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// Copyright 2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build wasm
package main
import (
"context"
"sync"
"time"
"github.com/matrix-org/dendrite/federationsender/api"
go_http_js_libp2p "github.com/matrix-org/go-http-js-libp2p"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
)
type libp2pPublicRoomsProvider struct {
node *go_http_js_libp2p.P2pLocalNode
providers []go_http_js_libp2p.PeerInfo
fedSender api.FederationSenderInternalAPI
fedClient *gomatrixserverlib.FederationClient
}
func NewLibP2PPublicRoomsProvider(
node *go_http_js_libp2p.P2pLocalNode, fedSender api.FederationSenderInternalAPI, fedClient *gomatrixserverlib.FederationClient,
) *libp2pPublicRoomsProvider {
p := &libp2pPublicRoomsProvider{
node: node,
fedSender: fedSender,
fedClient: fedClient,
}
node.RegisterFoundProviders(p.foundProviders)
return p
}
func (p *libp2pPublicRoomsProvider) foundProviders(peerInfos []go_http_js_libp2p.PeerInfo) {
// work out the diff then poke for new ones
seen := make(map[string]bool, len(p.providers))
for _, pr := range p.providers {
seen[pr.Id] = true
}
var newPeers []gomatrixserverlib.ServerName
for _, pi := range peerInfos {
if !seen[pi.Id] {
newPeers = append(newPeers, gomatrixserverlib.ServerName(pi.Id))
}
}
if len(newPeers) > 0 {
var res api.PerformServersAliveResponse
// ignore errors, we don't care.
p.fedSender.PerformServersAlive(context.Background(), &api.PerformServersAliveRequest{
Servers: newPeers,
}, &res)
}
p.providers = peerInfos
}
func (p *libp2pPublicRoomsProvider) Rooms() []gomatrixserverlib.PublicRoom {
return bulkFetchPublicRoomsFromServers(context.Background(), p.fedClient, p.homeservers())
}
func (p *libp2pPublicRoomsProvider) homeservers() []string {
result := make([]string, len(p.providers))
for i := range p.providers {
result[i] = p.providers[i].Id
}
return result
}
// bulkFetchPublicRoomsFromServers fetches public rooms from the list of homeservers.
// Returns a list of public rooms.
func bulkFetchPublicRoomsFromServers(
ctx context.Context, fedClient *gomatrixserverlib.FederationClient, homeservers []string,
) (publicRooms []gomatrixserverlib.PublicRoom) {
limit := 200
// follow pipeline semantics, see https://blog.golang.org/pipelines for more info.
// goroutines send rooms to this channel
roomCh := make(chan gomatrixserverlib.PublicRoom, int(limit))
// signalling channel to tell goroutines to stop sending rooms and quit
done := make(chan bool)
// signalling to say when we can close the room channel
var wg sync.WaitGroup
wg.Add(len(homeservers))
// concurrently query for public rooms
for _, hs := range homeservers {
go func(homeserverDomain string) {
defer wg.Done()
util.GetLogger(ctx).WithField("hs", homeserverDomain).Info("Querying HS for public rooms")
fres, err := fedClient.GetPublicRooms(ctx, gomatrixserverlib.ServerName(homeserverDomain), int(limit), "", false, "")
if err != nil {
util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Warn(
"bulkFetchPublicRoomsFromServers: failed to query hs",
)
return
}
for _, room := range fres.Chunk {
// atomically send a room or stop
select {
case roomCh <- room:
case <-done:
util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Info("Interrupted whilst sending rooms")
return
}
}
}(hs)
}
// Close the room channel when the goroutines have quit so we don't leak, but don't let it stop the in-flight request.
// This also allows the request to fail fast if all HSes experience errors as it will cause the room channel to be
// closed.
go func() {
wg.Wait()
util.GetLogger(ctx).Info("Cleaning up resources")
close(roomCh)
}()
// fan-in results with timeout. We stop when we reach the limit.
FanIn:
for len(publicRooms) < int(limit) || limit == 0 {
// add a room or timeout
select {
case room, ok := <-roomCh:
if !ok {
util.GetLogger(ctx).Info("All homeservers have been queried, returning results.")
break FanIn
}
publicRooms = append(publicRooms, room)
case <-time.After(15 * time.Second): // we've waited long enough, let's tell the client what we got.
util.GetLogger(ctx).Info("Waited 15s for federated public rooms, returning early")
break FanIn
case <-ctx.Done(): // the client hung up on us, let's stop.
util.GetLogger(ctx).Info("Client hung up, returning early")
break FanIn
}
}
// tell goroutines to stop
close(done)
return publicRooms
}
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