%%%----------------------------------------------------------------- %%% Overload protection configuration %%! *** NOTE *** %%! It's important that: %%! TOGGLE_SYNC_QLEN < DROP_NEW_REQS_QLEN < FLUSH_REQS_QLEN %%! and that DROP_NEW_REQS_QLEN >= 2. %%! Otherwise the handler could end up in drop mode with no new %%! log requests to process. This would cause all future requests %%! to be dropped (no switch to async mode would ever take place). %% This specifies the message_queue_len value where the log %% requests switch from asynchronous casts to synchronous calls. -define(TOGGLE_SYNC_QLEN, 10). %% Above this message_queue_len, log requests will be dropped, %% i.e. no log requests get sent to the handler process. -define(DROP_NEW_REQS_QLEN, 200). %% Above this message_queue_len, the handler process will flush %% its mailbox and only leave this number of messages in it. -define(FLUSH_REQS_QLEN, 1000). %% Never flush more than this number of messages in one go, %% or the handler will be unresponsive for seconds (keep this %% number as large as possible or the mailbox could grow large). -define(FLUSH_MAX_N, 5000). %% BURST_LIMIT is the max number of log requests allowed to be %% written within a BURST_WINDOW_TIME time frame. -define(ENABLE_BURST_LIMIT, true). -define(BURST_LIMIT_SIZE, 500). -define(BURST_WINDOW_TIME, 1000). %% This enables/disables the feature to automatically get the %% handler terminated if it gets too loaded (and can't keep up). -define(ENABLE_KILL_OVERLOADED, false). %% If the message_queue_len goes above this size even after %% flushing has been performed, the handler is terminated. -define(HANDLER_OVERLOADED_QLEN, 20000). %% If the memory usage exceeds this level -define(HANDLER_OVERLOADED_MEM, 3000000). %% This is the default time that the handler will wait before %% restarting and accepting new requests. The value 'never' %% disables restarts. -define(HANDLER_RESTART_AFTER, 5000). %%-define(HANDLER_RESTART_AFTER, never). %% The handler sends asynchronous write requests to the process %% controlling the i/o device, but every once in this interval %% will the write request be synchronous, so that the i/o device %% process doesn't get overloaded. This gives the handler time %% to keep up with its mailbox in overload situations, even if %% the i/o is slow. -define(CONTROLLER_SYNC_INTERVAL, 20). %% The handler will not perform a file sync operation if the %% mailbox size is greater than this number. This is to ensure %% the handler process doesn't get overloaded while waiting for %% an expensive file sync operation to finish. -define(FILESYNC_OK_QLEN, 2). %% Do a file/disk_log sync operation every integer() millisec %% (if necessary) or set to 'no_repeat' to only do file sync when %% the handler is idle. Note that file sync is not guaranteed to %% happen automatically if this operation is disabled. -define(FILESYNC_REPEAT_INTERVAL, 5000). %%-define(FILESYNC_REPEAT_INTERVAL, no_repeat). %% This is the time after last message received that we think/hope %% that the handler has an empty mailbox (no new log request has %% come in). -define(IDLE_DETECT_TIME_MSEC, 100). -define(IDLE_DETECT_TIME_USEC, 100000). %% Default disk log option values -define(DISK_LOG_TYPE, wrap). -define(DISK_LOG_MAX_NO_FILES, 10). -define(DISK_LOG_MAX_NO_BYTES, 1048576). %%%----------------------------------------------------------------- %%% Overload protection macros -define(timestamp(), erlang:monotonic_time(microsecond)). -define(get_mode(HandlerName), case ets:lookup(HandlerName, mode) of [{mode,sync}] -> case whereis(HandlerName)==self() of true -> async; _ -> sync end; [{mode,M}] -> M; _ -> async end). -define(set_mode(HandlerName, M), begin ets:insert(HandlerName, {mode,M}), M end). -define(change_mode(HandlerName, M0, M1), if M0 == M1 -> M0; true -> ets:insert(HandlerName, {mode,M1}), M1 end). -define(min(X1, X2), if X2 == undefined -> X1; X2 < X1 -> X2; true -> X1 end). -define(max(X1, X2), if X2 == undefined -> X1; X2 > X1 -> X2; true -> X1 end). -define(diff_time(OS_T1, OS_T0), OS_T1-OS_T0). %%%----------------------------------------------------------------- %%% The test hook macros make it possible to observe and manipulate %%% internal handler functionality. When enabled, these macros will %%% slow down execution and therefore should not be include in code %%% to be officially released. %% -define(TEST_HOOKS, true). -ifdef(TEST_HOOKS). -define(TEST_HOOKS_TAB, logger_h_test_hooks). -define(init_test_hooks(), _ = case ets:whereis(?TEST_HOOKS_TAB) of undefined -> ets:new(?TEST_HOOKS_TAB, [named_table,public]); _ -> ok end, ets:insert(?TEST_HOOKS_TAB, {internal_log,{logger,internal_log}}), ets:insert(?TEST_HOOKS_TAB, {file_write,ok}), ets:insert(?TEST_HOOKS_TAB, {file_datasync,ok}), ets:insert(?TEST_HOOKS_TAB, {disk_log_blog,ok}), ets:insert(?TEST_HOOKS_TAB, {disk_log_sync,ok})). -define(set_internal_log(MOD_FUNC), ets:insert(?TEST_HOOKS_TAB, {internal_log,MOD_FUNC})). -define(set_result(OPERATION, RESULT), ets:insert(?TEST_HOOKS_TAB, {OPERATION,RESULT})). -define(set_defaults(), ets:insert(?TEST_HOOKS_TAB, {internal_log,{logger,internal_log}}), ets:insert(?TEST_HOOKS_TAB, {file_write,ok}), ets:insert(?TEST_HOOKS_TAB, {file_datasync,ok}), ets:insert(?TEST_HOOKS_TAB, {disk_log_blog,ok}), ets:insert(?TEST_HOOKS_TAB, {disk_log_sync,ok})). -define(internal_log(TYPE, TERM), try ets:lookup(?TEST_HOOKS_TAB, internal_log) of [{_,{LMOD,LFUNC}}] -> apply(LMOD, LFUNC, [TYPE,TERM]); _ -> logger:internal_log(TYPE, TERM) catch _:_ -> logger:internal_log(TYPE, TERM) end). -define(file_write(DEVICE, DATA), try ets:lookup(?TEST_HOOKS_TAB, file_write) of [{_,ok}] -> file:write(DEVICE, DATA); [{_,ERROR}] -> ERROR catch _:_ -> file:write(DEVICE, DATA) end). -define(file_datasync(DEVICE), try ets:lookup(?TEST_HOOKS_TAB, file_datasync) of [{_,ok}] -> file:datasync(DEVICE); [{_,ERROR}] -> ERROR catch _:_ -> file:datasync(DEVICE) end). -define(disk_log_blog(LOG, DATA), try ets:lookup(?TEST_HOOKS_TAB, disk_log_blog) of [{_,ok}] -> disk_log:blog(LOG, DATA); [{_,ERROR}] -> ERROR catch _:_ -> disk_log:blog(LOG, DATA) end). -define(disk_log_sync(LOG), try ets:lookup(?TEST_HOOKS_TAB, disk_log_sync) of [{_,ok}] -> disk_log:sync(LOG); [{_,ERROR}] -> ERROR catch _:_ -> disk_log:sync(LOG) end). -define(DEFAULT_CALL_TIMEOUT, 5000). -else. % DEFAULTS! -define(TEST_HOOKS_TAB, undefined). -define(init_test_hooks(), ok). -define(set_internal_log(_MOD_FUNC), ok). -define(set_result(_OPERATION, _RESULT), ok). -define(set_defaults(), ok). -define(internal_log(TYPE, TERM), logger:internal_log(TYPE, TERM)). -define(file_write(DEVICE, DATA), file:write(DEVICE, DATA)). -define(file_datasync(DEVICE), file:datasync(DEVICE)). -define(disk_log_blog(LOG, DATA), disk_log:blog(LOG, DATA)). -define(disk_log_sync(LOG), disk_log:sync(LOG)). -define(DEFAULT_CALL_TIMEOUT, 10000). -endif. %%%----------------------------------------------------------------- %%% These macros enable statistics counters in the state of the %%% handler which is useful for analysing the overload protection %%% behaviour. These counters should not be included in code to be %%% officially released (as some counters will grow very large %%% over time). %%-define(SAVE_STATS, true). -ifdef(SAVE_STATS). -define(merge_with_stats(STATE), STATE#{flushes => 0, flushed => 0, drops => 0, casts => 0, calls => 0, max_qlen => 0, max_time => 0}). -define(update_max_qlen(QLEN, STATE), begin #{max_qlen := QLEN0} = STATE, STATE#{max_qlen => ?max(QLEN0,QLEN)} end). -define(update_calls_or_casts(CALL_OR_CAST, INC, STATE), case CALL_OR_CAST of cast -> #{casts := CASTS0} = STATE, STATE#{casts => CASTS0+INC}; call -> #{calls := CALLS0} = STATE, STATE#{calls => CALLS0+INC} end). -define(update_max_time(TIME, STATE), begin #{max_time := TIME0} = STATE, STATE#{max_time => ?max(TIME0,TIME)} end). -define(update_other(OTHER, VAR, INCVAL, STATE), begin #{OTHER := VAR} = STATE, STATE#{OTHER => VAR+INCVAL} end). -else. % DEFAULT! -define(merge_with_stats(STATE), STATE). -define(update_max_qlen(_QLEN, STATE), STATE). -define(update_calls_or_casts(_CALL_OR_CAST, _INC, STATE), STATE). -define(update_max_time(_TIME, STATE), STATE). -define(update_other(_OTHER, _VAR, _INCVAL, STATE), STATE). -endif. %%%----------------------------------------------------------------- %%% These macros enable callbacks that make it possible to analyse %%% the overload protection behaviour from outside the handler %%% process (including dropped requests on the client side). %%% An external callback module (?OBSERVER_MOD) is required which %%% is not part of the kernel application. For this reason, these %%% callbacks should not be included in code to be officially released. %%-define(OBSERVER_MOD, logger_test). -ifdef(OBSERVER_MOD). -define(start_observation(NAME), ?OBSERVER:start_observation(NAME)). -define(observe(NAME,EVENT), ?OBSERVER:observe(NAME,EVENT)). -else. % DEFAULT! -define(start_observation(_NAME), ok). -define(observe(_NAME,_EVENT), ok). -endif. %%! <---