client: working on alloc context

client/alloc_context.go

@@ -1,37 +1,76 @@
 package client
 
-import "github.com/hashicorp/nomad/nomad/structs"
+import (
+	"log"
+	"sync"
+
+	"github.com/hashicorp/nomad/nomad/structs"
+)
 
 // AllocContext is used to wrap an allocation and provide the execution context.
 type AllocContext struct {
 	client *Client
-	alloc  *structs.Allocation
+	logger *log.Logger
+
+	alloc *structs.Allocation
+
+	updateCh chan *structs.Allocation
+
+	destroy     bool
+	destroyCh   chan struct{}
+	destroyLock sync.Mutex
 }
 
 // NewAllocContext is used to create a new allocation context
 func NewAllocContext(client *Client, alloc *structs.Allocation) *AllocContext {
 	ctx := &AllocContext{
-		client: client,
-		alloc:  alloc,
+		client:   client,
+		logger:   client.logger,
+		alloc:    alloc,
+		updateCh: make(chan *structs.Allocation, 8),
 	}
 	return ctx
 }
 
 // Alloc returns the associated allocation
-func (ctx *AllocContext) Alloc() *structs.Allocation {
-	return ctx.alloc
+func (c *AllocContext) Alloc() *structs.Allocation {
+	return c.alloc
 }
 
 // Run is a long running goroutine used to manage an allocation
-func (ctx *AllocContext) Run() {
+func (c *AllocContext) Run() {
+	c.logger.Printf("[DEBUG] client: starting context for alloc '%s'", c.alloc.ID)
+
+	// TODO: Start
 	for {
+		select {
+		case update := <-c.updateCh:
+			// TODO: Update
+			c.alloc = update
+		case <-c.destroyCh:
+			// TODO: Destroy
+			return
+		}
 	}
 }
 
 // Update is used to update the allocation of the context
-func (ctx *AllocContext) Update(update *structs.Allocation) {
+func (c *AllocContext) Update(update *structs.Allocation) {
+	select {
+	case c.updateCh <- update:
+	default:
+		c.logger.Printf("[ERR] client: dropping update to alloc '%s'", update.ID)
+	}
 }
 
 // Destroy is used to indicate that the allocation context should be destroyed
-func (ctx *AllocContext) Destroy() {
+func (c *AllocContext) Destroy() {
+	c.destroyLock.Lock()
+	defer c.destroyLock.Unlock()
+
+	if c.destroy {
+		return
+	}
+	c.destroy = true
+	close(c.destroyCh)
 }