Tweak gc to keep up to --storage-keep-hint-slots=5 newest slots with …

…unique hints, even if those slots are old (#34)

## PRs in the Stack
- ➡ #34

(The stack is managed by
[git-grok](https://github.com/dimikot/git-grok).)

README.md

@@ -60,10 +60,17 @@ ones, so rsync can run efficiently.
     # Default: /mnt
     storage-dir: ''
 
-    # Remove slots created earlier than this many seconds ago.
+    # Remove slots created earlier than this many seconds ago. The exception is
+    # the newest slot (it's always kept), and also up to --storage-keep-hint-slots
+    # slots related to unique hints.
     # Default: 14400 (4 hours).
     storage-max-age-sec: ''
 
+    # Defines the number of unique hints, for which ci-storage will keep at
+    # least one newest slot, even if is past --storage-max-age-sec.
+    # Default: 5.
+    storage-keep-hint-slots: ''
+
     # Id of the slot to store to or load from. Use "*" to load a smart-random
     # slot (e.g. most recent or best in terms of layer compatibility) and skip
     # if it does not exist.

action.yml

@@ -14,7 +14,10 @@ inputs:
     description: "Storage directory on the remote host. Notice that, when building the final directory on the storage host, owner and repo are always appended, so the path will be {storage-dir}/{owner}/{repo}/{slug(local-dir)} or {storage-dir}/{owner}/{repo}/{slug(local-dir)}.{layer-name}. Default: /mnt"
     required: false
   storage-max-age-sec:
-    description: "Remove slots created earlier than this many seconds ago. Default: 14400 (4 hours)."
+    description: "Remove slots created earlier than this many seconds ago. The exception is the newest slot (it's always kept), and also up to --storage-keep-hint-slots slots related to unique hints. Default: 3600 (1 hour)."
+    required: false
+  storage-keep-hint-slots:
+    description: "Defines the number of unique hints, for which ci-storage will keep at least one newest slot, even if is past --storage-max-age-sec. Default: 5."
     required: false
   slot-id:
     description: 'Id of the slot to store to or load from; use "*" to load a smart-random slot (e.g. most recent or best in terms of layer compatibility) and skip if it does not exist. Default: $GITHUB_RUN_ID (which is friendly to "Re-run failed jobs").'
@@ -58,6 +61,7 @@ runs:
         storage_host="${{ inputs.storage-host || '' }}"
         storage_dir="${{ inputs.storage-dir || '/mnt' }}/${{ github.repository }}"
         storage_max_age_sec="${{ inputs.storage-max-age-sec || '' }}"
+        storage_keep_hint_slots="${{ inputs.storage-keep-hint-slots || '' }}"
         slot_id="${{ inputs.slot-id }}"
         local_dir="${{ inputs.local-dir || '.' }}"
         hint="${{ inputs.hint || '' }}"
@@ -103,6 +107,7 @@ runs:
           --storage-host="$storage_host"
           --storage-dir="$storage_dir"
           --storage-max-age-sec="$storage_max_age_sec"
+          --storage-keep-hint-slots="$storage_keep_hint_slots"
           --slot-id="$slot_id"
           --local-dir="$local_dir"
           --hint="$hint"

ci-storage

@@ -17,6 +17,7 @@ import typing
 
 STORAGE_MAX_AGE_SEC_DEFAULT = 3600
 STORAGE_MAX_AGE_SEC_BAK = 60
+STORAGE_KEEP_HINT_SLOTS_DEFAULT = 5
 STORAGE_DIR_DEFAULT = "~/ci-storage"
 META_FILE = ".ci-storage.meta"
 EMPTY_DIR = ".ci-storage.empty-dir"
@@ -76,7 +77,14 @@ def main():
         type=str,
         default=str(STORAGE_MAX_AGE_SEC_DEFAULT),
         required=False,
-        help="Remove slots created earlier than this many seconds ago.",
+        help="Remove slots created earlier than this many seconds ago. The exception is the newest slot (it's always kept), and also up to --storage-keep-hint-slots slots related to unique hints.",
+    )
+    parser.add_argument(
+        "--storage-keep-hint-slots",
+        type=str,
+        default=str(STORAGE_KEEP_HINT_SLOTS_DEFAULT),
+        required=False,
+        help="Defines the number of unique hints, for which ci-storage will keep at least one newest slot, even if is past --storage-max-age-sec.",
     )
     parser.add_argument(
         "--slot-id",
@@ -131,6 +139,9 @@ def main():
     storage_max_age_sec: int = int(
         args.storage_max_age_sec or str(STORAGE_MAX_AGE_SEC_DEFAULT)
     )
+    storage_keep_hint_slots: int = int(
+        args.storage_keep_hint_slots or str(STORAGE_KEEP_HINT_SLOTS_DEFAULT)
+    )
     slot_ids: list[str] = " ".join(args.slot_id).split()
     local_dir: str = re.sub(r"/+$", "", args.local_dir)
     hints: list[str] = [
@@ -175,6 +186,7 @@ def main():
             storage_host=storage_host,
             storage_dir=storage_dir,
             storage_max_age_sec=storage_max_age_sec,
+            storage_keep_hint_slots=storage_keep_hint_slots,
         )
     elif action == "load":
         if not slot_ids:
@@ -432,12 +444,13 @@ def action_maintenance(
     storage_host: str | None,
     storage_dir: str,
     storage_max_age_sec: int,
+    storage_keep_hint_slots: int,
 ):
     print(
         check_output_script(
             host=storage_host,
             script=SCRIPTS["MAINTENANCE"],
-            args=[storage_dir, str(storage_max_age_sec)],
+            args=[storage_dir, str(storage_max_age_sec), str(storage_keep_hint_slots)],
             indent=True,
         ),
         end="",
@@ -933,7 +946,8 @@ SLOT_INFOS = textwrap.dedent(
                         age_sec => time() - $inode_ctime,
                         dir => $dir,
                         meta => $meta,
-                        is_garbage => $slot_id =~ /\./ ? 1 : 0,
+                        meta_hints => $meta =~ /^hints=(.*)/m ? [grep(/./s, split(/\s+/s, $1))] : [],
+                        is_tmp_or_bak => $slot_id =~ /\./ ? 1 : 0,
                         is_bak => $slot_id =~ /\.bak\.\d+$/s ? 1 : 0,
                     };
                 } else {
@@ -969,7 +983,7 @@ SCRIPTS = {
         }
         %(SLOT_INFOS)s
         my @slot_infos =
-            grep { !$_->{is_garbage} }
+            grep { !$_->{is_tmp_or_bak} }
             slot_infos($storage_dir);
         if (@slot_infos) {
             my $newest_dir = $slot_infos[0]{dir};
@@ -1028,6 +1042,7 @@ SCRIPTS = {
         *STDERR->autoflush(1);
         my $storage_dir = $ARGV[0] or die("storage_dir argument required\n");
         my $storage_max_age_sec = $ARGV[1] or die("storage_max_age_sec argument required\n");
+        my $storage_keep_hint_slots = $ARGV[2] or die("storage_keep_hint_slots argument required\n");
         length($storage_dir) >= 3 or die("storage_dir is suspiciously short\n");
         my $lock_file = "$storage_dir/maintenance.lock";
         open(my $lock, ">>", $lock_file) or die("open $lock_file: $!\n");
@@ -1037,22 +1052,44 @@ SCRIPTS = {
         }
         %(SLOT_INFOS)s
         my @slot_infos = slot_infos($storage_dir);
-        my $slot_dir_newest = (map { $_->{dir} } grep { !$_->{is_garbage} } @slot_infos)[0];
+        my $slot_dir_newest = (map { $_->{dir} } grep { !$_->{is_tmp_or_bak} } @slot_infos)[0];
+        my %%slot_dir_newest_per_hint =
+            map { $_->{meta_hints}[0], $_->{dir} }
+            grep { !$_->{is_tmp_or_bak} && defined($_->{meta_hints}[0]) }
+            reverse(@slot_infos);
         my @rm_dirs = ();
+        my $kept_per_hint_slots = 0;
         foreach my $info (@slot_infos) {
             my $dir = $info->{dir};
             my $age_sec = $info->{age_sec};
             my $is_bak = $info->{is_bak};
-            if (defined($slot_dir_newest) && $dir eq $slot_dir_newest) {
-                # Never delete the latest slot, even if it is old.
+            my $hint = $info->{meta_hints}[0];
+            my $suffix = (defined($hint) ? "hint=$hint, " : "") . "age=${age_sec}s";
+            if (
+                defined($slot_dir_newest) &&
+                $dir eq $slot_dir_newest
+            ) {
+                print("keeping $dir, the newest slot overall ($suffix)\n");
+                next;
+            }
+            if (
+                defined($hint) &&
+                defined($slot_dir_newest_per_hint{$hint}) &&
+                $dir eq $slot_dir_newest_per_hint{$hint} &&
+                $kept_per_hint_slots < $storage_keep_hint_slots
+            ) {
+                print("keeping $dir, the newest slot with this hint ($suffix)\n");
+                $kept_per_hint_slots++;
                 next;
             }
             if (
                 $age_sec > $storage_max_age_sec ||
                 $is_bak && $age_sec > %(STORAGE_MAX_AGE_SEC_BAK)d
             ) {
                 push(@rm_dirs, $dir);
-                print("will remove $dir (age: $age_sec sec) in background\n");
+                print("will remove $dir in background ($suffix)\n");
+            } else {
+                print("keeping $dir, new enough ($suffix)\n");
             }
         }
         if (!@rm_dirs) {

tests/0070-keeps-newest-slot-per-each-hint-on-gc.test.sh

@@ -0,0 +1,51 @@
+#!/bin/bash
+source ./common.sh
+
+ci-storage \
+  --slot-id=myslot-a1 \
+  --hint="a" \
+  store
+ci-storage \
+  --slot-id=myslot-a2 \
+  --hint="a" \
+  store
+
+ci-storage \
+  --slot-id=myslot-b1 \
+  --hint="b" \
+  store
+ci-storage \
+  --slot-id=myslot-b2 \
+  --hint="b" \
+  store
+
+ci-storage \
+  --slot-id=myslot-c1 \
+  --hint="c" \
+  store
+ci-storage \
+  --slot-id=myslot-c2 \
+  --hint="c" \
+  store
+
+ci-storage \
+  --slot-id=myslot-d1 \
+  --hint="d" \
+  store
+ci-storage \
+  --slot-id=myslot-d2 \
+  --hint="d" \
+  store
+
+ci-storage \
+  --slot-id=myslot-x \
+  --hint="x" \
+  --storage-keep-hint-slots=2 \
+  store
+
+grep -qF 'myslot-x, the newest slot overall' "$OUT"
+grep -qF 'myslot-d2, the newest slot with this hint (hint=d' "$OUT"
+grep -qF 'myslot-c2, the newest slot with this hint (hint=c' "$OUT"
+grep -qF 'myslot-b2, new enough' "$OUT"
+grep -qF 'myslot-a2, new enough' "$OUT"
+