From 21a67b797e40df930b83bd407ffc165b3f4b91b2 Mon Sep 17 00:00:00 2001 From: Filipe David Manana Date: Mon, 26 Apr 2010 13:04:40 +0200 Subject: Add file:advise/4 - a wrapper to the POSIX syscall posix_fadvise Useful for informing the Operating System about the access pattern for a file's data, so that it can adapt the caching strategy to maximize disk IO performance. --- lib/kernel/doc/src/file.xml | 19 +++++++++ lib/kernel/src/file.erl | 16 +++++++- lib/kernel/src/file_io_server.erl | 8 ++++ lib/kernel/src/ram_file.erl | 33 +++++++++++++++- lib/kernel/test/file_SUITE.erl | 77 ++++++++++++++++++++++++++++++++++++- lib/kernel/test/prim_file_SUITE.erl | 75 +++++++++++++++++++++++++++++++++++- 6 files changed, 224 insertions(+), 4 deletions(-) (limited to 'lib/kernel') diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml index c94df62d1f..382262d1ee 100644 --- a/lib/kernel/doc/src/file.xml +++ b/lib/kernel/doc/src/file.xml @@ -61,6 +61,25 @@ time() = {{Year, Month, Day}, {Hour, Minute, Second}} Must denote a valid date and time + + advise(IoDevice, Offset, Length, Advise) -> ok | {error, Reason} + Predeclare an access pattern for file data + + IoDevice = io_device() + Offset = int() + Length = int() + Advise = posix_file_advise() + posix_file_advise() = normal | sequential | random | no_reuse + | will_need | dont_need + Reason = ext_posix() + + +

advise/4 can be used to announce an intention to access file + data in a specific pattern in the future, thus allowing the + operating system to perform appropriate optimizations.

+

On some platforms, this function might have no effect.

+ + change_group(Filename, Gid) -> ok | {error, Reason} Change group of a file diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl index 5da359fdf1..a694ed0708 100644 --- a/lib/kernel/src/file.erl +++ b/lib/kernel/src/file.erl @@ -36,7 +36,7 @@ %% Specialized -export([ipread_s32bu_p32bu/3]). %% Generic file contents. --export([open/2, close/1, +-export([open/2, close/1, advise/4, read/2, write/2, pread/2, pread/3, pwrite/2, pwrite/3, read_line/1, @@ -89,6 +89,8 @@ -type date() :: {pos_integer(), pos_integer(), pos_integer()}. -type time() :: {non_neg_integer(), non_neg_integer(), non_neg_integer()}. -type date_time() :: {date(), time()}. +-type posix_file_advise() :: 'normal' | 'sequential' | 'random' | 'no_reuse' | + 'will_need' | 'dont_need'. %%%----------------------------------------------------------------- %%% General functions @@ -352,6 +354,18 @@ close(#file_descriptor{module = Module} = Handle) -> close(_) -> {error, badarg}. +-spec advise(File :: io_device(), Offset :: integer(), + Length :: integer(), Advise :: posix_file_advise()) -> + 'ok' | {'error', posix()}. + +advise(File, Offset, Length, Advise) when is_pid(File) -> + R = file_request(File, {advise, Offset, Length, Advise}), + wait_file_reply(File, R); +advise(#file_descriptor{module = Module} = Handle, Offset, Length, Advise) -> + Module:advise(Handle, Offset, Length, Advise); +advise(_, _, _, _) -> + {error, badarg}. + -spec read(File :: io_device(), Size :: non_neg_integer()) -> 'eof' | {'ok', [char()] | binary()} | {'error', posix()}. diff --git a/lib/kernel/src/file_io_server.erl b/lib/kernel/src/file_io_server.erl index d0b30192b3..39dc32bb79 100644 --- a/lib/kernel/src/file_io_server.erl +++ b/lib/kernel/src/file_io_server.erl @@ -198,6 +198,14 @@ io_reply(From, ReplyAs, Reply) -> %%%----------------------------------------------------------------- %%% file requests +file_request({advise,Offset,Length,Advise}, + #state{handle=Handle}=State) -> + case ?PRIM_FILE:advise(Handle, Offset, Length, Advise) of + {error,_}=Reply -> + {stop,normal,Reply,State}; + Reply -> + {reply,Reply,State} + end; file_request({pread,At,Sz}, #state{handle=Handle,buf=Buf,read_mode=ReadMode}=State) -> case position(Handle, At, Buf) of diff --git a/lib/kernel/src/ram_file.erl b/lib/kernel/src/ram_file.erl index 0230cb4e0a..2bfb2cd021 100644 --- a/lib/kernel/src/ram_file.erl +++ b/lib/kernel/src/ram_file.erl @@ -28,7 +28,7 @@ %% Specialized file operations -export([get_size/1, get_file/1, set_file/2, get_file_close/1]). --export([compress/1, uncompress/1, uuencode/1, uudecode/1]). +-export([compress/1, uncompress/1, uuencode/1, uudecode/1, advise/4]). -export([open_mode/1]). %% used by ftp-file @@ -71,6 +71,7 @@ -define(RAM_FILE_UUENCODE, 35). -define(RAM_FILE_UUDECODE, 36). -define(RAM_FILE_SIZE, 37). +-define(RAM_FILE_ADVISE, 38). %% Open modes for RAM_FILE_OPEN -define(RAM_FILE_MODE_READ, 1). @@ -91,6 +92,14 @@ -define(RAM_FILE_RESP_NUMBER, 3). -define(RAM_FILE_RESP_INFO, 4). +%% POSIX file advises +-define(POSIX_FADV_NORMAL, 0). +-define(POSIX_FADV_RANDOM, 1). +-define(POSIX_FADV_SEQUENTIAL, 2). +-define(POSIX_FADV_WILLNEED, 3). +-define(POSIX_FADV_DONTNEED, 4). +-define(POSIX_FADV_NOREUSE, 5). + %% -------------------------------------------------------------------------- %% Generic file contents operations. %% @@ -352,6 +361,28 @@ uudecode(#file_descriptor{module = ?MODULE, data = Port}) -> uudecode(#file_descriptor{}) -> {error, enotsup}. +advise(#file_descriptor{module = ?MODULE, data = Port}, Offset, + Length, Advise) -> + Cmd0 = <>, + case Advise of + normal -> + call_port(Port, <>); + random -> + call_port(Port, <>); + sequential -> + call_port(Port, <>); + will_need -> + call_port(Port, <>); + dont_need -> + call_port(Port, <>); + no_reuse -> + call_port(Port, <>); + _ -> + {error, einval} + end; +advise(#file_descriptor{}, _Offset, _Length, _Advise) -> + {error, enotsup}. + %%%----------------------------------------------------------------- diff --git a/lib/kernel/test/file_SUITE.erl b/lib/kernel/test/file_SUITE.erl index 2e6c3aba16..1d652679b0 100644 --- a/lib/kernel/test/file_SUITE.erl +++ b/lib/kernel/test/file_SUITE.erl @@ -82,6 +82,8 @@ -export([read_line_1/1, read_line_2/1, read_line_3/1,read_line_4/1]). +-export([advise/1]). + %% Debug exports -export([create_file_slow/2, create_file/2, create_bin/2]). -export([verify_file/2, verify_bin/3]). @@ -377,7 +379,9 @@ win_cur_dir_1(_Config) -> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -files(suite) -> [open,pos,file_info,consult,eval,script,truncate,sync,datasync]. +files(suite) -> + [open,pos,file_info,consult,eval,script,truncate, + sync,datasync,advise]. open(suite) -> [open1,old_modes,new_modes,path_open,close,access,read_write, pread_write,append,open_errors]. @@ -1402,6 +1406,77 @@ sync(Config) when is_list(Config) -> ?line test_server:timetrap_cancel(Dog), ok. +advise(suite) -> []; +advise(doc) -> "Tests that ?FILE_MODULE:advise/4 at least doesn't crash."; +advise(Config) when is_list(Config) -> + ?line Dog = test_server:timetrap(test_server:seconds(5)), + ?line PrivDir = ?config(priv_dir, Config), + ?line Advise = filename:join(PrivDir, + atom_to_list(?MODULE) + ++"_advise.fil"), + + Line1 = "Hello\n", + Line2 = "World!\n", + + ?line {ok, Fd} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = ?FILE_MODULE:advise(Fd, 0, 0, normal), + ?line ok = io:format(Fd, "~s", [Line1]), + ?line ok = io:format(Fd, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd), + + ?line {ok, Fd2} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = ?FILE_MODULE:advise(Fd2, 0, 0, random), + ?line ok = io:format(Fd2, "~s", [Line1]), + ?line ok = io:format(Fd2, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd2), + + ?line {ok, Fd3} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = ?FILE_MODULE:advise(Fd3, 0, 0, sequential), + ?line ok = io:format(Fd3, "~s", [Line1]), + ?line ok = io:format(Fd3, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd3), + + ?line {ok, Fd4} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = ?FILE_MODULE:advise(Fd4, 0, 0, will_need), + ?line ok = io:format(Fd4, "~s", [Line1]), + ?line ok = io:format(Fd4, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd4), + + ?line {ok, Fd5} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = ?FILE_MODULE:advise(Fd5, 0, 0, dont_need), + ?line ok = io:format(Fd5, "~s", [Line1]), + ?line ok = io:format(Fd5, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd5), + + ?line {ok, Fd6} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = ?FILE_MODULE:advise(Fd6, 0, 0, no_reuse), + ?line ok = io:format(Fd6, "~s", [Line1]), + ?line ok = io:format(Fd6, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd6), + + ?line {ok, Fd7} = ?FILE_MODULE:open(Advise, [write]), + ?line {error, einval} = ?FILE_MODULE:advise(Fd7, 0, 0, bad_advise), + ?line ok = ?FILE_MODULE:close(Fd7), + + %% test write without advise, then a read after an advise + ?line {ok, Fd8} = ?FILE_MODULE:open(Advise, [write]), + ?line ok = io:format(Fd8, "~s", [Line1]), + ?line ok = io:format(Fd8, "~s", [Line2]), + ?line ok = ?FILE_MODULE:close(Fd8), + ?line {ok, Fd9} = ?FILE_MODULE:open(Advise, [read]), + Offset = 0, + %% same as a 0 length in some implementations + Length = length(Line1) + length(Line2), + ?line ok = ?FILE_MODULE:advise(Fd9, Offset, Length, sequential), + ?line {ok, Line1} = ?FILE_MODULE:read_line(Fd9), + ?line {ok, Line2} = ?FILE_MODULE:read_line(Fd9), + ?line eof = ?FILE_MODULE:read_line(Fd9), + ?line ok = ?FILE_MODULE:close(Fd9), + + ?line [] = flush(), + ?line test_server:timetrap_cancel(Dog), + ok. + %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% diff --git a/lib/kernel/test/prim_file_SUITE.erl b/lib/kernel/test/prim_file_SUITE.erl index 842945e83c..21bdc06fdc 100644 --- a/lib/kernel/test/prim_file_SUITE.erl +++ b/lib/kernel/test/prim_file_SUITE.erl @@ -48,6 +48,8 @@ symlinks_a/1, symlinks_b/1, list_dir_limit/1]). +-export([advise/1]). + -include("test_server.hrl"). -include_lib("kernel/include/file.hrl"). @@ -380,7 +382,7 @@ win_cur_dir_1(_Config, Handle) -> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -files(suite) -> [open,pos,file_info,truncate,sync,datasync]. +files(suite) -> [open,pos,file_info,truncate,sync,datasync,advise]. open(suite) -> [open1,modes,close,access,read_write, pread_write,append]. @@ -1100,6 +1102,77 @@ sync(Config) when is_list(Config) -> ok. +advise(suite) -> []; +advise(doc) -> "Tests that ?PRIM_FILE:advise/4 at least doesn't crash."; +advise(Config) when is_list(Config) -> + ?line Dog = test_server:timetrap(test_server:seconds(5)), + ?line PrivDir = ?config(priv_dir, Config), + ?line Advise = filename:join(PrivDir, + atom_to_list(?MODULE) + ++"_advise.fil"), + + Line1 = "Hello\n", + Line2 = "World!\n", + + ?line {ok, Fd} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:advise(Fd, 0, 0, normal), + ?line ok = ?PRIM_FILE:write(Fd, Line1), + ?line ok = ?PRIM_FILE:write(Fd, Line2), + ?line ok = ?PRIM_FILE:close(Fd), + + ?line {ok, Fd2} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:advise(Fd2, 0, 0, random), + ?line ok = ?PRIM_FILE:write(Fd2, Line1), + ?line ok = ?PRIM_FILE:write(Fd2, Line2), + ?line ok = ?PRIM_FILE:close(Fd2), + + ?line {ok, Fd3} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:advise(Fd3, 0, 0, sequential), + ?line ok = ?PRIM_FILE:write(Fd3, Line1), + ?line ok = ?PRIM_FILE:write(Fd3, Line2), + ?line ok = ?PRIM_FILE:close(Fd3), + + ?line {ok, Fd4} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:advise(Fd4, 0, 0, will_need), + ?line ok = ?PRIM_FILE:write(Fd4, Line1), + ?line ok = ?PRIM_FILE:write(Fd4, Line2), + ?line ok = ?PRIM_FILE:close(Fd4), + + ?line {ok, Fd5} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:advise(Fd5, 0, 0, dont_need), + ?line ok = ?PRIM_FILE:write(Fd5, Line1), + ?line ok = ?PRIM_FILE:write(Fd5, Line2), + ?line ok = ?PRIM_FILE:close(Fd5), + + ?line {ok, Fd6} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:advise(Fd6, 0, 0, no_reuse), + ?line ok = ?PRIM_FILE:write(Fd6, Line1), + ?line ok = ?PRIM_FILE:write(Fd6, Line2), + ?line ok = ?PRIM_FILE:close(Fd6), + + ?line {ok, Fd7} = ?PRIM_FILE:open(Advise, [write]), + ?line {error, einval} = ?PRIM_FILE:advise(Fd7, 0, 0, bad_advise), + ?line ok = ?PRIM_FILE:close(Fd7), + + %% test write without advise, then a read after an advise + ?line {ok, Fd8} = ?PRIM_FILE:open(Advise, [write]), + ?line ok = ?PRIM_FILE:write(Fd8, Line1), + ?line ok = ?PRIM_FILE:write(Fd8, Line2), + ?line ok = ?PRIM_FILE:close(Fd8), + ?line {ok, Fd9} = ?PRIM_FILE:open(Advise, [read]), + Offset = 0, + %% same as a 0 length in some implementations + Length = length(Line1) + length(Line2), + ?line ok = ?PRIM_FILE:advise(Fd9, Offset, Length, sequential), + ?line {ok, Line1} = ?PRIM_FILE:read_line(Fd9), + ?line {ok, Line2} = ?PRIM_FILE:read_line(Fd9), + ?line eof = ?PRIM_FILE:read_line(Fd9), + ?line ok = ?PRIM_FILE:close(Fd9), + + ?line test_server:timetrap_cancel(Dog), + ok. + + %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% delete_a(suite) -> []; 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