Allow paging of instance status results. Closes #447.

The results of the get_all_instance_status method (DescribeInstanceStatus)
can be paged on the server side.  Previously boto did not provide any way
to access the next_token value or to pass it to subsequent calls to get
the next page of results.  This commit fixes that problem.

Requested-by: Anonymous
Signed-off-by: Mitch Garnaat <mitch@garnaat.com>

boto/ec2/connection.py

@@ -463,29 +463,44 @@ def get_all_instances(self, instance_ids=None, filters=None):
             self.build_filter_params(params, filters)
         return self.get_list('DescribeInstances', params,
                              [('item', Reservation)], verb='POST')
-    def get_all_instance_status(self, instance_ids=None, filters=None):
+
+    def get_all_instance_status(self, instance_ids=None,
+                                max_results=None, next_token=None,
+                                filters=None):
         """
         Retrieve all the instances in your account scheduled for maintenance.
 
         :type instance_ids: list
         :param instance_ids: A list of strings of instance IDs
 
+        :type max_results: int
+        :param max_results: The maximum number of paginated instance
+            items per response.
+
+        :type next_token: str
+        :param next_token: A string specifying the next paginated set
+            of results to return.
+
         :type filters: dict
         :param filters: Optional filters that can be used to limit
-                        the results returned.  Filters are provided
-                        in the form of a dictionary consisting of
-                        filter names as the key and filter values
-                        as the value.  The set of allowable filter
-                        names/values is dependent on the request
-                        being performed.  Check the EC2 API guide
-                        for details.
+            the results returned.  Filters are provided
+            in the form of a dictionary consisting of
+            filter names as the key and filter values
+            as the value.  The set of allowable filter
+            names/values is dependent on the request
+            being performed.  Check the EC2 API guide
+            for details.
 
         :rtype: list
         :return: A list of instances that have maintenance scheduled.
         """
         params = {}
         if instance_ids:
             self.build_list_params(params, instance_ids, 'InstanceId')
+        if max_results:
+            params['MaxResults'] = max_results
+        if next_token:
+            params['NextToken'] = next_token
         if filters:
             self.build_filter_params(params, filters)
         return self.get_object('DescribeInstanceStatus', params,

boto/ec2/instancestatus.py

@@ -115,10 +115,22 @@ def endElement(self, name, value, connection):
             setattr(self, name, value)
 
 class InstanceStatusSet(list):
+    """
+    A list object that contains the results of a call to
+    DescribeInstanceStatus request.  Each element of the
+    list will be an InstanceStatus object.
+
+    :ivar next_token: If the response was truncated by
+        the EC2 service, the next_token attribute of the
+        object will contain the string that needs to be
+        passed in to the next request to retrieve the next
+        set of results.
+    """
 
     def __init__(self, connection=None):
-        self.connection = connection
         list.__init__(self)
+        self.connection = connection
+        self.next_token = None
 
     def startElement(self, name, attrs, connection):
         if name == 'item':
@@ -129,5 +141,7 @@ def startElement(self, name, attrs, connection):
             return None
 
     def endElement(self, name, value, connection):
+        if name == 'NextToken':
+            self.next_token = value
         setattr(self, name, value)