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Diffstat (limited to 'src/mochiweb/mochilogfile2.erl')
-rw-r--r-- | src/mochiweb/mochilogfile2.erl | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/src/mochiweb/mochilogfile2.erl b/src/mochiweb/mochilogfile2.erl new file mode 100644 index 00000000..c34ee73a --- /dev/null +++ b/src/mochiweb/mochilogfile2.erl @@ -0,0 +1,140 @@ +%% @author Bob Ippolito <bob@mochimedia.com> +%% @copyright 2010 Mochi Media, Inc. + +%% @doc Write newline delimited log files, ensuring that if a truncated +%% entry is found on log open then it is fixed before writing. Uses +%% delayed writes and raw files for performance. +-module(mochilogfile2). +-author('bob@mochimedia.com'). + +-export([open/1, write/2, close/1, name/1]). + +%% @spec open(Name) -> Handle +%% @doc Open the log file Name, creating or appending as necessary. All data +%% at the end of the file will be truncated until a newline is found, to +%% ensure that all records are complete. +open(Name) -> + {ok, FD} = file:open(Name, [raw, read, write, delayed_write, binary]), + fix_log(FD), + {?MODULE, Name, FD}. + +%% @spec name(Handle) -> string() +%% @doc Return the path of the log file. +name({?MODULE, Name, _FD}) -> + Name. + +%% @spec write(Handle, IoData) -> ok +%% @doc Write IoData to the log file referenced by Handle. +write({?MODULE, _Name, FD}, IoData) -> + ok = file:write(FD, [IoData, $\n]), + ok. + +%% @spec close(Handle) -> ok +%% @doc Close the log file referenced by Handle. +close({?MODULE, _Name, FD}) -> + ok = file:sync(FD), + ok = file:close(FD), + ok. + +fix_log(FD) -> + {ok, Location} = file:position(FD, eof), + Seek = find_last_newline(FD, Location), + {ok, Seek} = file:position(FD, Seek), + ok = file:truncate(FD), + ok. + +%% Seek backwards to the last valid log entry +find_last_newline(_FD, N) when N =< 1 -> + 0; +find_last_newline(FD, Location) -> + case file:pread(FD, Location - 1, 1) of + {ok, <<$\n>>} -> + Location; + {ok, _} -> + find_last_newline(FD, Location - 1) + end. + +%% +%% Tests +%% +-include_lib("eunit/include/eunit.hrl"). +-ifdef(TEST). +name_test() -> + D = mochitemp:mkdtemp(), + FileName = filename:join(D, "open_close_test.log"), + H = open(FileName), + ?assertEqual( + FileName, + name(H)), + close(H), + file:delete(FileName), + file:del_dir(D), + ok. + +open_close_test() -> + D = mochitemp:mkdtemp(), + FileName = filename:join(D, "open_close_test.log"), + OpenClose = fun () -> + H = open(FileName), + ?assertEqual( + true, + filelib:is_file(FileName)), + ok = close(H), + ?assertEqual( + {ok, <<>>}, + file:read_file(FileName)), + ok + end, + OpenClose(), + OpenClose(), + file:delete(FileName), + file:del_dir(D), + ok. + +write_test() -> + D = mochitemp:mkdtemp(), + FileName = filename:join(D, "write_test.log"), + F = fun () -> + H = open(FileName), + write(H, "test line"), + close(H), + ok + end, + F(), + ?assertEqual( + {ok, <<"test line\n">>}, + file:read_file(FileName)), + F(), + ?assertEqual( + {ok, <<"test line\ntest line\n">>}, + file:read_file(FileName)), + file:delete(FileName), + file:del_dir(D), + ok. + +fix_log_test() -> + D = mochitemp:mkdtemp(), + FileName = filename:join(D, "write_test.log"), + file:write_file(FileName, <<"first line good\nsecond line bad">>), + F = fun () -> + H = open(FileName), + write(H, "test line"), + close(H), + ok + end, + F(), + ?assertEqual( + {ok, <<"first line good\ntest line\n">>}, + file:read_file(FileName)), + file:write_file(FileName, <<"first line bad">>), + F(), + ?assertEqual( + {ok, <<"test line\n">>}, + file:read_file(FileName)), + F(), + ?assertEqual( + {ok, <<"test line\ntest line\n">>}, + file:read_file(FileName)), + ok. + +-endif. |