hcl: Added basic hcl frontend

hcl/gapi.go

@@ -0,0 +1,155 @@
+// Mgmt
+// Copyright (C) 2013-2017+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package hcl
+
+import (
+	"fmt"
+	"log"
+	"sync"
+
+	"github.com/purpleidea/mgmt/gapi"
+	"github.com/purpleidea/mgmt/pgraph"
+	"github.com/purpleidea/mgmt/recwatch"
+)
+
+// GAPI ...
+type GAPI struct {
+	File *string
+
+	initialized   bool
+	data          gapi.Data
+	wg            sync.WaitGroup
+	closeChan     chan struct{}
+	configWatcher *recwatch.ConfigWatcher
+}
+
+// NewGAPI ...
+func NewGAPI(data gapi.Data, file *string) (*GAPI, error) {
+	if file == nil {
+		return nil, fmt.Errorf("empty file given")
+	}
+
+	obj := &GAPI{
+		File: file,
+	}
+	return obj, obj.Init(data)
+}
+
+// Init ...
+func (obj *GAPI) Init(d gapi.Data) error {
+	if obj.initialized {
+		return fmt.Errorf("already initialized")
+	}
+
+	if obj.File == nil {
+		return fmt.Errorf("file cannot be nil")
+	}
+
+	obj.data = d
+	obj.closeChan = make(chan struct{})
+	obj.initialized = true
+	obj.configWatcher = recwatch.NewConfigWatcher()
+
+	return nil
+}
+
+// Graph ...
+func (obj *GAPI) Graph() (*pgraph.Graph, error) {
+	config, err := loadHcl(obj.File)
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse graph: %s", err)
+	}
+
+	return graphFromConfig(config, obj.data)
+}
+
+// Next ...
+func (obj *GAPI) Next() chan gapi.Next {
+	ch := make(chan gapi.Next)
+	obj.wg.Add(1)
+
+	go func() {
+		defer obj.wg.Done()
+		defer close(ch)
+		if !obj.initialized {
+			next := gapi.Next{
+				Err:  fmt.Errorf("hcl: GAPI is not initialized"),
+				Exit: true,
+			}
+			ch <- next
+			return
+		}
+		startChan := make(chan struct{}) // start signal
+		close(startChan)                 // kick it off!
+
+		watchChan, configChan := make(chan error), make(chan error)
+		if obj.data.NoConfigWatch {
+			configChan = nil
+		} else {
+			configChan = obj.configWatcher.ConfigWatch(*obj.File) // simple
+		}
+		if obj.data.NoStreamWatch {
+			watchChan = nil
+		} else {
+			watchChan = obj.data.World.ResWatch()
+		}
+
+		for {
+			var err error
+			var ok bool
+
+			select {
+			case <-startChan:
+				startChan = nil
+			case err, ok = <-watchChan:
+			case err, ok = <-configChan:
+				if !ok {
+					return
+				}
+			case <-obj.closeChan:
+				return
+			}
+
+			log.Printf("hcl: generating new graph")
+			next := gapi.Next{
+				Err: err,
+			}
+
+			select {
+			case ch <- next:
+			case <-obj.closeChan:
+				return
+			}
+		}
+	}()
+
+	return ch
+}
+
+// Close ...
+func (obj *GAPI) Close() error {
+	if !obj.initialized {
+		return fmt.Errorf("hcl: GAPI is not initialized")
+	}
+
+	obj.configWatcher.Close()
+	close(obj.closeChan)
+	obj.wg.Wait()
+	obj.initialized = false
+	return nil
+}