架构图

TreeIndex关键结构
type revision struct {
main int64
sub int64
}
type generation struct {
ver int64
created revision
revs []revision
}
type keyIndex struct {
key []byte
modified revision
generations []generation
}BoltDb
value的结构:
type KeyValue struct {
// key is the key in bytes. An empty key is not allowed.
Key []byte `protobuf:"bytes,1,opt,name=key,proto3" json:"key,omitempty"`
// create_revision is the revision of last creation on this key.
CreateRevision int64 `protobuf:"varint,2,opt,name=create_revision,json=createRevision,proto3" json:"create_revision,omitempty"`
// mod_revision is the revision of last modification on this key.
ModRevision int64 `protobuf:"varint,3,opt,name=mod_revision,json=modRevision,proto3" json:"mod_revision,omitempty"`
// version is the version of the key. A deletion resets
// the version to zero and any modification of the key
// increases its version.
Version int64 `protobuf:"varint,4,opt,name=version,proto3" json:"version,omitempty"`
// value is the value held by the key, in bytes.
Value []byte `protobuf:"bytes,5,opt,name=value,proto3" json:"value,omitempty"`
// lease is the ID of the lease that attached to key.
// When the attached lease expires, the key will be deleted.
// If lease is 0, then no lease is attached to the key.
Lease int64 `protobuf:"varint,6,opt,name=lease,proto3" json:"lease,omitempty"`
XXX_NoUnkeyedLiteral struct{} `json:"-"`
XXX_unrecognized []byte `json:"-"`
XXX_sizecache int32 `json:"-"`
}