|
| 1 | +package godoc |
| 2 | + |
| 3 | +import ( |
| 4 | + "bytes" |
| 5 | + "compress/gzip" |
| 6 | + "log" |
| 7 | + "sync" |
| 8 | + |
| 9 | + "github.com/coocood/freecache" |
| 10 | + "github.com/pkg/errors" |
| 11 | +) |
| 12 | + |
| 13 | +// cacheSize 50M |
| 14 | +var cacheSize = 50 * 1024 * 1024 |
| 15 | + |
| 16 | +// cacheTTL600s 10 minutes |
| 17 | +var cacheTTL600s = 600 |
| 18 | + |
| 19 | +var cache = sync.OnceValue(func() *freecache.Cache { |
| 20 | + c := freecache.NewCache(cacheSize) |
| 21 | + |
| 22 | + return c |
| 23 | +}) |
| 24 | + |
| 25 | +func getWithFn(key string, fn func() ([]byte, error)) ([]byte, error) { |
| 26 | + v, exist, err := get(key) |
| 27 | + if err != nil { |
| 28 | + return v, err |
| 29 | + } |
| 30 | + if exist { |
| 31 | + return v, nil |
| 32 | + } |
| 33 | + // not exist |
| 34 | + v, err = fn() |
| 35 | + if err != nil { |
| 36 | + return v, err |
| 37 | + } |
| 38 | + |
| 39 | + go func() { |
| 40 | + defer func() { |
| 41 | + if t := recover(); t != nil { |
| 42 | + log.Println("recovered from ", t) |
| 43 | + } |
| 44 | + }() |
| 45 | + data, err := compress(v) |
| 46 | + if err != nil { |
| 47 | + log.Println(err) |
| 48 | + return |
| 49 | + } |
| 50 | + |
| 51 | + // set to cache |
| 52 | + err = cache().Set([]byte(key), data, cacheTTL600s) |
| 53 | + if errors.Is(err, freecache.ErrLargeEntry) { |
| 54 | + log.Print("large entry for key", key) |
| 55 | + return |
| 56 | + } |
| 57 | + if err != nil { |
| 58 | + log.Println(err) |
| 59 | + } |
| 60 | + }() |
| 61 | + |
| 62 | + return v, nil |
| 63 | +} |
| 64 | + |
| 65 | +func get(key string) ([]byte, bool, error) { |
| 66 | + data, err := cache().Get([]byte(key)) |
| 67 | + if errors.Is(err, freecache.ErrNotFound) { |
| 68 | + return nil, false, nil |
| 69 | + } |
| 70 | + if err != nil { |
| 71 | + return nil, false, errors.WithStack(err) |
| 72 | + } |
| 73 | + data, err = decompress(data) |
| 74 | + if err != nil { |
| 75 | + return nil, false, errors.WithStack(err) |
| 76 | + } |
| 77 | + |
| 78 | + return data, true, nil |
| 79 | +} |
| 80 | + |
| 81 | +func compress(data []byte) ([]byte, error) { |
| 82 | + var b bytes.Buffer |
| 83 | + gz, err := gzip.NewWriterLevel(&b, gzip.BestCompression) |
| 84 | + if err != nil { |
| 85 | + return nil, err |
| 86 | + } |
| 87 | + _, err = gz.Write(data) |
| 88 | + if err != nil { |
| 89 | + return nil, err |
| 90 | + } |
| 91 | + err = gz.Close() |
| 92 | + if err != nil { |
| 93 | + return nil, err |
| 94 | + } |
| 95 | + return b.Bytes(), nil |
| 96 | +} |
| 97 | + |
| 98 | +func decompress(data []byte) ([]byte, error) { |
| 99 | + b := bytes.NewBuffer(data) |
| 100 | + gz, err := gzip.NewReader(b) |
| 101 | + if err != nil { |
| 102 | + return nil, err |
| 103 | + } |
| 104 | + defer gz.Close() |
| 105 | + var res bytes.Buffer |
| 106 | + _, err = res.ReadFrom(gz) |
| 107 | + if err != nil { |
| 108 | + return nil, err |
| 109 | + } |
| 110 | + return res.Bytes(), nil |
| 111 | +} |
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