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feat(sharedcounter): persist counter to disk (#125)
make a shared counter util for persisting a unique deal id counter to disk
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| package storedcounter | ||
|
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||
| import ( | ||
| "encoding/binary" | ||
|
|
||
| "github.com/ipfs/go-datastore" | ||
| ) | ||
|
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| // StoredCounter is a counter that persists to a datastore as it increments | ||
| type StoredCounter struct { | ||
| ds datastore.Datastore | ||
| name datastore.Key | ||
| } | ||
|
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| // New returns a new StoredCounter for the given datastore and key | ||
| func New(ds datastore.Datastore, name datastore.Key) *StoredCounter { | ||
| return &StoredCounter{ds, name} | ||
| } | ||
|
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| // Next returns the next counter value, updating it on disk in the process | ||
| // if no counter is present, it creates one and returns a 0 value | ||
| func (sc *StoredCounter) Next() (uint64, error) { | ||
| has, err := sc.ds.Has(sc.name) | ||
| if err != nil { | ||
| return 0, err | ||
| } | ||
|
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| var next uint64 = 0 | ||
| if has { | ||
| curBytes, err := sc.ds.Get(sc.name) | ||
| if err != nil { | ||
| return 0, err | ||
| } | ||
| cur, _ := binary.Uvarint(curBytes) | ||
| next = cur + 1 | ||
| } | ||
| buf := make([]byte, binary.MaxVarintLen64) | ||
| size := binary.PutUvarint(buf, next) | ||
|
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| return next, sc.ds.Put(sc.name, buf[:size]) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,61 @@ | ||
| package storedcounter_test | ||
|
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| import ( | ||
| "testing" | ||
|
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| "github.com/ipfs/go-datastore" | ||
| "github.com/stretchr/testify/require" | ||
|
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| "github.com/filecoin-project/go-fil-markets/storedcounter" | ||
| ) | ||
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| func TestStoredCounter(t * testing.T) { | ||
| ds := datastore.NewMapDatastore() | ||
|
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| t.Run("test two instances with same data store and key count together", func(t *testing.T) { | ||
| key := datastore.NewKey("counter") | ||
| sc1 := storedcounter.New(ds, key) | ||
| next, err := sc1.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(0)) | ||
|
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| sc2 := storedcounter.New(ds, key) | ||
| next, err = sc2.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(1)) | ||
|
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| next, err = sc1.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(2)) | ||
|
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| next, err = sc2.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(3)) | ||
| }) | ||
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| t.Run("test two instances with same data store but different keys count seperate", func(t *testing.T) { | ||
|
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| key1 := datastore.NewKey("counter 1") | ||
| key2 := datastore.NewKey("counter 2") | ||
|
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| sc1 := storedcounter.New(ds, key1) | ||
| next, err := sc1.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(0)) | ||
|
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| sc2 := storedcounter.New(ds, key2) | ||
| next, err = sc2.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(0)) | ||
|
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| next, err = sc1.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(1)) | ||
|
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| next, err = sc2.Next() | ||
| require.NoError(t, err) | ||
| require.Equal(t, next, uint64(1)) | ||
| }) | ||
| } |