#
#
# add_dir "tests/netsync_dry_run"
# 
# add_file "tests/netsync_dry_run/__driver__.lua"
#  content [9a6da1188ff30933c6e060c0a6fe54cd2dc9ceee]
# 
# patch "cmd_netsync.cc"
#  from [f3cf1b10c6d49b1438d459f4f35eea59b57de5c2]
#    to [321f76a5fd979cc6ad642f745d5333437c6abdd0]
# 
# patch "network/netsync_session.cc"
#  from [1ebe5e1a734cd672fdeb29705edefe6f85a2c125]
#    to [278f41d23b866913c926d4a6be2b84a3f9df681b]
# 
# patch "network/netsync_session.hh"
#  from [227867a6d5efdac111d46e129c660fba1c327b4f]
#    to [b21b6f99547c74e3f02f55fa2ae144b832028fc0]
# 
# patch "refiner.cc"
#  from [e631259ef17957cc2e44d7b9b956db657b93bcf5]
#    to [2de8131df2595d5bcff5efe133ca1f768006d38f]
# 
# patch "refiner.hh"
#  from [76a2230251b87e779d7a938ae9e6982fe69ab105]
#    to [543f5789aa9f74593f909e4b80cea986639228b4]
# 
# patch "tests/common/netsync.lua"
#  from [2a0b34f969dc8806e497e2ec53231dfe84111e6d]
#    to [5b18be9929d1d852a5f931fd9756dd30c197c9c6]
#
============================================================
--- refiner.cc	e631259ef17957cc2e44d7b9b956db657b93bcf5
+++ refiner.cc	2de8131df2595d5bcff5efe133ca1f768006d38f
@@ -157,7 +157,9 @@ refiner::refiner(netcmd_item_type type, 
     queries_in_flight(0),
     calculated_items_to_send(false),
     done(false),
-    items_to_receive(0)
+    items_to_receive(0),
+    min_items_to_receive(0),
+    may_receive_more_than_min(false)
 {
   merkle_ptr root = merkle_ptr(new merkle_node());
   root->type = type;
@@ -282,6 +284,33 @@ refiner::process_refinement_command(refi
       if (their_node.get_slot_state(slot) == leaf_state)
         note_item_in_peer(their_node, slot);
 
+      // esimate how many items to receive
+      if (their_node.get_slot_state(slot) != empty_state
+          && our_node->get_slot_state(slot) != subtree_state)
+        {
+          if (our_node->get_slot_state(slot) == empty_state)
+            {
+              if (their_node.get_slot_state(slot) == leaf_state)
+                ++min_items_to_receive;
+              else
+                {
+                  min_items_to_receive += 2;
+                  may_receive_more_than_min = true;
+                }
+            }
+          else if (their_node.get_slot_state(slot) == leaf_state)
+            {
+              // pair of leaves
+              id our_slotval, their_slotval;
+              their_node.get_raw_slot(slot, their_slotval);
+              our_node->get_raw_slot(slot, our_slotval);
+              if (our_slotval != their_slotval)
+                ++min_items_to_receive;
+            }
+          // else they have a tree and we have a leaf, in which
+          // case there will be more queries
+        }
+
       if (ty == refinement_query)
         {
           // This block handles the interesting asymmetric cases of subtree
============================================================
--- refiner.hh	76a2230251b87e779d7a938ae9e6982fe69ab105
+++ refiner.hh	543f5789aa9f74593f909e4b80cea986639228b4
@@ -93,6 +93,10 @@ public:
   bool done;
   std::set<id> items_to_send;
   size_t items_to_receive;
+
+  // Estimate of what items_to_receive will be.
+  size_t min_items_to_receive;
+  bool may_receive_more_than_min;
 };
 
 
============================================================
--- cmd_netsync.cc	f3cf1b10c6d49b1438d459f4f35eea59b57de5c2
+++ cmd_netsync.cc	321f76a5fd979cc6ad642f745d5333437c6abdd0
@@ -279,7 +279,7 @@ CMD(push, "push", "", CMD_REF(network),
        "to the netsync server at the address ADDRESS."),
     options::opts::max_netsync_version | options::opts::min_netsync_version |
     options::opts::set_default | options::opts::exclude |
-    options::opts::keys_to_push)
+    options::opts::keys_to_push | options::opts::dryrun)
 {
   database db(app);
   key_store keys(app);
@@ -296,10 +296,10 @@ CMD_AUTOMATE(push, N_("[URL]\n[ADDRESS[:
 CMD_AUTOMATE(push, N_("[URL]\n[ADDRESS[:PORTNUMBER] [PATTERN ...]]"),
              N_("Pushes branches to a netsync server"),
              "",
-              options::opts::max_netsync_version |
-              options::opts::min_netsync_version |
-              options::opts::set_default | options::opts::exclude |
-              options::opts::keys_to_push)
+             options::opts::max_netsync_version |
+             options::opts::min_netsync_version |
+             options::opts::set_default | options::opts::exclude |
+             options::opts::keys_to_push | options::opts::dryrun)
 {
   database db(app);
   key_store keys(app);
@@ -320,7 +320,7 @@ CMD(pull, "pull", "", CMD_REF(network),
        "from the netsync server at the address ADDRESS."),
     options::opts::max_netsync_version | options::opts::min_netsync_version |
     options::opts::set_default | options::opts::exclude |
-    options::opts::auto_update)
+    options::opts::auto_update | options::opts::dryrun)
 {
   database db(app);
   key_store keys(app);
@@ -346,7 +346,8 @@ CMD_AUTOMATE(pull, N_("[URL]\n[ADDRESS[:
              "",
              options::opts::max_netsync_version |
              options::opts::min_netsync_version |
-             options::opts::set_default | options::opts::exclude)
+             options::opts::set_default | options::opts::exclude |
+             options::opts::dryrun)
 {
   database db(app);
   key_store keys(app);
@@ -367,7 +368,8 @@ CMD(sync, "sync", "", CMD_REF(network),
        "with the netsync server at the address ADDRESS."),
     options::opts::max_netsync_version | options::opts::min_netsync_version |
     options::opts::set_default | options::opts::exclude |
-    options::opts::keys_to_push | options::opts::auto_update)
+    options::opts::keys_to_push | options::opts::auto_update |
+    options::opts::dryrun)
 {
   database db(app);
   key_store keys(app);
@@ -397,7 +399,7 @@ CMD_AUTOMATE(sync, N_("[URL]\n[ADDRESS[:
              "",
              options::opts::max_netsync_version | options::opts::min_netsync_version |
              options::opts::set_default | options::opts::exclude |
-             options::opts::keys_to_push)
+             options::opts::keys_to_push | options::opts::dryrun)
 {
   database db(app);
   key_store keys(app);
============================================================
--- tests/common/netsync.lua	2a0b34f969dc8806e497e2ec53231dfe84111e6d
+++ tests/common/netsync.lua	5b18be9929d1d852a5f931fd9756dd30c197c9c6
@@ -28,29 +28,38 @@ end
   check(getstd("common/netsync-hooks_with_notes.lua", "netsync.lua"))
 end
 
-function netsync.internal.client(srv, oper, pat, n, res)
-  if n == nil then n = 2 end
-  if n == 1 then
-  args = {"--rcfile=netsync.lua", "--keydir=keys",
-          "--db=test.db", oper, srv.address}
-  else
-  args = {"--rcfile=netsync.lua", "--keydir=keys"..n,
-          "--db=test"..n..".db", oper, srv.address}
-  end
-  if type(pat) == "string" then
-    table.insert(args, pat)
-  elseif type(pat) == "table" then
-    for k, v in pairs(pat) do
-      table.insert(args, v)
-    end
-  elseif pat ~= nil then
-    err("Bad pattern type "..type(pat))
-  end
-  check(mtn(unpack(args)), res, false, false)
+function netsync.internal.client(srv, oper, pat, n, res, save_output)
+   if n == nil then n = 2 end
+   if n == 1 then
+      args = {"--rcfile=netsync.lua", "--keydir=keys",
+	      "--db=test.db", oper, srv.address}
+   else
+      args = {"--rcfile=netsync.lua", "--keydir=keys"..n,
+	      "--db=test"..n..".db", oper, srv.address}
+   end
+   if type(pat) == "string" then
+      table.insert(args, pat)
+   elseif type(pat) == "table" then
+      for k, v in pairs(pat) do
+	 table.insert(args, v)
+      end
+   elseif pat ~= nil then
+      err("Bad pattern type "..type(pat))
+   end
+   if save_output == nil then
+      save_output = false
+   end
+   check(mtn(unpack(args)), res, save_output, save_output)
 end
-function netsync.internal.pull(srv, pat, n, res) srv:client("pull", pat, n, res) end
-function netsync.internal.push(srv, pat, n, res) srv:client("push", pat, n, res) end
-function netsync.internal.sync(srv, pat, n, res) srv:client("sync", pat, n, res) end
+function netsync.internal.pull(srv, pat, n, res, save_output)
+   srv:client("pull", pat, n, res, save_output)
+end
+function netsync.internal.push(srv, pat, n, res, save_output)
+   srv:client("push", pat, n, res, save_output)
+end
+function netsync.internal.sync(srv, pat, n, res, save_output)
+   srv:client("sync", pat, n, res, save_output)
+end
 
 function netsync.start(opts, n, min)
   if type(opts) == "number" then
============================================================
--- network/netsync_session.cc	1ebe5e1a734cd672fdeb29705edefe6f85a2c125
+++ network/netsync_session.cc	278f41d23b866913c926d4a6be2b84a3f9df681b
@@ -99,6 +99,8 @@ netsync_session::netsync_session(session
   key_refiner(key_item, get_voice(), *this),
   cert_refiner(cert_item, get_voice(), *this),
   rev_refiner(revision_item, get_voice(), *this),
+  is_dry_run(opts.dryrun),
+  dry_run_keys_refined(false),
   rev_enumerator(project, *this),
   initiated_by_server(initiated_by_server)
 {
@@ -435,8 +437,68 @@ bool
 }
 
 bool
+netsync_session::dry_run_finished() const
+{
+  bool all = rev_refiner.done
+    && cert_refiner.done
+    && dry_run_keys_refined;
+
+  if (all)
+    {
+      if (role != source_role)
+        {
+          if (key_refiner.may_receive_more_than_min)
+            {
+              P(F("would receive %d revisions, %d certs, and at least %d keys")
+                % rev_refiner.items_to_receive
+                % cert_refiner.items_to_receive
+                % key_refiner.min_items_to_receive);
+            }
+          else
+            {
+              P(F("would receive %d revisions, %d certs, and %d keys")
+                % rev_refiner.items_to_receive
+                % cert_refiner.items_to_receive
+                % key_refiner.min_items_to_receive);
+            }
+        }
+      if (role != sink_role)
+        {
+          P(F("would send %d certs and %d keys")
+            % cert_refiner.items_to_send.size()
+            % key_refiner.items_to_send.size());
+          P(F("would send %d revisions:")
+            % rev_refiner.items_to_send.size());
+          map<branch_name, int> branch_counts;
+          for (set<id>::const_iterator i = rev_refiner.items_to_send.begin();
+               i != rev_refiner.items_to_send.end(); ++i)
+            {
+              revision_id const rid(*i);
+              set<branch_name> my_branches;
+              project.get_revision_branches(rid, my_branches);
+              for(set<branch_name>::iterator b = my_branches.begin();
+                  b != my_branches.end(); ++b)
+                {
+                  ++branch_counts[*b];
+                }
+            }
+          for (map<branch_name, int>::iterator i = branch_counts.begin();
+               i != branch_counts.end(); ++i)
+            {
+              P(F("%9d in branch %s") % i->second % i->first);
+            }
+        }
+    }
+
+  return all;
+}
+
+bool
 netsync_session::finished_working() const
 {
+  if (dry_run_finished())
+    return true;
+
   bool all = done_all_refinements()
     && received_all_items()
     && queued_all_items()
@@ -607,6 +669,11 @@ netsync_session::queue_done_cmd(netcmd_i
 {
   string typestr;
   netcmd_item_type_to_string(type, typestr);
+  if (is_dry_run && type == key_item)
+    {
+      dry_run_keys_refined = true;
+      return;
+    }
   L(FL("queueing 'done' command for %s (%d items)")
     % typestr % n_items);
   netcmd cmd(get_version());
============================================================
--- network/netsync_session.hh	227867a6d5efdac111d46e129c660fba1c327b4f
+++ network/netsync_session.hh	b21b6f99547c74e3f02f55fa2ae144b832028fc0
@@ -72,6 +72,11 @@ netsync_session:
   refiner cert_refiner;
   refiner rev_refiner;
 
+  // dry-run info
+  bool is_dry_run;
+  bool dry_run_keys_refined;
+  bool dry_run_finished() const;
+
   // Interface to ancestry grovelling.
   revision_enumerator rev_enumerator;
 
============================================================
--- /dev/null	
+++ tests/netsync_dry_run/__driver__.lua	9a6da1188ff30933c6e060c0a6fe54cd2dc9ceee
@@ -0,0 +1,51 @@
+include("common/netsync.lua")
+mtn_setup()
+netsync.setup()
+
+
+addfile("foo", "bar")
+commit("testbranch")
+baserev = base_revision()
+
+addfile("aaa", "aaa")
+commit("firstbranch")
+check(mtn("up", "-r", baserev), 0, false, false)
+
+addfile("bbb", "bbb")
+commit("secondbranch")
+
+
+srv1 = netsync.start()
+
+srv1:pull({"--dry-run", "*"}, 2, 0, true)
+check(qgrep("receive 3 revisions, 12 certs, and 1 keys", "stderr"))
+check(not qgrep("send", "stderr"))
+
+srv1:pull("{testbranch,firstbranch}", 2)
+srv1:pull("{testbranch,secondbranch}", 3)
+
+
+srv2 = netsync.start(2)
+
+srv2:pull({"--dry-run", "*"}, 3, 0, true)
+check(qgrep("receive 1 revisions, 4 certs, and 0 keys", "stderr"))
+check(not qgrep("send", "stderr"))
+
+srv2:push({"--dry-run", "*"}, 3, 0, true)
+check(qgrep("send 4 certs and 0 keys", "stderr"))
+check(qgrep("send 1 revision", "stderr"))
+check(qgrep("1 in branch secondbranch", "stderr"))
+check(not qgrep("receive", "stderr"))
+
+srv2:sync({"--dry-run", "*"}, 3, 0, true)
+check(qgrep("receive 1 revisions, 4 certs, and 0 keys", "stderr"))
+check(qgrep("send 4 certs and 0 keys", "stderr"))
+check(qgrep("send 1 revision", "stderr"))
+check(qgrep("1 in branch secondbranch", "stderr"))
+
+srv2:sync({"*"}, 3, 0, true)
+srv2:sync({"--dry-run", "*"}, 3, 0, true)
+check(qgrep("receive 0 revisions, 0 certs, and 0 keys", "stderr"))
+check(qgrep("send 0 certs and 0 keys", "stderr"))
+check(qgrep("send 0 revision", "stderr"))
+check(not qgrep("in branch", "stderr"))
\ No newline at end of file