reconstructor: restrict max objects per revert job

Previously the ssync Sender would attempt to revert all objects in a
partition within a single SSYNC request. With this change the
reconstructor daemon option max_objects_per_revert can be used to limit
the number of objects reverted inside a single SSYNC request for revert
type jobs i.e. when reverting handoff partitions.

If more than max_objects_per_revert are available, the remaining objects
will remain in the sender partition and will not be reverted until the
next call to ssync.Sender, which would currrently be the next time the
reconstructor visits that handoff partition.

Note that the option only applies to handoff revert jobs, not to sync
jobs.

Change-Id: If81760c80a4692212e3774e73af5ce37c02e8aff

1 files changed, 57 insertions, 0 deletions

diff --git a/doc/source/config/object_server_config.rst b/doc/source/config/object_server_config.rst
index 8dc5e3127..7f5c4737e 100644
--- a/doc/source/config/object_server_config.rst
+++ b/doc/source/config/object_server_config.rst
@@ -466,6 +466,63 @@ handoffs_only                false                     The handoffs_only mode op
                                                        temporary use and should be disabled
                                                        as soon as the emergency situation
                                                        has been resolved.
+rebuild_handoff_node_count   2                         The default strategy for unmounted
+                                                       drives will stage
+                                                       rebuilt data on a
+                                                       handoff node until
+                                                       updated rings are
+                                                       deployed.  Because
+                                                       fragments are rebuilt on
+                                                       offset handoffs based on
+                                                       fragment index and the
+                                                       proxy limits how deep it
+                                                       will search for EC frags
+                                                       we restrict how many
+                                                       nodes we'll try.
+                                                       Setting to 0 will
+                                                       disable rebuilds to
+                                                       handoffs and only
+                                                       rebuild fragments for
+                                                       unmounted devices to
+                                                       mounted primaries after
+                                                       a ring change. Setting
+                                                       to -1 means "no limit".
+max_objects_per_revert       0                         By default the reconstructor
+                                                       attempts to revert all
+                                                       objects from handoff
+                                                       partitions in a single
+                                                       batch using a single
+                                                       SSYNC request. In
+                                                       exceptional
+                                                       circumstances
+                                                       max_objects_per_revert
+                                                       can be used to
+                                                       temporarily limit the
+                                                       number of objects
+                                                       reverted by each
+                                                       reconstructor revert
+                                                       type job. If more than
+                                                       max_objects_per_revert
+                                                       are available in a
+                                                       sender's handoff
+                                                       partition, the remaining
+                                                       objects will remain in
+                                                       the handoff partition
+                                                       and will not be reverted
+                                                       until the next time the
+                                                       reconstructor visits
+                                                       that handoff partition
+                                                       i.e. with this option
+                                                       set, a single cycle of
+                                                       the reconstructor may
+                                                       not completely revert
+                                                       all handoff partitions.
+                                                       The option has no effect
+                                                       on reconstructor sync
+                                                       type jobs between
+                                                       primary partitions. A
+                                                       value of 0 (the default)
+                                                       means there is no limit.
 node_timeout                 DEFAULT or 10             Request timeout to external
                                                        services. The value used is the value
                                                        set in this section, or the value set