1package cache
2
3import (
4 "fmt"
5 "io"
6 "io/ioutil"
7 "os"
8 "strconv"
9 "sync"
10
11 "github.com/MichaelMure/git-bug/entities/bug"
12 "github.com/MichaelMure/git-bug/entities/identity"
13 "github.com/MichaelMure/git-bug/entity"
14 "github.com/MichaelMure/git-bug/repository"
15 "github.com/MichaelMure/git-bug/util/process"
16)
17
18// 1: original format
19// 2: added cache for identities with a reference in the bug cache
20// 3: no more legacy identity
21// 4: entities make their IDs from data, not git commit
22const formatVersion = 4
23
24// The maximum number of bugs loaded in memory. After that, eviction will be done.
25const defaultMaxLoadedBugs = 1000
26
27var _ repository.RepoCommon = &RepoCache{}
28var _ repository.RepoConfig = &RepoCache{}
29var _ repository.RepoKeyring = &RepoCache{}
30
31// RepoCache is a cache for a Repository. This cache has multiple functions:
32//
33// 1. After being loaded, a Bug is kept in memory in the cache, allowing for fast
34// access later.
35// 2. The cache maintain in memory and on disk a pre-digested excerpt for each bug,
36// allowing for fast querying the whole set of bugs without having to load
37// them individually.
38// 3. The cache guarantee that a single instance of a Bug is loaded at once, avoiding
39// loss of data that we could have with multiple copies in the same process.
40// 4. The same way, the cache maintain in memory a single copy of the loaded identities.
41//
42// The cache also protect the on-disk data by locking the git repository for its
43// own usage, by writing a lock file. Of course, normal git operations are not
44// affected, only git-bug related one.
45type RepoCache struct {
46 // the underlying repo
47 repo repository.ClockedRepo
48
49 // the name of the repository, as defined in the MultiRepoCache
50 name string
51
52 // resolvers for all known entities
53 resolvers entity.Resolvers
54
55 bugs *RepoCacheBug
56
57 muIdentity sync.RWMutex
58 // excerpt of identities data for all identities
59 identitiesExcerpts map[entity.Id]*IdentityExcerpt
60 // identities loaded in memory
61 identities map[entity.Id]*IdentityCache
62
63 // the user identity's id, if known
64 userIdentityId entity.Id
65}
66
67func NewRepoCache(r repository.ClockedRepo) (*RepoCache, error) {
68 return NewNamedRepoCache(r, "")
69}
70
71func NewNamedRepoCache(r repository.ClockedRepo, name string) (*RepoCache, error) {
72 c := &RepoCache{
73 repo: r,
74 name: name,
75 bugs: NewCache(r),
76 // maxLoadedBugs: defaultMaxLoadedBugs,
77 // bugs: make(map[entity.Id]*BugCache),
78 // loadedBugs: newLRUIdCache(),
79 // identities: make(map[entity.Id]*IdentityCache),
80 }
81
82 c.resolvers = makeResolvers(c)
83
84 err := c.lock()
85 if err != nil {
86 return &RepoCache{}, err
87 }
88
89 err = c.load()
90 if err == nil {
91 return c, nil
92 }
93
94 // Cache is either missing, broken or outdated. Rebuilding.
95 err = c.buildCache()
96 if err != nil {
97 return nil, err
98 }
99
100 return c, c.write()
101}
102
103// Bugs gives access to the Bug entities
104func (c *RepoCache) Bugs() *RepoCacheBug {
105 return c.bugs
106}
107
108// setCacheSize change the maximum number of loaded bugs
109func (c *RepoCache) setCacheSize(size int) {
110 c.maxLoadedBugs = size
111 c.evictIfNeeded()
112}
113
114// load will try to read from the disk all the cache files
115func (c *RepoCache) load() error {
116 err := c.loadBugCache()
117 if err != nil {
118 return err
119 }
120
121 return c.loadIdentityCache()
122}
123
124// write will serialize on disk all the cache files
125func (c *RepoCache) write() error {
126 err := c.writeBugCache()
127 if err != nil {
128 return err
129 }
130 return c.writeIdentityCache()
131}
132
133func (c *RepoCache) lock() error {
134 err := repoIsAvailable(c.repo)
135 if err != nil {
136 return err
137 }
138
139 f, err := c.repo.LocalStorage().Create(lockfile)
140 if err != nil {
141 return err
142 }
143
144 pid := fmt.Sprintf("%d", os.Getpid())
145 _, err = f.Write([]byte(pid))
146 if err != nil {
147 return err
148 }
149
150 return f.Close()
151}
152
153func (c *RepoCache) Close() error {
154 c.muBug.Lock()
155 defer c.muBug.Unlock()
156 c.muIdentity.Lock()
157 defer c.muIdentity.Unlock()
158
159 c.identities = make(map[entity.Id]*IdentityCache)
160 c.identitiesExcerpts = nil
161 c.bugs = make(map[entity.Id]*BugCache)
162 c.bugExcerpts = nil
163
164 err := c.repo.Close()
165 if err != nil {
166 return err
167 }
168
169 return c.repo.LocalStorage().Remove(lockfile)
170}
171
172func (c *RepoCache) buildCache() error {
173 _, _ = fmt.Fprintf(os.Stderr, "Building identity cache... ")
174
175 c.identitiesExcerpts = make(map[entity.Id]*IdentityExcerpt)
176
177 allIdentities := identity.ReadAllLocal(c.repo)
178
179 for i := range allIdentities {
180 if i.Err != nil {
181 return i.Err
182 }
183
184 c.identitiesExcerpts[i.Identity.Id()] = NewIdentityExcerpt(i.Identity)
185 }
186
187 _, _ = fmt.Fprintln(os.Stderr, "Done.")
188
189 _, _ = fmt.Fprintf(os.Stderr, "Building bug cache... ")
190
191 c.bugExcerpts = make(map[entity.Id]*BugExcerpt)
192
193 allBugs := bug.ReadAllWithResolver(c.repo, c.resolvers)
194
195 // wipe the index just to be sure
196 err := c.repo.ClearBleveIndex("bug")
197 if err != nil {
198 return err
199 }
200
201 for b := range allBugs {
202 if b.Err != nil {
203 return b.Err
204 }
205
206 snap := b.Bug.Compile()
207 c.bugExcerpts[b.Bug.Id()] = NewBugExcerpt(b.Bug, snap)
208
209 if err := c.addBugToSearchIndex(snap); err != nil {
210 return err
211 }
212 }
213
214 _, _ = fmt.Fprintln(os.Stderr, "Done.")
215
216 return nil
217}
218
219// repoIsAvailable check is the given repository is locked by a Cache.
220// Note: this is a smart function that will clean the lock file if the
221// corresponding process is not there anymore.
222// If no error is returned, the repo is free to edit.
223func repoIsAvailable(repo repository.RepoStorage) error {
224 // Todo: this leave way for a racey access to the repo between the test
225 // if the file exist and the actual write. It's probably not a problem in
226 // practice because using a repository will be done from user interaction
227 // or in a context where a single instance of git-bug is already guaranteed
228 // (say, a server with the web UI running). But still, that might be nice to
229 // have a mutex or something to guard that.
230
231 // Todo: this will fail if somehow the filesystem is shared with another
232 // computer. Should add a configuration that prevent the cleaning of the
233 // lock file
234
235 f, err := repo.LocalStorage().Open(lockfile)
236 if err != nil && !os.IsNotExist(err) {
237 return err
238 }
239
240 if err == nil {
241 // lock file already exist
242 buf, err := ioutil.ReadAll(io.LimitReader(f, 10))
243 if err != nil {
244 return err
245 }
246 if len(buf) == 10 {
247 return fmt.Errorf("the lock file should be < 10 bytes")
248 }
249
250 pid, err := strconv.Atoi(string(buf))
251 if err != nil {
252 return err
253 }
254
255 if process.IsRunning(pid) {
256 return fmt.Errorf("the repository you want to access is already locked by the process pid %d", pid)
257 }
258
259 // The lock file is just laying there after a crash, clean it
260
261 fmt.Println("A lock file is present but the corresponding process is not, removing it.")
262 err = f.Close()
263 if err != nil {
264 return err
265 }
266
267 err = repo.LocalStorage().Remove(lockfile)
268 if err != nil {
269 return err
270 }
271 }
272
273 return nil
274}