Refactoring of various internal APIs, particularly those dealing with replicating documents with attachments.

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@946803 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 42 insertions, 19 deletions

diff --git a/src/couchdb/couch_work_queue.erl b/src/couchdb/couch_work_queue.erl
index ca9445d3..3581aaf7 100644
--- a/src/couchdb/couch_work_queue.erl
+++ b/src/couchdb/couch_work_queue.erl
@@ -13,11 +13,11 @@
 -module(couch_work_queue).
 -behaviour(gen_server).
 
--export([new/2,queue/2,dequeue/1,close/1]).
+-export([new/2,queue/2,dequeue/1,dequeue/2,close/1]).
 -export([init/1, terminate/2, handle_call/3, handle_cast/2, code_change/3, handle_info/2]).
 
 -record(q, {
-    buffer=[],
+    queue=queue:new(),
     blocked=[],
     max_size,
     max_items,
@@ -34,7 +34,10 @@ queue(Wq, Item) ->
     gen_server:call(Wq, {queue, Item}, infinity).
 
 dequeue(Wq) ->
-    try gen_server:call(Wq, dequeue, infinity)
+    dequeue(Wq, all).
+    
+dequeue(Wq, MaxItems) ->
+    try gen_server:call(Wq, {dequeue, MaxItems}, infinity)
     catch
         _:_ -> closed
     end.
@@ -48,13 +51,13 @@ init({MaxSize,MaxItems}) ->
 
 terminate(_Reason, #q{work_waiter=nil}) ->
     ok;
-terminate(_Reason, #q{work_waiter=WW}) ->
-    gen_server:reply(WW, closed).
+terminate(_Reason, #q{work_waiter={WWFrom, _}}) ->
+    gen_server:reply(WWFrom, closed).
     
 handle_call({queue, Item}, From, #q{work_waiter=nil}=Q0) ->
     Q = Q0#q{size=Q0#q.size + byte_size(term_to_binary(Item)),
                 items=Q0#q.items + 1,
-                buffer=[Item | Q0#q.buffer]},
+                queue=queue:in(Item, Q0#q.queue)},
     case (Q#q.size >= Q#q.max_size) orelse
             (Q#q.items >= Q#q.max_items) of
     true ->
@@ -62,24 +65,44 @@ handle_call({queue, Item}, From, #q{work_waiter=nil}=Q0) ->
     false ->
         {reply, ok, Q}
     end;
-handle_call({queue, Item}, _From, #q{work_waiter=WW}=Q) ->
-    gen_server:reply(WW, {ok, [Item]}),
+handle_call({queue, Item}, _From, #q{work_waiter={WWFrom, _Max}}=Q) ->
+    gen_server:reply(WWFrom, {ok, [Item]}),
     {reply, ok, Q#q{work_waiter=nil}};
-handle_call(dequeue, _From, #q{work_waiter=WW}) when WW /= nil ->
+handle_call({dequeue, _Max}, _From, #q{work_waiter=WW}) when WW /= nil ->
     exit("Only one caller allowed to wait for work at a time");
-handle_call(dequeue, From, #q{items=0}=Q) ->
-    {noreply, Q#q{work_waiter=From}};
-handle_call(dequeue, _From, #q{buffer=Buff, max_size=MaxSize,
-        max_items=MaxItems, close_on_dequeue=Close}=Q) ->
-    [gen_server:reply(From, ok) || From <- Q#q.blocked],
-    Q2 = #q{max_size=MaxSize, max_items=MaxItems},
-    if Close ->
-        {stop, normal, {ok, Buff}, Q2};
+handle_call({dequeue, Max}, From, #q{items=0}=Q) ->
+    {noreply, Q#q{work_waiter={From, Max}}};
+handle_call({dequeue, Max}, _From, #q{queue=Queue, max_size=MaxSize,
+        max_items=MaxItems, items=Items,close_on_dequeue=Close}=Q) ->
+    if Max >= Items orelse Max == all ->
+        [gen_server:reply(From, ok) || From <- Q#q.blocked],
+        Q2 = #q{max_size=MaxSize, max_items=MaxItems},
+        if Close ->
+            {stop, normal, {ok, queue:to_list(Queue)}, Q2};
+        true ->
+            {reply, {ok, queue:to_list(Queue)}, Q2}
+        end;
     true ->
-        {reply, {ok, Buff}, #q{max_size=MaxSize, max_items=MaxItems}}
+        {DequeuedItems, Queue2, Blocked2} = 
+                dequeue_items(Max, Queue, Q#q.blocked, []),
+        {reply, {ok, DequeuedItems},
+                Q#q{items=Items-Max,blocked=Blocked2,queue=Queue2}}
     end.
 
-handle_cast(close, #q{buffer=[]}=Q) ->
+dequeue_items(0, Queue, Blocked, DequeuedAcc) ->
+    {lists:reverse(DequeuedAcc), Queue, Blocked};
+dequeue_items(NumItems, Queue, Blocked, DequeuedAcc) ->
+    {{value, Item}, Queue2} = queue:out(Queue),
+    case Blocked of
+    [] ->
+        Blocked2 = Blocked;
+    [From|Blocked2] ->
+        gen_server:reply(From, ok)
+    end,
+    dequeue_items(NumItems-1, Queue2, Blocked2, [Item | DequeuedAcc]).
+    
+
+handle_cast(close, #q{items=0}=Q) ->
     {stop, normal, Q};
 handle_cast(close, Q) ->
     {noreply, Q#q{close_on_dequeue=true}}.