From 6b0ba750e6dabe016ec88d448cac40a0ba8ed3ee Mon Sep 17 00:00:00 2001
From: Max Schaefer <max@semmle.com>
Date: Thu, 12 Mar 2020 08:30:14 +0000
Subject: [PATCH] Put gzip writer on top of bufio writer.

---
 extractor/trap/labels.go     |  4 ++--
 extractor/trap/trapwriter.go | 27 ++++++++++++++-------------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/extractor/trap/labels.go b/extractor/trap/labels.go
index 9c63f76dbe0..d6bce8b5bb5 100644
--- a/extractor/trap/labels.go
+++ b/extractor/trap/labels.go
@@ -55,7 +55,7 @@ func (l *Labeler) GlobalID(key string) Label {
 	label, exists := l.keyLabels[key]
 	if !exists {
 		id := l.nextID()
-		fmt.Fprintf(l.tw.w, "%s=@\"%s\"\n", id, escapeString(key))
+		fmt.Fprintf(l.tw.zip, "%s=@\"%s\"\n", id, escapeString(key))
 		label = Label{id}
 		l.keyLabels[key] = label
 	}
@@ -83,7 +83,7 @@ func (l *Labeler) LocalID(nd interface{}) Label {
 // FreshID creates a fresh label and returns it
 func (l *Labeler) FreshID() Label {
 	id := l.nextID()
-	fmt.Fprintf(l.tw.w, "%s=*\n", id)
+	fmt.Fprintf(l.tw.zip, "%s=*\n", id)
 	return Label{id}
 }
 
diff --git a/extractor/trap/trapwriter.go b/extractor/trap/trapwriter.go
index f5527bdb6ca..aadc04f9f48 100644
--- a/extractor/trap/trapwriter.go
+++ b/extractor/trap/trapwriter.go
@@ -17,8 +17,8 @@ import (
 
 // A Writer provides methods for writing data to a TRAP file
 type Writer struct {
-	w            *bufio.Writer
 	zip          *gzip.Writer
+	w            *bufio.Writer
 	file         *os.File
 	Labeler      *Labeler
 	path         string
@@ -43,10 +43,11 @@ func NewWriter(path string, pkg *packages.Package) (*Writer, error) {
 	if err != nil {
 		return nil, err
 	}
-	zipWriter := gzip.NewWriter(tmpFile)
+	bufioWriter := bufio.NewWriter(tmpFile)
+	zipWriter := gzip.NewWriter(bufioWriter)
 	tw := &Writer{
-		bufio.NewWriter(zipWriter),
 		zipWriter,
+		bufioWriter,
 		tmpFile,
 		nil,
 		path,
@@ -74,15 +75,15 @@ func trapFolder() (string, error) {
 
 // Close the underlying file writer
 func (tw *Writer) Close() error {
-	err := tw.w.Flush()
+	err := tw.zip.Close()
 	if err != nil {
-		// throw away close error because write errors are likely to be more important
+		// return zip-close error, but ignore file-close error
 		tw.file.Close()
 		return err
 	}
-	err = tw.zip.Close()
+	err = tw.w.Flush()
 	if err != nil {
-		// return zip-close error, but ignore file-close error
+		// throw away close error because write errors are likely to be more important
 		tw.file.Close()
 		return err
 	}
@@ -120,22 +121,22 @@ func capStringLength(s string) string {
 
 // Emit writes out a tuple of values for the given `table`
 func (tw *Writer) Emit(table string, values []interface{}) error {
-	fmt.Fprintf(tw.w, "%s(", table)
+	fmt.Fprintf(tw.zip, "%s(", table)
 	for i, value := range values {
 		if i > 0 {
-			fmt.Fprint(tw.w, ", ")
+			fmt.Fprint(tw.zip, ", ")
 		}
 		switch value := value.(type) {
 		case Label:
-			fmt.Fprint(tw.w, value.id)
+			fmt.Fprint(tw.zip, value.id)
 		case string:
-			fmt.Fprintf(tw.w, "\"%s\"", escapeString(capStringLength(value)))
+			fmt.Fprintf(tw.zip, "\"%s\"", escapeString(capStringLength(value)))
 		case int:
-			fmt.Fprintf(tw.w, "%d", value)
+			fmt.Fprintf(tw.zip, "%d", value)
 		default:
 			return errors.New("Cannot emit value")
 		}
 	}
-	fmt.Fprintf(tw.w, ")\n")
+	fmt.Fprintf(tw.zip, ")\n")
 	return nil
 }