json.Unmarshal造成内存分配问题

[vvfan]

接口: AssumeRole
描述:

在使用sts client时，使用 AssumeRole 方法，获取结果
若 client 和 request 均未设置 readTimeout

则在 获取timeout 时，经过 getAPIMaxTimeout 方法
使用了 json.Unmarshal, 而 apiTimeouts 是个很大的string
在大量调用时，会造成很大的 alloc_space

以下代码:

client, err := sts.NewClientWithAccessKey(<RegionId>, <AccessKeyId>, <AccessKeySecret>)
request := sts.CreateAssumeRoleRequest()
request.Scheme = "https"
request.RoleArn = <RoleArn>
request.RoleSessionName = <BucketName>
request.DurationSeconds = "3600"
request.Policy = policy

responseSts, err := client.AssumeRole(request)
if err != nil {
	return stsResponse, err
}

...........

sdk/api_timeout.go

func (client *Client) getTimeout(request requests.AcsRequest) (time.Duration, time.Duration) {
	readTimeout := defaultReadTimeout
	connectTimeout := defaultConnectTimeout

	reqReadTimeout := request.GetReadTimeout()
	reqConnectTimeout := request.GetConnectTimeout()
	if reqReadTimeout != 0*time.Millisecond {
		readTimeout = reqReadTimeout
	} else if client.readTimeout != 0*time.Millisecond {
		readTimeout = client.readTimeout
	} else if client.httpClient.Timeout != 0 {
		readTimeout = client.httpClient.Timeout
	} else if timeout, ok := getAPIMaxTimeout(request.GetProduct(), request.GetActionName()); ok {
		readTimeout = timeout
	}

	if reqConnectTimeout != 0*time.Millisecond {
		connectTimeout = reqConnectTimeout
	} else if client.connectTimeout != 0*time.Millisecond {
		connectTimeout = client.connectTimeout
	}
	return readTimeout, connectTimeout
} 

[JacksonTian]

fixed by #596