英文:
How to avoid nested map allocations in my data structure?
问题
我有一个结构体，其中有一个嵌套的CustomersIndex映射，它分配了一堆内部映射，导致内存增加。我进行了性能分析，所以我注意到了这一点。我想知道是否有任何方法可以重新设计我的CustomersIndex数据结构，而不使用嵌套映射？
以下是在我的代码中填充它的方式：
const (
departmentsKey = "departments"
)
type CustomerManifest struct {
Customers []definitions.Customer
CustomersIndex map[int]map[int]definitions.Customer
}
这是在我的下面代码中对其进行填充的方式：
func updateData(mdmCache *mdm.Cache) map[string]interface{} {
memCache := mdmCache.MemCache()
var customers []definitions.Customer
var customersIndex = map[int]map[int]definitions.Customer{}
for _, r := range memCache.Customer {
customer := definitions.Customer{
Id: int(r.Id),
SetId: int(r.DepartmentSetId),
}
customers = append(customers, customer)
_, yes := customersIndex[customer.SetId]
if !yes {
customersIndex[customer.SetId] = make(map[int]definitions.Customer)
}
customersIndex[customer.SetId][customer.Id] = customer
}
return map[string]interface{}{
departmentsKey: &CustomerManifest{Customers: customers, CustomersIndex: customersIndex},
}
}
这是我获取CustomersIndex嵌套映射的方式：
func (c *Client) GetCustomerIndex() map[int]map[int]definitions.Customer {
c.mutex.RLock()
defer c.mutex.RUnlock()
customersIndex := c.data[departmentsKey].(*CustomerManifest).CustomersIndex
return customersIndex
}
有没有办法设计我的CustomersIndex，而不使用嵌套映射？
英文:
I have a below struct where I have a nested map for CustomersIndex which allocates bunch of internal maps causing memory increase. I profiled it so I noticed this. I am trying to see if there is any way to redesign my CustomersIndex data structure which doesn't uses nested map?
const (
departmentsKey = "departments"
)
type CustomerManifest struct {
Customers []definitions.Customer
CustomersIndex map[int]map[int]definitions.Customer
}
This is the way it is being populated here in my below code:
func updateData(mdmCache *mdm.Cache) map[string]interface{} {
memCache := mdmCache.MemCache()
var customers []definitions.Customer
var customersIndex = map[int]map[int]definitions.Customer{}
for _, r := range memCache.Customer {
customer := definitions.Customer{
Id: int(r.Id),
SetId: int(r.DepartmentSetId),
}
customers = append(customers, customer)
_, yes := customersIndex[customer.SetId]
if !yes {
customersIndex[customer.SetId] = make(map[int]definitions.Customer)
}
customersIndex[customer.SetId][customer.Id] = customer
}
return map[string]interface{}{
departmentsKey: &CustomerManifest{Customers: customers, CustomersIndex: customersIndex},
}
}
And this is the way I am getting my CustomersIndex nested map.
func (c *Client) GetCustomerIndex() map[int]map[int]definitions.Customer {
c.mutex.RLock()
defer c.mutex.RUnlock()
customersIndex := c.data[departmentsKey].(*CustomerManifest).CustomersIndex
return customersIndex
}
Is there any way to design my CustomersIndex in a way where I don't have to use nested map?
答案1
得分: 1
直到你往其中放入值之前，你不需要分配一个地图。
type CustomerManifest struct {
Customers []definitions.Customer
CustomersIndex map[int]map[int]definitions.Customer
}
func (m *CustomerManifest) AddCustomerDefinition(x, y int, customer definitions.Customer) {
// 获取现有的地图，如果存在。
innerMap := m.CustomersIndex[x]
// 如果不存在，分配它。
if innerMap == nil {
innerMap = make(map[int]definitions.Customer)
m.CustomersIndex[x] = innerMap
}
// 将值添加到现在存在的内部地图中。
innerMap[y] = customer
}
英文:
You don't need to allocate a map until you put values in it.
type CustomerManifest struct {
Customers []definitions.Customer
CustomersIndex map[int]map[int]definitions.Customer
}
func (m *CustomerManifest) AddCustomerDefinition(x, y int, customer definitions.Customer) {
// Get the existing map, if exists.
innerMap := m.CustomersIndex[x]
// If it doesn't exist, allocate it.
if innerMap == nil {
innerMap = make(map[int]definitions.Customer)
m.CustomersIndex[x] = innerMap
}
// Add the value to the inner map, which now exists.
innerMap[y] = customer
}
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