feat(cfg): opt-in Swarm.ResourceMgr

This ensures we can safely test the resource manager without impacting
default behavior.

- Resource manager is disabled by default
    - Default for Swarm.ResourceMgr.Enabled is false for now
- Swarm.ResourceMgr.Limits allows user to tweak limits per specific
  scope in a way that is persisted across restarts
- 'ipfs swarm limit system' outputs human-readable json
- 'ipfs swarm limit system new-limits.json' sets new runtime limits
  (but does not change Swarm.ResourceMgr.Limits in the config)

Conventions to make libp2p devs life easier:
- 'IPFS_RCMGR=1 ipfs daemon' overrides the config and enables resource manager
- 'limit.json' overrides implicit defaults from libp2p (if present)

config/swarm.go

@@ -49,6 +49,9 @@ type SwarmConfig struct {
 
 	// ConnMgr configures the connection manager.
 	ConnMgr ConnMgr
+
+	// ResourceMgr configures the libp2p Network Resource Manager
+	ResourceMgr ResourceMgr
 }
 
 type RelayClient struct {
@@ -129,3 +132,36 @@ type ConnMgr struct {
 	HighWater   int
 	GracePeriod string
 }
+
+// ResourceMgr defines configuration options for the libp2p Network Resource Manager
+// <https://github.com/libp2p/go-libp2p-resource-manager#readme>
+type ResourceMgr struct {
+	// Enables the Network Resource Manager feature
+	Enabled Flag `json:",omitempty"`
+
+	// Limits is a map of Resource Scope.
+	Limits map[string]ResourceMgrScopeConfig `json:",omitempty"`
+}
+
+const (
+	ResourceMgrSystemScope         = "system"
+	ResourceMgrTransientScope      = "transient"
+	ResourceMgrServiceScopePrefix  = "svc:"
+	ResourceMgrProtocolScopePrefix = "proto:"
+	ResourceMgrPeerScopePrefix     = "peer:"
+)
+
+// libp2p Network Resource Manager config for a scope (ipfs swarm stats|limit)
+type ResourceMgrScopeConfig struct {
+	Dynamic bool `json:",omitempty"`
+	// set if Dynamic is false
+	Memory int64 `json:",omitempty"`
+	// set if Dynamic is true
+	MemoryFraction float64 `json:",omitempty"`
+	MinMemory      int64   `json:",omitempty"`
+	MaxMemory      int64   `json:",omitempty"`
+
+	Streams, StreamsInbound, StreamsOutbound int
+	Conns, ConnsInbound, ConnsOutbound       int
+	FD                                       int
+}

core/commands/config.go

@@ -215,18 +215,20 @@ NOTE: For security reasons, this command will omit your private key and remote s
 		return cmds.EmitOnce(res, &cfg)
 	},
 	Encoders: cmds.EncoderMap{
-		cmds.Text: cmds.MakeTypedEncoder(func(req *cmds.Request, w io.Writer, out *map[string]interface{}) error {
-			buf, err := config.HumanOutput(out)
-			if err != nil {
-				return err
-			}
-			buf = append(buf, byte('\n'))
-			_, err = w.Write(buf)
-			return err
-		}),
+		cmds.Text: HumanJsonEncoder,
 	},
 }
 
+var HumanJsonEncoder = cmds.MakeTypedEncoder(func(req *cmds.Request, w io.Writer, out *map[string]interface{}) error {
+	buf, err := config.HumanOutput(out)
+	if err != nil {
+		return err
+	}
+	buf = append(buf, byte('\n'))
+	_, err = w.Write(buf)
+	return err
+})
+
 // Scrubs value and returns error if missing
 func scrubValue(m map[string]interface{}, key []string) (map[string]interface{}, error) {
 	return scrubMapInternal(m, key, false)