diff --git a/lib/ruote/redis/storage.rb b/lib/ruote/redis/storage.rb
index 1cfaa70..10f84cd 100644
--- a/lib/ruote/redis/storage.rb
+++ b/lib/ruote/redis/storage.rb
@@ -128,85 +128,108 @@ def put(doc, opts={})
 
       # regular put
 
-      rev = doc['_rev'].to_i
       key = key_for(doc)
-
-      current_rev = @redis.get(key).to_i
-
-      return true if current_rev == 0 && rev > 0
-      return do_get(doc, current_rev) if rev != current_rev
-
-      nrev = @redis.incr(key).to_i
-
-      # the setnx here is crucial in multiple workers env...
-
-      r = @redis.setnx(
-        key_rev_for(doc, nrev),
-        to_json(doc.merge('_rev' => nrev), opts))
-
-      return get(doc['type'], doc['_id']) if r == false
-
-      @redis.set(key, nrev)
-      @redis.del(key_rev_for(doc, rev)) if rev > 0
-
-      doc['_rev'] = nrev if opts[:update_rev]
-
-      nil
+      rev = doc['_rev']
+
+      lock(key) do
+
+        current_doc = do_get(key)
+        current_rev = current_doc ? current_doc['_rev'] : nil
+
+        if current_rev && rev != current_rev
+          #
+          # version in storage is newer than version being put,
+          # (eturn version in storage)
+          #
+          current_doc
+
+        elsif rev && current_rev.nil?
+          #
+          # document deleted, put fails (return true)
+          #
+          true
+
+        else
+          #
+          # put is successful (return nil)
+          #
+          nrev = (rev.to_i + 1).to_s
+          @redis.set(key, to_json(doc.merge('_rev' => nrev)))
+          doc['_rev'] = nrev if opts[:update_rev]
+
+          nil
+        end
+      end
     end
 
     def get(type, key)
 
-      return from_json(@redis.get(key_for(type, key))) if MAS.include?(type)
-        # 'copy' case
-
-      do_get(type, key, @redis.get(key_for(type, key)))
+      do_get(key_for(type, key))
     end
 
     def delete(doc)
 
-      raise ArgumentError.new(
-        "can't delete doc without _rev") unless doc['_rev']
+      rev = doc['_rev']
 
-      r = put(doc, :delete => true)
+      raise ArgumentError.new("can't delete doc without _rev") unless rev
 
-      return r if r != nil
+      key = key_for(doc)
 
-      @redis.keys_to_a("#{key_for(doc)}*").sort.each { |k|
-        Thread.pass # lingering a bit...
-        @redis.del(k)
-      }
-        # deleting the key_rev last and making 1 'keys' call preliminarily
+      lock(key) do
 
-      nil
+        current_doc = do_get(key)
+
+        if current_doc.nil?
+          #
+          # document is [already] gone, delete fails (return true)
+          #
+          true
+
+        elsif current_doc['_rev'] != rev
+          #
+          # version in storage doesn't match version to delete
+          # (return version in storage)
+          #
+          current_doc
+
+        else
+          #
+          # delete is successful (return nil)
+          #
+          @redis.del(key)
+
+          nil
+        end
+      end
     end
 
     def get_many(type, key=nil, opts={})
 
       keys = key ? Array(key) : nil
 
-      ids = if type == 'msgs' || type == 'schedules'
-
-        @redis.keys_to_a("#{type}/*")
+      #ids = if type == 'msgs' || type == 'schedules'
+      #  @redis.keys_to_a("#{type}/*")
 
-      elsif keys == nil
+      ids = if keys == nil
 
-        @redis.keys_to_a("#{type}/*/*")
+        @redis.keys_to_a("#{type}/*")
 
       elsif keys.first.is_a?(String)
 
-        keys.collect { |k| @redis.keys_to_a("#{type}/*!#{k}/*") }.flatten
+        keys.collect { |k| @redis.keys_to_a("#{type}/*!#{k}") }.flatten
 
       else #if keys.first.is_a?(Regexp)
 
-        @redis.keys_to_a("#{type}/*/*").select { |i|
+        @redis.keys_to_a("#{type}/*").select { |i|
 
-          i = i[type.length + 1..i.rindex('/') - 1]
-            # removing "^type/" and "/\d+$"
+          i = i[type.length + 1..-1]
+            # removing "^type/"
 
           keys.find { |k| k.match(i) }
         }
       end
 
+      ids = ids.reject { |i| i.match(LOCK_KEY) }
       ids = ids.sort
       ids = ids.reverse if opts[:descending]
 
@@ -228,13 +251,10 @@ def get_many(type, key=nil, opts={})
 
     def ids(type)
 
-      @redis.keys_to_a("#{type}/*").inject([]) { |a, k|
-
-        if m = k.match(/^[^\/]+\/([^\/]+)$/)
-          a << m[1]
-        end
-
-        a
+      @redis.keys_to_a("#{type}/*").reject { |i|
+        i.match(LOCK_KEY)
+      }.collect { |i|
+        i.split('/').last
       }.sort
     end
 
@@ -271,38 +291,51 @@ def purge_type!(type)
 
     protected
 
-    #   key_for(doc)
-    #   key_for(type, key)
-    #
-    def key_for(*args)
+    LOCK_KEY = /-lock$/
 
-      a = args.first
+    def lock(key, &block)
 
-     (a.is_a?(Hash) ? [ a['type'], a['_id'] ] : args[0, 2]).join('/')
+      kl = "#{key}-lock"
+
+      #p [ kl, :locking, Thread.current.object_id, Time.now.to_f ]
+
+      #while @redis.setnx(kl, 'null') == false; sleep(0.007); end
+      loop do
+        r = @redis.setnx(kl, Time.now.to_f.to_s)
+        #p [ :setnx, r ]
+        if r == false
+          sleep 0.007
+        else
+          break
+        end
+      end
+
+      #p [ kl, :locked, Thread.current.object_id, Time.now.to_f ]
+
+      #@redis.expire(kl, 2)
+
+      result = block.call
+
+      @redis.del(kl)
+
+      #p [ kl, :unlocked, Thread.current.object_id, Time.now.to_f ]
+
+      result
     end
 
-    #   key_rev_for(doc)
-    #   key_rev_for(doc, rev)
-    #   key_rev_for(type, key, rev)
+    #   key_for(doc)
+    #   key_for(type, key)
     #
-    def key_rev_for(*args)
+    def key_for(*args)
 
-      as = nil
       a = args.first
 
-      if a.is_a?(Hash)
-        as = [ a['type'], a['_id'], a['_rev'] ] if a.is_a?(Hash)
-        as[2] = args[1] if args[1]
-      else
-        as = args[0, 3]
-      end
-
-      as.join('/')
+     (a.is_a?(Hash) ? [ a['type'], a['_id'] ] : args[0, 2]).join('/')
     end
 
-    def do_get(*args)
+    def do_get(key)
 
-      from_json(@redis.get(key_rev_for(*args)))
+      from_json(@redis.get(key))
     end
 
     def from_json(s)
@@ -318,7 +351,7 @@ def to_json(doc, opts={})
 
     # Don't put configuration if it's already in
     #
-    #(avoid storages from trashing configuration...)
+    # (prevent storages from trashing configuration...)
     #
     def put_configuration