cmd/utils: move cache sanity check to SetEthConfig (ethereum#22510)

Move the cache sanity check to the SetEthConfig function
to allow the config file to load.

cmd/geth/main.go

@@ -19,9 +19,7 @@ package main
 
 import (
 	"fmt"
-	"math"
 	"os"
-	godebug "runtime/debug"
 	"sort"
 	"strconv"
 	"strings"
@@ -41,7 +39,6 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/node"
-	gopsutil "github.com/shirou/gopsutil/mem"
 	"gopkg.in/urfave/cli.v1"
 )
 
@@ -300,25 +297,6 @@ func prepare(ctx *cli.Context) {
 		log.Info("Dropping default light client cache", "provided", ctx.GlobalInt(utils.CacheFlag.Name), "updated", 128)
 		ctx.GlobalSet(utils.CacheFlag.Name, strconv.Itoa(128))
 	}
-	// Cap the cache allowance and tune the garbage collector
-	mem, err := gopsutil.VirtualMemory()
-	if err == nil {
-		if 32<<(^uintptr(0)>>63) == 32 && mem.Total > 2*1024*1024*1024 {
-			log.Warn("Lowering memory allowance on 32bit arch", "available", mem.Total/1024/1024, "addressable", 2*1024)
-			mem.Total = 2 * 1024 * 1024 * 1024
-		}
-		allowance := int(mem.Total / 1024 / 1024 / 3)
-		if cache := ctx.GlobalInt(utils.CacheFlag.Name); cache > allowance {
-			log.Warn("Sanitizing cache to Go's GC limits", "provided", cache, "updated", allowance)
-			ctx.GlobalSet(utils.CacheFlag.Name, strconv.Itoa(allowance))
-		}
-	}
-	// Ensure Go's GC ignores the database cache for trigger percentage
-	cache := ctx.GlobalInt(utils.CacheFlag.Name)
-	gogc := math.Max(20, math.Min(100, 100/(float64(cache)/1024)))
-
-	log.Debug("Sanitizing Go's GC trigger", "percent", int(gogc))
-	godebug.SetGCPercent(int(gogc))
 
 	// Start metrics export if enabled
 	utils.SetupMetrics(ctx)

cmd/utils/flags.go

@@ -22,9 +22,11 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math"
 	"math/big"
 	"os"
 	"path/filepath"
+	godebug "runtime/debug"
 	"strconv"
 	"strings"
 	"text/tabwriter"
@@ -65,6 +67,7 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/netutil"
 	"github.com/ethereum/go-ethereum/params"
 	pcsclite "github.com/gballet/go-libpcsclite"
+	gopsutil "github.com/shirou/gopsutil/mem"
 	"gopkg.in/urfave/cli.v1"
 )
 
@@ -1473,6 +1476,26 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
 	setWhitelist(ctx, cfg)
 	setLes(ctx, cfg)
 
+	// Cap the cache allowance and tune the garbage collector
+	mem, err := gopsutil.VirtualMemory()
+	if err == nil {
+		if 32<<(^uintptr(0)>>63) == 32 && mem.Total > 2*1024*1024*1024 {
+			log.Warn("Lowering memory allowance on 32bit arch", "available", mem.Total/1024/1024, "addressable", 2*1024)
+			mem.Total = 2 * 1024 * 1024 * 1024
+		}
+		allowance := int(mem.Total / 1024 / 1024 / 3)
+		if cache := ctx.GlobalInt(CacheFlag.Name); cache > allowance {
+			log.Warn("Sanitizing cache to Go's GC limits", "provided", cache, "updated", allowance)
+			ctx.GlobalSet(CacheFlag.Name, strconv.Itoa(allowance))
+		}
+	}
+	// Ensure Go's GC ignores the database cache for trigger percentage
+	cache := ctx.GlobalInt(CacheFlag.Name)
+	gogc := math.Max(20, math.Min(100, 100/(float64(cache)/1024)))
+
+	log.Debug("Sanitizing Go's GC trigger", "percent", int(gogc))
+	godebug.SetGCPercent(int(gogc))
+
 	if ctx.GlobalIsSet(SyncModeFlag.Name) {
 		cfg.SyncMode = *GlobalTextMarshaler(ctx, SyncModeFlag.Name).(*downloader.SyncMode)
 	}