runtime: Remove now unnecessary pad field from ParFor.

    
    It is not needed due to the removal of the ctx field.
    
    Reviewed-on: https://go-review.googlesource.com/16525

From-SVN: r229616

3 files changed, 180 insertions, 2 deletions

diff --git a/libgo/go/bufio/bufio.go b/libgo/go/bufio/bufio.go
index d3c68fe6fe5..3bbb933df35 100644
--- a/libgo/go/bufio/bufio.go
+++ b/libgo/go/bufio/bufio.go
@@ -144,6 +144,39 @@ func (b *Reader) Peek(n int) ([]byte, error) {
 	return b.buf[b.r : b.r+n], err
 }
 
+// Discard skips the next n bytes, returning the number of bytes discarded.
+//
+// If Discard skips fewer than n bytes, it also returns an error.
+// If 0 <= n <= b.Buffered(), Discard is guaranteed to succeed without
+// reading from the underlying io.Reader.
+func (b *Reader) Discard(n int) (discarded int, err error) {
+	if n < 0 {
+		return 0, ErrNegativeCount
+	}
+	if n == 0 {
+		return
+	}
+	remain := n
+	for {
+		skip := b.Buffered()
+		if skip == 0 {
+			b.fill()
+			skip = b.Buffered()
+		}
+		if skip > remain {
+			skip = remain
+		}
+		b.r += skip
+		remain -= skip
+		if remain == 0 {
+			return n, nil
+		}
+		if b.err != nil {
+			return n - remain, b.readErr()
+		}
+	}
+}
+
 // Read reads data into p.
 // It returns the number of bytes read into p.
 // It calls Read at most once on the underlying Reader,
@@ -367,7 +400,6 @@ func (b *Reader) ReadBytes(delim byte) (line []byte, err error) {
 	// accumulating full buffers.
 	var frag []byte
 	var full [][]byte
-	err = nil
 
 	for {
 		var e error
diff --git a/libgo/go/bufio/bufio_test.go b/libgo/go/bufio/bufio_test.go
index 550dac9173f..666c44e15a9 100644
--- a/libgo/go/bufio/bufio_test.go
+++ b/libgo/go/bufio/bufio_test.go
@@ -1268,6 +1268,135 @@ func TestWriterReset(t *testing.T) {
 	}
 }
 
+func TestReaderDiscard(t *testing.T) {
+	tests := []struct {
+		name     string
+		r        io.Reader
+		bufSize  int // 0 means 16
+		peekSize int
+
+		n int // input to Discard
+
+		want    int   // from Discard
+		wantErr error // from Discard
+
+		wantBuffered int
+	}{
+		{
+			name:         "normal case",
+			r:            strings.NewReader("abcdefghijklmnopqrstuvwxyz"),
+			peekSize:     16,
+			n:            6,
+			want:         6,
+			wantBuffered: 10,
+		},
+		{
+			name:         "discard causing read",
+			r:            strings.NewReader("abcdefghijklmnopqrstuvwxyz"),
+			n:            6,
+			want:         6,
+			wantBuffered: 10,
+		},
+		{
+			name:         "discard all without peek",
+			r:            strings.NewReader("abcdefghijklmnopqrstuvwxyz"),
+			n:            26,
+			want:         26,
+			wantBuffered: 0,
+		},
+		{
+			name:         "discard more than end",
+			r:            strings.NewReader("abcdefghijklmnopqrstuvwxyz"),
+			n:            27,
+			want:         26,
+			wantErr:      io.EOF,
+			wantBuffered: 0,
+		},
+		// Any error from filling shouldn't show up until we
+		// get past the valid bytes. Here we return we return 5 valid bytes at the same time
+		// as an error, but test that we don't see the error from Discard.
+		{
+			name: "fill error, discard less",
+			r: newScriptedReader(func(p []byte) (n int, err error) {
+				if len(p) < 5 {
+					panic("unexpected small read")
+				}
+				return 5, errors.New("5-then-error")
+			}),
+			n:            4,
+			want:         4,
+			wantErr:      nil,
+			wantBuffered: 1,
+		},
+		{
+			name: "fill error, discard equal",
+			r: newScriptedReader(func(p []byte) (n int, err error) {
+				if len(p) < 5 {
+					panic("unexpected small read")
+				}
+				return 5, errors.New("5-then-error")
+			}),
+			n:            5,
+			want:         5,
+			wantErr:      nil,
+			wantBuffered: 0,
+		},
+		{
+			name: "fill error, discard more",
+			r: newScriptedReader(func(p []byte) (n int, err error) {
+				if len(p) < 5 {
+					panic("unexpected small read")
+				}
+				return 5, errors.New("5-then-error")
+			}),
+			n:            6,
+			want:         5,
+			wantErr:      errors.New("5-then-error"),
+			wantBuffered: 0,
+		},
+		// Discard of 0 shouldn't cause a read:
+		{
+			name:         "discard zero",
+			r:            newScriptedReader(), // will panic on Read
+			n:            0,
+			want:         0,
+			wantErr:      nil,
+			wantBuffered: 0,
+		},
+		{
+			name:         "discard negative",
+			r:            newScriptedReader(), // will panic on Read
+			n:            -1,
+			want:         0,
+			wantErr:      ErrNegativeCount,
+			wantBuffered: 0,
+		},
+	}
+	for _, tt := range tests {
+		br := NewReaderSize(tt.r, tt.bufSize)
+		if tt.peekSize > 0 {
+			peekBuf, err := br.Peek(tt.peekSize)
+			if err != nil {
+				t.Errorf("%s: Peek(%d): %v", tt.name, tt.peekSize, err)
+				continue
+			}
+			if len(peekBuf) != tt.peekSize {
+				t.Errorf("%s: len(Peek(%d)) = %v; want %v", tt.name, tt.peekSize, len(peekBuf), tt.peekSize)
+				continue
+			}
+		}
+		discarded, err := br.Discard(tt.n)
+		if ge, we := fmt.Sprint(err), fmt.Sprint(tt.wantErr); discarded != tt.want || ge != we {
+			t.Errorf("%s: Discard(%d) = (%v, %v); want (%v, %v)", tt.name, tt.n, discarded, ge, tt.want, we)
+			continue
+		}
+		if bn := br.Buffered(); bn != tt.wantBuffered {
+			t.Errorf("%s: after Discard, Buffered = %d; want %d", tt.name, bn, tt.wantBuffered)
+		}
+	}
+
+}
+
 // An onlyReader only implements io.Reader, no matter what other methods the underlying implementation may have.
 type onlyReader struct {
 	io.Reader
@@ -1278,6 +1407,23 @@ type onlyWriter struct {
 	io.Writer
 }
 
+// A scriptedReader is an io.Reader that executes its steps sequentially.
+type scriptedReader []func(p []byte) (n int, err error)
+
+func (sr *scriptedReader) Read(p []byte) (n int, err error) {
+	if len(*sr) == 0 {
+		panic("too many Read calls on scripted Reader. No steps remain.")
+	}
+	step := (*sr)[0]
+	*sr = (*sr)[1:]
+	return step(p)
+}
+
+func newScriptedReader(steps ...func(p []byte) (n int, err error)) io.Reader {
+	sr := scriptedReader(steps)
+	return &sr
+}
+
 func BenchmarkReaderCopyOptimal(b *testing.B) {
 	// Optimal case is where the underlying reader implements io.WriterTo
 	srcBuf := bytes.NewBuffer(make([]byte, 8192))
diff --git a/libgo/go/bufio/scan.go b/libgo/go/bufio/scan.go
index 364d1596139..7a349fa8fab 100644
--- a/libgo/go/bufio/scan.go
+++ b/libgo/go/bufio/scan.go
@@ -109,7 +109,7 @@ func (s *Scanner) Text() string {
 // After Scan returns false, the Err method will return any error that
 // occurred during scanning, except that if it was io.EOF, Err
 // will return nil.
-// Split panics if the split function returns 100 empty tokens without
+// Scan panics if the split function returns 100 empty tokens without
 // advancing the input. This is a common error mode for scanners.
 func (s *Scanner) Scan() bool {
 	// Loop until we have a token.