_ref()?;
             let event = parse_calendar_event(&schedule).ok()?;
-            compute_next_event(&event, last, false).ok()
+            // ignore errors
+            compute_next_event(&event, last, false).unwrap_or_else(|_| None)
         })();
     }
 
diff --git a/src/bin/proxmox-backup-proxy.rs b/src/bin/proxmox-backup-proxy.rs
index dd081dfe..2b43c5ac 100644
--- a/src/bin/proxmox-backup-proxy.rs
+++ b/src/bin/proxmox-backup-proxy.rs
@@ -301,7 +301,8 @@ async fn schedule_datastore_garbage_collection() {
         };
 
         let next = match compute_next_event(&event, last, false) {
-            Ok(next) => next,
+            Ok(Some(next)) => next,
+            Ok(None) => continue,
             Err(err) => {
                 eprintln!("compute_next_event for '{}' failed - {}", event_str, err);
                 continue;
@@ -412,7 +413,8 @@ async fn schedule_datastore_prune() {
         };
 
         let next = match compute_next_event(&event, last, false) {
-            Ok(next) => next,
+            Ok(Some(next)) => next,
+            Ok(None) => continue,
             Err(err) => {
                 eprintln!("compute_next_event for '{}' failed - {}", event_str, err);
                 continue;
@@ -520,7 +522,8 @@ async fn schedule_datastore_sync_jobs() {
         };
 
         let next = match compute_next_event(&event, last, false) {
-            Ok(next) => next,
+            Ok(Some(next)) => next,
+            Ok(None) => continue,
             Err(err) => {
                 eprintln!("compute_next_event for '{}' failed - {}", event_str, err);
                 continue;
diff --git a/src/tools/systemd/time.rs b/src/tools/systemd/time.rs
index 8bb2a8f7..2e99e289 100644
--- a/src/tools/systemd/time.rs
+++ b/src/tools/systemd/time.rs
@@ -1,4 +1,4 @@
-use anyhow::{bail, Error};
+use anyhow::Error;
 use bitflags::bitflags;
 
 pub use super::parse_time::*;
@@ -155,7 +155,7 @@ pub fn compute_next_event(
     event: &CalendarEvent,
     last: i64,
     utc: bool,
-) -> Result<i64, Error> {
+) -> Result<Option<i64>, Error> {
 
     let last = last + 1; // at least one second later
 
@@ -166,8 +166,9 @@ pub fn compute_next_event(
     let mut count = 0;
 
     loop {
-        if count > 1000 { // should not happen
-            bail!("unable to compute next calendar event");
+        // cancel after 1000 loops
+        if count > 1000 {
+            return Ok(None);
         } else {
             count += 1;
         }
@@ -235,13 +236,15 @@ pub fn compute_next_event(
         }
 
         let next = t.into_epoch()?;
-        return Ok(next)
+        return Ok(Some(next))
     }
 }
 
 #[cfg(test)]
 mod test {
 
+    use anyhow::bail;
+
     use super::*;
     use proxmox::tools::time::*;
 
@@ -268,7 +271,7 @@ mod test {
             };
 
             match compute_next_event(&event, last, true) {
-                Ok(next) => {
+                Ok(Some(next)) => {
                     if next == expect {
                         println!("next {:?} => {}", event, next);
                     } else {
@@ -276,6 +279,7 @@ mod test {
                               event, gmtime(next), gmtime(expect));
                     }
                 }
+                Ok(None) => bail!("next {:?} failed to find a timestamp", event),
                 Err(err) => bail!("compute next for '{}' failed - {}", v, err),
             }