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forgejo/modules/git/batch_reader.go
Lunny Xiao 0ca13c5eae
[PORT] Refactor the usage of batch catfile (gitea#31754)
When opening a repository, it will call `ensureValidRepository` and also
`CatFileBatch`. But sometimes these will not be used until repository
closed. So it's a waste of CPU to invoke 3 times git command for every
open repository.

This PR removed all of these from `OpenRepository` but only kept
checking whether the folder exists. When a batch is necessary, the
necessary functions will be invoked.

---
Conflict resolution: Because of the removal of go-git in ()
`_nogogit.go` files were either renamed or merged into the 'common'
file. Git does handle the renames correctly, but for those that were
merged has to be manually copied pasted over. The patch looks the same,
201 additions 90 deletions as the original patch.

(cherry picked from commit c03baab678ba5b2e9d974aea147e660417f5d3f7)
2024-08-26 03:48:51 +02:00

347 lines
9.4 KiB
Go

// Copyright 2020 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package git
import (
"bufio"
"bytes"
"context"
"fmt"
"io"
"math"
"runtime"
"strconv"
"strings"
"code.gitea.io/gitea/modules/log"
"github.com/djherbis/buffer"
"github.com/djherbis/nio/v3"
)
// WriteCloserError wraps an io.WriteCloser with an additional CloseWithError function
type WriteCloserError interface {
io.WriteCloser
CloseWithError(err error) error
}
// ensureValidGitRepository runs git rev-parse in the repository path - thus ensuring that the repository is a valid repository.
// Run before opening git cat-file.
// This is needed otherwise the git cat-file will hang for invalid repositories.
func ensureValidGitRepository(ctx context.Context, repoPath string) error {
stderr := strings.Builder{}
err := NewCommand(ctx, "rev-parse").
SetDescription(fmt.Sprintf("%s rev-parse [repo_path: %s]", GitExecutable, repoPath)).
Run(&RunOpts{
Dir: repoPath,
Stderr: &stderr,
})
if err != nil {
return ConcatenateError(err, (&stderr).String())
}
return nil
}
// catFileBatchCheck opens git cat-file --batch-check in the provided repo and returns a stdin pipe, a stdout reader and cancel function
func catFileBatchCheck(ctx context.Context, repoPath string) (WriteCloserError, *bufio.Reader, func()) {
batchStdinReader, batchStdinWriter := io.Pipe()
batchStdoutReader, batchStdoutWriter := io.Pipe()
ctx, ctxCancel := context.WithCancel(ctx)
closed := make(chan struct{})
cancel := func() {
ctxCancel()
_ = batchStdoutReader.Close()
_ = batchStdinWriter.Close()
<-closed
}
// Ensure cancel is called as soon as the provided context is cancelled
go func() {
<-ctx.Done()
cancel()
}()
_, filename, line, _ := runtime.Caller(2)
filename = strings.TrimPrefix(filename, callerPrefix)
go func() {
stderr := strings.Builder{}
err := NewCommand(ctx, "cat-file", "--batch-check").
SetDescription(fmt.Sprintf("%s cat-file --batch-check [repo_path: %s] (%s:%d)", GitExecutable, repoPath, filename, line)).
Run(&RunOpts{
Dir: repoPath,
Stdin: batchStdinReader,
Stdout: batchStdoutWriter,
Stderr: &stderr,
UseContextTimeout: true,
})
if err != nil {
_ = batchStdoutWriter.CloseWithError(ConcatenateError(err, (&stderr).String()))
_ = batchStdinReader.CloseWithError(ConcatenateError(err, (&stderr).String()))
} else {
_ = batchStdoutWriter.Close()
_ = batchStdinReader.Close()
}
close(closed)
}()
// For simplicities sake we'll use a buffered reader to read from the cat-file --batch-check
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(ctx context.Context, 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 := nio.Pipe(buffer.New(32 * 1024))
ctx, ctxCancel := context.WithCancel(ctx)
closed := make(chan struct{})
cancel := func() {
ctxCancel()
_ = batchStdinWriter.Close()
_ = batchStdoutReader.Close()
<-closed
}
// Ensure cancel is called as soon as the provided context is cancelled
go func() {
<-ctx.Done()
cancel()
}()
_, filename, line, _ := runtime.Caller(2)
filename = strings.TrimPrefix(filename, callerPrefix)
go func() {
stderr := strings.Builder{}
err := NewCommand(ctx, "cat-file", "--batch").
SetDescription(fmt.Sprintf("%s cat-file --batch [repo_path: %s] (%s:%d)", GitExecutable, repoPath, filename, line)).
Run(&RunOpts{
Dir: repoPath,
Stdin: batchStdinReader,
Stdout: batchStdoutWriter,
Stderr: &stderr,
UseContextTimeout: true,
})
if err != nil {
_ = batchStdoutWriter.CloseWithError(ConcatenateError(err, (&stderr).String()))
_ = batchStdinReader.CloseWithError(ConcatenateError(err, (&stderr).String()))
} else {
_ = batchStdoutWriter.Close()
_ = batchStdinReader.Close()
}
close(closed)
}()
// For simplicities sake we'll us a buffered reader to read from the cat-file --batch
batchReader := bufio.NewReaderSize(batchStdoutReader, 32*1024)
return batchStdinWriter, batchReader, cancel
}
// ReadBatchLine reads the header line from cat-file --batch
// We expect:
// <sha> SP <type> SP <size> LF
// sha is a hex encoded here
func ReadBatchLine(rd *bufio.Reader) (sha []byte, typ string, size int64, err error) {
typ, err = rd.ReadString('\n')
if err != nil {
return sha, typ, size, err
}
if len(typ) == 1 {
typ, err = rd.ReadString('\n')
if err != nil {
return sha, typ, size, err
}
}
idx := strings.IndexByte(typ, ' ')
if idx < 0 {
log.Debug("missing space typ: %s", typ)
return sha, typ, size, ErrNotExist{ID: string(sha)}
}
sha = []byte(typ[:idx])
typ = typ[idx+1:]
idx = strings.IndexByte(typ, ' ')
if idx < 0 {
return sha, typ, size, ErrNotExist{ID: string(sha)}
}
sizeStr := typ[idx+1 : len(typ)-1]
typ = typ[:idx]
size, err = strconv.ParseInt(sizeStr, 10, 64)
return sha, typ, size, err
}
// ReadTagObjectID reads a tag object ID hash from a cat-file --batch stream, throwing away the rest of the stream.
func ReadTagObjectID(rd *bufio.Reader, size int64) (string, error) {
var id string
var n int64
headerLoop:
for {
line, err := rd.ReadBytes('\n')
if err != nil {
return "", err
}
n += int64(len(line))
idx := bytes.Index(line, []byte{' '})
if idx < 0 {
continue
}
if string(line[:idx]) == "object" {
id = string(line[idx+1 : len(line)-1])
break headerLoop
}
}
// Discard the rest of the tag
return id, DiscardFull(rd, size-n+1)
}
// ReadTreeID reads a tree ID from a cat-file --batch stream, throwing away the rest of the stream.
func ReadTreeID(rd *bufio.Reader, size int64) (string, error) {
var id string
var n int64
headerLoop:
for {
line, err := rd.ReadBytes('\n')
if err != nil {
return "", err
}
n += int64(len(line))
idx := bytes.Index(line, []byte{' '})
if idx < 0 {
continue
}
if string(line[:idx]) == "tree" {
id = string(line[idx+1 : len(line)-1])
break headerLoop
}
}
// Discard the rest of the commit
return id, DiscardFull(rd, size-n+1)
}
// git tree files are a list:
// <mode-in-ascii> SP <fname> NUL <binary Hash>
//
// Unfortunately this 20-byte notation is somewhat in conflict to all other git tools
// Therefore we need some method to convert these binary hashes to hex hashes
// constant hextable to help quickly convert between binary and hex representation
const hextable = "0123456789abcdef"
// BinToHexHeash converts a binary Hash into a hex encoded one. Input and output can be the
// same byte slice to support in place conversion without allocations.
// This is at least 100x quicker that hex.EncodeToString
func BinToHex(objectFormat ObjectFormat, sha, out []byte) []byte {
for i := objectFormat.FullLength()/2 - 1; i >= 0; i-- {
v := sha[i]
vhi, vlo := v>>4, v&0x0f
shi, slo := hextable[vhi], hextable[vlo]
out[i*2], out[i*2+1] = shi, slo
}
return out
}
// ParseTreeLine reads an entry from a tree in a cat-file --batch stream
// This carefully avoids allocations - except where fnameBuf is too small.
// It is recommended therefore to pass in an fnameBuf large enough to avoid almost all allocations
//
// Each line is composed of:
// <mode-in-ascii-dropping-initial-zeros> SP <fname> NUL <binary HASH>
//
// We don't attempt to convert the raw HASH to save a lot of time
func ParseTreeLine(objectFormat ObjectFormat, rd *bufio.Reader, modeBuf, fnameBuf, shaBuf []byte) (mode, fname, sha []byte, n int, err error) {
var readBytes []byte
// Read the Mode & fname
readBytes, err = rd.ReadSlice('\x00')
if err != nil {
return mode, fname, sha, n, err
}
idx := bytes.IndexByte(readBytes, ' ')
if idx < 0 {
log.Debug("missing space in readBytes ParseTreeLine: %s", readBytes)
return mode, fname, sha, n, &ErrNotExist{}
}
n += idx + 1
copy(modeBuf, readBytes[:idx])
if len(modeBuf) >= idx {
modeBuf = modeBuf[:idx]
} else {
modeBuf = append(modeBuf, readBytes[len(modeBuf):idx]...)
}
mode = modeBuf
readBytes = readBytes[idx+1:]
// Deal with the fname
copy(fnameBuf, readBytes)
if len(fnameBuf) > len(readBytes) {
fnameBuf = fnameBuf[:len(readBytes)]
} else {
fnameBuf = append(fnameBuf, readBytes[len(fnameBuf):]...)
}
for err == bufio.ErrBufferFull {
readBytes, err = rd.ReadSlice('\x00')
fnameBuf = append(fnameBuf, readBytes...)
}
n += len(fnameBuf)
if err != nil {
return mode, fname, sha, n, err
}
fnameBuf = fnameBuf[:len(fnameBuf)-1]
fname = fnameBuf
// Deal with the binary hash
idx = 0
length := objectFormat.FullLength() / 2
for idx < length {
var read int
read, err = rd.Read(shaBuf[idx:length])
n += read
if err != nil {
return mode, fname, sha, n, err
}
idx += read
}
sha = shaBuf
return mode, fname, sha, n, err
}
var callerPrefix string
func init() {
_, filename, _, _ := runtime.Caller(0)
callerPrefix = strings.TrimSuffix(filename, "modules/git/batch_reader.go")
}
func DiscardFull(rd *bufio.Reader, discard int64) error {
if discard > math.MaxInt32 {
n, err := rd.Discard(math.MaxInt32)
discard -= int64(n)
if err != nil {
return err
}
}
for discard > 0 {
n, err := rd.Discard(int(discard))
discard -= int64(n)
if err != nil {
return err
}
}
return nil
}