[couchdb] branch optimize-ddoc-cache updated (ee00280 -> bc8ddc1)

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davisp pushed a change to branch optimize-ddoc-cache
in repository https://gitbox.apache.org/repos/asf/couchdb.git.


    omit ee00280  FIXUP: Process processes in the process of dying
     new bc8ddc1  FIXUP: Process processes in the process of dying

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Summary of changes:
 src/ddoc_cache/src/ddoc_cache_entry.erl       |  5 +++-
 src/ddoc_cache/test/ddoc_cache_entry_test.erl | 35 ++++++++++++++-------------
 2 files changed, 22 insertions(+), 18 deletions(-)

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[couchdb] 01/01: FIXUP: Process processes in the process of dying

[da...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

davisp pushed a commit to branch optimize-ddoc-cache
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit bc8ddc1a3c55f8d5ec82b05ba495d60006e7dcb7
Author: Paul J. Davis <pa...@gmail.com>
AuthorDate: Thu Jul 20 14:02:57 2017 -0500

    FIXUP: Process processes in the process of dying
    
    Turns out we could go to evict an entry just after it had decided to
    leave the cache (i.e., its ddoc was just deleted). When that happens
    ddoc_cache_lru would die trying to shut the process down becuase the
    process died normal earlier than expected.
---
 src/ddoc_cache/src/ddoc_cache_entry.erl       | 23 ++++++++++++++++++-----
 src/ddoc_cache/test/ddoc_cache_entry_test.erl | 18 ++++++++++++++++++
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/src/ddoc_cache/src/ddoc_cache_entry.erl b/src/ddoc_cache/src/ddoc_cache_entry.erl
index 63a2efa..ef6868e 100644
--- a/src/ddoc_cache/src/ddoc_cache_entry.erl
+++ b/src/ddoc_cache/src/ddoc_cache_entry.erl
@@ -45,6 +45,9 @@
 -include("ddoc_cache.hrl").
 
 
+-define(ENTRY_SHUTDOWN_TIMEOUT, 5000).
+
+
 -record(st, {
     key,
     val,
@@ -77,7 +80,17 @@ start_link(Key, Default) ->
 
 
 shutdown(Pid) ->
-    ok = gen_server:call(Pid, shutdown).
+    Ref = erlang:monitor(process, Pid),
+    ok = gen_server:cast(Pid, shutdown),
+    receive
+        {'DOWN', Ref, process, Pid, normal} ->
+            ok;
+        {'DOWN', Ref, process, Pid, Reason} ->
+            erlang:exit(Reason)
+    after ?ENTRY_SHUTDOWN_TIMEOUT ->
+        erlang:demonitor(Ref, [flush]),
+        erlang:exit({timeout, {entry_shutdown, Pid}})
+    end.
 
 
 open(Pid, Key) ->
@@ -170,10 +183,6 @@ handle_call(open, From, #st{opener = Pid} = St) when is_pid(Pid) ->
 handle_call(open, _From, St) ->
     {reply, St#st.val, St};
 
-handle_call(shutdown, _From, St) ->
-    remove_from_cache(St),
-    {stop, normal, ok, St};
-
 handle_call(Msg, _From, St) ->
     {stop, {bad_call, Msg}, {bad_call, Msg}, St}.
 
@@ -227,6 +236,10 @@ handle_cast(refresh, #st{opener = Pid} = St) when is_pid(Pid) ->
     },
     {noreply, NewSt};
 
+handle_cast(shutdown, St) ->
+    remove_from_cache(St),
+    {stop, normal, St};
+
 handle_cast(Msg, St) ->
     {stop, {bad_cast, Msg}, St}.
 
diff --git a/src/ddoc_cache/test/ddoc_cache_entry_test.erl b/src/ddoc_cache/test/ddoc_cache_entry_test.erl
index 381185c..49b24a9 100644
--- a/src/ddoc_cache/test/ddoc_cache_entry_test.erl
+++ b/src/ddoc_cache/test/ddoc_cache_entry_test.erl
@@ -137,3 +137,21 @@ handles_bad_messages(_) ->
 handles_code_change(_) ->
     CCExpect = {ok, bar},
     ?assertEqual(CCExpect, ddoc_cache_entry:code_change(foo, bar, baz)).
+
+
+handles_bad_shutdown_test_() ->
+    {timeout, 10, ?_test(begin
+        ErrorPid = spawn(fun() ->
+            receive
+               _ -> exit(bad_shutdown)
+            end
+        end),
+        ?assertExit(bad_shutdown, ddoc_cache_entry:shutdown(ErrorPid)),
+        NotDeadYetPid = spawn(fun() ->
+            timer:sleep(infinity)
+        end),
+        ?assertExit(
+                {timeout, {entry_shutdown, NotDeadYetPid}},
+                ddoc_cache_entry:shutdown(NotDeadYetPid)
+            )
+    end)}.

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