aboutsummaryrefslogtreecommitdiffstats
path: root/lib/kernel/src/group_history.erl
diff options
context:
space:
mode:
Diffstat (limited to 'lib/kernel/src/group_history.erl')
-rw-r--r--lib/kernel/src/group_history.erl341
1 files changed, 341 insertions, 0 deletions
diff --git a/lib/kernel/src/group_history.erl b/lib/kernel/src/group_history.erl
new file mode 100644
index 0000000000..5ca5e2d1dd
--- /dev/null
+++ b/lib/kernel/src/group_history.erl
@@ -0,0 +1,341 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%%
+%% Licensed 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.
+%%
+%% %CopyrightEnd%
+%%
+-module(group_history).
+-export([load/0, add/1]).
+
+%% Make a minimal size that should encompass set of lines and then make
+%% a file rotation for N files of this size.
+-define(DEFAULT_HISTORY_FILE, "erlang-shell-log").
+-define(MAX_HISTORY_FILES, 10).
+-define(DEFAULT_SIZE, 1024*512). % 512 kb total default
+-define(DEFAULT_STATUS, disabled).
+-define(MIN_HISTORY_SIZE, (50*1024)). % 50 kb, in bytes
+-define(DEFAULT_DROP, []).
+-define(DISK_LOG_FORMAT, internal). % since we want repairs
+-define(LOG_NAME, '$#group_history').
+-define(VSN, {0,1,0}).
+
+%%%%%%%%%%%%%%
+%%% PUBLIC %%%
+%%%%%%%%%%%%%%
+
+%% @doc Loads the shell history from memory. This function should only be
+%% called from group:server/3 to inject itself in the previous commands
+%% stack.
+-spec load() -> [string()].
+load() ->
+ wait_for_kernel_safe_sup(),
+ case history_status() of
+ enabled ->
+ case open_log() of
+ {ok, ?LOG_NAME} ->
+ read_full_log(?LOG_NAME);
+ {repaired, ?LOG_NAME, {recovered, Good}, {badbytes, Bad}} ->
+ report_repairs(?LOG_NAME, Good, Bad),
+ read_full_log(?LOG_NAME);
+ {error, {need_repair, _FileName}} ->
+ repair_log(?LOG_NAME);
+ {error, {arg_mismatch, repair, true, false}} ->
+ repair_log(?LOG_NAME);
+ {error, {name_already_open, _}} ->
+ show_rename_warning(),
+ read_full_log(?LOG_NAME);
+ {error, {size_mismatch, Current, New}} ->
+ show_size_warning(Current, New),
+ resize_log(?LOG_NAME, Current, New),
+ load();
+ {error, {invalid_header, {vsn, Version}}} ->
+ upgrade_version(?LOG_NAME, Version),
+ load();
+ {error, Reason} ->
+ handle_open_error(Reason),
+ disable_history(),
+ []
+ end;
+ _ ->
+ []
+ end.
+
+%% @doc adds a log line to the erlang history log, if configured to do so.
+-spec add(iodata()) -> ok.
+add(Line) -> add(Line, history_status()).
+
+add(Line, enabled) ->
+ case lists:member(Line, to_drop()) of
+ false ->
+ case disk_log:log(?LOG_NAME, Line) of
+ ok ->
+ ok;
+ {error, no_such_log} ->
+ _ = open_log(), % a wild attempt we hope works!
+ disk_log:log(?LOG_NAME, Line);
+ {error, _Other} ->
+ % just ignore, we're too late
+ ok
+ end;
+ true ->
+ ok
+ end;
+add(_Line, disabled) ->
+ ok.
+
+%%%%%%%%%%%%%%%
+%%% PRIVATE %%%
+%%%%%%%%%%%%%%%
+
+%% Because loading the shell happens really damn early, processes we depend on
+%% might not be there yet. Luckily, the load function is called from the shell
+%% after a new process has been spawned, so we can block in here
+wait_for_kernel_safe_sup() ->
+ case whereis(kernel_safe_sup) of
+ undefined ->
+ timer:sleep(50),
+ wait_for_kernel_safe_sup();
+ _ ->
+ ok
+ end.
+
+%% Repair the log out of band
+repair_log(Name) ->
+ Opts = lists:keydelete(size, 1, log_options()),
+ case disk_log:open(Opts) of
+ {repaired, ?LOG_NAME, {recovered, Good}, {badbytes, Bad}} ->
+ report_repairs(?LOG_NAME, Good, Bad);
+ _ ->
+ ok
+ end,
+ _ = disk_log:close(Name),
+ load().
+
+%% Return whether the shell history is enabled or not
+-spec history_status() -> enabled | disabled.
+history_status() ->
+ case is_user() orelse application:get_env(kernel, shell_history) of
+ true -> disabled; % don't run for user proc
+ {ok, enabled} -> enabled;
+ undefined -> ?DEFAULT_STATUS;
+ _ -> disabled
+ end.
+
+%% Return whether the user process is running this
+-spec is_user() -> boolean().
+is_user() ->
+ case process_info(self(), registered_name) of
+ {registered_name, user} -> true;
+ _ -> false
+ end.
+
+%% Open a disk_log file while ensuring the required path is there.
+open_log() ->
+ Opts = log_options(),
+ _ = ensure_path(Opts),
+ disk_log:open(Opts).
+
+%% Return logger options
+log_options() ->
+ Path = find_path(),
+ File = filename:join([Path, ?DEFAULT_HISTORY_FILE]),
+ Size = find_wrap_values(),
+ [{name, ?LOG_NAME},
+ {file, File},
+ {repair, true},
+ {format, internal},
+ {type, wrap},
+ {size, Size},
+ {distributed, []},
+ {notify, false},
+ {head, {vsn, ?VSN}},
+ {quiet, true},
+ {mode, read_write}].
+
+-spec ensure_path([{file, string()} | {atom(), _}, ...]) -> ok | {error, term()}.
+ensure_path(Opts) ->
+ {file, Path} = lists:keyfind(file, 1, Opts),
+ filelib:ensure_dir(Path).
+
+%% @private read the logs from an already open file. Treat closed files
+%% as wrong and returns an empty list to avoid crash loops in the shell.
+-spec read_full_log(term()) -> [string()].
+read_full_log(Name) ->
+ case disk_log:chunk(Name, start) of
+ {error, no_such_log} ->
+ show_unexpected_close_warning(),
+ [];
+ eof ->
+ [];
+ {Cont, Logs} ->
+ lists:reverse(maybe_drop_header(Logs) ++ read_full_log(Name, Cont))
+ end.
+
+read_full_log(Name, Cont) ->
+ case disk_log:chunk(Name, Cont) of
+ {error, no_such_log} ->
+ show_unexpected_close_warning(),
+ [];
+ eof ->
+ [];
+ {NextCont, Logs} ->
+ maybe_drop_header(Logs) ++ read_full_log(Name, NextCont)
+ end.
+
+maybe_drop_header([{vsn, _} | Rest]) -> Rest;
+maybe_drop_header(Logs) -> Logs.
+
+-spec handle_open_error(_) -> ok.
+handle_open_error({arg_mismatch, OptName, CurrentVal, NewVal}) ->
+ show('$#erlang-history-arg-mismatch',
+ "Log file argument ~p changed value from ~p to ~p "
+ "and cannot be automatically updated. Please clear the "
+ "history files and try again.~n",
+ [OptName, CurrentVal, NewVal]);
+handle_open_error({not_a_log_file, FileName}) ->
+ show_invalid_file_warning(FileName);
+handle_open_error({invalid_index_file, FileName}) ->
+ show_invalid_file_warning(FileName);
+handle_open_error({invalid_header, Term}) ->
+ show('$#erlang-history-invalid-header',
+ "Shell history expects to be able to use the log files "
+ "which currently have unknown headers (~p) and may belong to "
+ "another mechanism. History logging will be "
+ "disabled.~n",
+ [Term]);
+handle_open_error({file_error, FileName, Reason}) ->
+ show('$#erlang-history-file-error',
+ "Error handling File ~s. Reason: ~p~n"
+ "History logging will be disabled.~n",
+ [FileName, Reason]);
+handle_open_error(Err) ->
+ show_unexpected_warning({disk_log, open, 1}, Err).
+
+find_wrap_values() ->
+ ConfSize = case application:get_env(kernel, shell_history_file_bytes) of
+ undefined -> ?DEFAULT_SIZE;
+ {ok, S} -> S
+ end,
+ SizePerFile = max(?MIN_HISTORY_SIZE, ConfSize div ?MAX_HISTORY_FILES),
+ FileCount = if SizePerFile > ?MIN_HISTORY_SIZE ->
+ ?MAX_HISTORY_FILES
+ ; SizePerFile =< ?MIN_HISTORY_SIZE ->
+ max(1, ConfSize div SizePerFile)
+ end,
+ {SizePerFile, FileCount}.
+
+report_repairs(_, _, 0) ->
+ %% just a regular close repair
+ ok;
+report_repairs(_, Good, Bad) ->
+ show('$#erlang-history-report-repairs',
+ "The shell history log file was corrupted and was repaired. "
+ "~p bytes were recovered and ~p were lost.~n", [Good, Bad]).
+
+resize_log(Name, _OldSize, NewSize) ->
+ show('$#erlang-history-resize-attempt',
+ "Attempting to resize the log history file to ~p...", [NewSize]),
+ Opts = lists:keydelete(size, 1, log_options()),
+ _ = case disk_log:open(Opts) of
+ {error, {need_repair, _}} ->
+ _ = repair_log(Name),
+ disk_log:open(Opts);
+ _ ->
+ ok
+ end,
+ case disk_log:change_size(Name, NewSize) of
+ ok ->
+ show('$#erlang-history-resize-result',
+ "ok~n", []);
+ {error, {new_size_too_small, _}} ->
+ show('$#erlang-history-resize-result',
+ "failed (new size is too small)~n", []),
+ disable_history();
+ {error, Reason} ->
+ show('$#erlang-history-resize-result',
+ "failed (~p)~n", [Reason]),
+ disable_history()
+ end.
+
+upgrade_version(_Name, Unsupported) ->
+ %% We only know of one version and can't support a newer one
+ show('$#erlang-history-upgrade',
+ "The version for the shell logs found on disk (~p) is "
+ "not supported by the current version (~p)~n",
+ [Unsupported, ?VSN]),
+ disable_history().
+
+disable_history() ->
+ show('$#erlang-history-disable', "Disabling shell history logging.~n", []),
+ application:set_env(kernel, shell_history, force_disabled).
+
+find_path() ->
+ case application:get_env(kernel, shell_history_path) of
+ undefined -> filename:basedir(user_cache, "erlang-history");
+ {ok, Path} -> Path
+ end.
+
+to_drop() ->
+ case application:get_env(kernel, shell_history_drop) of
+ undefined ->
+ application:set_env(kernel, shell_history_drop, ?DEFAULT_DROP),
+ ?DEFAULT_DROP;
+ {ok, V} when is_list(V) -> [Ln++"\n" || Ln <- V];
+ {ok, _} -> ?DEFAULT_DROP
+ end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Output functions %%%
+%%%%%%%%%%%%%%%%%%%%%%%%
+show_rename_warning() ->
+ show('$#erlang-history-rename-warn',
+ "A history file with a different path has already "
+ "been started for the shell of this node. The old "
+ "name will keep being used for this session.~n",
+ []).
+
+show_invalid_file_warning(FileName) ->
+ show('$#erlang-history-invalid-file',
+ "Shell history expects to be able to use the file ~s "
+ "which currently exists and is not a file usable for "
+ "history logging purposes. History logging will be "
+ "disabled.~n", [FileName]).
+
+show_unexpected_warning({M,F,A}, Term) ->
+ show('$#erlang-history-unexpected-return',
+ "unexpected return value from ~p:~p/~p: ~p~n"
+ "shell history will be disabled for this session.~n",
+ [M,F,A,Term]).
+
+show_unexpected_close_warning() ->
+ show('$#erlang-history-unexpected-close',
+ "The shell log file has mysteriousy closed. Ignoring "
+ "currently unread history.~n", []).
+
+show_size_warning(_Current, _New) ->
+ show('$#erlang-history-size',
+ "The configured log history file size is different from "
+ "the size of the log file on disk.~n", []).
+
+show(Key, Format, Args) ->
+ case get(Key) of
+ undefined ->
+ io:format(standard_error, Format, Args),
+ put(Key, true),
+ ok;
+ true ->
+ ok
+ end.