java: grow buffers to the right capacity before use

avoids reallocations when buffers grow repeatedly for large files, and oversizing (as buffer capacity doubles when capacity is reached) Signed-off-by: Mark Frost <[email protected]>
quay · Jan 4, 2024 · a020a5e · a020a5e
1 parent 07ae3f0
commit a020a5e
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 0 deletions.
diff --git a/java/jar/jar.go b/java/jar/jar.go
@@ -275,6 +275,7 @@ func extractInner(ctx context.Context, p srcPath, z *zip.Reader) ([]Info, error)
 		}
 		defer rc.Close()
 		buf.Reset()
+		buf.Grow(int(fi.Size()))
 		h.Reset()
 		sz, err := buf.ReadFrom(io.TeeReader(rc, h))
 		if err != nil {

diff --git a/java/packagescanner.go b/java/packagescanner.go
@@ -147,6 +147,10 @@ func (s *Scanner) Scan(ctx context.Context, layer *claircore.Layer) ([]*claircor
 		if err != nil {
 			return nil, err
 		}
+		fStat, err := f.Stat()
+		if err == nil {
+			buf.Grow(int(fStat.Size()))
+		}
 		sz, err := buf.ReadFrom(io.TeeReader(f, sh))
 		f.Close()
 		if err != nil {