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| author | Filipe David Manana <[email protected]> | 2010-04-26 13:04:40 +0200 |
|---|---|---|
| committer | Raimo Niskanen <[email protected]> | 2010-05-20 15:48:17 +0200 |
| commit | 21a67b797e40df930b83bd407ffc165b3f4b91b2 (patch) | |
| tree | 268a10e8d1d4cd00c30d3f5ded8f103d9699167a /erts/preloaded/src/prim_file.erl | |
| parent | 3f53a96a8bd0cd4a18f819b6857e6a764706ede5 (diff) | |
| download | otp-21a67b797e40df930b83bd407ffc165b3f4b91b2.tar.gz otp-21a67b797e40df930b83bd407ffc165b3f4b91b2.tar.bz2 otp-21a67b797e40df930b83bd407ffc165b3f4b91b2.zip | |
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.
Diffstat (limited to 'erts/preloaded/src/prim_file.erl')
| -rw-r--r-- | erts/preloaded/src/prim_file.erl | 38 |
1 files changed, 37 insertions, 1 deletions
diff --git a/erts/preloaded/src/prim_file.erl b/erts/preloaded/src/prim_file.erl index 53c741e66e..e9df5752ab 100644 --- a/erts/preloaded/src/prim_file.erl +++ b/erts/preloaded/src/prim_file.erl @@ -25,7 +25,7 @@ %%% Interface towards a single file's contents. Uses ?FD_DRV. %% Generic file contents operations --export([open/2, close/1, datasync/1, sync/1, position/2, truncate/1, +-export([open/2, close/1, datasync/1, sync/1, advise/4, position/2, truncate/1, write/2, pwrite/2, pwrite/3, read/2, read_line/1, pread/2, pread/3, copy/3]). %% Specialized file operations @@ -97,6 +97,7 @@ -define(FILE_ALTNAME, 28). -define(FILE_READ_LINE, 29). -define(FILE_FDATASYNC, 30). +-define(FILE_ADVISE, 31). %% Driver responses -define(FILE_RESP_OK, 0). @@ -131,6 +132,13 @@ %% IPREAD variants -define(IPREAD_S32BU_P32BU, 0). +%% 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). %%%----------------------------------------------------------------- @@ -221,7 +229,35 @@ close(#file_descriptor{module = ?MODULE, data = {Port, _}}) -> close(Port) when is_port(Port) -> drv_close(Port). +-define(ADVISE(Offs, Len, Adv), + <<?FILE_ADVISE, Offs:64/signed, Len:64/signed, + Adv:32/signed>>). +%% Returns {error, Reason} | ok. +advise(#file_descriptor{module = ?MODULE, data = {Port, _}}, + Offset, Length, Advise) -> + case Advise of + normal -> + Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_NORMAL), + drv_command(Port, Cmd); + random -> + Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_RANDOM), + drv_command(Port, Cmd); + sequential -> + Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_SEQUENTIAL), + drv_command(Port, Cmd); + will_need -> + Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_WILLNEED), + drv_command(Port, Cmd); + dont_need -> + Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_DONTNEED), + drv_command(Port, Cmd); + no_reuse -> + Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_NOREUSE), + drv_command(Port, Cmd); + _ -> + {error, einval} + end. %% Returns {error, Reason} | ok. write(#file_descriptor{module = ?MODULE, data = {Port, _}}, Bytes) -> |