1package cache
2
3import (
4 "bytes"
5 "encoding/gob"
6 "fmt"
7 "io"
8 "io/ioutil"
9 "os"
10 "path"
11 "strconv"
12 "strings"
13
14 "github.com/MichaelMure/git-bug/bug"
15 "github.com/MichaelMure/git-bug/bug/operations"
16 "github.com/MichaelMure/git-bug/repository"
17 "github.com/MichaelMure/git-bug/util"
18)
19
20type RepoCache struct {
21 repo repository.Repo
22 excerpts map[string]BugExcerpt
23 bugs map[string]*BugCache
24}
25
26func NewRepoCache(r repository.Repo) (*RepoCache, error) {
27 c := &RepoCache{
28 repo: r,
29 bugs: make(map[string]*BugCache),
30 }
31
32 err := c.lock()
33 if err != nil {
34 return &RepoCache{}, err
35 }
36
37 err = c.loadExcerpts()
38 if err == nil {
39 return c, nil
40 }
41
42 c.buildAllExcerpt()
43
44 return c, c.writeExcerpts()
45}
46
47// Repository return the underlying repository.
48// If you use this, make sure to never change the repo state.
49func (c *RepoCache) Repository() repository.Repo {
50 return c.repo
51}
52
53func (c *RepoCache) lock() error {
54 lockPath := repoLockFilePath(c.repo)
55
56 err := repoIsAvailable(c.repo)
57 if err != nil {
58 return err
59 }
60
61 f, err := os.Create(lockPath)
62 if err != nil {
63 return err
64 }
65
66 pid := fmt.Sprintf("%d", os.Getpid())
67 _, err = f.WriteString(pid)
68 if err != nil {
69 return err
70 }
71
72 return f.Close()
73}
74
75func (c *RepoCache) Close() error {
76 lockPath := repoLockFilePath(c.repo)
77 return os.Remove(lockPath)
78}
79
80// bugUpdated is a callback to trigger when the excerpt of a bug changed,
81// that is each time a bug is updated
82func (c *RepoCache) bugUpdated(id string) error {
83 b, ok := c.bugs[id]
84 if !ok {
85 panic("missing bug in the cache")
86 }
87
88 c.excerpts[id] = NewBugExcerpt(b.bug, b.Snapshot())
89
90 return c.writeExcerpts()
91}
92
93// loadExcerpts will try to read from the disk the bug excerpt file
94func (c *RepoCache) loadExcerpts() error {
95 excerptsPath := repoExcerptsFilePath(c.repo)
96
97 f, err := os.Open(excerptsPath)
98 if err != nil {
99 return err
100 }
101
102 decoder := gob.NewDecoder(f)
103
104 var excerpts map[string]BugExcerpt
105
106 err = decoder.Decode(&excerpts)
107 if err != nil {
108 return err
109 }
110
111 c.excerpts = excerpts
112 return nil
113}
114
115// writeExcerpts will serialize on disk the BugExcerpt array
116func (c *RepoCache) writeExcerpts() error {
117 var data bytes.Buffer
118
119 encoder := gob.NewEncoder(&data)
120
121 err := encoder.Encode(c.excerpts)
122 if err != nil {
123 return err
124 }
125
126 excerptsPath := repoExcerptsFilePath(c.repo)
127
128 f, err := os.Create(excerptsPath)
129 if err != nil {
130 return err
131 }
132
133 _, err = f.Write(data.Bytes())
134 if err != nil {
135 return err
136 }
137
138 return f.Close()
139}
140
141func repoExcerptsFilePath(repo repository.Repo) string {
142 return path.Join(repo.GetPath(), ".git", "git-bug", excerptsFile)
143}
144
145func (c *RepoCache) buildAllExcerpt() {
146 c.excerpts = make(map[string]BugExcerpt)
147
148 allBugs := bug.ReadAllLocalBugs(c.repo)
149
150 for b := range allBugs {
151 snap := b.Bug.Compile()
152 c.excerpts[b.Bug.Id()] = NewBugExcerpt(b.Bug, &snap)
153 }
154}
155
156func (c *RepoCache) ResolveBug(id string) (*BugCache, error) {
157 cached, ok := c.bugs[id]
158 if ok {
159 return cached, nil
160 }
161
162 b, err := bug.ReadLocalBug(c.repo, id)
163 if err != nil {
164 return nil, err
165 }
166
167 cached = NewBugCache(c, b)
168 c.bugs[id] = cached
169
170 return cached, nil
171}
172
173func (c *RepoCache) ResolveBugPrefix(prefix string) (*BugCache, error) {
174 // preallocate but empty
175 matching := make([]string, 0, 5)
176
177 for id := range c.bugs {
178 if strings.HasPrefix(id, prefix) {
179 matching = append(matching, id)
180 }
181 }
182
183 // TODO: should check matching bug in the repo as well
184
185 if len(matching) > 1 {
186 return nil, fmt.Errorf("Multiple matching bug found:\n%s", strings.Join(matching, "\n"))
187 }
188
189 if len(matching) == 1 {
190 b := c.bugs[matching[0]]
191 return b, nil
192 }
193
194 b, err := bug.FindLocalBug(c.repo, prefix)
195
196 if err != nil {
197 return nil, err
198 }
199
200 cached := NewBugCache(c, b)
201 c.bugs[b.Id()] = cached
202
203 return cached, nil
204}
205
206func (c *RepoCache) AllBugIds() ([]string, error) {
207 return bug.ListLocalIds(c.repo)
208}
209
210// ClearAllBugs clear all bugs kept in memory
211func (c *RepoCache) ClearAllBugs() {
212 c.bugs = make(map[string]*BugCache)
213}
214
215// NewBug create a new bug
216// The new bug is written in the repository (commit)
217func (c *RepoCache) NewBug(title string, message string) (*BugCache, error) {
218 return c.NewBugWithFiles(title, message, nil)
219}
220
221// NewBugWithFiles create a new bug with attached files for the message
222// The new bug is written in the repository (commit)
223func (c *RepoCache) NewBugWithFiles(title string, message string, files []util.Hash) (*BugCache, error) {
224 author, err := bug.GetUser(c.repo)
225 if err != nil {
226 return nil, err
227 }
228
229 b, err := operations.CreateWithFiles(author, title, message, files)
230 if err != nil {
231 return nil, err
232 }
233
234 err = b.Commit(c.repo)
235 if err != nil {
236 return nil, err
237 }
238
239 cached := NewBugCache(c, b)
240 c.bugs[b.Id()] = cached
241
242 return cached, nil
243}
244
245// Fetch retrieve update from a remote
246// This does not change the local bugs state
247func (c *RepoCache) Fetch(remote string) (string, error) {
248 return bug.Fetch(c.repo, remote)
249}
250
251func (c *RepoCache) MergeAll(remote string) <-chan bug.MergeResult {
252 return bug.MergeAll(c.repo, remote)
253}
254
255// Pull does a Fetch and merge the updates into the local bug states
256func (c *RepoCache) Pull(remote string, out io.Writer) error {
257 return bug.Pull(c.repo, out, remote)
258}
259
260// Push update a remote with the local changes
261func (c *RepoCache) Push(remote string) (string, error) {
262 return bug.Push(c.repo, remote)
263}
264
265func repoLockFilePath(repo repository.Repo) string {
266 return path.Join(repo.GetPath(), ".git", "git-bug", lockfile)
267}
268
269// repoIsAvailable check is the given repository is locked by a Cache.
270// Note: this is a smart function that will cleanup the lock file if the
271// corresponding process is not there anymore.
272// If no error is returned, the repo is free to edit.
273func repoIsAvailable(repo repository.Repo) error {
274 lockPath := repoLockFilePath(repo)
275
276 // Todo: this leave way for a racey access to the repo between the test
277 // if the file exist and the actual write. It's probably not a problem in
278 // practice because using a repository will be done from user interaction
279 // or in a context where a single instance of git-bug is already guaranteed
280 // (say, a server with the web UI running). But still, that might be nice to
281 // have a mutex or something to guard that.
282
283 // Todo: this will fail if somehow the filesystem is shared with another
284 // computer. Should add a configuration that prevent the cleaning of the
285 // lock file
286
287 f, err := os.Open(lockPath)
288
289 if err != nil && !os.IsNotExist(err) {
290 return err
291 }
292
293 if err == nil {
294 // lock file already exist
295 buf, err := ioutil.ReadAll(io.LimitReader(f, 10))
296 if err != nil {
297 return err
298 }
299 if len(buf) == 10 {
300 return fmt.Errorf("The lock file should be < 10 bytes")
301 }
302
303 pid, err := strconv.Atoi(string(buf))
304 if err != nil {
305 return err
306 }
307
308 if util.ProcessIsRunning(pid) {
309 return fmt.Errorf("The repository you want to access is already locked by the process pid %d", pid)
310 }
311
312 // The lock file is just laying there after a crash, clean it
313
314 fmt.Println("A lock file is present but the corresponding process is not, removing it.")
315 err = f.Close()
316 if err != nil {
317 return err
318 }
319
320 os.Remove(lockPath)
321 if err != nil {
322 return err
323 }
324 }
325
326 return nil
327}