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feat: use deferred initialization of the asnStore #3

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merged 2 commits into from
Aug 25, 2020
Merged

feat: use deferred initialization of the asnStore #3

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38b74d1
feat: use deferred initialization of the asnStore
aschmahmann Aug 25, 2020
d8ddb2e
feat: use background goroutine for indirectAsnStore initialization
aschmahmann Aug 25, 2020
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42 changes: 33 additions & 9 deletions asn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,14 +8,10 @@ import (
"github.com/libp2p/go-cidranger"
)

var Store *asnStore
var Store *indirectAsnStore

func init() {
s, err := NewAsnStore()
if err != nil {
panic(err)
}
Store = s
Store = newIndirectAsnStore()
}

type networkWithAsn struct {
Expand Down Expand Up @@ -53,9 +49,7 @@ func (a *asnStore) AsnForIPv6(ip net.IP) (string, error) {
return n.asn, nil
}

// NewAsnStore returns a `asnStore` that can be queried for the Autonomous System Numbers
// for a given IP address or a multiaddress which contains an IP address.
func NewAsnStore() (*asnStore, error) {
func newAsnStore() (*asnStore, error) {
cr := cidranger.NewPCTrieRanger()

for k, v := range ipv6CidrToAsnMap {
Expand All @@ -71,3 +65,33 @@ func NewAsnStore() (*asnStore, error) {

return &asnStore{cr}, nil
}

type indirectAsnStore struct {
store *asnStore
doneLoading chan struct{}
}

// AsnForIPv6 returns the AS number for the given IPv6 address.
// If no mapping exists for the given IP, this function will
// return an empty ASN and a nil error.
Comment on lines +75 to +76
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is there a default cidr prefix for unknown mappings?

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@aschmahmann aschmahmann Aug 25, 2020 •
edited
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Can you elaborate a little more? I'm not understanding the question

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if 2 ips in the same /64 are looked up in a space that isn't in the mapping, will they get the same empty ASN, or different ones?
when we make a new ASN in response to a query, we should maybe save it in the mapping with some default prefix so that other IPs close to it cluster with it.

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@aschmahmann aschmahmann Aug 25, 2020 •
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will they get the same empty ASN, or different ones?

We return "" and when this is used in kbucket we just reject ASNs named "".

Note, this is why we're going to have to change your test in go-ipfs to use an ipv6 associated with a real ASN https://github.com/ipfs/go-ipfs/blob/fe9f49aeb71c753b92ed41922c493ff3bf08ef56/test/integration/wan_lan_dht_test.go#L54

func (a *indirectAsnStore) AsnForIPv6(ip net.IP) (string, error) {
<-a.doneLoading
return a.store.AsnForIPv6(ip)
}

func newIndirectAsnStore() *indirectAsnStore {
a := &indirectAsnStore{
doneLoading: make(chan struct{}),
}

go func() {
defer close(a.doneLoading)
store, err := newAsnStore()
if err != nil {
panic(err)
}
a.store = store
}()

return a
}