Report cache purge index fill ratios

Author: eldryoth

docs/cache-backends.md

@@ -157,12 +157,13 @@ internal cache implementation.
   stores, disk evictions, and purges. Activity blocks include derived
   `requests` and `hit_ratio_per_mille` fields so operators can read hit-rate
   health without external JSON post-processing. Memory and disk tier status
-  also reports `fill_ratio_per_mille`, `purge_index_entries`, and
-  `purge_index_max_entries`, and totals report the same values split by memory
-  and disk tiers, so operators can tell whether storage is under pressure and
-  whether indexed scope, prefix, and wildcard purges have useful coverage or
-  are near the bounded index cap. `POST /_fluxheim/cache/activity/reset`
-  resets vhost and route activity counters without clearing cached objects.
+  also reports `fill_ratio_per_mille`, `purge_index_entries`,
+  `purge_index_max_entries`, and `purge_index_fill_ratio_per_mille`, and
+  totals report the same values split by memory and disk tiers, so operators
+  can tell whether storage is under pressure and whether indexed scope, prefix,
+  and wildcard purges have useful coverage or are near the bounded index cap.
+  `POST /_fluxheim/cache/activity/reset` resets vhost and route activity
+  counters without clearing cached objects.
 - `cache.status_header` can expose compact response debug states such as
   `HIT`, `MISS`, `STALE`, and `BYPASS`. `cache.status_reason_header` can expose
   bounded no-cache reasons such as `OriginNotCache`, `ResponseTooLarge`, or

src/admin.rs

@@ -1578,7 +1578,7 @@ fn cache_purge_results_json(results: &[crate::proxy::CachePurgeResult]) -> Strin
 #[cfg(feature = "cache")]
 fn cache_totals_json(totals: &crate::proxy::CacheRuntimeTotals) -> String {
     format!(
-        r#"{{"vhosts":{},"enabled_vhosts":{},"tiered_vhosts":{},"enabled_routes":{},"tiered_routes":{},"memory_entries":{},"memory_weighted_size_bytes":{},"memory_max_size_bytes":{},"memory_fill_ratio_per_mille":{},"memory_purge_index_entries":{},"memory_purge_index_max_entries":{},"disk_entries":{},"disk_size_bytes":{},"disk_max_size_bytes":{},"disk_fill_ratio_per_mille":{},"disk_purge_index_entries":{},"disk_purge_index_max_entries":{},"activity":{}}}"#,
+        r#"{{"vhosts":{},"enabled_vhosts":{},"tiered_vhosts":{},"enabled_routes":{},"tiered_routes":{},"memory_entries":{},"memory_weighted_size_bytes":{},"memory_max_size_bytes":{},"memory_fill_ratio_per_mille":{},"memory_purge_index_entries":{},"memory_purge_index_max_entries":{},"memory_purge_index_fill_ratio_per_mille":{},"disk_entries":{},"disk_size_bytes":{},"disk_max_size_bytes":{},"disk_fill_ratio_per_mille":{},"disk_purge_index_entries":{},"disk_purge_index_max_entries":{},"disk_purge_index_fill_ratio_per_mille":{},"activity":{}}}"#,
         totals.vhosts,
         totals.enabled_vhosts,
         totals.tiered_vhosts,
@@ -1593,12 +1593,20 @@ fn cache_totals_json(totals: &crate::proxy::CacheRuntimeTotals) -> String {
         ),
         totals.memory_purge_index_entries,
         totals.memory_purge_index_max_entries,
+        ratio_per_mille(
+            totals.memory_purge_index_entries,
+            totals.memory_purge_index_max_entries,
+        ),
         totals.disk_entries,
         totals.disk_size_bytes,
         totals.disk_max_size_bytes,
         ratio_per_mille(totals.disk_size_bytes, totals.disk_max_size_bytes),
         totals.disk_purge_index_entries,
         totals.disk_purge_index_max_entries,
+        ratio_per_mille(
+            totals.disk_purge_index_entries,
+            totals.disk_purge_index_max_entries,
+        ),
         cache_activity_json(&crate::cache::CacheActivityStats {
             hits: totals.hits,
             misses: totals.misses,
@@ -1654,14 +1662,15 @@ fn memory_cache_stats_json(stats: Option<&crate::cache::MemoryCacheStats>) -> St
     stats
         .map(|stats| {
             format!(
-                r#"{{"entries":{},"weighted_size_bytes":{},"max_size_bytes":{},"fill_ratio_per_mille":{},"max_object_bytes":{},"purge_index_entries":{},"purge_index_max_entries":{},"activity":{}}}"#,
+                r#"{{"entries":{},"weighted_size_bytes":{},"max_size_bytes":{},"fill_ratio_per_mille":{},"max_object_bytes":{},"purge_index_entries":{},"purge_index_max_entries":{},"purge_index_fill_ratio_per_mille":{},"activity":{}}}"#,
                 stats.entries,
                 stats.weighted_size_bytes,
                 stats.max_size_bytes.as_u64(),
                 ratio_per_mille(stats.weighted_size_bytes, stats.max_size_bytes.as_u64()),
                 stats.max_object_bytes.as_u64(),
                 stats.purge_index_entries,
                 stats.purge_index_max_entries,
+                ratio_per_mille(stats.purge_index_entries, stats.purge_index_max_entries),
                 cache_activity_json(&stats.activity)
             )
         })
@@ -1673,14 +1682,15 @@ fn disk_cache_stats_json(stats: Option<&crate::cache::DiskCacheStats>) -> String
     stats
         .map(|stats| {
             format!(
-                r#"{{"entries":{},"size_bytes":{},"max_size_bytes":{},"fill_ratio_per_mille":{},"max_object_bytes":{},"purge_index_entries":{},"purge_index_max_entries":{},"activity":{}}}"#,
+                r#"{{"entries":{},"size_bytes":{},"max_size_bytes":{},"fill_ratio_per_mille":{},"max_object_bytes":{},"purge_index_entries":{},"purge_index_max_entries":{},"purge_index_fill_ratio_per_mille":{},"activity":{}}}"#,
                 stats.entries,
                 stats.size_bytes,
                 stats.max_size_bytes.as_u64(),
                 ratio_per_mille(stats.size_bytes, stats.max_size_bytes.as_u64()),
                 stats.max_object_bytes.as_u64(),
                 stats.purge_index_entries,
                 stats.purge_index_max_entries,
+                ratio_per_mille(stats.purge_index_entries, stats.purge_index_max_entries),
                 cache_activity_json(&stats.activity)
             )
         })
@@ -2472,10 +2482,12 @@ mod tests {
         assert!(body.contains(r#""memory_fill_ratio_per_mille":0"#));
         assert!(body.contains(r#""memory_purge_index_entries":0"#));
         assert!(body.contains(r#""memory_purge_index_max_entries":131072"#));
+        assert!(body.contains(r#""memory_purge_index_fill_ratio_per_mille":0"#));
         assert!(body.contains(r#""disk_entries":0"#));
         assert!(body.contains(r#""disk_fill_ratio_per_mille":0"#));
         assert!(body.contains(r#""disk_purge_index_entries":0"#));
         assert!(body.contains(r#""disk_purge_index_max_entries":65536"#));
+        assert!(body.contains(r#""disk_purge_index_fill_ratio_per_mille":0"#));
         assert!(body.contains(
             r#""activity":{"hits":0,"misses":0,"requests":0,"hit_ratio_per_mille":0,"stores":0,"store_refusals":0,"evictions":0,"purges":0"#
         ));
@@ -2486,6 +2498,7 @@ mod tests {
         assert!(body.contains(r#""fill_ratio_per_mille":0"#));
         assert!(body.contains(r#""purge_index_entries":0"#));
         assert!(body.contains(r#""purge_index_max_entries":65536"#));
+        assert!(body.contains(r#""purge_index_fill_ratio_per_mille":0"#));
         assert!(body.contains(r#""disk":{"entries":0"#));
         assert!(body.contains(r#""routes":[{"name":"assets""#));