fix: prevent cache size underflow (#4986)

Author: acha-bill

pkg/storer/cachestore.go

@@ -10,7 +10,7 @@ import (
 	"fmt"
 	"time"
 
-	storage "github.com/ethersphere/bee/v2/pkg/storage"
+	"github.com/ethersphere/bee/v2/pkg/storage"
 	"github.com/ethersphere/bee/v2/pkg/storer/internal/transaction"
 	"github.com/ethersphere/bee/v2/pkg/swarm"
 )
@@ -39,7 +39,7 @@ func (db *DB) cacheWorker(ctx context.Context) {
 				continue
 			}
 
-			evict := size - capc
+			evict := uint64(size - capc)
 			if evict < db.reserveOptions.cacheMinEvictCount { // evict at least a min count
 				evict = db.reserveOptions.cacheMinEvictCount
 			}

pkg/storer/internal/cache/cache.go

@@ -14,7 +14,7 @@ import (
 	"sync/atomic"
 	"time"
 
-	storage "github.com/ethersphere/bee/v2/pkg/storage"
+	"github.com/ethersphere/bee/v2/pkg/storage"
 	"github.com/ethersphere/bee/v2/pkg/storer/internal/transaction"
 	"github.com/ethersphere/bee/v2/pkg/swarm"
 	"golang.org/x/sync/errgroup"
@@ -61,12 +61,14 @@ func New(ctx context.Context, store storage.Reader, capacity uint64) (*Cache, er
 }
 
 // Size returns the current size of the cache.
-func (c *Cache) Size() uint64 {
-	return uint64(c.size.Load())
+func (c *Cache) Size() int64 {
+	return c.size.Load()
 }
 
 // Capacity returns the capacity of the cache.
-func (c *Cache) Capacity() uint64 { return uint64(c.capacity) }
+func (c *Cache) Capacity() int64 {
+	return int64(c.capacity)
+}
 
 // Putter returns a Storage.Putter instance which adds the chunk to the underlying
 // chunkstore and also adds a Cache entry for the chunk.

pkg/storer/internal/cache/export_test.go

@@ -9,7 +9,7 @@ import (
 	"fmt"
 	"time"
 
-	storage "github.com/ethersphere/bee/v2/pkg/storage"
+	"github.com/ethersphere/bee/v2/pkg/storage"
 	"github.com/ethersphere/bee/v2/pkg/storer/internal/transaction"
 	"github.com/ethersphere/bee/v2/pkg/swarm"
 )
@@ -43,7 +43,7 @@ func (c *Cache) RemoveOldestMaxBatch(ctx context.Context, st transaction.Storage
 
 func (c *Cache) State(store storage.Reader) CacheState {
 	state := CacheState{}
-	state.Size = c.Size()
+	state.Size = uint64(c.Size())
 	runner := swarm.ZeroAddress
 
 	err := store.Iterate(