machi/src/machi_projection_store.erl

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%% -------------------------------------------------------------------
%%
%% Copyright (c) 2007-2015 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.
%%
%% -------------------------------------------------------------------
-module(machi_projection_store).
-include("machi_projection.hrl").
%% API
-export([
start_link/3,
write/3, write/4
]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-record(state, {
public_dir = "" :: string(),
private_dir = "" :: string(),
wedged = true :: boolean(),
wedge_notify_pid :: pid() | atom(),
max_public_epoch = -1 :: non_neg_integer(),
max_private_epoch = -1 :: non_neg_integer()
}).
start_link(RegName, DataDir, NotifyWedgeStateChanges) ->
gen_server:start_link({local, RegName},
?MODULE, [DataDir, NotifyWedgeStateChanges], []).
write(PidSpec, ProjType, Proj) ->
write(PidSpec, ProjType, Proj, infinity).
write(PidSpec, ProjType, Proj, Timeout)
when ProjType == 'public' orelse ProjType == 'private',
is_record(Proj, projection_v1) ->
g_call(PidSpec, {write, ProjType, Proj}, Timeout).
init([DataDir, NotifyWedgeStateChanges]) ->
lclock_init(),
PublicDir = machi_util:make_projection_filename(DataDir, "public"),
PrivateDir = machi_util:make_projection_filename(DataDir, "private"),
ok = filelib:ensure_dir(PublicDir ++ "/ignored"),
ok = filelib:ensure_dir(PrivateDir ++ "/ignored"),
MaxPublicEpoch = find_max_epoch(PublicDir),
MaxPrivateEpoch = find_max_epoch(PrivateDir),
{ok, #state{public_dir=PublicDir,
private_dir=PrivateDir,
wedged=true,
wedge_notify_pid=NotifyWedgeStateChanges,
max_public_epoch=MaxPublicEpoch,
max_private_epoch=MaxPrivateEpoch}}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%
g_call(PidSpec, Arg, Timeout) ->
LC1 = lclock_get(),
{Res, LC2} = gen_server:call(PidSpec, {Arg, LC1}, Timeout),
lclock_update(LC2),
Res.
%%%%%%%%%%%%%%%%%%%%%%%%%%%
handle_call({{write, ProjType, Proj}, LC1}, _From, S) ->
LC2 = lclock_update(LC1),
{Reply, NewS} = do_proj_write(ProjType, Proj, S),
{reply, {Reply, LC2}, NewS};
handle_call(_Request, _From, S) ->
Reply = whaaaaaaaaaaaaa,
{reply, Reply, S}.
handle_cast(_Msg, S) ->
{noreply, S}.
handle_info(_Info, S) ->
{noreply, S}.
terminate(_Reason, _S) ->
ok.
code_change(_OldVsn, S, _Extra) ->
{ok, S}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%
do_proj_write(ProjType, #projection_v1{epoch_number=Epoch}=Proj, S) ->
%% TODO: We probably ought to check the projection checksum for sanity, eh?
Dir = pick_path(ProjType, S),
Path = filename:join(Dir, epoch2name(Epoch)),
case file:read_file_info(Path) of
{ok, _FI} ->
{{error, written}, S};
{error, enoent} ->
{ok, FH} = file:open(Path, [write, raw, binary]),
ok = file:write(FH, term_to_binary(Proj)),
ok = file:sync(FH),
ok = file:close(FH),
{ok, S};
{error, Else} ->
{{error, Else}, S}
end.
pick_path(public, S) ->
S#state.public_dir;
pick_path(private, S) ->
S#state.private_dir.
epoch2name(Epoch) ->
machi_util:int_to_hexstr(Epoch, 32).
name2epoch(Name) ->
machi_util:hexstr_to_int(Name).
find_max_epoch(Dir) ->
Fs = lists:sort(filelib:wildcard("*", Dir)),
if Fs == [] ->
-1;
true ->
name2epoch(lists:last(Fs))
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%
-ifdef(TEST).
lclock_init() ->
lamport_clock:init().
lclock_get() ->
lamport_clock:get().
lclock_update(LC) ->
lamport_clock:update(LC).
-else. % TEST
lclock_init() ->
ok.
lclock_get() ->
ok.
lclock_update(_LC) ->
ok.
-endif. % TEST