From cc068dee6d8b8762b5e8f10df6244313feb47633 Mon Sep 17 00:00:00 2001
From: Simon MacMullen <simon@rabbitmq.com>
Date: Wed, 26 Nov 2014 15:47:22 +0000
Subject: Create a way to mutate pids and use that rather than creating "fake"
 pids.

---
 Makefile                      |  2 +-
 src/rabbit_misc.erl           | 31 ++++++++++++++++++++++---------
 src/rabbit_mnesia_offline.erl |  2 +-
 3 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/Makefile b/Makefile
index c955a8fc..51db8d4c 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ TMPDIR ?= /tmp
 
 RABBITMQ_NODENAME ?= rabbit
 RABBITMQ_SERVER_START_ARGS ?=
-RABBITMQ_MNESIA_DIR ?= $(TMPDIR)/rabbitmq-$(RABBITMQ_NODENAME)-mnesia
+RABBITMQ_MNESIA_DIR ?= $(TMPDIR)/rabbitmq-mnesia
 RABBITMQ_PLUGINS_EXPAND_DIR ?= $(TMPDIR)/rabbitmq-$(RABBITMQ_NODENAME)-plugins-scratch
 RABBITMQ_LOG_BASE ?= $(TMPDIR)
 
diff --git a/src/rabbit_misc.erl b/src/rabbit_misc.erl
index 3e2c88ee..20d7051c 100644
--- a/src/rabbit_misc.erl
+++ b/src/rabbit_misc.erl
@@ -44,7 +44,8 @@
 -export([format/2, format_many/1, format_stderr/2]).
 -export([unfold/2, ceil/1, queue_fold/3]).
 -export([sort_field_table/1]).
--export([pid_to_string/1, string_to_pid/1, node_to_fake_pid/1]).
+-export([pid_to_string/1, string_to_pid/1,
+         pid_change_node/2, node_to_fake_pid/1]).
 -export([version_compare/2, version_compare/3]).
 -export([version_minor_equivalent/2]).
 -export([dict_cons/3, orddict_cons/3, gb_trees_cons/3]).
@@ -196,6 +197,7 @@
         (rabbit_framing:amqp_table()) -> rabbit_framing:amqp_table()).
 -spec(pid_to_string/1 :: (pid()) -> string()).
 -spec(string_to_pid/1 :: (string()) -> pid()).
+-spec(pid_change_node/2 :: (pid(), node()) -> pid()).
 -spec(node_to_fake_pid/1 :: (atom()) -> pid()).
 -spec(version_compare/2 :: (string(), string()) -> 'lt' | 'eq' | 'gt').
 -spec(version_compare/3 ::
@@ -686,11 +688,7 @@ sort_field_table(Arguments) ->
 %% regardless of what node we are running on. The representation also
 %% permits easy identification of the pid's node.
 pid_to_string(Pid) when is_pid(Pid) ->
-    %% see http://erlang.org/doc/apps/erts/erl_ext_dist.html (8.10 and
-    %% 8.7)
-    <<131,103,100,NodeLen:16,NodeBin:NodeLen/binary,Id:32,Ser:32,Cre:8>>
-        = term_to_binary(Pid),
-    Node = binary_to_term(<<131,100,NodeLen:16,NodeBin:NodeLen/binary>>),
+    {Node, Cre, Id, Ser} = decompose_pid(Pid),
     format("<~s.~B.~B.~B>", [Node, Cre, Id, Ser]).
 
 %% inverse of above
@@ -701,17 +699,32 @@ string_to_pid(Str) ->
     case re:run(Str, "^<(.*)\\.(\\d+)\\.(\\d+)\\.(\\d+)>\$",
                 [{capture,all_but_first,list}]) of
         {match, [NodeStr, CreStr, IdStr, SerStr]} ->
-            <<131,NodeEnc/binary>> = term_to_binary(list_to_atom(NodeStr)),
             [Cre, Id, Ser] = lists:map(fun list_to_integer/1,
                                        [CreStr, IdStr, SerStr]),
-            binary_to_term(<<131,103,NodeEnc/binary,Id:32,Ser:32,Cre:8>>);
+            compose_pid(list_to_atom(NodeStr), Cre, Id, Ser);
         nomatch ->
             throw(Err)
     end.
 
+pid_change_node(Pid, NewNode) ->
+    {_OldNode, Cre, Id, Ser} = decompose_pid(Pid),
+    compose_pid(NewNode, Cre, Id, Ser).
+
 %% node(node_to_fake_pid(Node)) =:= Node.
 node_to_fake_pid(Node) ->
-    string_to_pid(format("<~s.0.0.0>", [Node])).
+    compose_pid(Node, 0, 0, 0).
+
+decompose_pid(Pid) when is_pid(Pid) ->
+    %% see http://erlang.org/doc/apps/erts/erl_ext_dist.html (8.10 and
+    %% 8.7)
+    <<131,103,100,NodeLen:16,NodeBin:NodeLen/binary,Id:32,Ser:32,Cre:8>>
+        = term_to_binary(Pid),
+    Node = binary_to_term(<<131,100,NodeLen:16,NodeBin:NodeLen/binary>>),
+    {Node, Cre, Id, Ser}.
+
+compose_pid(Node, Cre, Id, Ser) ->
+    <<131,NodeEnc/binary>> = term_to_binary(Node),
+    binary_to_term(<<131,103,NodeEnc/binary,Id:32,Ser:32,Cre:8>>).
 
 version_compare(A, B, lte) ->
     case version_compare(A, B) of
diff --git a/src/rabbit_mnesia_offline.erl b/src/rabbit_mnesia_offline.erl
index a8608dfa..24f7709d 100644
--- a/src/rabbit_mnesia_offline.erl
+++ b/src/rabbit_mnesia_offline.erl
@@ -124,6 +124,6 @@ update_term(N1, N2, T) when is_tuple(T) ->
 update_term(N1, N2, N1) ->
     N2;
 update_term(N1, N2, Pid) when is_pid(Pid), node(Pid) == N1 ->
-    rabbit_misc:node_to_fake_pid(N2);
+    rabbit_misc:pid_change_node(Pid, N2);
 update_term(_N1, _N2, Term) ->
     Term.
-- 
cgit v1.2.1