From 257f06a10c291b37dd6dad0678101d93312cab8d Mon Sep 17 00:00:00 2001
From: Igor Serebryany <igor.serebryany@airbedandbreakfast.com>
Date: Wed, 5 Feb 2014 23:44:24 -0800
Subject: [PATCH 1/2] always create sequential nodes

this makes it trivially possible to do leader election in synapse.
---
 lib/nerve/reporter.rb        | 21 ++++++++++++++++-----
 lib/nerve/service_watcher.rb |  4 ++--
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/lib/nerve/reporter.rb b/lib/nerve/reporter.rb
index 6565bc60..222a98c9 100644
--- a/lib/nerve/reporter.rb
+++ b/lib/nerve/reporter.rb
@@ -12,8 +12,11 @@ def initialize(opts)
 
       @path = opts['hosts'].shuffle.join(',') + opts['path']
       @data = parse_data(opts['data'] || '')
+
       @key = opts['key']
       @key.insert(0,'/') unless @key[0] == '/'
+      @key.insert(-1, '_') unless @key[-1] == '_'
+      @full_key = nil
     end
 
     def start()
@@ -43,15 +46,23 @@ def ping?
     private
 
     def zk_delete
-      @zk.delete(@key, :ignore => :no_node)
+      if @full_key
+        @zk.delete(@full_key, :ignore => :no_node)
+        @full_key = nil
+      end
+    end
+
+    def zk_create
+      @full_key = @zk.create(@key, :data => @data, :mode => :ephemeral_sequential)
     end
 
     def zk_save
-      log.debug "nerve: writing data #{@data.class} to zk at #{@key} with #{@data.inspect}"
+      return zk_create unless @full_key
+
       begin
-        @zk.set(@key,@data)
-      rescue ZK::Exceptions::NoNode => e
-        @zk.create(@key,:data => @data, :mode => :ephemeral)
+        @zk.set(@full_key, @data)
+      rescue ZK::Exceptions::NoNode
+        zk_create
       end
     end
 
diff --git a/lib/nerve/service_watcher.rb b/lib/nerve/service_watcher.rb
index db3f779c..e91fb3bd 100644
--- a/lib/nerve/service_watcher.rb
+++ b/lib/nerve/service_watcher.rb
@@ -21,8 +21,8 @@ def initialize(service={})
       @reporter = Reporter.new({
           'hosts' => service['zk_hosts'],
           'path' => service['zk_path'],
-          'key' => "#{service['instance_id']}_#{@name}",
-          'data' => {'host' => service['host'], 'port' => service['port']},
+          'key' => "/#{service['instance_id']}_",
+          'data' => {'host' => service['host'], 'port' => service['port'], 'name' => service['instance_id']},
         })
 
       # instantiate the checks for this service

From d2376ffa29fb190e763f393ae666ffbcdc58ac07 Mon Sep 17 00:00:00 2001
From: Igor Serebryany <igor.serebryany@airbedandbreakfast.com>
Date: Wed, 5 Feb 2014 23:48:45 -0800
Subject: [PATCH 2/2] Revert "begin by reporting the service as down"

This reverts commit 4390e9d6c57f28b28dc7b3fdc7c714553efb1a8f.

Now that we're creating all nodes as sequential nodes, there's no
reason to do this.
---
 lib/nerve/service_watcher.rb | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/nerve/service_watcher.rb b/lib/nerve/service_watcher.rb
index e91fb3bd..1bd8913a 100644
--- a/lib/nerve/service_watcher.rb
+++ b/lib/nerve/service_watcher.rb
@@ -52,9 +52,7 @@ def initialize(service={})
     def run()
       log.info "nerve: starting service watch #{@name}"
 
-      # begin by reporting down
       @reporter.start()
-      @reporter.report_down
       was_up = false
 
       until $EXIT