From 4ddb75549c6565b5a2ca9edec0d965bdf53eed11 Mon Sep 17 00:00:00 2001
From: Paul Joseph Davis <davisp@apache.org>
Date: Thu, 17 Sep 2009 04:04:46 +0000
Subject: Fixes COUCHDB-396

Makes the stats calculated over a moving window isntead of calculated for non-overlapping timeframes. This should make trend monitoring more robust.

Thanks once again to Bob Dionne for double checking this.



git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@816043 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_httpd_stats_handlers.erl | 67 +++++++++++++-----------------
 1 file changed, 30 insertions(+), 37 deletions(-)

(limited to 'src/couchdb/couch_httpd_stats_handlers.erl')

diff --git a/src/couchdb/couch_httpd_stats_handlers.erl b/src/couchdb/couch_httpd_stats_handlers.erl
index 81ff2621..40444bf8 100644
--- a/src/couchdb/couch_httpd_stats_handlers.erl
+++ b/src/couchdb/couch_httpd_stats_handlers.erl
@@ -12,51 +12,44 @@
 
 -module(couch_httpd_stats_handlers).
 -include("couch_db.hrl").
--include("couch_stats.hrl").
 
 -export([handle_stats_req/1]).
--import(couch_httpd,
-    [send_json/2,send_json/3,send_json/4,send_method_not_allowed/2,
-    start_json_response/2,send_chunk/2,end_json_response/1,
-    start_chunked_response/3, send_error/4]).
-
--define(b2a(V), list_to_atom(binary_to_list(V))).
-
--record(stats_query_args, {
-    range='0',
-    flush=false
-}).
+-import(couch_httpd, [
+    send_json/2, send_json/3, send_json/4, send_method_not_allowed/2,
+    start_json_response/2, send_chunk/2, end_json_response/1,
+    start_chunked_response/3, send_error/4
+]).
 
 handle_stats_req(#httpd{method='GET', path_parts=[_]}=Req) ->
-    send_json(Req, couch_stats_aggregator:all());
+    flush(Req),
+    send_json(Req, couch_stats_aggregator:all(range(Req)));
 
-handle_stats_req(#httpd{method='GET', path_parts=[_Stats, Module, Key]}=Req) ->
-    #stats_query_args{
-        range=Range,
-        flush=Flush
-    } = parse_stats_query(Req),
+handle_stats_req(#httpd{method='GET', path_parts=[_, _Mod]}) ->
+    throw({bad_request, <<"Stat names must have exactly to parts.">>});
 
-    case Flush of
-        true ->
-            couch_stats_aggregator:time_passed();
-        _ -> ok
-    end,
+handle_stats_req(#httpd{method='GET', path_parts=[_, Mod, Key]}=Req) ->
+    flush(Req),
+    Stats = couch_stats_aggregator:get_json({?b2a(Mod), ?b2a(Key)}, range(Req)),
+    send_json(Req, {[{Mod, {[{Key, Stats}]}}]});
 
-    Stats = couch_stats_aggregator:get_json({?b2a(Module), ?b2a(Key)}, Range),
-    Response = {[{Module, {[{Key, Stats}]}}]},
-    send_json(Req, Response);
+handle_stats_req(#httpd{method='GET', path_parts=[_, _Mod, _Key | _Extra]}) ->
+    throw({bad_request, <<"Stat names must have exactly two parts.">>});
 
 handle_stats_req(Req) ->
     send_method_not_allowed(Req, "GET").
 
-parse_stats_query(Req) ->
-    lists:foldl(fun({Key,Value}, Args) ->
-        case {Key, Value} of
-        {"range", Range} ->
-            Args#stats_query_args{range=list_to_atom(Range)};
-        {"flush", "true"} ->
-            Args#stats_query_args{flush=true};
-        _Else -> % unknown key value pair, ignore.
-            Args
-        end
-    end, #stats_query_args{}, couch_httpd:qs(Req)).
+range(Req) ->
+    case proplists:get_value("range", couch_httpd:qs(Req)) of
+        undefined ->
+            0;
+        Value ->
+            list_to_integer(Value)
+    end.
+
+flush(Req) ->
+    case proplists:get_value("flush", couch_httpd:qs(Req)) of
+        "true" ->
+            couch_stats_aggregator:collect_sample();
+        _Else ->
+            ok
+    end.
-- 
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