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Snapshot Work - Interim Commit

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Some initial work to get snapshots going.

Changes required, as need to snapshot through the Bookie to ensure that
there is no race between extracting the Bookie's in-memory view and the
Penciller's view if a push_to_mem has occurred inbetween.

A lot still outstanding, especially around Inker snapshots, and handling
timeouts
This commit is contained in:
martinsumner 2016-09-23 18:50:29 +01:00
parent d3e985ed80
commit c64d67d9fb
5 changed files with 160 additions and 75 deletions
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96
src/leveled_penciller.erl
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@ -235,6 +235,7 @@
pcl_close/1,
pcl_registersnapshot/2,
pcl_updatesnapshotcache/3,
pcl_loadsnapshot/2,
pcl_getstartupsequencenumber/1,
roll_new_tree/3,
clean_testdir/1]).
@ -254,7 +255,7 @@
-define(PROMPT_WAIT_ONL0, 5).
-define(L0PEND_RESET, {false, null, null}).
-record(l0snapshot, {increments = [] :: list,
-record(l0snapshot, {increments = [] :: list(),
tree = gb_trees:empty() :: gb_trees:tree(),
ledger_sqn = 0 :: integer()}).
@ -269,9 +270,13 @@
clerk :: pid(),
levelzero_pending = ?L0PEND_RESET :: tuple(),
memtable_copy = #l0snapshot{} :: #l0snapshot{},
levelzero_snapshot = gb_trees:empty() :: gb_trees:tree(),
memtable,
backlog = false :: boolean(),
memtable_maxsize :: integer()}).
memtable_maxsize :: integer(),
is_snapshot = false :: boolean(),
snapshot_fully_loaded = false :: boolean(),
source_penciller :: pid()}).
@ -313,6 +318,9 @@ pcl_registersnapshot(Pid, Snapshot) ->
pcl_updatesnapshotcache(Pid, Tree, SQN) ->
gen_server:cast(Pid, {update_snapshotcache, Tree, SQN}).
pcl_loadsnapshot(Pid, Increment) ->
gen_server:call(Pid, {load_snapshot, Increment}, infinity).
pcl_close(Pid) ->
gen_server:call(Pid, close).
@ -322,10 +330,21 @@ pcl_close(Pid) ->
%%%============================================================================
init([PCLopts]) ->
case PCLopts#penciller_options.root_path of
undefined ->
{ok, #state{}};
_RootPath ->
case {PCLopts#penciller_options.root_path,
PCLopts#penciller_options.start_snapshot} of
{undefined, true} ->
SrcPenciller = PCLopts#penciller_options.source_penciller,
{ok, {LedgerSQN,
MemTableCopy,
Manifest}} = pcl_registersnapshot(SrcPenciller, self()),
{ok, #state{memtable_copy=MemTableCopy,
is_snapshot=true,
source_penciller=SrcPenciller,
manifest=Manifest,
ledger_sqn=LedgerSQN}};
%% Need to do something about timeout
{_RootPath, false} ->
start_from_file(PCLopts)
end.
@ -474,6 +493,22 @@ handle_call({register_snapshot, Snapshot}, _From, State) ->
State#state.manifest,
State#state.memtable_copy},
State#state{registered_snapshots = Rs}};
handle_call({load_snapshot, Increment}, _From, State) ->
MemTableCopy = State#state.memtable_copy,
{Tree0, TreeSQN0} = roll_new_tree(MemTableCopy#l0snapshot.tree,
MemTableCopy#l0snapshot.increments,
MemTableCopy#l0snapshot.ledger_sqn),
if
TreeSQN0 > MemTableCopy#l0snapshot.ledger_sqn ->
pcl_updatesnapshotcache(State#state.source_penciller,
Tree0,
TreeSQN0)
end,
{Tree1, TreeSQN1} = roll_new_tree(Tree0, [Increment], TreeSQN0),
io:format("Snapshot loaded to start at SQN~w~n", [TreeSQN1]),
{reply, ok, State#state{levelzero_snapshot=Tree1,
ledger_sqn=TreeSQN1,
snapshot_fully_loaded=true}};
handle_call(close, _From, State) ->
{stop, normal, ok, State}.
@ -539,19 +574,6 @@ terminate(_Reason, State) ->
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%============================================================================
%%% External functions
%%%============================================================================
roll_new_tree(Tree, [], HighSQN) ->
{Tree, HighSQN};
roll_new_tree(Tree, [{SQN, KVList}|TailIncs], HighSQN) when SQN >= HighSQN ->
UpdTree = lists:foldl(fun({K, V}, TreeAcc) ->
gb_trees:enter(K, V, TreeAcc) end,
Tree,
KVList),
roll_new_tree(UpdTree, TailIncs, SQN).
%%%============================================================================
%%% Internal functions
@ -829,6 +851,19 @@ return_work(State, From) ->
{State, none}
end.
%% This takes the three parts of a memtable copy - the increments, the tree
%% and the SQN at which the tree was formed, and outputs a new tree
roll_new_tree(Tree, [], HighSQN) ->
{Tree, HighSQN};
roll_new_tree(Tree, [{SQN, KVList}|TailIncs], HighSQN) when SQN >= HighSQN ->
UpdTree = lists:foldl(fun({K, V}, TreeAcc) ->
gb_trees:enter(K, V, TreeAcc) end,
Tree,
KVList),
roll_new_tree(UpdTree, TailIncs, SQN).
%% Update the memtable copy if the tree created advances the SQN
cache_tree_in_memcopy(MemCopy, Tree, SQN) ->
case MemCopy#l0snapshot.ledger_sqn of
@ -855,7 +890,6 @@ add_increment_to_memcopy(MemCopy, SQN, KVList) ->
Incs = MemCopy#l0snapshot.increments ++ [{SQN, KVList}],
MemCopy#l0snapshot{increments=Incs}.
close_files(?MAX_LEVELS - 1, _Manifest) ->
ok;
close_files(Level, Manifest) ->
@ -1182,5 +1216,27 @@ memcopy_test() ->
Size1 = gb_trees:size(Tree1),
?assertMatch(2000, Size1),
?assertMatch(3000, HighSQN1).
memcopy_updatecache_test() ->
KVL1 = lists:map(fun(X) -> {"Key" ++ integer_to_list(X),
"Value" ++ integer_to_list(X) ++ "A"} end,
lists:seq(1, 1000)),
KVL2 = lists:map(fun(X) -> {"Key" ++ integer_to_list(X),
"Value" ++ integer_to_list(X) ++ "B"} end,
lists:seq(1001, 2000)),
KVL3 = lists:map(fun(X) -> {"Key" ++ integer_to_list(X),
"Value" ++ integer_to_list(X) ++ "C"} end,
lists:seq(1, 1000)),
MemCopy0 = #l0snapshot{},
MemCopy1 = add_increment_to_memcopy(MemCopy0, 1000, KVL1),
MemCopy2 = add_increment_to_memcopy(MemCopy1, 2000, KVL2),
MemCopy3 = add_increment_to_memcopy(MemCopy2, 3000, KVL3),
?assertMatch(0, MemCopy3#l0snapshot.ledger_sqn),
{Tree1, HighSQN1} = roll_new_tree(gb_trees:empty(), MemCopy3#l0snapshot.increments, 0),
MemCopy4 = cache_tree_in_memcopy(MemCopy3, Tree1, HighSQN1),
?assertMatch(0, length(MemCopy4#l0snapshot.increments)),
Size2 = gb_trees:size(MemCopy4#l0snapshot.tree),
?assertMatch(2000, Size2),
?assertMatch(3000, MemCopy4#l0snapshot.ledger_sqn).
-endif.