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0.3.1
Macula HTTP/3 Mesh SDK — connect, subscribe, publish, call, advertise
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Files
src/macula_feeder.erl
%%%-------------------------------------------------------------------
%%% @doc Behaviour for supervised content feeders (the put/share side).
%%%
%%% `start_link/4,5' returns immediately with a pid, delivers the
%%% outcome to `Module:handle_fed/2', and publishes
%%% `sharing.put_started_v1' / `sharing.put_completed_v1' mesh facts
%%% around the transfer — including `outcome => cancelled' if the
%%% feeder is stopped before the put resolves.
%%%
%%% This is content sharing, not general-purpose RPC streaming — see
%%% `macula_streamer' / `macula_stream_sink' for that (`streaming.*'
%%% facts belong to that pair).
%%%
%%% == Real cancel, real underneath ==
%%%
%%% Internally this drives `macula_content_transfer' (PLAN_PUSH_UPLOAD.md
%%% Phase 4) rather than a blocking `macula:put_content/2' call run in
%%% a linked worker — that blocking shape had no addressable handle to
%%% the actual transfer, so `cancel/1' (`gen_server:stop/1') could only
%%% ever kill the local worker process waiting on it, never touch the
%%% underlying stream. A `macula_content_transfer' cancelled that way
%%% doesn't even notice: nothing links a `gen_server:call' caller's
%%% death to the callee, so it would run to completion, or sit
%%% resolved-but-never-reaped, forever — orphaned, leaking its
%%% `content_stream_bufs' entry on the link and its
%%% `macula_content_transfer_registry' entry, for no purpose. This
%%% module now holds the `macula_content_transfer' pid directly (a
%%% `content_transfer' state field, alongside the lightweight resolve
%%% + await proxy `worker', which asks this process to start the
%%% transfer) so `cancel/1' can call
%%% `macula_content_transfer:cancel/1' on it for real — the same
%%% peer-visible QUIC RESET_STREAM abort described there, not a local
%%% kill with nothing downstream the wiser. The share_id this module
%%% already minted for its own `sharing.*' mesh facts is threaded
%%% through as `macula_content_transfer''s own `share_id' too, so both
%%% layers resolve to the same id.
%%%
%%% == Direct-dial ==
%%%
%%% `start_link/4,5' puts through the pool's own connected link
%%% (whichever `pick_connected_link/1' picks). `start_link_direct/4,5'
%%% is the direct-dial counterpart: unlike `macula_download''s (which
%%% resolves an MCID to find out WHO has it), a PUT already knows its
%%% own target — the caller names `Station' directly, and it is
%%% resolved to a dialable endpoint via that station's own signed
%%% `station_endpoint' record (`macula_direct_dial:resolve_station_endpoint/2',
%%% a fast, non-addressable DHT lookup that stays a plain blocking call
%%% inside the resolve+await proxy — nothing has ever needed to cancel
%%% mid-resolve) and dialed in one hop via `macula_content_transfer:
%%% start_put_station/5', deliberately seeding that specific station
%%% instead of whichever the pool picks. See `macula_direct_dial''s
%%% module doc, "Content" section, for the trust model.
%%%
%%% == Transfer I/O ==
%%%
%%% A feeder starts, awaits and cancels its transfer with `start_put/3',
%%% `start_put_station/5', `await/1' and `cancel/1', the
%%% `macula_content_transfer' ones by default; resolves its station for
%%% `start_link_direct' with `resolve_station_endpoint/2',
%%% `macula_direct_dial''s by default; and announces its facts with
%%% `fact_publish', `macula:publish/4' by default. `start_link/6' and
%%% `start_link_direct/7' take them in their start options, the four
%%% transfer functions as `transfer_io', checked by
%%% `macula_content_transfer:transfer_io/2', and pass a `link_io' option on
%%% to the transfer they start. A function of another shape is refused
%%% with `function_clause', in the caller.
%%%
%%% == Example ==
%%%
%%% ```
%%% -module(doc_feeder).
%%% -behaviour(macula_feeder).
%%% -export([init/1, handle_fed/2]).
%%%
%%% init(Parent) -> {ok, Parent}.
%%%
%%% handle_fed(Result, Parent) ->
%%% Parent ! {fed, Result},
%%% {stop, normal, Parent}.
%%% '''
%%%
%%% ```
%%% {ok, Pid} = macula_feeder:start_link(doc_feeder, Pool, Realm,
%%% Bytes, self()).
%%% '''
%%% @end
%%%-------------------------------------------------------------------
-module(macula_feeder).
-behaviour(gen_server).
-export([start_link/4, start_link/5, start_link/6]).
-export([start_link_direct/5, start_link_direct/6, start_link_direct/7]).
-export([cancel/1]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2]).
-callback init(Args :: term()) ->
{ok, State :: term()} | {stop, Reason :: term()}.
-callback handle_fed(Result :: {ok, macula:mcid()} | {error, term()}, State :: term()) ->
{noreply, NewState :: term()} | {stop, Reason :: term(), NewState :: term()}.
-define(PUT_STARTED, <<"sharing.put_started_v1">>).
-define(PUT_COMPLETED, <<"sharing.put_completed_v1">>).
%% Bounds only the QUIC handshake wait when `start_link_direct/5,6'
%% must dial a fresh link — matches `macula_client:connect/2''s own
%% `connect_timeout_ms' default. The block/manifest transfer that
%% follows has its own separate, internal timeouts regardless.
-define(DIRECT_DIAL_CONNECT_TIMEOUT_MS, 30_000).
-export_type([start_opts/0]).
-type start_opts() :: #{transfer_io => macula_content_transfer:transfer_io(),
resolve_station_endpoint => fun((macula:pool(), macula_node_keys:node_id()) ->
{ok, binary()} | {error, term()}),
fact_publish => macula_lifetime_announcer:publish(),
link_io => macula_content_transfer:link_io()}.
-record(fstate, {
module :: module(),
pool :: macula:pool(),
realm :: macula:realm(),
announce :: boolean(),
transfer_io :: macula_content_transfer:transfer_io(),
fact_publish :: macula_lifetime_announcer:publish(),
share_id :: binary(),
worker :: pid(),
content_transfer :: pid() | undefined,
completed :: boolean(),
user :: term()
}).
%% @doc Start a feeder. Puts `Bytes' into content storage via `Pool'.
-spec start_link(module(), macula:pool(), macula:realm(), binary()) ->
{ok, pid()} | {error, term()}.
start_link(Module, Pool, Realm, Bytes) ->
start_link(Module, Pool, Realm, Bytes, undefined).
%% @doc As `start_link/4', with `Args' passed to `Module:init/1'.
-spec start_link(module(), macula:pool(), macula:realm(), binary(), term()) ->
{ok, pid()} | {error, term()}.
start_link(Module, Pool, Realm, Bytes, Args) ->
start_link(Module, Pool, Realm, Bytes, Args, #{}).
%% @doc As `start_link/5', with start options (see "Transfer I/O" above).
-spec start_link(module(), macula:pool(), macula:realm(), binary(), term(), start_opts()) ->
{ok, pid()} | {error, term()}.
start_link(Module, Pool, Realm, Bytes, Args, Opts) when is_map(Opts) ->
gen_server:start_link(?MODULE,
{pooled, Module, Pool, Realm, Bytes, true, Args, functions(Opts)}, []).
%% @doc As `start_link/4', but resolves `Station''s own
%% `station_endpoint' and dials it directly instead of putting through
%% the pool's existing links. See the "Direct-dial" section above.
-spec start_link_direct(module(), macula:pool(), <<_:256>>,
macula:realm(), binary()) ->
{ok, pid()} | {error, term()}.
start_link_direct(Module, Pool, Station, Realm, Bytes) ->
start_link_direct(Module, Pool, Station, Realm, Bytes, undefined).
%% @doc As `start_link_direct/5', with `Args' passed to `Module:init/1'.
-spec start_link_direct(module(), macula:pool(), <<_:256>>,
macula:realm(), binary(), term()) ->
{ok, pid()} | {error, term()}.
start_link_direct(Module, Pool, Station, Realm, Bytes, Args) ->
start_link_direct(Module, Pool, Station, Realm, Bytes, Args, #{}).
%% @doc As `start_link_direct/6', with start options (see "Transfer I/O"
%% above).
-spec start_link_direct(module(), macula:pool(), macula_node_keys:node_id(),
macula:realm(), binary(), term(), start_opts()) ->
{ok, pid()} | {error, term()}.
start_link_direct(Module, Pool, Station, Realm, Bytes, Args, Opts) when is_map(Opts) ->
gen_server:start_link(?MODULE,
{direct, Module, Pool, Station, Realm, Bytes, true, Args, functions(Opts)}, []).
%% @doc Cancel an in-flight feed. Publishes `sharing.put_completed_v1'
%% with `outcome => cancelled' if the put had not resolved yet.
-spec cancel(pid()) -> ok.
cancel(Pid) -> gen_server:stop(Pid).
%% The functions a feeder runs on, from its start options or else the
%% defaults; one of another shape is refused with function_clause, in the
%% caller. `link_io' goes on to the transfer the feeder starts.
functions(Opts) ->
TransferIo = macula_content_transfer:transfer_io(default_transfer_io(),
maps:get(transfer_io, Opts, undefined)),
#{transfer_io => TransferIo,
resolve_station_endpoint =>
arity_2(maps:get(resolve_station_endpoint, Opts,
fun macula_direct_dial:resolve_station_endpoint/2)),
fact_publish => arity_4(maps:get(fact_publish, Opts, fun macula:publish/4)),
transfer_opts => maps:with([link_io], Opts)}.
default_transfer_io() ->
#{start_put => fun macula_content_transfer:start_put/3,
start_put_station => fun macula_content_transfer:start_put_station/5,
await => fun macula_content_transfer:await/1,
cancel => fun macula_content_transfer:cancel/1}.
arity_2(Fun) when is_function(Fun, 2) -> Fun.
arity_4(Fun) when is_function(Fun, 4) -> Fun.
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
%% @private
init({pooled, Module, Pool, Realm, Bytes, Announce, InitArgs, Functions}) ->
start_feeder(Module, InitArgs, Pool, Realm, Bytes, Announce, Functions,
fun(ShareId) -> spawn_worker(pooled, Functions, Pool, Bytes, ShareId) end);
init({direct, Module, Pool, Station, Realm, Bytes, Announce, InitArgs, Functions}) ->
start_feeder(Module, InitArgs, Pool, Realm, Bytes, Announce, Functions,
fun(ShareId) -> spawn_worker(direct, Functions, Pool, Station, Bytes, ShareId) end).
start_feeder(Module, InitArgs, Pool, Realm, Bytes, Announce,
#{transfer_io := TransferIo, fact_publish := FactPublish}, SpawnFun) ->
process_flag(trap_exit, true),
case Module:init(InitArgs) of
{ok, UserState} ->
ShareId = crypto:strong_rand_bytes(16),
publish(Announce, FactPublish, Pool, Realm, ?PUT_STARTED,
#{share_id => ShareId, size => byte_size(Bytes)}),
Worker = SpawnFun(ShareId),
{ok, #fstate{module = Module, pool = Pool, realm = Realm,
announce = Announce, transfer_io = TransferIo,
fact_publish = FactPublish, share_id = ShareId,
worker = Worker, content_transfer = undefined,
completed = false, user = UserState}};
{stop, Reason} ->
{stop, Reason}
end.
%% The lightweight proxy: have this feeder start the addressable
%% transfer (see `run_transfer/2'), block for the outcome, reap the
%% transfer (a no-op if it's already being cancelled from outside, see
%% `reap_content_transfer/1'), report the outcome.
spawn_worker(pooled, #{transfer_io := TransferIo, transfer_opts := TransferOpts}, Pool, Bytes,
ShareId) ->
Parent = self(),
Start = pooled_put(TransferIo, Pool, Bytes, TransferOpts#{share_id => ShareId}),
spawn_link(fun() -> run_transfer(Parent, TransferIo, Start) end).
%% Resolving `Station''s endpoint stays a plain blocking DHT lookup
%% here (matches what `macula_direct_dial:put_content/4' already did);
%% only the transfer itself becomes addressable.
spawn_worker(direct, Functions, Pool, Station, Bytes, ShareId) ->
Parent = self(),
spawn_link(fun() -> direct_worker_run(Functions, Pool, Station, Bytes, ShareId, Parent) end).
direct_worker_run(#{transfer_io := TransferIo, transfer_opts := TransferOpts,
resolve_station_endpoint := ResolveStationEndpoint},
Pool, Station, Bytes, ShareId, Parent) ->
case ResolveStationEndpoint(Pool, Station) of
{ok, DialUrl} ->
Opts = TransferOpts#{share_id => ShareId, expected_node_id => Station},
run_transfer(Parent, TransferIo, station_put(TransferIo, Pool, DialUrl, Bytes, Opts));
{error, Reason} ->
Parent ! {feed_result, {error, {unresolved, Reason}}}
end.
pooled_put(#{start_put := StartPut}, Pool, Bytes, Opts) ->
fun() -> StartPut(Pool, Bytes, Opts) end.
station_put(#{start_put_station := StartPutStation}, Pool, DialUrl, Bytes, Opts) ->
fun() -> StartPutStation(Pool, DialUrl, Bytes, ?DIRECT_DIAL_CONNECT_TIMEOUT_MS, Opts) end.
%% This feeder starts the transfer itself, in a call from the worker, so
%% the transfer's pid is in the state before any `cancel/1' is handled:
%% a cancel handled first finds nothing started, and a cancel handled
%% after finds the pid.
run_transfer(Parent, #{await := Await} = TransferIo, Start) ->
{ok, CTPid} = gen_server:call(Parent, {start_transfer, Start}, infinity),
Result = Await(CTPid),
reap_content_transfer(TransferIo, CTPid),
Parent ! {feed_result, Result}.
%% @private
handle_call({start_transfer, Start}, _From, State) ->
Started = Start(),
{reply, Started, record_transfer(Started, State)};
handle_call(_Request, _From, State) ->
{reply, {error, unsupported}, State}.
record_transfer({ok, CTPid}, State) -> State#fstate{content_transfer = CTPid};
record_transfer(_NotStarted, State) -> State.
%% @private
handle_cast(_Msg, State) -> {noreply, State}.
%% @private
handle_info({feed_result, Result}, State) ->
NewState = announce_completed(State, Result),
#fstate{module = Module, user = User} = NewState,
deliver(Module:handle_fed(Result, User), NewState#fstate{content_transfer = undefined});
handle_info({'EXIT', Worker, Reason}, #fstate{worker = Worker} = State)
when Reason =/= normal ->
{stop, {worker_crashed, Reason}, State};
handle_info(_Msg, State) ->
{noreply, State}.
deliver({noreply, NewUser}, State) -> {noreply, State#fstate{user = NewUser}};
deliver({stop, Reason, NewUser}, State) -> {stop, Reason, State#fstate{user = NewUser}}.
%% @private
terminate(_Reason, #fstate{worker = Worker, completed = true}) ->
unlink(Worker),
exit(Worker, kill),
ok;
terminate(_Reason, #fstate{transfer_io = TransferIo, content_transfer = CTPid} = State) ->
unlink(State#fstate.worker),
exit(State#fstate.worker, kill),
reap_content_transfer(TransferIo, CTPid),
_ = announce_completed(State, {error, cancelled}),
ok.
%% Killing the proxy `worker' does NOT cascade into stopping the
%% `macula_content_transfer' it waits on — that gen_server traps exits
%% and doesn't recognize this feeder or the proxy as one of ITS OWN
%% tracked workers, so an incoming exit signal just falls through its
%% catch-all `handle_info' clause, unnoticed. This is the actual fix:
%% reach in and cancel it explicitly. `undefined' covers a cancel
%% handled before the worker asked for the transfer to start (still
%% resolving, for direct-dial): nothing was started. `catch' covers the
%% benign race where the proxy's own natural reap (in `run_transfer/2')
%% and an external `cancel/1' land at the same time — the second
%% `cancel/1' call reaches an already-dead pid.
reap_content_transfer(_TransferIo, undefined) -> ok;
reap_content_transfer(#{cancel := Cancel}, CTPid) ->
try Cancel(CTPid) catch _:_ -> ok end,
ok.
announce_completed(#fstate{completed = true} = State, _Result) ->
State;
announce_completed(#fstate{pool = Pool, realm = Realm, announce = Announce,
fact_publish = FactPublish, share_id = ShareId} = State,
Result) ->
publish(Announce, FactPublish, Pool, Realm, ?PUT_COMPLETED,
outcome_fields(#{share_id => ShareId}, Result)),
State#fstate{completed = true}.
outcome_fields(Base, {ok, Mcid}) ->
Base#{outcome => completed, mcid => Mcid, chunked => is_chunked_mcid(Mcid)};
outcome_fields(Base, {error, cancelled}) ->
Base#{outcome => cancelled};
outcome_fields(Base, {error, Reason}) ->
Base#{outcome => failed, reason => Reason}.
is_chunked_mcid(<<2, 16#56, _/binary>>) -> true;
is_chunked_mcid(_) -> false.
publish(false, _FactPublish, _, _, _, _) -> ok;
publish(true, FactPublish, Pool, Realm, Topic, Payload) ->
_ = FactPublish(Pool, Realm, Topic, Payload), ok.