feat(dsrepl): add more primitive operations to modify DB sites
This commit is contained in:
Andrew Mayorov
parent
bb8ffee18c
commit
df6c5b35fe
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@ -46,6 +46,8 @@
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%% Site / shard allocation:
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-export([
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join_db_site/2,
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leave_db_site/2,
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assign_db_sites/2,
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replica_set_transitions/2,
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update_replica_set/3,
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@ -62,6 +64,7 @@
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open_db_trans/2,
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allocate_shards_trans/1,
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assign_db_sites_trans/2,
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modify_db_sites_trans/2,
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update_replica_set_trans/3,
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update_db_config_trans/2,
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drop_db_trans/1,
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@ -227,7 +230,7 @@ open_db(DB, DefaultOpts) ->
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transaction(fun ?MODULE:open_db_trans/2, [DB, DefaultOpts]).
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-spec update_db_config(emqx_ds:db(), emqx_ds_replication_layer:builtin_db_opts()) ->
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emqx_ds_replication_layer:builtin_db_opts() | {error, _}.
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emqx_ds_replication_layer:builtin_db_opts() | {error, nonexistent_db}.
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update_db_config(DB, DefaultOpts) ->
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transaction(fun ?MODULE:update_db_config_trans/2, [DB, DefaultOpts]).
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@ -235,26 +238,36 @@ update_db_config(DB, DefaultOpts) ->
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drop_db(DB) ->
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transaction(fun ?MODULE:drop_db_trans/1, [DB]).
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-spec assign_db_sites(emqx_ds:db(), [site()]) -> ok.
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assign_db_sites(DB, Sites) ->
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case mria:transaction(?SHARD, fun ?MODULE:assign_db_sites_trans/2, [DB, Sites]) of
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{atomic, ok} ->
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ok;
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{aborted, Reason} ->
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{error, Reason}
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end.
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%%===============================================================================
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%% Site / shard allocation API
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%%===============================================================================
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%% @doc Join a site to the set of sites the DB is replicated across.
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-spec join_db_site(emqx_ds:db(), site()) ->
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ok | {error, nonexistent_db | nonexistent_sites}.
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join_db_site(DB, Site) ->
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transaction(fun ?MODULE:modify_db_sites_trans/2, [DB, [{add, Site}]]).
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%% @doc Make a site leave the set of sites the DB is replicated across.
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-spec leave_db_site(emqx_ds:db(), site()) ->
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ok | {error, nonexistent_db | nonexistent_sites}.
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leave_db_site(DB, Site) ->
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transaction(fun ?MODULE:modify_db_sites_trans/2, [DB, [{del, Site}]]).
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%% @doc Assign a set of sites to the DB for replication.
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-spec assign_db_sites(emqx_ds:db(), [site()]) ->
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ok | {error, nonexistent_db | nonexistent_sites}.
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assign_db_sites(DB, Sites) ->
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transaction(fun ?MODULE:assign_db_sites_trans/2, [DB, Sites]).
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%% @doc List the sites the DB is replicated across.
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-spec db_sites(emqx_ds:db()) -> [site()].
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db_sites(DB) ->
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Recs = mnesia:dirty_match_object(?SHARD_TAB, ?SHARD_PAT({DB, '_'})),
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lists:foldl(
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fun(#?SHARD_TAB{replica_set = RS}, Acc) ->
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ordsets:union(ordsets:from_list(RS), Acc)
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end,
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ordsets:new(),
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Recs
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).
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list_db_sites(Recs).
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%% @doc List the sequence of transitions that should be conducted in order to
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%% bring the set of replicas for a DB shard in line with the target set.
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-spec replica_set_transitions(emqx_ds:db(), emqx_ds_replication_layer:shard_id()) ->
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[transition()] | undefined.
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replica_set_transitions(DB, Shard) ->
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@ -265,6 +278,8 @@ replica_set_transitions(DB, Shard) ->
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undefined
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end.
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%% @doc Update the set of replication sites for a shard.
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%% To be called after a `transition()` has been conducted successfully.
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-spec update_replica_set(emqx_ds:db(), emqx_ds_replication_layer:shard_id(), transition()) -> ok.
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update_replica_set(DB, Shard, Trans) ->
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case mria:transaction(?SHARD, fun ?MODULE:update_replica_set_trans/3, [DB, Shard, Trans]) of
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@ -274,6 +289,7 @@ update_replica_set(DB, Shard, Trans) ->
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{error, Reason}
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end.
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%% @doc Get the current set of replication sites for a shard.
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-spec replica_set(emqx_ds:db(), emqx_ds_replication_layer:shard_id()) ->
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[site()] | undefined.
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replica_set(DB, Shard) ->
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@ -284,6 +300,9 @@ replica_set(DB, Shard) ->
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undefined
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end.
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%% @doc Get the target set of replication sites for a DB shard.
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%% Target set is updated every time the set of replication sites for the DB changes.
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%% See `join_db_site/2`, `leave_db_site/2`, `assign_db_sites/2`.
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-spec target_set(emqx_ds:db(), emqx_ds_replication_layer:shard_id()) ->
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[site()] | undefined.
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target_set(DB, Shard) ->
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@ -390,6 +409,18 @@ assign_db_sites_trans(DB, Sites) ->
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Reallocation
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).
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-spec modify_db_sites_trans(emqx_ds:db(), [transition()]) -> ok.
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modify_db_sites_trans(DB, Modifications) ->
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Shards = mnesia:match_object(?SHARD_TAB, ?SHARD_PAT({DB, '_'}), write),
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Sites0 = list_db_target_sites(Shards),
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Sites = lists:foldl(fun apply_transition/2, Sites0, Modifications),
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case Sites of
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Sites0 ->
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ok;
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_Chagned ->
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assign_db_sites_trans(DB, Sites)
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end.
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update_replica_set_trans(DB, Shard, Trans) ->
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case mnesia:read(?SHARD_TAB, {DB, Shard}, write) of
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[Record = #?SHARD_TAB{replica_set = ReplicaSet0, target_set = TargetSet0}] ->
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@ -406,27 +437,26 @@ update_replica_set_trans(DB, Shard, Trans) ->
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end.
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-spec update_db_config_trans(emqx_ds:db(), emqx_ds_replication_layer:builtin_db_opts()) ->
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ok | {error, _}.
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emqx_ds_replication_layer:builtin_db_opts().
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update_db_config_trans(DB, UpdateOpts) ->
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case mnesia:wread({?META_TAB, DB}) of
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[#?META_TAB{db_props = Opts}] ->
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Opts = db_config_trans(DB, write),
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%% Since this is an update and not a reopen,
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%% we should keep the shard number and replication factor
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%% and not create a new shard server
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ChangeableOpts = maps:without([n_shards, n_sites, replication_factor], UpdateOpts),
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EffectiveOpts = maps:merge(Opts, ChangeableOpts),
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mnesia:write(#?META_TAB{
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ok = mnesia:write(#?META_TAB{
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db = DB,
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db_props = EffectiveOpts
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}),
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EffectiveOpts;
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[] ->
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{error, no_database}
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end.
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EffectiveOpts.
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-spec db_config_trans(emqx_ds:db()) -> emqx_ds_replication_layer:builtin_db_opts().
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db_config_trans(DB) ->
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case mnesia:read(?META_TAB, DB, read) of
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db_config_trans(DB, read).
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db_config_trans(DB, LockType) ->
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case mnesia:read(?META_TAB, DB, LockType) of
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[#?META_TAB{db_props = Config}] ->
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Config;
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[] ->
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@ -488,6 +518,27 @@ ensure_site() ->
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persistent_term:put(?emqx_ds_builtin_site, Site),
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ok.
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%% @doc Returns sorted list of sites shards are replicated across.
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-spec list_db_sites([_Shard]) -> [site()].
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list_db_sites(Shards) ->
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flatmap_sorted_set(fun get_shard_sites/1, Shards).
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-spec list_db_target_sites([_Shard]) -> [site()].
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list_db_target_sites(Shards) ->
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flatmap_sorted_set(fun get_shard_target_sites/1, Shards).
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-spec get_shard_sites(_Shard) -> [site()].
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get_shard_sites(#?SHARD_TAB{replica_set = ReplicaSet}) ->
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ReplicaSet.
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-spec get_shard_target_sites(_Shard) -> [site()].
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get_shard_target_sites(#?SHARD_TAB{target_set = Sites}) when is_list(Sites) ->
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Sites;
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get_shard_target_sites(#?SHARD_TAB{target_set = undefined} = Shard) ->
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get_shard_sites(Shard).
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-spec compute_allocation([Shard], [Site], emqx_ds_replication_layer:builtin_db_opts()) ->
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[{Shard, [Site, ...]}].
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compute_allocation(Shards, Sites, Opts) ->
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NSites = length(Sites),
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ReplicationFactor = maps:get(replication_factor, Opts),
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@ -512,6 +563,8 @@ compute_transitions(TargetSet, ReplicaSet) ->
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Deletions = ReplicaSet -- TargetSet,
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intersperse([{add, S} || S <- Additions], [{del, S} || S <- Deletions]).
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%% @doc Apply a transition to a list of sites, preserving sort order.
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-spec apply_transition(transition(), [site()]) -> [site()].
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apply_transition({add, S}, Sites) ->
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lists:usort([S | Sites]);
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apply_transition({del, S}, Sites) ->
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@ -530,8 +583,12 @@ eval_qlc(Q) ->
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end.
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transaction(Fun, Args) ->
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{atomic, Result} = mria:transaction(?SHARD, Fun, Args),
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Result.
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case mria:transaction(?SHARD, Fun, Args) of
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{atomic, Result} ->
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Result;
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{aborted, Reason} ->
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{error, Reason}
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end.
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%% @doc Intersperse elements of two lists.
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%% Example: intersperse([1, 2], [3, 4, 5]) -> [1, 3, 2, 4, 5].
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@ -542,3 +599,14 @@ intersperse([], L2) ->
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L2;
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intersperse([H1 | T1], L2) ->
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[H1 | intersperse(L2, T1)].
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%% @doc Map list into a list of sets and return union, as a sorted list.
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-spec flatmap_sorted_set(fun((X) -> [Y]), [X]) -> [Y].
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flatmap_sorted_set(Fun, L) ->
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ordsets:to_list(
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lists:foldl(
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fun(X, Acc) -> ordsets:union(ordsets:from_list(Fun(X)), Acc) end,
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ordsets:new(),
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L
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)
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).
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