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-rw-r--r--apps/mem3/src/mem3.erl103
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+-module(mem3).
+
+-export([start/0, stop/0, restart/0, nodes/0, shards/1, shards/2,
+ choose_shards/2]).
+-export([compare_nodelists/0, compare_shards/1]).
+
+-include("mem3.hrl").
+
+start() ->
+ application:start(mem3).
+
+stop() ->
+ application:stop(mem3).
+
+restart() ->
+ stop(),
+ start().
+
+%% @doc Detailed report of cluster-wide membership state. Queries the state
+%% on all member nodes and builds a dictionary with unique states as the
+%% key and the nodes holding that state as the value. Also reports member
+%% nodes which fail to respond and nodes which are connected but are not
+%% cluster members. Useful for debugging.
+-spec compare_nodelists() -> [{{cluster_nodes, [node()]} | bad_nodes
+ | non_member_nodes, [node()]}].
+compare_nodelists() ->
+ Nodes = mem3:nodes(),
+ AllNodes = erlang:nodes([this, visible]),
+ {Replies, BadNodes} = gen_server:multi_call(Nodes, mem3_nodes, get_nodelist),
+ Dict = lists:foldl(fun({Node, Nodelist}, D) ->
+ orddict:append({cluster_nodes, Nodelist}, Node, D)
+ end, orddict:new(), Replies),
+ [{non_member_nodes, AllNodes -- Nodes}, {bad_nodes, BadNodes} | Dict].
+
+-spec compare_shards(DbName::iodata()) -> [{bad_nodes | [#shard{}], [node()]}].
+compare_shards(DbName) when is_list(DbName) ->
+ compare_shards(list_to_binary(DbName));
+compare_shards(DbName) ->
+ Nodes = mem3:nodes(),
+ {Replies, BadNodes} = rpc:multicall(mem3, shards, [DbName]),
+ GoodNodes = [N || N <- Nodes, not lists:member(N, BadNodes)],
+ Dict = lists:foldl(fun({Shards, Node}, D) ->
+ orddict:append(Shards, Node, D)
+ end, orddict:new(), lists:zip(Replies, GoodNodes)),
+ [{bad_nodes, BadNodes} | Dict].
+
+-spec nodes() -> [node()].
+nodes() ->
+ mem3_nodes:get_nodelist().
+
+-spec shards(DbName::iodata()) -> [#shard{}].
+shards(DbName) when is_list(DbName) ->
+ shards(list_to_binary(DbName));
+shards(DbName) ->
+ try ets:lookup(partitions, DbName) of
+ [] ->
+ mem3_util:load_shards_from_disk(DbName);
+ Else ->
+ Else
+ catch error:badarg ->
+ mem3_util:load_shards_from_disk(DbName)
+ end.
+
+-spec shards(DbName::iodata(), DocId::binary()) -> [#shard{}].
+shards(DbName, DocId) when is_list(DbName) ->
+ shards(list_to_binary(DbName), DocId);
+shards(DbName, DocId) when is_list(DocId) ->
+ shards(DbName, list_to_binary(DocId));
+shards(DbName, DocId) ->
+ HashKey = mem3_util:hash(DocId),
+ Head = #shard{
+ name = '_',
+ node = '_',
+ dbname = DbName,
+ range = ['$1','$2'],
+ ref = '_'
+ },
+ Conditions = [{'<', '$1', HashKey}, {'=<', HashKey, '$2'}],
+ try ets:select(partitions, [{Head, Conditions, ['$_']}]) of
+ [] ->
+ mem3_util:load_shards_from_disk(DbName, DocId);
+ Shards ->
+ Shards
+ catch error:badarg ->
+ mem3_util:load_shards_from_disk(DbName, DocId)
+ end.
+
+-spec choose_shards(DbName::iodata(), Options::list()) -> [#shard{}].
+choose_shards(DbName, Options) when is_list(DbName) ->
+ choose_shards(list_to_binary(DbName), Options);
+choose_shards(DbName, Options) ->
+ try shards(DbName)
+ catch error:E when E==database_does_not_exist; E==badarg ->
+ Nodes = mem3:nodes(),
+ NodeCount = length(Nodes),
+ N = mem3_util:n_val(couch_util:get_value(n, Options), NodeCount),
+ Q = mem3_util:to_integer(couch_util:get_value(q, Options,
+ couch_config:get("cluster", "q", "8"))),
+ % rotate to a random entry in the nodelist for even distribution
+ {A, B} = lists:split(crypto:rand_uniform(1,length(Nodes)+1), Nodes),
+ RotatedNodes = B ++ A,
+ mem3_util:create_partition_map(DbName, N, Q, RotatedNodes)
+ end.