From 78c4b06492c0db83aad654aed84f8d81670d5647 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Wed, 8 Jul 2015 16:35:21 +0100
Subject: [PATCH] Don't wait for certainty before responding to Claim

Conflicts:
	ipam/claim.go
---
 ipam/claim.go | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/ipam/claim.go b/ipam/claim.go
index 8d96e6e2..750ad950 100644
--- a/ipam/claim.go
+++ b/ipam/claim.go
@@ -3,6 +3,7 @@ package ipam
 import (
 	"fmt"
 
+	"github.com/weaveworks/weave/common"
 	"github.com/weaveworks/weave/ipam/address"
 	"github.com/weaveworks/weave/router"
 )
@@ -14,6 +15,18 @@ type claim struct {
 	hasBeenCancelled func() bool
 }
 
+func (c *claim) sendResult(result error) {
+	// Make sure we only send a result once, since listener stops listening after that
+	if c.resultChan != nil {
+		c.resultChan <- result
+		close(c.resultChan)
+		c.resultChan = nil
+	}
+	if result != nil {
+		common.Error.Println("[allocator] " + result.Error())
+	}
+}
+
 // Try returns true for success (or failure), false if we need to try again later
 func (c *claim) Try(alloc *Allocator) bool {
 	if (c.hasBeenCancelled)() {
@@ -24,7 +37,7 @@ func (c *claim) Try(alloc *Allocator) bool {
 	if !alloc.ring.Contains(c.addr) {
 		// Address not within our universe; assume user knows what they are doing
 		alloc.infof("Ignored address %s claimed by %s - not in our universe\n", c.addr, c.ident)
-		c.resultChan <- nil
+		c.sendResult(nil)
 		return true
 	}
 
@@ -34,6 +47,7 @@ func (c *claim) Try(alloc *Allocator) bool {
 	owner := alloc.ring.Owner(c.addr)
 	if owner == router.UnknownPeerName {
 		alloc.infof("Ring is empty; will try later.\n", c.addr, owner)
+		c.sendResult(nil) // don't make the caller wait
 		return false
 	}
 	if owner != alloc.ourName {
@@ -41,34 +55,34 @@ func (c *claim) Try(alloc *Allocator) bool {
 		if found {
 			name = " (" + name + ")"
 		}
-		c.resultChan <- fmt.Errorf("address %s is owned by other peer %s%s", c.addr.String(), owner, name)
+		c.sendResult(fmt.Errorf("address %s is owned by other peer %s%s", c.addr.String(), owner, name))
 		return true
 	}
 	// We are the owner, check we haven't given it to another container
 	existingIdent := alloc.findOwner(c.addr)
 	if existingIdent == c.ident {
 		// same identifier is claiming same address; that's OK
-		c.resultChan <- nil
+		c.sendResult(nil)
 		return true
 	}
 	if existingIdent == "" {
 		err := alloc.space.Claim(c.addr)
 		if err != nil {
-			c.resultChan <- err
+			c.sendResult(err)
 			return true
 		}
 		alloc.debugln("Claimed", c.addr, "for", c.ident)
 		alloc.addOwned(c.ident, c.addr)
-		c.resultChan <- nil
+		c.sendResult(nil)
 		return true
 	}
 	// Addr already owned by container on this machine
-	c.resultChan <- fmt.Errorf("address %s is already owned by %s", c.addr.String(), existingIdent)
+	c.sendResult(fmt.Errorf("address %s is already owned by %s", c.addr.String(), existingIdent))
 	return true
 }
 
 func (c *claim) Cancel() {
-	c.resultChan <- fmt.Errorf("Operation cancelled.")
+	c.sendResult(fmt.Errorf("Operation cancelled."))
 }
 
 func (c *claim) String() string {