eface

eface 结构体表示不包含任何方法的 interface{} 类型,包含指向底层数据和类型的两个指针
// go1.13.9 runtime/runtime2.go 197

  1. type eface struct {
  2.     _type *_type
  3.     data  unsafe.Pointer
  4. }

iface

iface 结构体表示包含方法的接口；
// go1.13.9 runtime/runtime2.go 192

  1. type iface struct {
  2.     tab  *itab
  3.     data unsafe.Pointer
  4. }

itab

// go1.13.9 runtime/runtime2.go 730

  1. type itab struct {
  2.     inter  *interfacetype
  3.     _type  *_type
  4.     link   *itab
  5.     hash   uint32 // copy of _type.hash. Used for type switches.
  6.     bad    bool   // type does not implement interface
  7.     inhash bool   // has this itab been added to hash?
  8.     unused [2]byte
  9.     fun    [1]uintptr // variable sized
  10. }

interfacetype

// go1.13.9 runtime/type.go 354

  1. type interfacetype struct {
  2.     typ     _type //类型
  3.     pkgpath name // 包路径
  4.     mhdr    []imethod //接口定义的函数列表
  5. }

_type

  1. type _type struct {
  2.     size       uintptr // 类型大小
  3.     ptrdata    uintptr // size of memory prefix holding all pointers
  4.     hash       uint32 // 类型hash
  5.     tflag      tflag  // 类型flag 
  6.     align      uint8  // 类型对齐
  7.     fieldalign uint8
  8.     kind       uint8  //类型
  9.     alg        *typeAlg
  10.     // gcdata stores the GC type data for the garbage collector.
  11.     // If the KindGCProg bit is set in kind, gcdata is a GC program.
  12.     // Otherwise it is a ptrmask bitmap. See mbitmap.go for details.
  13.     gcdata    *byte
  14.     str       nameOff
  15.     ptrToThis typeOff
  16. }

size类型占用的内存空间，为内存空间的分配提供信息；
hash 字段能够帮助我们快速确定类型是否相等