| 1 | package console |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "fmt" |
| 6 | "log" |
| 7 | "net/http" |
| 8 | "os" |
| 9 | "path/filepath" |
| 10 | "strings" |
| 11 | "sync" |
| 12 | ) |
| 13 | |
| 14 | // seedScratch is the console's one scratch reservation pool, shared by |
| 15 | // --from restores and import spools (seeded-instances spec §4 step 5, |
| 16 | // §5.2): an in-process counter over <console data>/scratch/seeds/, and the |
| 17 | // per-app and deployment limits on how many run at once. |
| 18 | type seedScratch struct { |
| 19 | root string |
| 20 | free func(string) (int64, error) |
| 21 | |
| 22 | mu sync.Mutex |
| 23 | capacity int64 |
| 24 | used int64 |
| 25 | running int |
| 26 | perApp map[string]bool |
| 27 | } |
| 28 | |
| 29 | const ( |
| 30 | seedScratchSlack = 1 << 30 // capacity is free space less this |
| 31 | seedScratchAllApps = 2 // reservations across the deployment; one per app |
| 32 | |
| 33 | // seedScratchPrefix starts the name of every entry the pool's users |
| 34 | // create directly inside the scratch directory. Start-up cleanup removes |
| 35 | // entries with this prefix and nothing else. |
| 36 | seedScratchPrefix = "from-" |
| 37 | ) |
| 38 | |
| 39 | func newSeedScratch(root string, free func(string) (int64, error)) *seedScratch { |
| 40 | p := &seedScratch{root: root, free: free, perApp: map[string]bool{}} |
| 41 | p.readCapacity() |
| 42 | return p |
| 43 | } |
| 44 | |
| 45 | // startSeedScratch is what NewServer calls: it clears the pool's leftovers |
| 46 | // and builds the pool. An empty directory, or one the cleanup refuses, |
| 47 | // leaves a pool with no capacity, so every reservation is a 507. |
| 48 | func startSeedScratch(dir string) *seedScratch { |
| 49 | usable := dir != "" |
| 50 | if usable { |
| 51 | if err := clearSeedScratch(dir); err != nil { |
| 52 | log.Printf("console: seed scratch %s: %v (the seed doors will refuse)", dir, err) |
| 53 | usable = false |
| 54 | } |
| 55 | } |
| 56 | return newSeedScratch(dir, func(d string) (int64, error) { |
| 57 | if !usable { |
| 58 | return 0, errors.New("no usable seed scratch directory") |
| 59 | } |
| 60 | return scratchFree(d) |
| 61 | }) |
| 62 | } |
| 63 | |
| 64 | func (p *seedScratch) dir() string { return p.root } |
| 65 | |
| 66 | // readCapacity is called with p.mu held, or before the pool is shared. |
| 67 | func (p *seedScratch) readCapacity() { |
| 68 | n, err := p.free(p.root) |
| 69 | if err != nil { |
| 70 | p.capacity = -1 // unavailable: below zero, so even a zero-byte reservation is refused |
| 71 | return |
| 72 | } |
| 73 | p.capacity = max(n-seedScratchSlack, 0) |
| 74 | } |
| 75 | |
| 76 | // reserve takes bytes for appKey (account/app), or answers why not. The |
| 77 | // returned release is safe to call more than once. |
| 78 | func (p *seedScratch) reserve(appKey string, bytes int64) (func(), *doorRefusal) { |
| 79 | p.mu.Lock() |
| 80 | defer p.mu.Unlock() |
| 81 | if p.perApp[appKey] { |
| 82 | app := appKey[strings.LastIndex(appKey, "/")+1:] |
| 83 | return nil, &doorRefusal{http.StatusTooManyRequests, fmt.Sprintf("another copy or upload is running for %s. Try again when it finishes.", app)} |
| 84 | } |
| 85 | if p.running >= seedScratchAllApps { |
| 86 | return nil, &doorRefusal{http.StatusTooManyRequests, "the console is already running two copies or uploads. Try again in a few minutes."} |
| 87 | } |
| 88 | if p.used == 0 { |
| 89 | p.readCapacity() |
| 90 | } |
| 91 | if bytes < 0 || bytes > p.capacity-p.used { |
| 92 | return nil, seedScratchFull() |
| 93 | } |
| 94 | p.used += bytes |
| 95 | p.running++ |
| 96 | p.perApp[appKey] = true |
| 97 | var once sync.Once |
| 98 | return func() { |
| 99 | once.Do(func() { |
| 100 | p.mu.Lock() |
| 101 | defer p.mu.Unlock() |
| 102 | p.used -= bytes |
| 103 | p.running-- |
| 104 | delete(p.perApp, appKey) |
| 105 | }) |
| 106 | }, nil |
| 107 | } |
| 108 | |
| 109 | // seedScratchFull is the 507 the pool answers, and what a door answers |
| 110 | // when it cannot make its directory in the scratch. |
| 111 | func seedScratchFull() *doorRefusal { |
| 112 | return &doorRefusal{http.StatusInsufficientStorage, "the console has no room for this right now. Try again later."} |
| 113 | } |
| 114 | |
| 115 | // clearSeedScratch removes what a crashed restore or spool left at console |
| 116 | // start (spec §4 "Cleanup", §5.2): the entries named seedScratchPrefix* that |
| 117 | // sit directly inside dir. Anything else in dir stays, and dir itself is |
| 118 | // never removed. A relative path or "/" is refused; an empty dir does |
| 119 | // nothing. A symlink entry is removed as a link, never followed. |
| 120 | func clearSeedScratch(dir string) error { |
| 121 | if dir == "" { |
| 122 | return nil |
| 123 | } |
| 124 | if !filepath.IsAbs(dir) || filepath.Clean(dir) == string(filepath.Separator) { |
| 125 | return fmt.Errorf("refusing to clear %q: it must be an absolute path other than /", dir) |
| 126 | } |
| 127 | dir = filepath.Clean(dir) |
| 128 | if err := os.MkdirAll(dir, 0o700); err != nil { |
| 129 | return err |
| 130 | } |
| 131 | // The directory holds copies of customer databases: narrow one that |
| 132 | // already existed with wider permissions. |
| 133 | if err := os.Chmod(dir, 0o700); err != nil { |
| 134 | return err |
| 135 | } |
| 136 | ents, err := os.ReadDir(dir) |
| 137 | if err != nil { |
| 138 | return err |
| 139 | } |
| 140 | var errs []error |
| 141 | for _, e := range ents { |
| 142 | if !strings.HasPrefix(e.Name(), seedScratchPrefix) { |
| 143 | continue |
| 144 | } |
| 145 | if err := os.RemoveAll(filepath.Join(dir, e.Name())); err != nil { |
| 146 | errs = append(errs, err) |
| 147 | } |
| 148 | } |
| 149 | return errors.Join(errs...) |
| 150 | } |
| 151 | |
amadan