On open repository open common cat file batch and batch-check (#15667)

Use common git cat-file --batch and git cat-file --batch-check to
significantly reduce calls to git.
    
Signed-off-by: Andrew Thornton <art27@cantab.net>

modules/context/repo.go

@@ -905,12 +905,18 @@ func (ctx *Context) IssueTemplatesFromDefaultBranch() []api.IssueTemplate {
 					log.Debug("DataAsync: %v", err)
 					continue
 				}
-				defer r.Close()
+				closed := false
+				defer func() {
+					if !closed {
+						_ = r.Close()
+					}
+				}()
 				data, err := ioutil.ReadAll(r)
 				if err != nil {
 					log.Debug("ReadAll: %v", err)
 					continue
 				}
+				_ = r.Close()
 				var it api.IssueTemplate
 				content, err := markdown.ExtractMetadata(string(data), &it)
 				if err != nil {

modules/git/batch_reader.go

@@ -13,9 +13,44 @@ import (
 	"strings"
 )
 
+// WriteCloserError wraps an io.WriteCloser with an additional CloseWithError function
+type WriteCloserError interface {
+	io.WriteCloser
+	CloseWithError(err error) error
+}
+
+// CatFileBatchCheck opens git cat-file --batch-check in the provided repo and returns a stdin pipe, a stdout reader and cancel function
+func CatFileBatchCheck(repoPath string) (WriteCloserError, *bufio.Reader, func()) {
+	batchStdinReader, batchStdinWriter := io.Pipe()
+	batchStdoutReader, batchStdoutWriter := io.Pipe()
+	cancel := func() {
+		_ = batchStdinReader.Close()
+		_ = batchStdinWriter.Close()
+		_ = batchStdoutReader.Close()
+		_ = batchStdoutWriter.Close()
+	}
+
+	go func() {
+		stderr := strings.Builder{}
+		err := NewCommand("cat-file", "--batch-check").RunInDirFullPipeline(repoPath, batchStdoutWriter, &stderr, batchStdinReader)
+		if err != nil {
+			_ = batchStdoutWriter.CloseWithError(ConcatenateError(err, (&stderr).String()))
+			_ = batchStdinReader.CloseWithError(ConcatenateError(err, (&stderr).String()))
+		} else {
+			_ = batchStdoutWriter.Close()
+			_ = batchStdinReader.Close()
+		}
+	}()
+
+	// For simplicities sake we'll us a buffered reader to read from the cat-file --batch
+	batchReader := bufio.NewReader(batchStdoutReader)
+
+	return batchStdinWriter, batchReader, cancel
+}
+
 // CatFileBatch opens git cat-file --batch in the provided repo and returns a stdin pipe, a stdout reader and cancel function
-func CatFileBatch(repoPath string) (*io.PipeWriter, *bufio.Reader, func()) {
-	// Next feed the commits in order into cat-file --batch, followed by their trees and sub trees as necessary.
+func CatFileBatch(repoPath string) (WriteCloserError, *bufio.Reader, func()) {
+	// We often want to feed the commits in order into cat-file --batch, followed by their trees and sub trees as necessary.
 	// so let's create a batch stdin and stdout
 	batchStdinReader, batchStdinWriter := io.Pipe()
 	batchStdoutReader, batchStdoutWriter := io.Pipe()
@@ -47,26 +82,28 @@ func CatFileBatch(repoPath string) (*io.PipeWriter, *bufio.Reader, func()) {
 // ReadBatchLine reads the header line from cat-file --batch
 // We expect:
 // <sha> SP <type> SP <size> LF
+// sha is a 40byte not 20byte here
 func ReadBatchLine(rd *bufio.Reader) (sha []byte, typ string, size int64, err error) {
 	sha, err = rd.ReadBytes(' ')
 	if err != nil {
 		return
 	}
 	sha = sha[:len(sha)-1]
 
-	typ, err = rd.ReadString(' ')
+	typ, err = rd.ReadString('\n')
 	if err != nil {
 		return
 	}
-	typ = typ[:len(typ)-1]
 
-	var sizeStr string
-	sizeStr, err = rd.ReadString('\n')
-	if err != nil {
+	idx := strings.Index(typ, " ")
+	if idx < 0 {
+		err = ErrNotExist{ID: string(sha)}
 		return
 	}
+	sizeStr := typ[idx+1 : len(typ)-1]
+	typ = typ[:idx]
 
-	size, err = strconv.ParseInt(sizeStr[:len(sizeStr)-1], 10, 64)
+	size, err = strconv.ParseInt(sizeStr, 10, 64)
 	return
 }
 
@@ -128,7 +165,7 @@ headerLoop:
 	}
 
 	// Discard the rest of the commit
-	discard := size - n
+	discard := size - n + 1
 	for discard > math.MaxInt32 {
 		_, err := rd.Discard(math.MaxInt32)
 		if err != nil {

modules/git/blob_nogogit.go

@@ -8,48 +8,54 @@ package git
 
 import (
 	"bufio"
+	"bytes"
 	"io"
-	"strconv"
-	"strings"
+	"io/ioutil"
+	"math"
 )
 
 // Blob represents a Git object.
 type Blob struct {
 	ID SHA1
 
-	gotSize  bool
-	size     int64
-	repoPath string
-	name     string
+	gotSize bool
+	size    int64
+	name    string
+	repo    *Repository
 }
 
 // DataAsync gets a ReadCloser for the contents of a blob without reading it all.
 // Calling the Close function on the result will discard all unread output.
 func (b *Blob) DataAsync() (io.ReadCloser, error) {
-	stdoutReader, stdoutWriter := io.Pipe()
+	wr, rd, cancel := b.repo.CatFileBatch()
 
-	go func() {
-		stderr := &strings.Builder{}
-		err := NewCommand("cat-file", "--batch").RunInDirFullPipeline(b.repoPath, stdoutWriter, stderr, strings.NewReader(b.ID.String()+"\n"))
-		if err != nil {
-			err = ConcatenateError(err, stderr.String())
-			_ = stdoutWriter.CloseWithError(err)
-		} else {
-			_ = stdoutWriter.Close()
-		}
-	}()
-
-	bufReader := bufio.NewReader(stdoutReader)
-	_, _, size, err := ReadBatchLine(bufReader)
+	_, err := wr.Write([]byte(b.ID.String() + "\n"))
 	if err != nil {
-		stdoutReader.Close()
+		cancel()
 		return nil, err
 	}
+	_, _, size, err := ReadBatchLine(rd)
+	if err != nil {
+		cancel()
+		return nil, err
+	}
+	b.gotSize = true
+	b.size = size
 
-	return &LimitedReaderCloser{
-		R: bufReader,
-		C: stdoutReader,
-		N: size,
+	if size < 4096 {
+		bs, err := ioutil.ReadAll(io.LimitReader(rd, size))
+		if err != nil {
+			cancel()
+			return nil, err
+		}
+		_, err = rd.Discard(1)
+		return ioutil.NopCloser(bytes.NewReader(bs)), err
+	}
+
+	return &blobReader{
+		rd:     rd,
+		n:      size,
+		cancel: cancel,
 	}, nil
 }
 
@@ -59,18 +65,66 @@ func (b *Blob) Size() int64 {
 		return b.size
 	}
 
-	size, err := NewCommand("cat-file", "-s", b.ID.String()).RunInDir(b.repoPath)
+	wr, rd, cancel := b.repo.CatFileBatchCheck()
+	defer cancel()
+	_, err := wr.Write([]byte(b.ID.String() + "\n"))
 	if err != nil {
-		log("error whilst reading size for %s in %s. Error: %v", b.ID.String(), b.repoPath, err)
+		log("error whilst reading size for %s in %s. Error: %v", b.ID.String(), b.repo.Path, err)
 		return 0
 	}
-
-	b.size, err = strconv.ParseInt(size[:len(size)-1], 10, 64)
+	_, _, b.size, err = ReadBatchLine(rd)
 	if err != nil {
-		log("error whilst parsing size %s for %s in %s. Error: %v", size, b.ID.String(), b.repoPath, err)
+		log("error whilst reading size for %s in %s. Error: %v", b.ID.String(), b.repo.Path, err)
 		return 0
 	}
+
 	b.gotSize = true
 
 	return b.size
 }
+
+type blobReader struct {
+	rd     *bufio.Reader
+	n      int64
+	cancel func()
+}
+
+func (b *blobReader) Read(p []byte) (n int, err error) {
+	if b.n <= 0 {
+		return 0, io.EOF
+	}
+	if int64(len(p)) > b.n {
+		p = p[0:b.n]
+	}
+	n, err = b.rd.Read(p)
+	b.n -= int64(n)
+	return
+}
+
+// Close implements io.Closer
+func (b *blobReader) Close() error {
+	if b.n > 0 {
+		for b.n > math.MaxInt32 {
+			n, err := b.rd.Discard(math.MaxInt32)
+			b.n -= int64(n)
+			if err != nil {
+				b.cancel()
+				return err
+			}
+			b.n -= math.MaxInt32
+		}
+		n, err := b.rd.Discard(int(b.n))
+		b.n -= int64(n)
+		if err != nil {
+			b.cancel()
+			return err
+		}
+	}
+	if b.n == 0 {
+		_, err := b.rd.Discard(1)
+		b.n--
+		b.cancel()
+		return err
+	}
+	return nil
+}

modules/git/blob_test.go

@@ -29,9 +29,10 @@ func TestBlob_Data(t *testing.T) {
 	r, err := testBlob.DataAsync()
 	assert.NoError(t, err)
 	require.NotNil(t, r)
-	defer r.Close()
 
 	data, err := ioutil.ReadAll(r)
+	assert.NoError(t, r.Close())
+
 	assert.NoError(t, err)
 	assert.Equal(t, output, string(data))
 }
@@ -54,7 +55,7 @@ func Benchmark_Blob_Data(b *testing.B) {
 		if err != nil {
 			b.Fatal(err)
 		}
-		defer r.Close()
 		ioutil.ReadAll(r)
+		_ = r.Close()
 	}
 }

modules/git/commit_info_nogogit.go

@@ -102,7 +102,7 @@ func (tes Entries) GetCommitsInfo(commit *Commit, treePath string, cache *LastCo
 }
 
 func getLastCommitForPathsByCache(commitID, treePath string, paths []string, cache *LastCommitCache) (map[string]*Commit, []string, error) {
-	wr, rd, cancel := CatFileBatch(cache.repo.Path)
+	wr, rd, cancel := cache.repo.CatFileBatch()
 	defer cancel()
 
 	var unHitEntryPaths []string
@@ -144,7 +144,7 @@ func GetLastCommitForPaths(commit *Commit, treePath string, paths []string) ([]*
 		}
 	}()
 
-	batchStdinWriter, batchReader, cancel := CatFileBatch(commit.repo.Path)
+	batchStdinWriter, batchReader, cancel := commit.repo.CatFileBatch()
 	defer cancel()
 
 	mapsize := 4096
@@ -237,6 +237,10 @@ revListLoop:
 					// FIXME: is there any order to the way strings are emitted from cat-file?
 					// if there is - then we could skip once we've passed all of our data
 				}
+				if _, err := batchReader.Discard(1); err != nil {
+					return nil, err
+				}
+
 				break treeReadingLoop
 			}
 
@@ -281,6 +285,9 @@ revListLoop:
 					return nil, err
 				}
 			}
+			if _, err := batchReader.Discard(1); err != nil {
+				return nil, err
+			}
 
 			// if we haven't found a treeID for the target directory our search is over
 			if len(treeID) == 0 {
@@ -345,6 +352,9 @@ revListLoop:
 		if err != nil {
 			return nil, err
 		}
+		if _, err := batchReader.Discard(1); err != nil {
+			return nil, err
+		}
 		commitCommits[i] = c
 	}
 

modules/git/last_commit_cache_nogogit.go

@@ -8,7 +8,6 @@ package git
 
 import (
 	"bufio"
-	"io"
 	"path"
 )
 
@@ -36,7 +35,7 @@ func NewLastCommitCache(repoPath string, gitRepo *Repository, ttl func() int64,
 }
 
 // Get get the last commit information by commit id and entry path
-func (c *LastCommitCache) Get(ref, entryPath string, wr *io.PipeWriter, rd *bufio.Reader) (interface{}, error) {
+func (c *LastCommitCache) Get(ref, entryPath string, wr WriteCloserError, rd *bufio.Reader) (interface{}, error) {
 	v := c.cache.Get(c.getCacheKey(c.repoPath, ref, entryPath))
 	if vs, ok := v.(string); ok {
 		log("LastCommitCache hit level 1: [%s:%s:%s]", ref, entryPath, vs)

modules/git/notes_nogogit.go

@@ -43,11 +43,18 @@ func GetNote(repo *Repository, commitID string, note *Note) error {
 	if err != nil {
 		return err
 	}
-	defer dataRc.Close()
+	closed := false
+	defer func() {
+		if !closed {
+			_ = dataRc.Close()
+		}
+	}()
 	d, err := ioutil.ReadAll(dataRc)
 	if err != nil {
 		return err
 	}
+	_ = dataRc.Close()
+	closed = true
 	note.Message = d
 
 	treePath := ""