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Test case for inner retries; add mrdb_stats.erl; update docs

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This commit is contained in:
Ulf Wiger
2022-11-03 12:41:14 +01:00
parent 95abe4e36e
commit 3635eac717
21 changed files with 2982 additions and 41 deletions
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src/mnesia_rocksdb_admin.erl
+2
View File
@@ -407,12 +407,14 @@ try_load_admin_db(Alias, AliasOpts, #st{ backends = Bs
%% We need to store the persistent ref explicitly here,
%% since mnesia knows nothing of our admin table.
AdminTab = {admin, Alias},
Stats = mrdb_stats:new(),
CfI = update_cf_info(AdminTab, #{ status => open
, name => AdminTab
, vsn => ?VSN
, encoding => {sext,{value,term}}
, attr_pos => #{key => 1,
value => 2}
, stats => Stats
, mountpoint => MP
, properties =>
#{ attributes => [key, val]
src/mrdb.erl
+74 -27
View File
@@ -117,7 +117,9 @@
| index()
| retainer().
-type retries() :: non_neg_integer().
-type inner() :: non_neg_integer().
-type outer() :: non_neg_integer().
-type retries() :: outer() | {inner(), outer()}.
%% activity type 'ets' makes no sense in this context
-type mnesia_activity_type() :: transaction
@@ -143,7 +145,7 @@
-type tx_activity() :: #{ type := 'tx'
, handle := tx_handle()
, attempt := non_neg_integer() }.
, attempt := 'undefined' | retries() }.
-type batch_activity() :: #{ type := 'batch'
, handle := batch_handle() }.
-type activity() :: tx_activity() | batch_activity().
@@ -256,6 +258,14 @@ release_snapshot(SHandle) ->
%% The re-run transaction may still fail, if new transactions, or non-transaction writes interfere with
%% the commit set. It will then be re-run again, until the retry count is exhausted.
%%
%% For finer-grained retries, it's possible to set `retries => {Inner, Outer}'. Setting the retries to a
%% single number, `Retries', is analogous to `{0, Retries}`. Each outer retry requests a 'mutex lock' by
%% waiting in a FIFO queue. Once it receives the lock, it will try the activity once + as many retries
%% as specified by `Inner'. If these fail, the activity again goes to the FIFO queue (ending up last
%% in line) if there are outer retries remaining. When all retries are exhaused, the activity aborts
%% with `retry_limit'. Note that transactions, being optimistic, do not request a lock on the first
%% attempt, but only on outer retries (the first retry is always an outer retry).
%%
%% Valid `TxOpts' are `#{no_snapshot => boolean(), retries => retries()}'.
%%
%% To simplify code adaptation, `tx | transaction | sync_transaction' are synonyms, and
@@ -277,32 +287,66 @@ activity(Type, Alias, F) ->
, alias => Alias
, db_ref => DbRef }
end,
do_activity(F, Alias, Ctxt, false).
do_activity(F, Alias, Ctxt).
do_activity(F, Alias, Ctxt, WithLock) ->
try run_f(F, Ctxt, WithLock, Alias) of
do_activity(F, Alias, Ctxt) ->
try try_f(F, Ctxt)
catch
throw:{?MODULE, busy} ->
retry_activity(F, Alias, Ctxt)
end.
try_f(F, Ctxt) ->
try run_f(F, Ctxt) of
Res ->
try commit_and_pop(Res)
catch
throw:{?MODULE, busy} ->
do_activity(F, Alias, Ctxt, true)
end
commit_and_pop(Res)
catch
Cat:Err ->
abort_and_pop(Cat, Err)
end.
-spec run_f(_, #{'activity':=#{'handle':=_, 'type':='batch' | 'tx', 'attempt'=>1, 'no_snapshot'=>boolean(), 'retries'=>non_neg_integer(), _=>_}, 'alias':=_, 'db_ref':=_, 'no_snapshot'=>boolean(), 'retries'=>non_neg_integer(), _=>_}, boolean(), _) -> any().
run_f(F, Ctxt, false, _) ->
run_f(F, Ctxt) ->
push_ctxt(Ctxt),
F();
run_f(F, Ctxt, true, Alias) ->
push_ctxt(incr_attempt(Ctxt)),
mrdb_mutex:do(Alias, F).
F().
incr_attempt(#{ activity := #{type := tx, attempt := A} = Act, db_ref := DbRef } = C) ->
incr_attempt(0, {_,O}) when O > 0 ->
{outer, {0,1}};
incr_attempt({I,O}, {Ri,Ro}) when is_integer(I), is_integer(O),
is_integer(Ri), is_integer(Ro) ->
if I < Ri -> {inner, {I+1, O}};
O < Ro -> {outer, {0, O+1}};
true ->
error
end;
incr_attempt(_, _) ->
error.
retry_activity(F, Alias, #{activity := #{ type := Type
, attempt := A
, retries := R} = Act} = Ctxt) ->
case incr_attempt(A, R) of
{RetryCtxt, A1} ->
Act1 = Act#{attempt := A1},
Ctxt1 = Ctxt#{activity := Act1},
try retry_activity_(RetryCtxt, F, Alias, restart_ctxt(Ctxt1))
catch
throw:{?MODULE, busy} ->
retry_activity(F, Alias, Ctxt1)
end;
error ->
return_abort(Type, error, retry_limit)
end.
retry_activity_(inner, F, Alias, Ctxt) ->
mrdb_stats:incr(Alias, inner_retries, 1),
try_f(F, Ctxt);
retry_activity_(outer, F, Alias, Ctxt) ->
mrdb_stats:incr(Alias, outer_retries, 1),
mrdb_mutex:do(Alias, fun() -> try_f(F, Ctxt) end).
restart_ctxt(#{ activity := #{type := tx} = Act, db_ref := DbRef } = C) ->
{ok, TxH} = rdb_transaction(DbRef, []),
Act1 = Act#{attempt := A+1, handle := TxH},
Act1 = Act#{handle := TxH},
C1 = C#{ activity := Act1 },
case maps:is_key(snapshot, C) of
true ->
@@ -375,10 +419,14 @@ check_tx_opts(Opts) ->
end.
check_retries(#{retries := Retries} = Opts) ->
if is_integer(Retries), Retries >= 0 ->
Opts;
true ->
error({invalid_tx_option, {retries, Retries}})
case Retries of
_ when is_integer(Retries), Retries >= 0 ->
Opts#{retries := {0, Retries}};
{Inner, Outer} when is_integer(Inner), is_integer(Outer),
Inner >= 0, Outer >= 0 ->
Opts;
_ ->
error({invalid_tx_option, {retries, Retries}})
end.
check_nosnap(#{no_snapshot := NoSnap} = Opts) ->
@@ -393,7 +441,7 @@ create_tx(Opts, DbRef) ->
{ok, TxH} = rdb_transaction(DbRef, []),
Opts#{activity => maps:merge(Opts, #{ type => tx
, handle => TxH
, attempt => 1})}.
, attempt => 0 })}.
maybe_snapshot(#{no_snapshot := NoSnap} = Opts, DbRef) ->
case NoSnap of
@@ -413,8 +461,7 @@ commit_and_pop(Res) ->
Res;
{error, {error, "Resource busy" ++ _ = Busy}} ->
case A of
#{retries := Retries, attempt := Att}
when Att =< Retries ->
#{retries := {I,O}} when I > 0; O > 0 ->
throw({?MODULE, busy});
_ ->
error({error, Busy})
@@ -530,7 +577,7 @@ new_tx(#{activity := _}, _) ->
new_tx(Tab, Opts) ->
#{db_ref := DbRef} = R = ensure_ref(Tab),
{ok, TxH} = rdb_transaction(DbRef, write_opts(R, Opts)),
R#{activity => #{type => tx, handle => TxH, attempt => 1}}.
R#{activity => #{type => tx, handle => TxH, attempt => 0}}.
-spec tx_ref(ref_or_tab() | db_ref() | db_ref(), tx_handle()) -> db_ref().
tx_ref(Tab, TxH) ->
@@ -540,7 +587,7 @@ tx_ref(Tab, TxH) ->
#{activity := #{type := tx, handle := OtherTxH}} ->
error({tx_handle_conflict, OtherTxH});
R ->
R#{activity => #{type => tx, handle => TxH, attempt => 1}}
R#{activity => #{type => tx, handle => TxH, attempt => 0}}
end.
-spec tx_commit(tx_handle() | db_ref()) -> ok.
src/mrdb_stats.erl
+74
View File
@@ -0,0 +1,74 @@
%% -*- mode: erlang; erlang-indent-level: 4; indent-tabs-mode: nil -*-
%% @doc Statistics API for the mnesia_rocksdb plugin
%%
%% Some counters are maintained for each active alias. Currently, the following
%% counters are supported:
%% * inner_retries
%% * outer_retries
%%
-module(mrdb_stats).
-export([new/0]).
-export([incr/3,
get/1,
get/2]).
-type alias() :: mnesia_rocksdb:alias().
-type db_ref() :: mrdb:db_ref().
-type counter() :: atom().
-type increment() :: integer().
-type counters() :: #{ counter() := integer() }.
new() ->
#{ ref => counters:new(map_size(ctr_meta()), [write_concurrency])
, meta => ctr_meta()}.
ctr_meta() ->
#{ inner_retries => 1
, outer_retries => 2 }.
-spec incr(alias() | db_ref(), counter(), increment()) -> ok.
%% @doc Increment `Ctr' counter for `Alias` with increment `N'.
%%
%% Note that the first argument may also be a `db_ref()' map,
%% corresponding to `mrdb:get_ref({admin, Alias})'.
%% @end
incr(Alias, Ctr, N) when is_atom(Alias) ->
#{stats := #{ref := Ref, meta := Meta}} = mrdb:get_ref({admin, Alias}),
incr_(Ref, Meta, Ctr, N);
incr(#{stats := #{ref := Ref, meta := Meta}}, Ctr, N) ->
incr_(Ref, Meta, Ctr, N).
-spec get(alias() | db_ref(), counter()) -> integer().
%% @doc Fetches the integer value of the known counter `Ctr' for `Alias'.
%% @end
get(Alias, Ctr) when is_atom(Alias) ->
#{stats := #{ref := Ref, meta := Meta}} = mrdb:get_ref({admin, Alias}),
get_(Ref, Meta, Ctr);
get(#{stats := #{ref := Ref, meta := Meta}}, Ctr) ->
get_(Ref, Meta, Ctr).
-spec get(alias() | db_ref()) -> counters().
%% @doc Fetches all known counters for `Alias', in the form of a map,
%% `#{Counter => Value}'.
%% @end
get(Alias) when is_atom(Alias) ->
get_(mrdb:get_ref({admin, Alias}));
get(Ref) when is_map(Ref) ->
get_(Ref).
get_(#{stats := #{ref := Ref, meta := Meta}}) ->
lists:foldl(
fun({K, P}, M) ->
M#{K := counters:get(Ref, P)}
end, Meta, maps:to_list(Meta)).
get_(Ref, Meta, Attr) ->
Ix = maps:get(Attr, Meta),
counters:get(Ref, Ix).
incr_(Ref, Meta, Attr, N) ->
Ix = maps:get(Attr, Meta),
counters:add(Ref, Ix, N).