// incrementOffset is a common incrementor method used between Increment and
// Decrement. If the key isn't set before, we will set the initial value. If
// there is a value present, we will add the given offset to that value and
// update the value with the new TTL.
func (c *Cache) incrementOffset(key string, initial, offset, ttl int64) error {
c.client.Do("WATCH", key)
if err := c.exists(key); err != nil {
c.client.Do("MULTI")
defer c.client.Do("EXEC")
return c.Set(key, encoding.Int64Bytes(initial), ttl)
}
getValue, _, err := c.Get(key)
if err != nil {
return err
}
val, ok := encoding.BytesInt64(getValue)
if !ok {
return errors.NewEncoding(key)
}
// We are watching our key. With using a transaction, we can check that this
// increment doesn't inflect with another concurrent request that might
// happen.
c.client.Do("MULTI")
defer c.client.Do("EXEC")
val += offset
if val < 0 {
return errors.NewValueBelowZero(key)
}
return c.Set(key, encoding.Int64Bytes(val), ttl)
}
func TestCache_Increment(t *testing.T) {
for _, cache := range testDrivers() {
cache.Increment("key1", 0, 1, 0)
cache.Increment("key1", 0, 1, 0)
v, _, _ := cache.Get("key1")
num, _ := encoding.BytesInt64(v)
if num != 1 {
tests.FailMsg(t, cache, "Expected the value to be 1, got %d", num)
}
cache.Set("key2", []byte("string value, not incrementable"), 0)
err := cache.Increment("key2", 0, 5, 0)
if err == nil {
tests.FailMsg(t, cache, "Expected the error not to be nil")
}
}
}
// incrementOffset is a common incrementor method used between Increment and
// Decrement. If the key isn't set before, we will set the initial value. If
// there is a value present, we will add the given offset to that value and
// update the value with the new TTL.
func (c *Cache) incrementOffset(key string, initial, offset, ttl int64) error {
if err := c.exists(key); err != nil {
return c.Set(key, encoding.Int64Bytes(initial), ttl)
}
val, ok := encoding.BytesInt64(c.items[key].value)
if !ok {
return errors.NewEncoding(key)
}
val += offset
if val < 0 {
return errors.NewValueBelowZero(key)
}
return c.Set(key, encoding.Int64Bytes(val), ttl)
}
func ExampleDecrement() {
cacher.Flush()
cacher.Decrement("key1", 10, 1, 0)
cacher.Decrement("key1", 10, 3, 0)
v, _, _ := cacher.Get("key1")
num, _ := encoding.BytesInt64(v)
fmt.Println(num)
cacher.Set("key2", []byte("string value, not decrementable"), 0)
ok := cacher.Decrement("key2", 0, 5, 0)
v2, _, _ := cacher.Get("key2")
fmt.Println(ok, string(v2))
// Output:
// 7
// Value for key `key2` could not be encoded. string value, not decrementable
}
// Compare compares a cached value given by the cache and the key to the value
// passed in as an interface. If the values do not match, the given test will
// receive a `FailNow()` call and print an appropiate error message.
func Compare(t *testing.T, cache cacher.Cacher, key string, value interface{}) {
_, ok := value.(int)
if ok {
val := int64(value.(int))
v, _, _ := cache.Get(key)
valInt, _ := encoding.BytesInt64(v)
if valInt != val {
msg := "Expected `" + key + "` to equal `" + strconv.FormatInt(val, 10) + "`, is `" + strconv.FormatInt(valInt, 10) + "`"
FailMsg(t, cache, msg)
}
} else {
value = value.(string)
if v, _, _ := cache.Get(key); string(v) != value {
msg := "Expected `" + key + "` to equal `" + value.(string) + "`"
FailMsg(t, cache, msg)
}
}
}