Reduce memory usage for chunked artifact uploads to MinIO (go-gitea#31325) (go-gitea#31338)

Backport go-gitea#31325 by @bohde

When using the MinIO storage driver for Actions Artifacts, we found that
the chunked artifact required significantly more memory usage to both
upload and merge than the local storage driver. This seems to be related
to hardcoding a value of `-1` for the size to the MinIO client [which
has a warning about memory usage in the respective
docs](https://pkg.go.dev/github.com/minio/minio-go/v7#Client.PutObject).
Specifying the size in both the upload and merge case reduces memory
usage of the MinIO client.

Co-authored-by: Rowan Bohde <[email protected]>
Co-authored-by: Kyle D <[email protected]>

Author: 3 people

routers/api/actions/artifacts_chunks.go

@@ -39,7 +39,7 @@ func saveUploadChunkBase(st storage.ObjectStorage, ctx *ArtifactContext,
 		r = io.TeeReader(r, hasher)
 	}
 	// save chunk to storage
-	writtenSize, err := st.Save(storagePath, r, -1)
+	writtenSize, err := st.Save(storagePath, r, contentSize)
 	if err != nil {
 		return -1, fmt.Errorf("save chunk to storage error: %v", err)
 	}
@@ -208,7 +208,7 @@ func mergeChunksForArtifact(ctx *ArtifactContext, chunks []*chunkFileItem, st st
 
 	// save merged file
 	storagePath := fmt.Sprintf("%d/%d/%d.%s", artifact.RunID%255, artifact.ID%255, time.Now().UnixNano(), extension)
-	written, err := st.Save(storagePath, mergedReader, -1)
+	written, err := st.Save(storagePath, mergedReader, artifact.FileCompressedSize)
 	if err != nil {
 		return fmt.Errorf("save merged file error: %v", err)
 	}