Federation sender event cache (#1614)

* Cache federation sender events

* Store in the correct cache

* Update federation event cache

* Fix Unset

* Give EDUs same caching treatment as PDUs

* Make federationsender_cache_size configurable

* Default caches configuration

* Fix unit tests

* Revert "Fix unit tests"

This reverts commit 24eb5d22524f20e1024b1475debe61ae20538a5a.

* Revert "Default caches configuration"

This reverts commit 464ecd1e64b9d2983f6fd5430e9607519d543cb3.

* Revert "Make federationsender_cache_size configurable"

This reverts commit 4631f5324151e006a15d6f19008f06361b994607.

1 files changed, 13 insertions, 2 deletions

diff --git a/federationsender/storage/shared/storage_pdus.go b/federationsender/storage/shared/storage_pdus.go
index 9ab0b094..09235a5e 100644
--- a/federationsender/storage/shared/storage_pdus.go
+++ b/federationsender/storage/shared/storage_pdus.go
@@ -85,17 +85,27 @@ func (d *Database) GetNextTransactionPDUs(
 			nids: nids,
 		}
 
-		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, nids)
+		retrieve := make([]int64, 0, len(nids))
+		for _, nid := range nids {
+			if event, ok := d.Cache.GetFederationSenderQueuedPDU(nid); ok {
+				events = append(events, event)
+			} else {
+				retrieve = append(retrieve, nid)
+			}
+		}
+
+		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, retrieve)
 		if err != nil {
 			return fmt.Errorf("SelectQueueJSON: %w", err)
 		}
 
-		for _, blob := range blobs {
+		for nid, blob := range blobs {
 			var event gomatrixserverlib.HeaderedEvent
 			if err := json.Unmarshal(blob, &event); err != nil {
 				return fmt.Errorf("json.Unmarshal: %w", err)
 			}
 			events = append(events, &event)
+			d.Cache.StoreFederationSenderQueuedPDU(nid, &event)
 		}
 
 		return nil
@@ -128,6 +138,7 @@ func (d *Database) CleanPDUs(
 			}
 			if count == 0 {
 				deleteNIDs = append(deleteNIDs, nid)
+				d.Cache.EvictFederationSenderQueuedPDU(nid)
 			}
 		}