backup: switch over to streaming Iterator improving memory usage

Avoid collecting the whole group list in memory only to iterate and
filter over it again.

Note that the change could result in a indentation change, so best
viewed with `-w` flag.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/api2/admin/datastore.rs

@@ -166,46 +166,39 @@ pub fn list_groups(
     let datastore = DataStore::lookup_datastore(&store, Some(Operation::Read))?;
     let list_all = (user_privs & PRIV_DATASTORE_AUDIT) != 0;
 
-    let group_info =
     datastore
-            .list_backup_groups()?
-            .into_iter()
-            .fold(Vec::new(), |mut group_info, group| {
+        .iter_backup_groups()?
+        .try_fold(Vec::new(), |mut group_info, group| {
+            let group = group?;
             let owner = match datastore.get_owner(&group) {
                 Ok(auth_id) => auth_id,
                 Err(err) => {
-                        eprintln!(
-                            "Failed to get owner of group '{}/{}' - {}",
-                            &store, group, err
-                        );
-                        return group_info;
+                    let id = &store;
+                    eprintln!("Failed to get owner of group '{}/{}' - {}", id, group, err);
+                    return Ok(group_info);
                 }
             };
             if !list_all && check_backup_owner(&owner, &auth_id).is_err() {
-                    return group_info;
+                return Ok(group_info);
             }
 
             let snapshots = match group.list_backups(&datastore.base_path()) {
                 Ok(snapshots) => snapshots,
-                    Err(_) => {
-                        return group_info;
-                    }
+                Err(_) => return Ok(group_info),
             };
 
             let backup_count: u64 = snapshots.len() as u64;
             if backup_count == 0 {
-                    return group_info;
+                return Ok(group_info);
             }
 
             let last_backup = snapshots
                 .iter()
-                    .fold(&snapshots[0], |last, curr| {
-                        if curr.is_finished()
-                            && curr.backup_dir.backup_time() > last.backup_dir.backup_time()
-                        {
-                            curr
+                .fold(&snapshots[0], |a, b| {
+                    if a.is_finished() && a.backup_dir.backup_time() > b.backup_dir.backup_time() {
+                        a
                     } else {
-                            last
+                        b
                     }
                 })
                 .to_owned();
@@ -223,10 +216,8 @@ pub fn list_groups(
                 comment,
             });
 
-                group_info
-            });
-
             Ok(group_info)
+        })
 }
 
 #[api(
@@ -417,16 +408,16 @@ pub fn list_snapshots(
 
     let datastore = DataStore::lookup_datastore(&store, Some(Operation::Read))?;
 
+    // FIXME: filter also owner before collecting, for doing that nicely the owner should move into
+    // backup group and provide an error free (Err -> None) accessor
     let groups = match (backup_type, backup_id) {
         (Some(backup_type), Some(backup_id)) => vec![BackupGroup::new(backup_type, backup_id)],
         (Some(backup_type), None) => datastore
-            .list_backup_groups()?
-            .into_iter()
+            .iter_backup_groups_ok()?
             .filter(|group| group.backup_type() == backup_type)
             .collect(),
         (None, Some(backup_id)) => datastore
-            .list_backup_groups()?
-            .into_iter()
+            .iter_backup_groups_ok()?
             .filter(|group| group.backup_id() == backup_id)
             .collect(),
         _ => datastore.list_backup_groups()?,
@@ -537,8 +528,7 @@ pub fn list_snapshots(
 
 fn get_snapshots_count(store: &DataStore, filter_owner: Option<&Authid>) -> Result<Counts, Error> {
     store
-        .list_backup_groups()?
-        .into_iter()
+        .iter_backup_groups_ok()?
         .filter(|group| {
             let owner = match store.get_owner(group) {
                 Ok(owner) => owner,

src/backup/verify.rs

@@ -537,9 +537,8 @@ pub fn verify_all_backups(
         }
     };
 
-    let mut list = match verify_worker.datastore.list_backup_groups() {
+    let mut list = match verify_worker.datastore.iter_backup_groups_ok() {
         Ok(list) => list
-            .into_iter()
             .filter(|group| !(group.backup_type() == "host" && group.backup_id() == "benchmark"))
             .filter(filter_by_owner)
             .collect::<Vec<BackupGroup>>(),

src/server/prune_job.rs

@@ -42,7 +42,8 @@ pub fn prune_datastore(
     let privs = user_info.lookup_privs(&auth_id, &["datastore", store]);
     let has_privs = privs & PRIV_DATASTORE_MODIFY != 0;
 
-    for group in datastore.list_backup_groups()? {
+    for group in datastore.iter_backup_groups()? {
+        let group = group?;
         let list = group.list_backups(&datastore.base_path())?;
 
         if !has_privs && !datastore.owns_backup(&group, &auth_id)? {

src/server/pull.rs

@@ -797,7 +797,8 @@ pub async fn pull_store(
 
     if params.remove_vanished {
         let result: Result<(), Error> = proxmox_lang::try_block!({
-            for local_group in params.store.list_backup_groups()? {
+            for local_group in params.store.iter_backup_groups()? {
+                let local_group = local_group?;
                 if new_groups.contains(&local_group) {
                     continue;
                 }