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Optimize pulls merging (#4921)
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* Optimize pulls merging

By utilizing `git clone -s --no-checkout` rather than cloning the whole
repo.

* Use sparse-checkout to speedup pulls merge

* Use bytes.Buffer instead of strings.Builder for backward compatibility

* Fix empty diff-tree output for repos with only the initial commit

* Fix missing argument for the format string

* Rework diff-tree-list generation

* Remove logging code

* File list for sparse-checkout must be prefix with /

Otherwise, they would match all files with the same name under
subdirectories.

* Update onto the rebased head

* Use referecen repo to avoid fetching objects
  • Loading branch information
@typeless @lafriks
typeless authored and lafriks committed Jan 23, 2019
1 parent 7d43437 commit 6ad834e
Showing 1 changed file with 86 additions and 16 deletions.
102 changes: 86 additions & 16 deletions models/pull.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@
package models

import (
"bufio"
"bytes"
"fmt"
"io/ioutil"
"os"
Expand Down Expand Up @@ -328,6 +330,34 @@ func (pr *PullRequest) CheckUserAllowedToMerge(doer *User) (err error) {
return nil
}

func getDiffTree(repoPath, baseBranch, headBranch string) (string, error) {
getDiffTreeFromBranch := func(repoPath, baseBranch, headBranch string) (string, error) {
var stdout, stderr string
// Compute the diff-tree for sparse-checkout
// The branch argument must be enclosed with double-quotes ("") in case it contains slashes (e.g "feature/test")
stdout, stderr, err := process.GetManager().ExecDir(-1, repoPath,
fmt.Sprintf("PullRequest.Merge (git diff-tree): %s", repoPath),
"git", "diff-tree", "--no-commit-id", "--name-only", "-r", "--root", baseBranch, headBranch)
if err != nil {
return "", fmt.Errorf("git diff-tree [%s base:%s head:%s]: %s", repoPath, baseBranch, headBranch, stderr)
}
return stdout, nil
}

list, err := getDiffTreeFromBranch(repoPath, baseBranch, headBranch)
if err != nil {
return "", err
}

// Prefixing '/' for each entry, otherwise all files with the same name in subdirectories would be matched.
out := bytes.Buffer{}
scanner := bufio.NewScanner(strings.NewReader(list))
for scanner.Scan() {
fmt.Fprintf(&out, "/%s\n", scanner.Text())
}
return out.String(), nil
}

// Merge merges pull request to base repository.
// FIXME: add repoWorkingPull make sure two merges does not happen at same time.
func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle MergeStyle, message string) (err error) {
Expand Down Expand Up @@ -371,36 +401,76 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle
var stderr string
if _, stderr, err = process.GetManager().ExecTimeout(5*time.Minute,
fmt.Sprintf("PullRequest.Merge (git clone): %s", tmpBasePath),
"git", "clone", baseGitRepo.Path, tmpBasePath); err != nil {
"git", "clone", "-s", "--no-checkout", "-b", pr.BaseBranch, baseGitRepo.Path, tmpBasePath); err != nil {
return fmt.Errorf("git clone: %s", stderr)
}

// Check out base branch.
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git checkout): %s", tmpBasePath),
"git", "checkout", pr.BaseBranch); err != nil {
return fmt.Errorf("git checkout: %s", stderr)
}
remoteRepoName := "head_repo"

// Add head repo remote.
addCacheRepo := func(staging, cache string) error {
p := filepath.Join(staging, ".git", "objects", "info", "alternates")
f, err := os.OpenFile(p, os.O_APPEND|os.O_WRONLY, 0600)
if err != nil {
return err
}
defer f.Close()
data := filepath.Join(cache, "objects")
if _, err := fmt.Fprintln(f, data); err != nil {
return err
}
return nil
}

if err := addCacheRepo(tmpBasePath, headRepoPath); err != nil {
return fmt.Errorf("addCacheRepo [%s -> %s]: %v", headRepoPath, tmpBasePath, err)
}
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git remote add): %s", tmpBasePath),
"git", "remote", "add", "head_repo", headRepoPath); err != nil {
"git", "remote", "add", remoteRepoName, headRepoPath); err != nil {
return fmt.Errorf("git remote add [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
}

// Merge commits.
// Fetch head branch
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git fetch): %s", tmpBasePath),
"git", "fetch", "head_repo"); err != nil {
"git", "fetch", remoteRepoName); err != nil {
return fmt.Errorf("git fetch [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
}

trackingBranch := path.Join(remoteRepoName, pr.HeadBranch)
stagingBranch := fmt.Sprintf("%s_%s", remoteRepoName, pr.HeadBranch)

// Enable sparse-checkout
sparseCheckoutList, err := getDiffTree(tmpBasePath, pr.BaseBranch, trackingBranch)
if err != nil {
return fmt.Errorf("getDiffTree: %v", err)
}

sparseCheckoutListPath := filepath.Join(tmpBasePath, ".git", "info", "sparse-checkout")
if err := ioutil.WriteFile(sparseCheckoutListPath, []byte(sparseCheckoutList), 0600); err != nil {
return fmt.Errorf("Writing sparse-checkout file to %s: %v", sparseCheckoutListPath, err)
}

if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git config): %s", tmpBasePath),
"git", "config", "--local", "core.sparseCheckout", "true"); err != nil {
return fmt.Errorf("git config [core.sparsecheckout -> true]: %v", stderr)
}

// Read base branch index
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git read-tree): %s", tmpBasePath),
"git", "read-tree", "HEAD"); err != nil {
return fmt.Errorf("git read-tree HEAD: %s", stderr)
}

// Merge commits.
switch mergeStyle {
case MergeStyleMerge:
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git merge --no-ff --no-commit): %s", tmpBasePath),
"git", "merge", "--no-ff", "--no-commit", "head_repo/"+pr.HeadBranch); err != nil {
"git", "merge", "--no-ff", "--no-commit", trackingBranch); err != nil {
return fmt.Errorf("git merge --no-ff --no-commit [%s]: %v - %s", tmpBasePath, err, stderr)
}

Expand All @@ -415,7 +485,7 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle
// Checkout head branch
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git checkout): %s", tmpBasePath),
"git", "checkout", "-b", "head_repo_"+pr.HeadBranch, "head_repo/"+pr.HeadBranch); err != nil {
"git", "checkout", "-b", stagingBranch, trackingBranch); err != nil {
return fmt.Errorf("git checkout: %s", stderr)
}
// Rebase before merging
Expand All @@ -433,14 +503,14 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle
// Merge fast forward
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git rebase): %s", tmpBasePath),
"git", "merge", "--ff-only", "-q", "head_repo_"+pr.HeadBranch); err != nil {
"git", "merge", "--ff-only", "-q", stagingBranch); err != nil {
return fmt.Errorf("git merge --ff-only [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
}
case MergeStyleRebaseMerge:
// Checkout head branch
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git checkout): %s", tmpBasePath),
"git", "checkout", "-b", "head_repo_"+pr.HeadBranch, "head_repo/"+pr.HeadBranch); err != nil {
"git", "checkout", "-b", stagingBranch, trackingBranch); err != nil {
return fmt.Errorf("git checkout: %s", stderr)
}
// Rebase before merging
Expand All @@ -458,7 +528,7 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle
// Prepare merge with commit
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git merge): %s", tmpBasePath),
"git", "merge", "--no-ff", "--no-commit", "-q", "head_repo_"+pr.HeadBranch); err != nil {
"git", "merge", "--no-ff", "--no-commit", "-q", stagingBranch); err != nil {
return fmt.Errorf("git merge --no-ff [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
}

Expand All @@ -475,7 +545,7 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle
// Merge with squash
if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
fmt.Sprintf("PullRequest.Merge (git squash): %s", tmpBasePath),
"git", "merge", "-q", "--squash", "head_repo/"+pr.HeadBranch); err != nil {
"git", "merge", "-q", "--squash", trackingBranch); err != nil {
return fmt.Errorf("git merge --squash [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
}
sig := pr.Issue.Poster.NewGitSig()
Expand Down

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