From ac1e00b0fe69278ef45955e9817665bf71a87ded Mon Sep 17 00:00:00 2001
From: Daniel <dhaavi@users.noreply.github.com>
Date: Fri, 16 Oct 2020 15:01:46 +0200
Subject: [PATCH] Fix locking when updating the interface cache in Put methods

Also, update the cache when fetching records from the database.
---
 database/interface.go       | 29 ++++++++++++++++++++++++-----
 database/interface_cache.go |  6 +++---
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/database/interface.go b/database/interface.go
index 9c6b4a9..d0a6552 100644
--- a/database/interface.go
+++ b/database/interface.go
@@ -188,6 +188,16 @@ func (i *Interface) getRecord(dbName string, dbKey string, mustBeWriteable bool)
 		return nil, db, ErrPermissionDenied
 	}
 
+	r.Lock()
+	ttl := r.Meta().GetRelativeExpiry()
+	r.Unlock()
+	i.updateCache(
+		r,
+		false, // writing
+		false, // remove
+		ttl,   // expiry
+	)
+
 	return r, db, nil
 }
 
@@ -243,14 +253,19 @@ func (i *Interface) Put(r record.Record) (err error) {
 	}
 
 	r.Lock()
-	defer r.Unlock()
 	i.options.Apply(r)
+	remove := r.Meta().IsDeleted()
+	ttl := r.Meta().GetRelativeExpiry()
+	r.Unlock()
 
-	written := i.updateCache(r, true)
+	// The record may not be locked when updating the cache.
+	written := i.updateCache(r, true, remove, ttl)
 	if written {
 		return nil
 	}
 
+	r.Lock()
+	defer r.Unlock()
 	return db.Put(r)
 }
 
@@ -271,18 +286,22 @@ func (i *Interface) PutNew(r record.Record) (err error) {
 	}
 
 	r.Lock()
-	defer r.Unlock()
-
 	if r.Meta() != nil {
 		r.Meta().Reset()
 	}
 	i.options.Apply(r)
+	remove := r.Meta().IsDeleted()
+	ttl := r.Meta().GetRelativeExpiry()
+	r.Unlock()
 
-	written := i.updateCache(r, true)
+	// The record may not be locked when updating the cache.
+	written := i.updateCache(r, true, remove, ttl)
 	if written {
 		return nil
 	}
 
+	r.Lock()
+	defer r.Unlock()
 	return db.Put(r)
 }
 
diff --git a/database/interface_cache.go b/database/interface_cache.go
index 3e349e5..5858b61 100644
--- a/database/interface_cache.go
+++ b/database/interface_cache.go
@@ -159,14 +159,15 @@ func (i *Interface) checkCache(key string) record.Record {
 	return nil
 }
 
-func (i *Interface) updateCache(r record.Record, write bool) (written bool) {
+// updateCache updates an entry in the
+func (i *Interface) updateCache(r record.Record, write bool, remove bool, ttl int64) (written bool) {
 	// Check if cache is in use.
 	if i.cache == nil {
 		return false
 	}
 
 	// Check if record should be deleted
-	if r.Meta().IsDeleted() {
+	if remove {
 		// Remove entry from cache.
 		i.cache.Remove(r.Key())
 		// Let write through to database storage.
@@ -174,7 +175,6 @@ func (i *Interface) updateCache(r record.Record, write bool) (written bool) {
 	}
 
 	// Update cache with record.
-	ttl := r.Meta().GetRelativeExpiry()
 	if ttl >= 0 {
 		_ = i.cache.SetWithExpire(
 			r.Key(),