feat(xo-server/vm.set): dont switch to DMC when changing memory

Fixes #4983

CHANGELOG.unreleased.md

@@ -9,6 +9,8 @@
 
 [Host/Load-balancer] Add option to disable migration (PR [#5706](https://github.com/vatesfr/xen-orchestra/pull/5706))
 
+- [VM] Don't switch a VM to use [DMC](https://docs.citrix.com/en-us/xencenter/7-1/dmc-about.html) when changing the memory [#4983](https://github.com/vatesfr/xen-orchestra/issues/4983)
+
 ### Bug fixes
 
 > Users must be able to say: “I had this issue, happy to know it's fixed”

packages/xo-server/src/xapi/mixins/vm.js

@@ -340,7 +340,24 @@ export default {
       set: 'memory_dynamic_min',
     },
 
-    memory: 'memoryMax',
+    _memory: {
+      addToLimits: true,
+      get: vm => +vm.memory_dynamic_max,
+      preprocess: parseSize,
+      set(memory, vm) {
+        return vm.$call('set_memory_limits', vm.memory_static_min, memory, memory, memory)
+      },
+    },
+
+    memory: {
+      dispatch(vm) {
+        const dynamicMin = vm.memory_dynamic_min
+        const useDmc = dynamicMin !== vm.memory_dynamic_max || dynamicMin !== vm.memory_static_max
+
+        return useDmc ? 'memoryMax' : '_memory'
+      },
+    },
+
     memoryMax: {
       addToLimits: true,
       limitName: 'memory',

packages/xo-server/src/xapi/utils.js

@@ -192,6 +192,10 @@ export const makeEditObject = specs => {
       }
     })
 
+    if ('dispatch' in spec) {
+      return spec
+    }
+
     const { get } = spec
     if (get) {
       spec.get = normalizeGet(get, name)
@@ -235,6 +239,11 @@ export const makeEditObject = specs => {
         return
       }
 
+      const { dispatch } = spec
+      if (dispatch) {
+        return set(value, dispatch(object))
+      }
+
       const { preprocess } = spec
       if (preprocess) {
         value = preprocess(value)