Refactor components

component/component.go

@@ -34,6 +34,10 @@ type Component interface {
 	// Context returns a new InstallationContext to be used during installation from the command line.
 	// Typically this should just pass through the parent, but might perform other tasks.
 	Context(parent InstallationContext) InstallationContext
+
+	// Base() returns a reference to a base component
+	// This is implemented by an embedding on ComponentBase
+	Base() *ComponentBase
 }
 
 // ComponentBase implements base functionality for a component
@@ -43,6 +47,11 @@ type ComponentBase struct {
 	Config *config.Config // Config is the configuration of the underlying distillery
 }
 
+// Base returns a reference to the ComponentBase
+func (cb *ComponentBase) Base() *ComponentBase {
+	return cb
+}
+
 // Path returns the path to this component
 func (cb ComponentBase) Path() string {
 	return cb.Dir

env/component.go

@@ -2,6 +2,8 @@ package env
 
 import (
 	"path/filepath"
+	"reflect"
+	"sync"
 	"time"
 
 	"github.com/FAU-CDI/wisski-distillery/component"
@@ -14,9 +16,63 @@ import (
 	"github.com/FAU-CDI/wisski-distillery/component/web"
 )
 
-// Stacks returns the Stacks of this distillery
+// components holds the various components of the distillery
+// It is inlined into the [Distillery] struct, and initialized using [makeComponent].
+type components struct {
+	// m protects the fields below
+	m sync.Mutex
+
+	// each component is only initialized once
+	web      *web.Web
+	self     *self.Self
+	resolver *resolver.Resolver
+	dis      *dis.Dis
+	ssh      *ssh.SSH
+	ts       *triplestore.Triplestore
+	sql      *sql.SQL
+}
+
+// makeComponent makes or returns a component inside the [component] struct of the distillery
+//
+// C is the type of component to initialize. It must be backed by a pointer, or makeComponent will panic.
+//
+// dis is the distillery to initialize components for
+// field is a pointer to the appropriate struct field within the distillery components
+// init is called with a new non-nil component to initialize it. It may be nil, to indicate no initialization is required.
+//
+// makeComponent returns the new or existing component instance
+func makeComponent[C component.Component](dis *Distillery, field *C, init func(C)) C {
+	dis.components.m.Lock()
+	defer dis.components.m.Unlock()
+
+	// get the typeof C and make sure that it is a pointer type!
+	typC := reflect.TypeOf((*C)(nil)).Elem()
+	if typC.Kind() != reflect.Pointer {
+		panic("makeComponent: C must be backed by a pointer")
+	}
+
+	// if the component is non-nil, then it has already been initialized
+	if !reflect.ValueOf(*field).IsNil() {
+		return *field
+	}
+
+	// create a new element, and call the initializer (if requested)
+	*field = reflect.New(typC.Elem()).Interface().(C)
+	if init != nil {
+		init(*field)
+	}
+
+	// apply the base configuration
+	base := (*field).Base()
+	base.Config = dis.Config
+	base.Dir = filepath.Join(dis.Config.DeployRoot, "core", (*field).Name())
+
+	// and eventually return it
+	return *field
+}
+
+// Components returns all components of the distillery
 func (dis *Distillery) Components() []component.Component {
-	// TODO: Do we want to cache these components?
 	return []component.Component{
 		dis.Web(),
 		dis.Self(),
@@ -28,63 +84,43 @@ func (dis *Distillery) Components() []component.Component {
 	}
 }
 
-// Web returns the web component belonging to this distillery
-func (dis *Distillery) Web() (web web.Web) {
-	dis.makeComponent(web, &web.ComponentBase)
-	return
+func (dis *Distillery) Web() *web.Web {
+	return makeComponent(dis, &dis.components.web, nil)
 }
 
-// Self returns the self component belonging to this distillery
-func (dis *Distillery) Self() (self self.Self) {
-	dis.makeComponent(self, &self.ComponentBase)
-	return
+func (dis *Distillery) Self() *self.Self {
+	return makeComponent(dis, &dis.components.self, nil)
 }
 
-// Resolver returns the resolver component belonging to this distillery
-func (dis *Distillery) Resolver() (resolver resolver.Resolver) {
-	resolver.ConfigName = "prefix.cfg" // TODO: Move into core?
-	resolver.Executable = dis.CurrentExecutable()
-
-	dis.makeComponent(resolver, &resolver.ComponentBase)
-	return
+func (dis *Distillery) Resolver() *resolver.Resolver {
+	return makeComponent(dis, &dis.components.resolver, func(resolver *resolver.Resolver) {
+		resolver.ConfigName = "prefix.cfg" // TODO: Move into core?
+		resolver.Executable = dis.CurrentExecutable()
+	})
 }
 
-// Dis returns the dis component belonging to this distillery
-func (dis *Distillery) Dis() (ddis dis.Dis) {
-	ddis.Executable = dis.CurrentExecutable()
-
-	dis.makeComponent(ddis, &ddis.ComponentBase)
-	return
+func (d *Distillery) Dis() *dis.Dis {
+	return makeComponent(d, &d.components.dis, func(ddis *dis.Dis) {
+		ddis.Executable = d.CurrentExecutable()
+	})
 }
 
-// SSH returns the SSH component belonging to this distillery
-func (dis *Distillery) SSH() (ssh ssh.SSH) {
-	dis.makeComponent(ssh, &ssh.ComponentBase)
-	return
+func (dis *Distillery) SSH() *ssh.SSH {
+	return makeComponent(dis, &dis.components.ssh, nil)
 }
 
-// SQL returns the SQL component belonging to this distillery
-func (dis *Distillery) SQL() (sql sql.SQL) {
-	sql.ServerURL = dis.Upstream.SQL
-	sql.PollContext = dis.Context()
-	sql.PollInterval = time.Second
-
-	dis.makeComponent(sql, &sql.ComponentBase)
-	return
+func (dis *Distillery) SQL() *sql.SQL {
+	return makeComponent(dis, &dis.components.sql, func(sql *sql.SQL) {
+		sql.ServerURL = dis.Upstream.SQL
+		sql.PollContext = dis.Context()
+		sql.PollInterval = time.Second
+	})
 }
 
-// Triplestore returns the TriplestoreComponent belonging to this distillery
-func (dis *Distillery) Triplestore() (ts triplestore.Triplestore) {
-	ts.BaseURL = "http://" + dis.Upstream.Triplestore
-	ts.PollContext = dis.Context()
-	ts.PollInterval = time.Second
-
-	dis.makeComponent(ts, &ts.ComponentBase)
-	return
-}
-
-// makeComponent updates the baseComponent belonging to component
-func (dis *Distillery) makeComponent(component component.Component, base *component.ComponentBase) {
-	base.Config = dis.Config
-	base.Dir = filepath.Join(dis.Config.DeployRoot, "core", component.Name())
+func (dis *Distillery) Triplestore() *triplestore.Triplestore {
+	return makeComponent(dis, &dis.components.ts, func(ts *triplestore.Triplestore) {
+		ts.BaseURL = "http://" + dis.Upstream.Triplestore
+		ts.PollContext = dis.Context()
+		ts.PollInterval = time.Second
+	})
 }

env/distillery.go

@@ -10,10 +10,21 @@ import (
 	"github.com/FAU-CDI/wisski-distillery/internal/fsx"
 )
 
-// Distillery represents a running instance for the distillery
+// Distillery represents an interface to the running distillery.
 type Distillery struct {
-	Config   *config.Config
-	Upstream Upstream // TODO: not sure this belongs here
+	// Config holds the configuration of the distillery.
+	// It is read directly from a configuration file.
+	Config *config.Config
+
+	// Upstream holds information to connect to the various running
+	// distillery components.
+	//
+	// NOTE(twiesing): This is intended to eventually allow full remote management of the distillery.
+	// But for now this will just hold upstream configuration.
+	Upstream Upstream
+
+	// components hold references to the various components of the distillery.
+	components
 }
 
 // Upstream are the upstream urls connecting to the various external components.
@@ -23,7 +34,7 @@ type Upstream struct {
 }
 
 // Context returns a new Context belonging to this distillery
-func (dis Distillery) Context() context.Context {
+func (dis *Distillery) Context() context.Context {
 	return context.Background()
 }
 

env/runtime.go

@@ -3,6 +3,6 @@ package env
 import "path/filepath"
 
 // RuntimeDir returns the path to the runtime directory
-func (dis Distillery) RuntimeDir() string {
+func (dis *Distillery) RuntimeDir() string {
 	return filepath.Join(dis.Config.DeployRoot, "runtime")
 }

env/snapshot.go

@@ -16,25 +16,25 @@ import (
 )
 
 // SnapshotsDir returns the path that contains all snapshot related data.
-func (dis Distillery) SnapshotsDir() string {
+func (dis *Distillery) SnapshotsDir() string {
 	return filepath.Join(dis.Config.DeployRoot, "snapshots")
 }
 
 // SnapshotsStagingPath returns the path to the directory containing a temporary staging area for snapshots.
 // Use NewSnapshotStagingDir to generate a new staging area.
-func (dis Distillery) SnapshotsStagingPath() string {
+func (dis *Distillery) SnapshotsStagingPath() string {
 	return filepath.Join(dis.SnapshotsDir(), "staging")
 }
 
 // SnapshotsArchivePath returns the path to the directory containing all exported archives.
 // Use NewSnapshotArchivePath to generate a path to a new archive in this directory.
-func (dis Distillery) SnapshotsArchivePath() string {
+func (dis *Distillery) SnapshotsArchivePath() string {
 	return filepath.Join(dis.SnapshotsDir(), "archives")
 }
 
 // NewSnapshotArchivePath returns the path to a new archive with the provided prefix.
 // The path is guaranteed to not exist.
-func (dis Distillery) NewSnapshotArchivePath(prefix string) (path string) {
+func (dis *Distillery) NewSnapshotArchivePath(prefix string) (path string) {
 	// TODO: Consider moving these into a subdirectory with the provided prefix.
 	for path == "" || fsx.Exists(path) {
 		name := dis.newSnapshotName(prefix) + ".tar.gz"
@@ -45,7 +45,7 @@ func (dis Distillery) NewSnapshotArchivePath(prefix string) (path string) {
 
 // newSnapshot name returns a new basename for a snapshot with the provided prefix.
 // The name is guaranteed to be unique within this process.
-func (Distillery) newSnapshotName(prefix string) string {
+func (*Distillery) newSnapshotName(prefix string) string {
 	suffix, _ := password.Password(64) // silently ignore any errors!
 	if prefix == "" {
 		prefix = "backup"
@@ -57,7 +57,7 @@ func (Distillery) newSnapshotName(prefix string) string {
 
 // NewSnapshotStagingDir returns the path to a new snapshot directory.
 // The directory is guaranteed to have been freshly created.
-func (dis Distillery) NewSnapshotStagingDir(prefix string) (path string, err error) {
+func (dis *Distillery) NewSnapshotStagingDir(prefix string) (path string, err error) {
 	for path == "" || os.IsExist(err) {
 		path = filepath.Join(dis.SnapshotsStagingPath(), dis.newSnapshotName(prefix))
 		err = os.Mkdir(path, os.ModeDir)

internal/fsx/copy.go

@@ -48,8 +48,6 @@ var ErrCopyNoDirectory = errors.New("dst is not a directory")
 //
 // onCopy, when not nil, is called for each file or directory being copied.
 func CopyDirectory(dst, src string, onCopy func(dst, src string)) error {
-	// TODO: Allow copying in parallel? Maybe with a mutex?
-
 	// sanity checks
 	if SameFile(src, dst) {
 		return ErrCopySameFile

internal/hostname/hostname.go

@@ -1,4 +1,4 @@
-// Package hostname provides hostname
+// Package hostname provides the hostname.
 package hostname
 
 import (