1 files changed, 56 insertions, 0 deletions
diff --git a/workhorse/internal/lsif_transformer/parser/cache.go b/workhorse/internal/lsif_transformer/parser/cache.go
new file mode 100644
index 00000000000..395069cd217
--- /dev/null
+++ b/workhorse/internal/lsif_transformer/parser/cache.go
@@ -0,0 +1,56 @@
+package parser
+
+import (
+	"encoding/binary"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+// This cache implementation is using a temp file to provide key-value data storage
+// It allows to avoid storing intermediate calculations in RAM
+// The stored data must be a fixed-size value or a slice of fixed-size values, or a pointer to such data
+type cache struct {
+	file      *os.File
+	chunkSize int64
+}
+
+func newCache(tempDir, filename string, data interface{}) (*cache, error) {
+	f, err := ioutil.TempFile(tempDir, filename)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := os.Remove(f.Name()); err != nil {
+		return nil, err
+	}
+
+	return &cache{file: f, chunkSize: int64(binary.Size(data))}, nil
+}
+
+func (c *cache) SetEntry(id Id, data interface{}) error {
+	if err := c.setOffset(id); err != nil {
+		return err
+	}
+
+	return binary.Write(c.file, binary.LittleEndian, data)
+}
+
+func (c *cache) Entry(id Id, data interface{}) error {
+	if err := c.setOffset(id); err != nil {
+		return err
+	}
+
+	return binary.Read(c.file, binary.LittleEndian, data)
+}
+
+func (c *cache) Close() error {
+	return c.file.Close()
+}
+
+func (c *cache) setOffset(id Id) error {
+	offset := int64(id) * c.chunkSize
+	_, err := c.file.Seek(offset, io.SeekStart)
+
+	return err
+}