feat: Cache system time instead of looking at the clock several times in a row

The system clock may be adjusted and even go back, so caching system time in code sections where
it's not supposed to change may even protect from races/bugs.

src/chat.rs

@@ -2806,12 +2806,14 @@ pub(crate) async fn create_send_msg_jobs(context: &Context, msg: &mut Message) -
         );
     }
 
+    let now = time();
+
     if rendered_msg.is_gossiped {
-        msg.chat_id.set_gossiped_timestamp(context, time()).await?;
+        msg.chat_id.set_gossiped_timestamp(context, now).await?;
     }
 
     if let Some(last_added_location_id) = rendered_msg.last_added_location_id {
-        if let Err(err) = location::set_kml_sent_timestamp(context, msg.chat_id, time()).await {
+        if let Err(err) = location::set_kml_sent_timestamp(context, msg.chat_id, now).await {
             error!(context, "Failed to set kml sent_timestamp: {err:#}.");
         }
         if !msg.hidden {
@@ -2830,7 +2832,7 @@ pub(crate) async fn create_send_msg_jobs(context: &Context, msg: &mut Message) -
     }
 
     if attach_selfavatar {
-        if let Err(err) = msg.chat_id.set_selfavatar_timestamp(context, time()).await {
+        if let Err(err) = msg.chat_id.set_selfavatar_timestamp(context, now).await {
             error!(context, "Failed to set selfavatar timestamp: {err:#}.");
         }
     }

src/contact.rs

@@ -1732,6 +1732,12 @@ impl RecentlySeenLoop {
     async fn run(context: Context, interrupt: Receiver<RecentlySeenInterrupt>) {
         type MyHeapElem = (Reverse<i64>, ContactId);
 
+        let now = SystemTime::now();
+        let now_ts = now
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_secs() as i64;
+
         // Priority contains all recently seen sorted by the timestamp
         // when they become not recently seen.
         //
@@ -1742,7 +1748,7 @@ impl RecentlySeenLoop {
             .query_map(
                 "SELECT id, last_seen FROM contacts
                  WHERE last_seen > ?",
-                (time() - SEEN_RECENTLY_SECONDS,),
+                (now_ts - SEEN_RECENTLY_SECONDS,),
                 |row| {
                     let contact_id: ContactId = row.get("id")?;
                     let last_seen: i64 = row.get("last_seen")?;
@@ -1757,8 +1763,6 @@ impl RecentlySeenLoop {
             .unwrap_or_default();
 
         loop {
-            let now = SystemTime::now();
-
             let (until, contact_id) =
                 if let Some((Reverse(timestamp), contact_id)) = unseen_queue.peek() {
                     (

src/imex.rs

@@ -534,7 +534,7 @@ async fn export_backup(context: &Context, dir: &Path, passphrase: String) -> Res
     let _d1 = DeleteOnDrop(temp_db_path.clone());
     let _d2 = DeleteOnDrop(temp_path.clone());
 
-    export_database(context, &temp_db_path, passphrase)
+    export_database(context, &temp_db_path, passphrase, now)
         .await
         .context("could not export database")?;
 
@@ -770,19 +770,27 @@ where
 /// overwritten.
 ///
 /// This also verifies that IO is not running during the export.
-async fn export_database(context: &Context, dest: &Path, passphrase: String) -> Result<()> {
+async fn export_database(
+    context: &Context,
+    dest: &Path,
+    passphrase: String,
+    timestamp: i64,
+) -> Result<()> {
     ensure!(
         !context.scheduler.is_running().await,
         "cannot export backup, IO is running"
     );
-    let now = time().try_into().context("32-bit UNIX time overflow")?;
+    let timestamp = timestamp.try_into().context("32-bit UNIX time overflow")?;
 
     // TODO: Maybe introduce camino crate for UTF-8 paths where we need them.
     let dest = dest
         .to_str()
         .with_context(|| format!("path {} is not valid unicode", dest.display()))?;
 
-    context.sql.set_raw_config_int("backup_time", now).await?;
+    context
+        .sql
+        .set_raw_config_int("backup_time", timestamp)
+        .await?;
     sql::housekeeping(context).await.log_err(context).ok();
     context
         .sql

src/imex/transfer.rs

@@ -52,6 +52,7 @@ use crate::context::Context;
 use crate::message::{Message, Viewtype};
 use crate::qr::{self, Qr};
 use crate::stock_str::backup_transfer_msg_body;
+use crate::tools::time;
 use crate::{e2ee, EventType};
 
 use super::{export_database, DBFILE_BACKUP_NAME};
@@ -158,7 +159,7 @@ impl BackupProvider {
         // Generate the token up front: we also use it to encrypt the database.
         let token = AuthToken::generate();
         context.emit_event(SendProgress::Started.into());
-        export_database(context, dbfile, token.to_string())
+        export_database(context, dbfile, token.to_string(), time())
             .await
             .context("Database export failed")?;
         context.emit_event(SendProgress::DatabaseExported.into());

src/location.rs

@@ -139,8 +139,9 @@ impl Kml {
                 match chrono::NaiveDateTime::parse_from_str(&val, "%Y-%m-%dT%H:%M:%SZ") {
                     Ok(res) => {
                         self.curr.timestamp = res.timestamp();
-                        if self.curr.timestamp > time() {
-                            self.curr.timestamp = time();
+                        let now = time();
+                        if self.curr.timestamp > now {
+                            self.curr.timestamp = now;
                         }
                     }
                     Err(_err) => {
@@ -333,12 +334,13 @@ pub async fn set(context: &Context, latitude: f64, longitude: f64, accuracy: f64
         return Ok(true);
     }
     let mut continue_streaming = false;
+    let now = time();
 
     let chats = context
         .sql
         .query_map(
             "SELECT id FROM chats WHERE locations_send_until>?;",
-            (time(),),
+            (now,),
             |row| row.get::<_, i32>(0),
             |chats| {
                 chats
@@ -356,7 +358,7 @@ pub async fn set(context: &Context, latitude: f64, longitude: f64, accuracy: f64
                     latitude,
                     longitude,
                     accuracy,
-                    time(),
+                    now,
                     chat_id,
                     ContactId::SELF,
                 )).await.context("Failed to store location")?;