Add node cache

README.md

@@ -65,7 +65,8 @@ rebalance-lnd](https://github.com/accumulator/rebalance-lnd).
       --allow-unbalance-from  let the source channel go below 50% local liquidity, use if you want to drain a channel; you should also set --pfrom to >50
       --allow-unbalance-to    let the target channel go above 50% local liquidity, use if you want to refill a channel; you should also set --pto to >50
   -s, --stat=                 save successful rebalance information to the specified CSV file
-
+      --node-cache=           save and load other nodes information to this file, improves cold start performance
+      --node-cache-lifetime=  the cache file will not be loaded if it's older than this time (in minutes) (default: 1440)
 ```
 
 Look in `config.json.sample` or `config.toml.sample` for corresponding keys,

cache.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"encoding/gob"
+	"log"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/gofrs/flock"
+)
+
+func lock() *flock.Flock {
+	return flock.New(filepath.Join(os.TempDir(), "regolancer.lock"))
+}
+
+func (r *regolancer) loadNodeCache(filename string, exp int) {
+	if filename == "" {
+		return
+	}
+	l := lock()
+	l.RLock()
+	defer l.Unlock()
+	f, err := os.Open(filename)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			logErrorF("Error opening node cache file: %s", err)
+		}
+		return
+	}
+	defer f.Close()
+	fi, err := f.Stat()
+	if err != nil {
+		logErrorF("Error getting node cache information: %s", err)
+		return
+	}
+	if time.Since(fi.ModTime()) > time.Minute*time.Duration(exp) {
+		log.Print("Node cache expired, not loading")
+		return
+	}
+	log.Printf("Loading node cache from %s", filename)
+	gob.NewDecoder(f).Decode(&r.nodeCache)
+}
+
+func (r *regolancer) saveNodeCache(filename string) {
+	if filename == "" {
+		return
+	}
+	log.Printf("Saving node cache to %s", filename)
+	l := lock()
+	l.Lock()
+	defer l.Unlock()
+	f, err := os.Create(filename)
+	if err != nil {
+		logErrorF("Error creating node cache file %s: %s", filename, err)
+		return
+	}
+	defer f.Close()
+	gob.NewEncoder(f).Encode(r.nodeCache)
+}

go.mod

@@ -43,6 +43,7 @@ require (
 	github.com/fergusstrange/embedded-postgres v1.10.0 // indirect
 	github.com/form3tech-oss/jwt-go v3.2.3+incompatible // indirect
 	github.com/go-errors/errors v1.0.1 // indirect
+	github.com/gofrs/flock v0.8.1 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/golang/snappy v0.0.4 // indirect
@@ -128,7 +129,7 @@ require (
 	go.uber.org/zap v1.17.0 // indirect
 	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3 // indirect
 	golang.org/x/net v0.0.0-20211216030914-fe4d6282115f // indirect
-	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
+	golang.org/x/sys v0.1.0 // indirect
 	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/time v0.0.0-20210220033141-f8bda1e9f3ba // indirect

go.sum

@@ -204,6 +204,8 @@ github.com/go-logfmt/logfmt v0.4.0/go.mod h1:3RMwSq7FuexP4Kalkev3ejPJsZTpXXBr9+V
 github.com/go-logfmt/logfmt v0.5.0/go.mod h1:wCYkCAKZfumFQihp8CzCvQ3paCTfi41vtzG1KdI/P7A=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=
+github.com/gofrs/flock v0.8.1/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
 github.com/gofrs/uuid v4.0.0+incompatible/go.mod h1:b2aQJv3Z4Fp6yNu3cdSllBxTCLRxnplIgP/c0N/04lM=
 github.com/gofrs/uuid v4.2.0+incompatible h1:yyYWMnhkhrKwwr8gAOcOCYxOOscHgDS9yZgBrnJfGa0=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
@@ -858,6 +860,8 @@ golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a h1:dGzPydgVsqGcTRVwiLJ1jVbufYwmzD3LfVPLKsKg+0k=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1 h1:v+OssWQX+hTHEmOBgwxdZxK4zHq3yOs8F9J7mk0PY8E=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=

main.go

@@ -6,6 +6,7 @@ import (
 	"log"
 	"math/rand"
 	"os"
+	"os/signal"
 	"strconv"
 	"strings"
 	"time"
@@ -45,6 +46,8 @@ type configParams struct {
 	AllowUnbalanceFrom bool     `long:"allow-unbalance-from" description:"let the source channel go below 50% local liquidity, use if you want to drain a channel; you should also set --pfrom to >50" json:"allow_unbalance_from" toml:"allow_unbalance_from"`
 	AllowUnbalanceTo   bool     `long:"allow-unbalance-to" description:"let the target channel go above 50% local liquidity, use if you want to refill a channel; you should also set --pto to >50" json:"allow_unbalance_to" toml:"allow_unbalance_to"`
 	StatFilename       string   `short:"s" long:"stat" description:"save successful rebalance information to the specified CSV file" json:"stat" toml:"stat"`
+	NodeCacheFilename  string   `long:"node-cache" description:"save and load other nodes information to this file, improves cold start performance"  json:"node_cache_filename" toml:"node_cache_filename"`
+	NodeCacheLifetime  int      `long:"node-cache-lifetime" description:"the cache file will not be loaded if it's older than this time (in minutes)" json:"node_cache_lifetime" toml:"node_cache_lifetime" default:"1440"`
 }
 
 var params, cfgParams configParams
@@ -285,6 +288,17 @@ func main() {
 	}
 	infoCtxCancel()
 	attempt := 1
+
+	r.loadNodeCache(params.NodeCacheFilename, params.NodeCacheLifetime)
+	defer r.saveNodeCache(params.NodeCacheFilename)
+	stopChan := make(chan os.Signal)
+	signal.Notify(stopChan, os.Interrupt)
+	go func() {
+		<-stopChan
+		r.saveNodeCache(params.NodeCacheFilename)
+		os.Exit(1)
+	}()
+
 	for {
 		attemptCtx, attemptCancel := context.WithTimeout(mainCtx, time.Minute*5)
 		_, retry := tryRebalance(attemptCtx, &r, &attempt)