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riak_object.erl
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%% -------------------------------------------------------------------
%%
%% riak_object: container for Riak data and metadata
%%
%% Copyright (c) 2007-2010 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License. You may obtain
%% a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% -------------------------------------------------------------------
%% @doc container for Riak data and metadata
-module(riak_object).
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
-endif.
-include("riak_kv_wm_raw.hrl").
-include("riak_object.hrl").
-export_type([riak_object/0, bucket/0, key/0, value/0, binary_version/0, index_value/0]).
-type key() :: binary().
-type bucket() :: binary() | {binary(), binary()}.
%% -type bkey() :: {bucket(), key()}.
-type value() :: term().
-ifdef(namespaced_types).
-type riak_object_dict() :: dict:dict().
-else.
-type riak_object_dict() :: dict().
-endif.
-record(r_content, {
metadata :: riak_object_dict() | list(),
value :: term()
}).
%% Used by the merge function to accumulate contents
-record(merge_acc, {
drop=orddict:new() :: orddict:orddict(),
keep=ordsets:new() :: ordsets:ordset(#r_content{}),
crdt=orddict:new() :: orddict:orddict(),
error=[] :: list(binary())
}).
%% Opaque container for Riak objects, a.k.a. riak_object()
-record(r_object, {
bucket :: bucket(),
key :: key(),
contents :: [#r_content{}],
vclock = vclock:fresh() :: vclock:vclock(),
updatemetadata=dict:store(clean, true, dict:new()) :: riak_object_dict(),
updatevalue :: term()
}).
-opaque riak_object() :: #r_object{}.
-type merge_acc() :: #merge_acc{}.
-type r_content() :: #r_content{}.
-type index_op() :: add | remove.
-type index_value() :: integer() | binary().
-type binary_version() :: v0 | v1.
-define(MAX_KEY_SIZE, 65536).
-define(LASTMOD_LEN, 29). %% static length of rfc1123_date() type. Hard-coded in Erlang.
-define(V1_VERS, 1).
-define(MAGIC, 53). %% Magic number, as opposed to 131 for Erlang term-to-binary magic
%% Shanley's(11) + Joe's(42)
-define(EMPTY_VTAG_BIN, <<"e">>).
-export([new/3, new/4, ensure_robject/1, ancestors/1, reconcile/2, equal/2]).
-export([increment_vclock/2, increment_vclock/3, prune_vclock/3, vclock_descends/2, all_actors/1]).
-export([actor_counter/2]).
-export([key/1, get_metadata/1, get_metadatas/1, get_values/1, get_dotted_values/1, get_value/1]).
-export([hash/1, hash/2, approximate_size/2, value_size/1]).
-export([vclock_encoding_method/0, vclock/1, vclock_header/1, encode_vclock/1, decode_vclock/1]).
-export([encode_vclock/2, decode_vclock/2]).
-export([update/5, update_value/2, update_metadata/2, bucket/1, bucket_only/1, type/1, value_count/1]).
-export([get_update_metadata/1, get_update_value/1, get_contents/1]).
-export([merge/2, apply_updates/1, syntactic_merge/2]).
-export([to_json/1, from_json/1]).
-export([index_data/1, diff_index_data/2]).
-export([index_specs/1, diff_index_specs/2]).
-export([to_binary/2, from_binary/3, to_binary_version/4, binary_version/1]).
-export([set_contents/2, set_vclock/2]). %% INTERNAL, only for riak_*
-export([is_robject/1]).
-export([update_last_modified/1, update_last_modified/2]).
-export([strict_descendant/2, new_actor_epoch/2]).
%% @doc Constructor for new riak objects.
-spec new(Bucket::bucket(), Key::key(), Value::value()) -> riak_object().
new({T, B}, K, V) when is_binary(T), is_binary(B), is_binary(K) ->
new_int({T, B}, K, V, no_initial_metadata);
new(B, K, V) when is_binary(B), is_binary(K) ->
new_int(B, K, V, no_initial_metadata).
%% @doc Constructor for new riak objects with an initial content-type.
-spec new(Bucket::bucket(), Key::key(), Value::value(),
string() | riak_object_dict() | no_initial_metadata) -> riak_object().
new({T, B}, K, V, C) when is_binary(T), is_binary(B), is_binary(K), is_list(C) ->
new_int({T, B}, K, V, dict:from_list([{?MD_CTYPE, C}]));
new(B, K, V, C) when is_binary(B), is_binary(K), is_list(C) ->
new_int(B, K, V, dict:from_list([{?MD_CTYPE, C}]));
%% @doc Constructor for new riak objects with an initial metadata dict.
%%
%% NOTE: Removed "is_tuple(MD)" guard to make Dialyzer happy. The previous clause
%% has a guard for string(), so this clause is OK without the guard.
new({T, B}, K, V, MD) when is_binary(T), is_binary(B), is_binary(K) ->
new_int({T, B}, K, V, MD);
new(B, K, V, MD) when is_binary(B), is_binary(K) ->
new_int(B, K, V, MD).
%% internal version after all validation has been done
new_int(B, K, V, MD) ->
case size(K) > ?MAX_KEY_SIZE of
true ->
throw({error,key_too_large});
false ->
case MD of
no_initial_metadata ->
Contents = [#r_content{metadata=dict:new(), value=V}],
#r_object{bucket=B,key=K,
contents=Contents,vclock=vclock:fresh()};
_ ->
Contents = [#r_content{metadata=MD, value=V}],
#r_object{bucket=B,key=K,updatemetadata=MD,
contents=Contents,vclock=vclock:fresh()}
end
end.
is_robject(#r_object{}) ->
true;
is_robject(_) ->
false.
%% @doc Ensure the incoming term is a riak_object.
-spec ensure_robject(any()) -> riak_object().
ensure_robject(Obj = #r_object{}) -> Obj.
%% @doc Deep (expensive) comparison of Riak objects.
-spec equal(riak_object(), riak_object()) -> true | false.
equal(Obj1,Obj2) ->
(Obj1#r_object.bucket =:= Obj2#r_object.bucket)
andalso (Obj1#r_object.key =:= Obj2#r_object.key)
andalso vclock:equal(vclock(Obj1),vclock(Obj2))
andalso equal2(Obj1,Obj2).
equal2(Obj1,Obj2) ->
UM1 = lists:keysort(1, dict:to_list(Obj1#r_object.updatemetadata)),
UM2 = lists:keysort(1, dict:to_list(Obj2#r_object.updatemetadata)),
(UM1 =:= UM2)
andalso (Obj1#r_object.updatevalue =:= Obj2#r_object.updatevalue)
andalso begin
Cont1 = lists:sort(Obj1#r_object.contents),
Cont2 = lists:sort(Obj2#r_object.contents),
equal_contents(Cont1,Cont2)
end.
equal_contents([],[]) -> true;
equal_contents(_,[]) -> false;
equal_contents([],_) -> false;
equal_contents([C1|R1],[C2|R2]) ->
MD1 = lists:keysort(1, dict:to_list(C1#r_content.metadata)),
MD2 = lists:keysort(1, dict:to_list(C2#r_content.metadata)),
(MD1 =:= MD2)
andalso (C1#r_content.value =:= C2#r_content.value)
andalso equal_contents(R1,R2).
%% @doc Given a list of riak_object()s, return the objects that are pure
%% ancestors of other objects in the list, if any. The changes in the
%% objects returned by this function are guaranteed to be reflected in
%% the other objects in Objects, and can safely be discarded from the list
%% without losing data.
-spec ancestors([riak_object()]) -> [riak_object()].
ancestors(pure_baloney_to_fool_dialyzer) ->
[#r_object{vclock = vclock:fresh()}];
ancestors(Objects) ->
[ O2 || O1 <- Objects, O2 <- Objects, strict_descendant(O1, O2) ].
%% @doc returns true if the `riak_object()' at `O1' is a strict
%% descendant of that at `O2'. This means that the first object
%% causally dominates the second.
%% @see vclock:dominates/2
-spec strict_descendant(riak_object(), riak_object()) -> boolean().
strict_descendant(O1, O2) ->
vclock:dominates(riak_object:vclock(O1), riak_object:vclock(O2)).
%% @doc Reconcile a list of riak objects. If AllowMultiple is true,
%% the riak_object returned may contain multiple values if Objects
%% contains sibling versions (objects that could not be syntactically
%% merged). If AllowMultiple is false, the riak_object returned will
%% contain the value of the most-recently-updated object, as per the
%% X-Riak-Last-Modified header.
-spec reconcile([riak_object()], boolean()) -> riak_object().
reconcile(Objects, AllowMultiple) ->
RObj = reconcile(remove_dominated(Objects)),
case AllowMultiple of
false ->
Contents = [most_recent_content(RObj#r_object.contents)],
RObj#r_object{contents=Contents};
true ->
RObj
end.
%% @private remove all Objects from the list that are causally
%% dominated by any other object in the list. Only concurrent /
%% conflicting objects will remain.
remove_dominated(Objects) ->
All = sets:from_list(Objects),
Del = sets:from_list(ancestors(Objects)),
sets:to_list(sets:subtract(All, Del)).
%% @private pairwise merge the objects in the list so that a single,
%% merged riak_object remains that contains all sibling values. Only
%% called with a list of conflicting objects. Use `remove_dominated/1'
%% to get such a list first.
reconcile(Objects) ->
lists:foldl(fun syntactic_merge/2,
hd(Objects),
tl(Objects)).
most_recent_content(AllContents) ->
hd(lists:sort(fun compare_content_dates/2, AllContents)).
compare_content_dates(C1,C2) ->
D1 = dict:fetch(<<"X-Riak-Last-Modified">>, C1#r_content.metadata),
D2 = dict:fetch(<<"X-Riak-Last-Modified">>, C2#r_content.metadata),
%% true if C1 was modifed later than C2
Cmp1 = riak_core_util:compare_dates(D1, D2),
%% true if C2 was modifed later than C1
Cmp2 = riak_core_util:compare_dates(D2, D1),
%% check for deleted objects
Del1 = dict:is_key(<<"X-Riak-Deleted">>, C1#r_content.metadata),
Del2 = dict:is_key(<<"X-Riak-Deleted">>, C2#r_content.metadata),
SameDate = (Cmp1 =:= Cmp2),
case {SameDate, Del1, Del2} of
{false, _, _} ->
Cmp1;
{true, true, false} ->
false;
{true, false, true} ->
true;
_ ->
%% Dates equal and either both present or both deleted, compare
%% by opaque contents.
C1 < C2
end.
%% @doc Merge the contents and vclocks of OldObject and NewObject.
%% Note: This function calls apply_updates on NewObject.
%% Depending on whether DVV is enabled or not, then may merge
%% dropping dotted and dominated siblings, otherwise keeps all
%% unique sibling values. NOTE: as well as being a Syntactic
%% merge, this is also now a semantic merge for CRDTs. Only
%% call with concurrent objects. Use `syntactic_merge/2' if one
%% object may strictly dominate another.
-spec merge(riak_object(), riak_object()) -> riak_object().
merge(OldObject, NewObject) ->
NewObj1 = apply_updates(NewObject),
Bucket = bucket(OldObject),
case riak_kv_util:get_write_once(Bucket) of
true ->
merge_write_once(OldObject, NewObj1);
_ ->
DVV = dvv_enabled(Bucket),
{Time, {CRDT, Contents}} = timer:tc(fun merge_contents/3,
[NewObject, OldObject, DVV]),
ok = riak_kv_stat:update({riak_object_merge, CRDT, Time}),
OldObject#r_object{contents=Contents,
vclock=vclock:merge([OldObject#r_object.vclock,
NewObj1#r_object.vclock]),
updatemetadata=dict:store(clean, true, dict:new()),
updatevalue=undefined}
end.
%% @doc Special case write_once merge, in the case where the write_once property is
%% set on the bucket (type). In this case, take the lesser (in lexical order)
%% of the SHA1 hash of each object.
%%
-spec merge_write_once(riak_object(), riak_object()) -> riak_object().
merge_write_once(OldObject, NewObject) ->
ok = riak_kv_stat:update(write_once_merge),
case crypto:hash(sha, term_to_binary(OldObject)) =< crypto:hash(sha, term_to_binary(NewObject)) of
true ->
OldObject;
_ ->
NewObject
end.
%% @doc Merge the r_objects contents by converting the inner dict to
%% a list, ensuring a sane order, and merging into a unique list.
merge_contents(NewObject, OldObject, false) ->
Result = lists:umerge(fun compare/2,
lists:usort(fun compare/2, NewObject#r_object.contents),
lists:usort(fun compare/2, OldObject#r_object.contents)),
{undefined, Result};
%% @private with DVV enabled, use event dots in sibling metadata to
%% remove dominated siblings and stop fake concurrency that causes
%% sibling explsion. Also, since every sibling is iterated over (some
%% twice!) why not merge CRDTs here, too?
merge_contents(NewObject, OldObject, true) ->
Bucket = bucket(NewObject),
Key = key(NewObject),
MergeAcc0 = prune_object_siblings(OldObject, vclock(NewObject)),
MergeAcc = prune_object_siblings(NewObject, vclock(OldObject), MergeAcc0),
#merge_acc{crdt=CRDT, error=Error} = MergeAcc,
riak_kv_crdt:log_merge_errors(Bucket, Key, CRDT, Error),
merge_acc_to_contents(Bucket, MergeAcc).
%% Optimisation. To save converting every meta dict to a list sorting,
%% comparing, and coverting back again, we use this optimisation, that
%% shortcuts out the meta_data comparison, if the obects aren't equal,
%% we needn't compare meta_data at all. `compare/2' is an "ordering
%% fun". Return true if A =< B, false otherwise.
%%
%% @see lists:usort/2
compare(A=#r_content{value=VA}, B=#r_content{value=VB}) ->
if VA < VB ->
true;
VA > VB ->
false;
true ->
%% values are equal, compare metadata
compare_metadata(A, B)
end.
%% Optimisation. Used by `compare/2' ordering fun. Only convert, sort,
%% and compare the meta_data dictionaries if they are the same
%% size. Called by an ordering function, this too is an ordering
%% function.
%%
%% @see compare/2
%% @see lists:usort/3
compare_metadata(#r_content{metadata=MA}, #r_content{metadata=MB}) ->
ASize = dict:size(MA),
BSize = dict:size(MB),
if ASize < BSize ->
true;
ASize > BSize ->
false;
true ->
%% same size metadata, need to do actual compare
lists:sort(dict:to_list(MA)) =< lists:sort(dict:to_list(MB))
end.
%% @private de-duplicates, removes dominated siblings, merges CRDTs
-spec prune_object_siblings(riak_object(), vclock:vclock()) -> merge_acc().
prune_object_siblings(Object, Clock) ->
prune_object_siblings(Object, Clock, #merge_acc{}).
-spec prune_object_siblings(riak_object(), vclock:vclock(), merge_acc())
-> merge_acc().
prune_object_siblings(Object, Clock, MergeAcc) ->
lists:foldl(fun(Contents, Acc) ->
fold_contents(Contents, Acc, Clock)
end,
MergeAcc,
Object#r_object.contents).
%% @private called once for each content entry for each object being
%% merged. Its job is to drop siblings that are causally dominated,
%% remove duplicate values, and merge CRDT values down to a single
%% value.
%%
%% When a Riak takes a PUT, a `dot' is generated. (See assign_dot/2)
%% for the PUT and placed in `riak_object' metadata. The cases below
%% use this `dot' to decide if a sibling value has been superceded,
%% and should therefore be dropped.
%%
%% Based on the work by Baquero et al:
%%
%% Efficient causality tracking in distributed storage systems with
%% dotted version vectors
%% http://doi.acm.org/10.1145/2332432.2332497
%% Nuno Preguiça, Carlos Bauqero, Paulo Sérgio Almeida, Victor Fonte,
%% and Ricardo Gonçalves. 2012
-spec fold_contents(r_content(), merge_acc(), vclock:vclock()) -> merge_acc().
fold_contents({r_content, Dict, Value}=C0, MergeAcc, Clock) ->
#merge_acc{drop=Drop, keep=Keep, crdt=CRDT, error=Error} = MergeAcc,
case get_dot(Dict) of
{ok, {Dot, PureDot}} ->
case {vclock:descends_dot(Clock, Dot),
is_drop_candidate(PureDot, Drop)} of
{true, true} ->
%% When the exact same dot is present in both
%% objects siblings, we keep that value. Without
%% this merging an object with itself would result
%% in an object with no values at all, since an
%% object's vector clock always dominates all its
%% dots. However, due to riak_kv#679, and
%% backup-restore it is possible for two objects
%% to have dots with the same {id, count} but
%% different timestamps (see is_drop_candidate/2
%% below), and for the referenced values to be
%% _different_ too. We need to include both dotted
%% values, and let the list sort/merge ensure that
%% only one sibling for a pair of normal dots is
%% returned. Hence get the other dots contents,
%% should be identical, but Skewed Dots mean we
%% can't guarantee that, the merge will dedupe for
%% us.
DC = get_drop_candidate(PureDot, Drop),
MergeAcc#merge_acc{keep=[C0, DC | Keep]};
{true, false} ->
%% The `dot' is dominated by the other object's
%% vclock. This means that the other object has a
%% value that is the result of a PUT that
%% reconciled this sibling value, we can therefore
%% (potentialy, see above) drop this value.
MergeAcc#merge_acc{drop=add_drop_candidate(PureDot, C0,
Drop)};
{false, _} ->
%% The other object's vclock does not contain (or
%% dominate) this sibling's `dot'. That means this
%% is a genuinely concurrent (or sibling) value
%% and should be kept for the user to reconcile.
MergeAcc#merge_acc{keep=[C0|Keep]}
end;
undefined ->
%% Both CRDTs and legacy data don't have dots. Legacy data
%% because it was written before DVV (or with DVV turned
%% off.) That means keep this sibling. We cannot know if
%% it is dominated. This is the pre-DVV behaviour.
%%
%% CRDTs values do not get a dot as they are merged by
%% Riak, not by the client. A CRDT PUT _NEVER_ overwrites
%% existing values in Riak, it is always merged with
%% them. The resulting value then does not have a single
%% event origin. Instead it is a merge of many events. In
%% DVVSets (referenced above) there is an `anonymous list'
%% for values that have no single event. In Riak we
%% already have that, by having an `undefined' dot. We
%% could store all the dots for a CRDT as a clock, but it
%% would need complex logic to prune.
%%
%% Since there are no dots for CRDT values, there can be
%% sibling values on disk. Which is a concern for sibling
%% explosion scenarios. To avoid such scenarios we call
%% out to CRDT logic to merge CRDTs into a single value
%% here.
case riak_kv_crdt:merge_value({Dict, Value}, {CRDT, [], []}) of
{CRDT, [], [E]} ->
%% An error occurred trying to merge this sibling
%% value. This means it was CRDT with some
%% corruption of the binary format, or maybe a
%% user's opaque binary that happens to match the
%% CRDT binary start tag. Either way, gather the
%% error for later logging.
MergeAcc#merge_acc{error=[E | Error]};
{CRDT, [{Dict, Value}], E} when is_list(E)->
%% The sibling value was not a CRDT, but a
%% (legacy?) un-dotted user opaque value. Add it
%% to the list of values to keep.
MergeAcc#merge_acc{keep=[C0|Keep], error=E ++ Error};
{CRDT2, [], []} ->
%% The sibling was a CRDT and the CRDT accumulator
%% has been updated.
MergeAcc#merge_acc{crdt=CRDT2}
end
end.
%% Store a pure dot and it's contents as a possible candidate to be
%% dropped.
%%
%% @see is_drop_candidate/2
add_drop_candidate(Dot, Contents, Dict) ->
orddict:store(Dot, Contents, Dict).
%% Check if a pure dot is already present as a drop candidate.
is_drop_candidate(Dot, Dict) ->
orddict:is_key(Dot, Dict).
%% fetch a drop candidate by it's pure dot
get_drop_candidate(Dot, Dict) ->
orddict:fetch(Dot, Dict).
%% @private Transform a `merge_acc()' to a list of `r_content()'. The
%% merge accumulator contains a list of non CRDT (opaque) sibling
%% values (`keep') and merged CRDT values (`crdt'). Due to bucket
%% types it should really only ever contain one or the other (and the
%% accumulated CRDTs should have a single value), but it is better to
%% be safe.
-spec merge_acc_to_contents(riak_object:bucket(), merge_acc())
-> list(r_content()).
merge_acc_to_contents(Bucket, MergeAcc) ->
#merge_acc{keep=Keep, crdt=CRDTs} = MergeAcc,
%% Convert the non-CRDT sibling values back to dict metadata values.
%%
%% For improved performance, fold_contents/3 does not check for duplicates
%% when constructing the "Keep" list (eg. using an ordset), but instead
%% simply prepends kept siblings to the list. Here, we convert Keep into an
%% ordset equivalent with reverse/unique sort.
Keep2 = lists:usort(fun compare/2, lists:reverse(Keep)),
%% Iterate the set of converged CRDT values and turn them into
%% `r_content' entries. by generating their metadata entry and
%% binary encoding their contents. Bucket Types should ensure this
%% accumulator only has one entry ever.
case orddict:size(CRDTs) > 0 of
true ->
BProps = riak_core_bucket:get_bucket(Bucket),
orddict:fold(
fun(_Type, {Meta, CRDT0}, {_, Contents}) ->
CRDT = riak_kv_crdt:maybe_apply_props(BProps, CRDT0),
{riak_kv_crdt:to_mod(CRDT),
[{r_content, riak_kv_crdt:meta(Meta, CRDT),
riak_kv_crdt:to_binary(CRDT)} | Contents]}
end,
{undefined, Keep2},
CRDTs);
false ->
{undefined, Keep2}
end.
%% @private Get the dot from the passed metadata dict (if present and
%% valid). It turns out, due to weirdness, it is possible to have two
%% dots with the same id and counter, but different timestamps (backup
%% and restore, riak_kv#679). In that case, it is possible to drop
%% both dots, as both are dominted, but not equal. Here we strip the
%% timestamp component when comparing dots. A `dot' in riak_object is
%% just a {binary(), pos_integer()} pair.
%%
%% @see vclock:destructure_dot/1
-spec get_dot(riak_object_dict()) -> {ok, {vclock:vclock_node(), pos_integer()}} | undefined.
get_dot(Dict) ->
case dict:find(?DOT, Dict) of
{ok, Dot} ->
case vclock:valid_dot(Dot) of
true ->
PureDot = vclock:pure_dot(Dot),
{ok, {Dot, PureDot}};
false ->
undefined
end;
error ->
undefined
end.
%% @private used by get_dotted_values to re-use get_dot/1
get_vc_dot(Dict) ->
case get_dot(Dict) of
{ok, {Dot, _PDot}} ->
Dot;
_ -> undefined
end.
%% @doc Promote pending updates (made with the update_value() and
%% update_metadata() calls) to this riak_object.
-spec apply_updates(riak_object()) -> riak_object().
apply_updates(Object=#r_object{}) ->
VL = case Object#r_object.updatevalue of
undefined ->
[C#r_content.value || C <- Object#r_object.contents];
_ ->
[Object#r_object.updatevalue]
end,
MD = case dict:find(clean, Object#r_object.updatemetadata) of
{ok,_} ->
MDs = [C#r_content.metadata || C <- Object#r_object.contents],
case Object#r_object.updatevalue of
undefined -> MDs;
_ -> [hd(MDs)]
end;
error ->
[dict:erase(clean,Object#r_object.updatemetadata) || _X <- VL]
end,
Contents = [#r_content{metadata=M,value=V} || {M,V} <- lists:zip(MD, VL)],
Object#r_object{contents=Contents,
updatemetadata=dict:store(clean, true, dict:new()),
updatevalue=undefined}.
%% @doc Return the containing bucket for this riak_object.
-spec bucket(riak_object()) -> bucket().
bucket(#r_object{bucket=Bucket}) -> Bucket.
%% @doc Return the containing bucket for this riak_object without any type
%% information, if present.
-spec bucket_only(riak_object()) -> binary().
bucket_only(#r_object{bucket={_Type, Bucket}}) -> Bucket;
bucket_only(#r_object{bucket=Bucket}) -> Bucket.
%% @doc Return the containing bucket-type for this riak_object.
-spec type(riak_object()) -> binary() | undefined.
type(#r_object{bucket={Type, _Bucket}}) -> Type;
type(#r_object{bucket=_Bucket}) -> undefined.
%% @doc Return the key for this riak_object.
-spec key(riak_object()) -> key().
key(#r_object{key=Key}) -> Key.
%% @doc Return the vector clock for this riak_object.
-spec vclock(riak_object()) -> vclock:vclock().
vclock(#r_object{vclock=VClock}) -> VClock.
%% @doc Return the number of values (siblings) of this riak_object.
-spec value_count(riak_object()) -> non_neg_integer().
value_count(#r_object{contents=Contents}) -> length(Contents).
%% @doc Return the contents (a list of {metadata, value} tuples) for
%% this riak_object.
-spec get_contents(riak_object()) -> [{riak_object_dict(), value()}].
get_contents(#r_object{contents=Contents}) ->
[{Content#r_content.metadata, Content#r_content.value} ||
Content <- Contents].
%% @doc Assert that this riak_object has no siblings and return its associated
%% metadata. This function will fail with a badmatch error if the
%% object has siblings (value_count() > 1).
-spec get_metadata(riak_object()) -> riak_object_dict().
get_metadata(O=#r_object{}) ->
% this blows up intentionally (badmatch) if more than one content value!
[{Metadata,_V}] = get_contents(O),
Metadata.
%% @doc Return a list of the metadata values for this riak_object.
-spec get_metadatas(riak_object()) -> [riak_object_dict()].
get_metadatas(#r_object{contents=Contents}) ->
[Content#r_content.metadata || Content <- Contents].
%% @doc Return a list of object values for this riak_object.
-spec get_values(riak_object()) -> [value()].
get_values(#r_object{contents=C}) -> [Content#r_content.value || Content <- C].
%% @doc Return a list of object values and their dots for this riak_object.
-spec get_dotted_values(riak_object()) -> [{vclock:dot(), value()}].
get_dotted_values(#r_object{contents=C}) ->
[{get_vc_dot(Content#r_content.metadata) , Content#r_content.value} || Content <- C].
%% @doc Assert that this riak_object has no siblings and return its associated
%% value. This function will fail with a badmatch error if the object
%% has siblings (value_count() > 1).
-spec get_value(riak_object()) -> value().
get_value(Object=#r_object{}) ->
% this blows up intentionally (badmatch) if more than one content value!
[{_M,Value}] = get_contents(Object),
Value.
%% @doc calculates the canonical hash of a riak object
%% Old API which uses the version .
%% DEPRECATED
-spec hash(riak_object()) -> binary().
hash(Obj=#r_object{}) ->
case riak_kv_entropy_manager:get_version() of
0 ->
vclock_hash(Obj);
legacy ->
legacy_hash(Obj)
end.
%% @doc calculates the canonical hash of a riak object depending on version
-spec hash(riak_object(), non_neg_integer() | legacy) -> binary().
hash(Obj=#r_object{}, _Version=0) ->
vclock_hash(Obj);
hash(Obj=#r_object{}, _Version) ->
legacy_hash(Obj).
%% @private return the legacy full object hash of the riak_object
-spec legacy_hash(riak_object()) -> binary().
legacy_hash(Obj=#r_object{}) ->
UpdObj = riak_object:set_vclock(Obj, lists:sort(vclock(Obj))),
Hash = erlang:phash2(to_binary(v0, UpdObj)),
term_to_binary(Hash).
%% @private return the hash of the vclock
-spec vclock_hash(riak_object()) -> binary().
vclock_hash(Obj=#r_object{}) ->
Hash = erlang:phash2(lists:sort(vclock(Obj))),
term_to_binary(Hash).
%% @doc Set the updated metadata of an object to M.
-spec update_metadata(riak_object(), riak_object_dict()) -> riak_object().
update_metadata(Object=#r_object{}, M) ->
Object#r_object{updatemetadata=dict:erase(clean, M)}.
%% @doc Set the updated value of an object to V
-spec update_value(riak_object(), value()) -> riak_object().
update_value(Object=#r_object{}, V) -> Object#r_object{updatevalue=V}.
%% @doc Return the updated metadata of this riak_object.
-spec get_update_metadata(riak_object()) -> riak_object_dict().
get_update_metadata(#r_object{updatemetadata=UM}) -> UM.
%% @doc Return the updated value of this riak_object.
-spec get_update_value(riak_object()) -> value().
get_update_value(#r_object{updatevalue=UV}) -> UV.
%% @doc INTERNAL USE ONLY. Set the vclock of riak_object O to V.
-spec set_vclock(riak_object(), vclock:vclock()) -> riak_object().
set_vclock(Object=#r_object{}, VClock) -> Object#r_object{vclock=VClock}.
%% @doc vnode uses to add a new actor epoch to the vclock, a replica
%% write showed local amnesia
-spec new_actor_epoch(riak_object(), vclock:vclock_node()) -> riak_object().
new_actor_epoch(Object=#r_object{vclock=VC}, ClientId) ->
NewClock = vclock:increment(ClientId, VC),
Object#r_object{vclock=NewClock}.
%% @doc Increment the entry for ClientId in O's vclock.
-spec increment_vclock(riak_object(), vclock:vclock_node()) -> riak_object().
increment_vclock(Object=#r_object{bucket=B}, ClientId) ->
NewClock = vclock:increment(ClientId, Object#r_object.vclock),
{ok, Dot} = vclock:get_dot(ClientId, NewClock),
assign_dot(Object#r_object{vclock=NewClock}, Dot, dvv_enabled(B)).
%% @doc Increment the entry for ClientId in O's vclock.
-spec increment_vclock(riak_object(), vclock:vclock_node(), vclock:timestamp()) -> riak_object().
increment_vclock(Object=#r_object{bucket=B}, ClientId, Timestamp) ->
NewClock = vclock:increment(ClientId, Timestamp, Object#r_object.vclock),
{ok, Dot} = vclock:get_dot(ClientId, NewClock),
%% If it is true that we only ever increment the vclock to create
%% a frontier object, then there must only ever be a single value
%% when we increment, so add the dot here.
assign_dot(Object#r_object{vclock=NewClock}, Dot, dvv_enabled(B)).
%% @doc Prune vclock
-spec prune_vclock(riak_object(), vclock:timestamp(), [proplists:property()]) ->
riak_object().
prune_vclock(Obj=#r_object{vclock=VC}, PruneTime, BucketProps) ->
VC2 = vclock:prune(VC, PruneTime, BucketProps),
Obj#r_object{vclock=VC2}.
%% @doc Does the `riak_object' descend the provided `vclock'?
-spec vclock_descends(riak_object(), vclock:vclock()) -> boolean().
vclock_descends(#r_object{vclock=ObjVC}, VC) ->
vclock:descends(ObjVC, VC).
%% @doc get the list of all actors that have touched this object.
-spec all_actors(riak_object()) -> [binary()] | [].
all_actors(#r_object{vclock=VC}) ->
vclock:all_nodes(VC).
%%$ @doc get the counter for the given actor, 0 if not present
-spec actor_counter(vclock:vclock_node(), riak_object()) ->
non_neg_integer().
actor_counter(Actor, #r_object{vclock=VC}) ->
vclock:get_counter(Actor, VC).
%% @private assign the dot to the value only if DVV is enabled. Only
%% call with a valid dot. Only assign dot when there is a single value
%% in contents.
-spec assign_dot(riak_object(), vclock:dot(), boolean()) -> riak_object().
assign_dot(Object, Dot, true) ->
#r_object{contents=[C=#r_content{metadata=Meta0}]} = Object,
Object#r_object{contents=[C#r_content{metadata=dict:store(?DOT, Dot, Meta0)}]};
assign_dot(Object, _Dot, _DVVEnabled) ->
Object.
%% @private is dvv enabled on this node?
-spec dvv_enabled(bucket()) -> boolean().
dvv_enabled(Bucket) ->
BProps = riak_core_bucket:get_bucket(Bucket),
%% default to `true`, since legacy buckets should have `false` by
%% default, and typed should have `true` and `undefined` is not a
%% valid return.
proplists:get_value(dvv_enabled, BProps, true).
%% @doc Prepare a list of index specifications
%% to pass to the backend. This function is for
%% the case where there is no existing object
%% stored for a key and therefore no existing
%% index data.
-spec index_specs(riak_object()) ->
[{index_op(), binary(), index_value()}].
index_specs(Obj) ->
Indexes = index_data(Obj),
assemble_index_specs(Indexes, add).
%% @doc Prepare a list of index specifications to pass to the
%% backend. If the object passed as the first parameter does not have
%% siblings, the function will assemble specs to replace all of its
%% indexes with the indexes specified in the object passed as the
%% second parameter. If there are siblings only the unique new
%% indexes are added.
-spec diff_index_specs('undefined' | riak_object(),
'undefined' | riak_object()) ->
[{index_op(), binary(), index_value()}].
diff_index_specs(Obj, OldObj) ->
OldIndexes = index_data(OldObj),
AllIndexes = index_data(Obj),
diff_index_data(OldIndexes, AllIndexes).
-spec diff_index_data([{binary(), index_value()}],
[{binary(), index_value()}]) ->
[{index_op(), binary(), index_value()}].
diff_index_data(OldIndexes, AllIndexes) ->
OldIndexSet = ordsets:from_list(OldIndexes),
AllIndexSet = ordsets:from_list(AllIndexes),
diff_specs_core(AllIndexSet, OldIndexSet).
diff_specs_core(AllIndexSet, OldIndexSet) ->
NewIndexSet = ordsets:subtract(AllIndexSet, OldIndexSet),
RemoveIndexSet =
ordsets:subtract(OldIndexSet, AllIndexSet),
NewIndexSpecs =
assemble_index_specs(ordsets:subtract(NewIndexSet, OldIndexSet),
add),
RemoveIndexSpecs =
assemble_index_specs(RemoveIndexSet,
remove),
NewIndexSpecs ++ RemoveIndexSpecs.
%% @doc Get a list of {Index, Value} tuples from the
%% metadata of an object.
-spec index_data(riak_object()) -> [{binary(), index_value()}].
index_data(undefined) ->
[];
index_data(Obj) ->
MetaDatas = get_metadatas(Obj),
lists:flatten([dict:fetch(?MD_INDEX, MD)
|| MD <- MetaDatas,
dict:is_key(?MD_INDEX, MD)]).
%% @doc Assemble a list of index specs in the
%% form of triplets of the form
%% {IndexOperation, IndexField, IndexValue}.
-spec assemble_index_specs([{binary(), binary()}], index_op()) ->
[{index_op(), binary(), binary()}].
assemble_index_specs(Indexes, IndexOp) ->
[{IndexOp, Index, Value} || {Index, Value} <- Indexes].
%% @doc INTERNAL USE ONLY. Set the contents of riak_object to the
%% {Metadata, Value} pairs in MVs. Normal clients should use the
%% set_update_[value|metadata]() + apply_updates() method for changing
%% object contents.
-spec set_contents(riak_object(), [{riak_object_dict(), value()}]) -> riak_object().
set_contents(Object=#r_object{}, MVs) when is_list(MVs) ->
Object#r_object{contents=[#r_content{metadata=M,value=V} || {M, V} <- MVs]}.
-spec vclock_header(riak_object()) -> {Name::string(), Value::string()}.
%% @doc Transform the Erlang representation of the document's vclock
%% into something suitable for an HTTP header
vclock_header(Doc) ->
VClock = riak_object:vclock(Doc),
EncodedVClock = binary_to_list(base64:encode(encode_vclock(VClock))),
{?HEAD_VCLOCK, EncodedVClock}.
%% @doc Converts a riak_object into its JSON equivalent
%% @deprecated use `riak_object_json:encode' directly
-spec to_json(riak_object()) -> {struct, list(any())}.
to_json(Obj) ->
lager:warning("Change uses of riak_object:to_json/1 to riak_object_json:encode/1"),
riak_object_json:encode(Obj).
%% @deprecated Use `riak_object_json:decode' now.
from_json(JsonObj) ->
lager:warning("Change uses of riak_object:from_json/1 to riak_object_json:decode/1"),
riak_object_json:decode(JsonObj).
is_updated(_Object=#r_object{updatemetadata=M,updatevalue=V}) ->
case dict:find(clean, M) of
error -> true;
{ok,_} ->
case V of
undefined -> false;
_ -> true
end
end.
%% @doc a Put merge. Update a stored riak_object with the value from a
%% new riak_object that has been put. Must be serialised by the
%% `Actor' provided.
-spec update(LWW :: boolean(), LocalObj :: riak_object(),
NewObj :: riak_object(), Actor ::vclock:vclock_node(),
TimeStamp :: vclock:timestamp()) ->
riak_object().
update(true, _OldObject, NewObject, Actor, Timestamp) ->
increment_vclock(NewObject, Actor, Timestamp);
update(false, OldObject, NewObject, Actor, Timestamp) ->
%% Get the vclock we have for the local / old object
LocalVC = vclock(OldObject),
%% get the vclock from the new object
PutVC = vclock(NewObject),
%% Optimisation: if the new object's vclock descends from the old
%% object's vclock, then don't merge values, just increment the
%% clock and overwrite.
case vclock:descends(PutVC, LocalVC) of
true ->
increment_vclock(NewObject, Actor, Timestamp);
false ->
%% The new object is concurrent with some other value, so
%% merge the new object and the old object.
MergedClock = vclock:merge([PutVC, LocalVC]),
FrontierClock = vclock:increment(Actor, Timestamp, MergedClock),
{ok, Dot} = vclock:get_dot(Actor, FrontierClock),
%% Assign an event to the new value
Bucket = bucket(OldObject),
DottedPutObject = assign_dot(NewObject, Dot, dvv_enabled(Bucket)),
MergedObject = merge(DottedPutObject, OldObject),
set_vclock(MergedObject, FrontierClock)
end.
-spec syntactic_merge(riak_object(), riak_object()) -> riak_object().
syntactic_merge(CurrentObject, NewObject) ->
%% Paranoia in case objects were incorrectly stored
%% with update information. Vclock is not updated
%% but since no data is lost the objects will be
%% fixed if rewritten.
UpdatedNew = case is_updated(NewObject) of
true -> apply_updates(NewObject);
false -> NewObject
end,
UpdatedCurr = case is_updated(CurrentObject) of
true -> apply_updates(CurrentObject);
false -> CurrentObject
end,
case ancestors([UpdatedCurr, UpdatedNew]) of
[] -> merge(UpdatedCurr, UpdatedNew);
[Ancestor] ->
case equal(Ancestor, UpdatedCurr) of
true -> UpdatedNew;
false -> UpdatedCurr
end
end.
%% @doc Get an approximation of object size by adding together the bucket, key,
%% vectorclock, and all of the siblings. This is more complex than
%% calling term_to_binary/1, but it should be easier on memory,
%% especially for objects with large values.
-spec approximate_size(binary_version(), riak_object()) -> integer().
approximate_size(Vsn, Obj=#r_object{bucket=Bucket,key=Key,vclock=VClock}) ->
Contents = get_contents(Obj),
size(Bucket) + size(Key) + size(term_to_binary(VClock)) + contents_size(Vsn, Contents).
contents_size(Vsn, Contents) ->
lists:sum([metadata_size(Vsn, MD) + value_size(Val) || {MD, Val} <- Contents]).
metadata_size(v0, MD) ->
size(term_to_binary(MD));
metadata_size(v1, MD) ->
size(meta_bin(MD)).
value_size(Value) when is_binary(Value) -> size(Value);
value_size(Value) -> size(term_to_binary(Value)).
%% @doc Convert riak object to binary form
-spec to_binary(binary_version(), riak_object()) -> binary().
to_binary(v0, RObj) ->
term_to_binary(RObj);
to_binary(v1, #r_object{contents=Contents, vclock=VClock}) ->
new_v1(VClock, Contents).
%% @doc convert a binary encoded riak object to a different
%% encoding version. If the binary is already in the desired
%% encoding this is a no-op
-spec to_binary_version(binary_version(), bucket(), key(), binary()) -> binary().
to_binary_version(v0, _, _, <<131,_/binary>>=Bin) ->
Bin;
to_binary_version(v1, _, _, <<?MAGIC:8/integer, 1:8/integer, _/binary>>=Bin) ->
Bin;
to_binary_version(Vsn, B, K, Bin) when is_binary(Bin) ->
to_binary(Vsn, from_binary(B, K, Bin));
to_binary_version(Vsn, _B, _K, Obj = #r_object{}) ->
to_binary(Vsn, Obj).
%% @doc return the binary version the riak object binary is encoded in
-spec binary_version(binary()) -> binary_version().
binary_version(<<131,_/binary>>) -> v0;
binary_version(<<?MAGIC:8/integer, 1:8/integer, _/binary>>) -> v1.
%% @doc Convert binary object to riak object
-spec from_binary(bucket(),key(),binary()) ->
riak_object() | {error, 'bad_object_format'}.
from_binary(_B,_K,<<131, _Rest/binary>>=ObjTerm) ->
binary_to_term(ObjTerm);
from_binary(B,K,<<?MAGIC:8/integer, 1:8/integer, Rest/binary>>=_ObjBin) ->
%% Version 1 of binary riak object
case Rest of
<<VclockLen:32/integer, VclockBin:VclockLen/binary, SibCount:32/integer, SibsBin/binary>> ->
Vclock = binary_to_term(VclockBin),
Contents = sibs_of_binary(SibCount, SibsBin),
#r_object{bucket=B,key=K,contents=Contents,vclock=Vclock};
_Other ->
{error, bad_object_format}
end;
from_binary(_B, _K, Obj = #r_object{}) ->
Obj.
sibs_of_binary(Count,SibsBin) ->
sibs_of_binary(Count, SibsBin, []).
sibs_of_binary(0, <<>>, Result) -> lists:reverse(Result);