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Signed-off-by: Ivan Milchev <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,48 @@ | ||
| package memoize | ||
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| import ( | ||
| "time" | ||
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| "github.com/patrickmn/go-cache" | ||
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Check failure on line 6 in providers-sdk/v1/util/memoize/memoize.go
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| "golang.org/x/sync/singleflight" | ||
| ) | ||
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| // Memoizer allows you to memoize function calls. Memoizer is safe for concurrent use by multiple goroutines. | ||
| type Memoizer struct { | ||
| // Storage exposes the underlying cache of memoized results to manipulate as desired - for example, to Flush(). | ||
| Storage *cache.Cache | ||
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| group singleflight.Group | ||
| } | ||
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| // NewMemoizer creates a new Memoizer with the configured expiry and cleanup policies. | ||
| // If desired, use cache.NoExpiration to cache values forever. | ||
| func NewMemoizer(defaultExpiration, cleanupInterval time.Duration) *Memoizer { | ||
| return &Memoizer{ | ||
| Storage: cache.New(defaultExpiration, cleanupInterval), | ||
| group: singleflight.Group{}, | ||
| } | ||
| } | ||
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| // Memoize executes and returns the results of the given function, unless there was a cached value of the same key. | ||
| // Only one execution is in-flight for a given key at a time. | ||
| // The boolean return value indicates whether v was previously stored. | ||
| func (m *Memoizer) Memoize(key string, fn func() (interface{}, error)) (interface{}, error, bool) { | ||
| // Check cache | ||
| value, found := m.Storage.Get(key) | ||
| if found { | ||
| return value, nil, true | ||
| } | ||
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| // Combine memoized function with a cache store | ||
| value, err, _ := m.group.Do(key, func() (interface{}, error) { | ||
| data, innerErr := fn() | ||
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| if innerErr == nil { | ||
| m.Storage.Set(key, data, cache.DefaultExpiration) | ||
| } | ||
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| return data, innerErr | ||
| }) | ||
| return value, err, false | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,76 @@ | ||
| package memoize | ||
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| import ( | ||
| "errors" | ||
| "testing" | ||
| "time" | ||
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| "github.com/stretchr/testify/assert" | ||
| ) | ||
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| // TestBasic adopts the code from readme.md into a simple test case | ||
| func TestBasic(t *testing.T) { | ||
| expensiveCalls := 0 | ||
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| // Function tracks how many times its been called | ||
| expensive := func() (interface{}, error) { | ||
| expensiveCalls++ | ||
| return expensiveCalls, nil | ||
| } | ||
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| cache := NewMemoizer(90*time.Second, 10*time.Minute) | ||
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| // First call SHOULD NOT be cached | ||
| result, err, cached := cache.Memoize("key1", expensive) | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, result.(int), 1) | ||
| assert.False(t, cached) | ||
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| // Second call on same key SHOULD be cached | ||
| result, err, cached = cache.Memoize("key1", expensive) | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, result.(int), 1) | ||
| assert.True(t, cached) | ||
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| // First call on a new key SHOULD NOT be cached | ||
| result, err, cached = cache.Memoize("key2", expensive) | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, result.(int), 2) | ||
| assert.False(t, cached) | ||
| } | ||
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| // TestFailure checks that failed function values are not cached | ||
| func TestFailure(t *testing.T) { | ||
| calls := 0 | ||
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| // This function will fail IFF it has not been called before. | ||
| twoForTheMoney := func() (interface{}, error) { | ||
| calls++ | ||
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| if calls == 1 { | ||
| return calls, errors.New("Try again") | ||
| } else { | ||
| return calls, nil | ||
| } | ||
| } | ||
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| cache := NewMemoizer(90*time.Second, 10*time.Minute) | ||
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| // First call should fail, and not be cached | ||
| result, err, cached := cache.Memoize("key1", twoForTheMoney) | ||
| assert.Error(t, err) | ||
| assert.Equal(t, result.(int), 1) | ||
| assert.False(t, cached) | ||
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| // Second call should succeed, and not be cached | ||
| result, err, cached = cache.Memoize("key1", twoForTheMoney) | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, result.(int), 2) | ||
| assert.False(t, cached) | ||
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| // Third call should succeed, and be cached | ||
| result, err, cached = cache.Memoize("key1", twoForTheMoney) | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, result.(int), 2) | ||
| assert.True(t, cached) | ||
| } |
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