pluggable-discovery handling in grpc Instances (WIP)

serial-discovery must be moved from commands/board to commands

commands/board/list.go

@@ -55,20 +55,15 @@ func BoardList(ctx context.Context, req *rpc.BoardListReq) (*rpc.BoardListResp,
 		}
 	}
 
-	serialDiscovery, err := discovery.NewFromCommandLine(serialDiscoveryTool.InstallDir.Join("serial-discovery").String())
+	// TODO: move to 'commands' modules
+	_, err := discovery.NewFromCommandLine(serialDiscoveryTool.InstallDir.Join("serial-discovery").String())
 	if err != nil {
 		formatter.PrintError(err, "Error setting up serial-discovery tool.")
 		os.Exit(cli.ErrCoreConfig)
 	}
 
-	// Find all installed discoveries
-	discoveries := append(discovery.ExtractDiscoveriesFromPlatforms(pm), serialDiscovery)
-
 	resp := &rpc.BoardListResp{Ports: []*rpc.DetectedPort{}}
-	for _, disc := range discoveries {
-		disc.Start()
-		defer disc.Close()
-
+	for _, disc := range commands.GetDiscoveries(req) {
 		ports, err := disc.List()
 		if err != nil {
 			fmt.Printf("Error getting port list from discovery %s: %s\n", disc.ID, err)

commands/discoveries.go

@@ -0,0 +1,70 @@
+//
+// This file is part of arduino-cli.
+//
+// Copyright 2018 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to modify or
+// otherwise use the software for commercial activities involving the Arduino
+// software without disclosing the source code of your own applications. To purchase
+// a commercial license, send an email to [email protected].
+//
+
+package commands
+
+import (
+	"sync"
+
+	"github.com/arduino/arduino-cli/arduino/discovery"
+)
+
+type sharedDiscovery struct {
+	discovery      *discovery.Discovery
+	referenceCount int
+}
+
+// this map contains all the running pluggable-discoveries instances
+var sharedDiscoveries = map[string]*sharedDiscovery{}
+var sharedDiscoveriesMutex sync.Mutex
+
+// StartSharedDiscovery starts a discovery or returns the instance of an already
+// started shared discovery.
+func StartSharedDiscovery(disc *discovery.Discovery) (*discovery.Discovery, error) {
+	sharedDiscoveriesMutex.Lock()
+	defer sharedDiscoveriesMutex.Unlock()
+
+	instance, started := sharedDiscoveries[disc.ID]
+	if started {
+		instance.referenceCount++
+		return instance.discovery, nil
+	}
+	sharedDiscoveries[disc.ID] = &sharedDiscovery{
+		discovery:      disc,
+		referenceCount: 1,
+	}
+	err := disc.Start()
+	return disc, err
+}
+
+// StopSharedDiscovery will dispose an instance of a shared discovery if it is
+// no more needed.
+func StopSharedDiscovery(disc *discovery.Discovery) error {
+	sharedDiscoveriesMutex.Lock()
+	defer sharedDiscoveriesMutex.Unlock()
+
+	instance, started := sharedDiscoveries[disc.ID]
+	if started {
+		instance.referenceCount--
+
+		if instance.referenceCount == 0 {
+			delete(sharedDiscoveries, disc.ID)
+			return instance.discovery.Close()
+		}
+	}
+	return nil
+}

commands/instances.go

@@ -26,8 +26,8 @@ import (
 	"time"
 
 	"github.com/arduino/arduino-cli/arduino/cores/packageindex"
-
 	"github.com/arduino/arduino-cli/arduino/cores/packagemanager"
+	"github.com/arduino/arduino-cli/arduino/discovery"
 	"github.com/arduino/arduino-cli/arduino/libraries"
 	"github.com/arduino/arduino-cli/arduino/libraries/librariesmanager"
 	"github.com/arduino/arduino-cli/configs"
@@ -46,10 +46,11 @@ var instancesCount int32 = 1
 // instantiate as many as needed by providing a different configuration
 // for each one.
 type CoreInstance struct {
-	config     *configs.Configuration
-	pm         *packagemanager.PackageManager
-	lm         *librariesmanager.LibrariesManager
-	getLibOnly bool
+	config      *configs.Configuration
+	pm          *packagemanager.PackageManager
+	lm          *librariesmanager.LibrariesManager
+	getLibOnly  bool
+	discoveries []*discovery.Discovery
 }
 
 type InstanceContainer interface {
@@ -72,6 +73,32 @@ func GetLibraryManager(req InstanceContainer) *librariesmanager.LibrariesManager
 	return i.lm
 }
 
+func GetDiscoveries(req InstanceContainer) []*discovery.Discovery {
+	i, ok := instances[req.GetInstance().GetId()]
+	if !ok {
+		return nil
+	}
+	return i.discoveries
+}
+
+func (instance *CoreInstance) startDiscoveries(downloadCB DownloadProgressCB, taskCB TaskProgressCB) error {
+	discoveriesToStop := instance.discoveries
+	discoveriesToStart := discovery.ExtractDiscoveriesFromPlatforms(instance.pm)
+
+	instance.discoveries = []*discovery.Discovery{}
+	for _, disc := range discoveriesToStart {
+		sharedDisc, err := StartSharedDiscovery(disc)
+		if err != nil {
+			return fmt.Errorf("starting discovery: %s", err)
+		}
+		instance.discoveries = append(instance.discoveries, sharedDisc)
+	}
+	for _, disc := range discoveriesToStop {
+		StopSharedDiscovery(disc)
+	}
+	return nil
+}
+
 func Init(ctx context.Context, req *rpc.InitReq, downloadCB DownloadProgressCB, taskCB TaskProgressCB) (*rpc.InitResp, error) {
 	inConfig := req.GetConfiguration()
 	if inConfig == nil {
@@ -108,6 +135,10 @@ func Init(ctx context.Context, req *rpc.InitReq, downloadCB DownloadProgressCB,
 	instancesCount++
 	instances[handle] = instance
 
+	if err := instance.startDiscoveries(downloadCB, taskCB); err != nil {
+		// TODO: handle discovery errors
+		fmt.Println(err)
+	}
 	return &rpc.InitResp{
 		Instance:             &rpc.Instance{Id: handle},
 		PlatformsIndexErrors: reqPltIndex,
@@ -120,6 +151,11 @@ func Destroy(ctx context.Context, req *rpc.DestroyReq) (*rpc.DestroyResp, error)
 	if _, ok := instances[id]; !ok {
 		return nil, fmt.Errorf("invalid handle")
 	}
+
+	for _, disc := range GetDiscoveries(req) {
+		StopSharedDiscovery(disc)
+	}
+
 	delete(instances, id)
 	return &rpc.DestroyResp{}, nil
 }
@@ -207,6 +243,9 @@ func Rescan(ctx context.Context, req *rpc.RescanReq) (*rpc.RescanResp, error) {
 	}
 	coreInstance.pm = pm
 	coreInstance.lm = lm
+
+	coreInstance.startDiscoveries(nil, nil)
+
 	return &rpc.RescanResp{
 		PlatformsIndexErrors: reqPltIndex,
 		LibrariesIndexError:  reqLibIndex,