[performance] overhaul struct (+ result) caching library for simplicity, performance and multiple-result lookups (#2535)

* rewrite cache library as codeberg.org/gruf/go-structr, implement in gotosocial

* use actual go-structr release version (not just commit hash)

* revert go toolchain changes (damn you go for auto changing this)

* fix go mod woes

* ensure %w is used in calls to errs.Appendf()

* fix error checking

* fix possible panic

* remove unnecessary start/stop functions, move to main Cache{} struct, add note regarding which caches require start/stop

* fix copy-paste artifact... :innocent:

* fix all comment copy-paste artifacts

* remove dropID() function, now we can just use slices.DeleteFunc()

* use util.Deduplicate() instead of collate(), move collate to util

* move orderByIDs() to util package and "generify"

* add a util.DeleteIf() function, use this to delete entries on failed population

* use slices.DeleteFunc() instead of util.DeleteIf() (i had the logic mixed up in my head somehow lol)

* add note about how collate differs from deduplicate

3 files changed, 9 insertions, 8 deletions

diff --git a/internal/transport/deliver.go b/internal/transport/deliver.go
index e2dbc4829..71b065719 100644
--- a/internal/transport/deliver.go
+++ b/internal/transport/deliver.go
@@ -82,7 +82,7 @@ func (t *transport) BatchDeliver(ctx context.Context, b []byte, recipients []*ur
 				// Attempt to deliver data to recipient.
 				if err := t.deliver(ctx, b, to); err != nil {
 					mutex.Lock() // safely append err to accumulator.
-					errs.Appendf("error delivering to %s: %v", to, err)
+					errs.Appendf("error delivering to %s: %w", to, err)
 					mutex.Unlock()
 				}
 			}
diff --git a/internal/transport/finger.go b/internal/transport/finger.go
index 49648c7e9..385af5e1c 100644
--- a/internal/transport/finger.go
+++ b/internal/transport/finger.go
@@ -36,7 +36,8 @@ import (
 func (t *transport) webfingerURLFor(targetDomain string) (string, bool) {
 	url := "https://" + targetDomain + "/.well-known/webfinger"
 
-	wc := t.controller.state.Caches.GTS.Webfinger()
+	wc := t.controller.state.Caches.GTS.Webfinger
+
 	// We're doing the manual locking/unlocking here to be able to
 	// safely call Cache.Get instead of Get, as the latter updates the
 	// item expiry which we don't want to do here
@@ -95,7 +96,7 @@ func (t *transport) Finger(ctx context.Context, targetUsername string, targetDom
 			// If we got a response we consider successful on a cached URL, i.e one set
 			// by us later on when a host-meta based webfinger request succeeded, set it
 			// again here to renew the TTL
-			t.controller.state.Caches.GTS.Webfinger().Set(targetDomain, url)
+			t.controller.state.Caches.GTS.Webfinger.Set(targetDomain, url)
 		}
 		if rsp.StatusCode == http.StatusGone {
 			return nil, fmt.Errorf("account has been deleted/is gone")
@@ -151,7 +152,7 @@ func (t *transport) Finger(ctx context.Context, targetUsername string, targetDom
 		// we asked for is gone. This means the endpoint itself is valid and we should
 		// cache it for future queries to the same domain
 		if rsp.StatusCode == http.StatusGone {
-			t.controller.state.Caches.GTS.Webfinger().Set(targetDomain, host)
+			t.controller.state.Caches.GTS.Webfinger.Set(targetDomain, host)
 			return nil, fmt.Errorf("account has been deleted/is gone")
 		}
 		// We've reached the end of the line here, both the original request
@@ -162,7 +163,7 @@ func (t *transport) Finger(ctx context.Context, targetUsername string, targetDom
 	// Set the URL in cache here, since host-meta told us this should be the
 	// valid one, it's different from the default and our request to it did
 	// not fail in any manner
-	t.controller.state.Caches.GTS.Webfinger().Set(targetDomain, host)
+	t.controller.state.Caches.GTS.Webfinger.Set(targetDomain, host)
 
 	return io.ReadAll(rsp.Body)
 }
diff --git a/internal/transport/finger_test.go b/internal/transport/finger_test.go
index c012af62c..380a4aff9 100644
--- a/internal/transport/finger_test.go
+++ b/internal/transport/finger_test.go
@@ -31,7 +31,7 @@ type FingerTestSuite struct {
 }
 
 func (suite *FingerTestSuite) TestFinger() {
-	wc := suite.state.Caches.GTS.Webfinger()
+	wc := suite.state.Caches.GTS.Webfinger
 	suite.Equal(0, wc.Len(), "expect webfinger cache to be empty")
 
 	_, err := suite.transport.Finger(context.TODO(), "brand_new_person", "unknown-instance.com")
@@ -43,7 +43,7 @@ func (suite *FingerTestSuite) TestFinger() {
 }
 
 func (suite *FingerTestSuite) TestFingerWithHostMeta() {
-	wc := suite.state.Caches.GTS.Webfinger()
+	wc := suite.state.Caches.GTS.Webfinger
 	suite.Equal(0, wc.Len(), "expect webfinger cache to be empty")
 
 	_, err := suite.transport.Finger(context.TODO(), "someone", "misconfigured-instance.com")
@@ -60,7 +60,7 @@ func (suite *FingerTestSuite) TestFingerWithHostMetaCacheStrategy() {
 		suite.T().Skip("this test is flaky on CI for as of yet unknown reasons")
 	}
 
-	wc := suite.state.Caches.GTS.Webfinger()
+	wc := suite.state.Caches.GTS.Webfinger
 
 	// Reset the sweep frequency so nothing interferes with the test
 	wc.Stop()