backups plugin with NTLARS revision history; shopfloor dashboard upcoming cards and state chips

plugins/backups/services/retention.py

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+"""Revision retention.
+
+Dedup already keeps growth low - a revision appears only when a setting really
+changed - so retention exists for the pathological case, not the normal one: a
+value that flaps (or two PCs alternately claiming one machine number) would
+otherwise append a revision every collection cycle forever.
+
+Two independent limits, both off by default at 0:
+
+  retentioncount  keep at most N revisions per asset per kind
+  retentiondays   additionally drop anything older than N days
+
+The NEWEST and the OLDEST revision are never pruned. The newest is the one a
+tech restores from; the oldest is the earliest known-good baseline, which is
+usually the most valuable row in the table and the one a naive "keep last N"
+would delete first.
+"""
+
+from datetime import datetime, timedelta
+
+from shopdb.api import db
+
+from ..models import BackupRevision
+
+
+def prune(assetid, backupkind, retentioncount=0, retentiondays=0):
+    """Delete surplus revisions for one asset+kind. Returns the number removed.
+
+    Caller commits. Returns 0 when both limits are disabled.
+    """
+    retentioncount = int(retentioncount or 0)
+    retentiondays = int(retentiondays or 0)
+    if retentioncount <= 0 and retentiondays <= 0:
+        return 0
+
+    revisions = (db.session.query(BackupRevision)
+                 .filter(BackupRevision.assetid == assetid,
+                         BackupRevision.backupkind == backupkind)
+                 .order_by(BackupRevision.backuprevisionid.desc())
+                 .all())
+    if len(revisions) <= 2:
+        return 0                      # newest + oldest are both protected
+
+    newest = revisions[0]
+    oldest = revisions[-1]
+    protected = {newest.backuprevisionid, oldest.backuprevisionid}
+
+    doomed = []
+
+    if retentioncount > 0 and len(revisions) > retentioncount:
+        # Walk from the oldest END of the middle, so the surplus dropped is
+        # always the least recent, never the newest.
+        for revision in revisions[retentioncount:]:
+            if revision.backuprevisionid not in protected:
+                doomed.append(revision)
+
+    if retentiondays > 0:
+        cutoff = datetime.utcnow() - timedelta(days=retentiondays)
+        for revision in revisions:
+            if revision.backuprevisionid in protected:
+                continue
+            stamp = revision.collectedat or revision.createdat
+            if stamp and stamp < cutoff and revision not in doomed:
+                doomed.append(revision)
+
+    for revision in doomed:
+        db.session.delete(revision)
+    return len(doomed)