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libarchive: add capability to unpack to mem.buffer

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The performance and number of processes for a "depmod -a" with gzipped
modules was abysmal. This patch adds a code path without fork,
benefiting all users of xmalloc_open_zipped_read_close.

"modinfo radeon.ko.gz", a single-file reader, got 30% faster.
"depmod -a", which used to fork over 800 times, got 20% faster.

Heavily based on a patch by Lauri Kasanen <curaga@operamail.com>

function                                             old     new   delta
setup_transformer_on_fd                                -     159    +159
transformer_write                                      -     122    +122
fork_transformer                                       -     112    +112
xmalloc_open_zipped_read_close                        63     118     +55
read_bunzip                                         1866    1896     +30
xtransformer_write                                     -      19     +19
unzip_main                                          2449    2462     +13
bbunpack                                             755     766     +11
unpack_lzma_stream                                  2717    2723      +6
unpack_xz_stream                                    2393    2397      +4
unpack_Z_stream                                     1173    1175      +2
inflate_unzip                                        111     105      -6
check_signature16                                     70      63      -7
unpack_bz2_stream                                    359     349     -10
unpack_unxz                                           12       -     -12
unpack_unlzma                                         12       -     -12
unpack_uncompress                                     12       -     -12
unpack_gunzip                                         12       -     -12
unpack_bunzip2                                        12       -     -12
open_transformer                                     106      92     -14
inflate_unzip_internal                              1945    1916     -29
unpack_gz_stream                                     693     655     -38
open_zipped                                           89      47     -42
setup_unzip_on_fd                                    142      53     -89
------------------------------------------------------------------------------
(add/remove: 4/5 grow/shrink: 7/8 up/down: 533/-295)          Total: 238 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2014-12-07 00:44:00 +01:00
parent e7800f351a
commit b4c11c1397
14 changed files with 243 additions and 127 deletions
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11
archival/libarchive/decompress_bunzip2.c
View File

@@ -731,7 +731,7 @@ void FAST_FUNC dealloc_bunzip(bunzip_data *bd)
/* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */
IF_DESKTOP(long long) int FAST_FUNC
unpack_bz2_stream(transformer_state_t *xstate, int src_fd, int dst_fd)
unpack_bz2_stream(transformer_state_t *xstate)
{
IF_DESKTOP(long long total_written = 0;)
bunzip_data *bd;
@@ -739,14 +739,14 @@ unpack_bz2_stream(transformer_state_t *xstate, int src_fd, int dst_fd)
int i;
unsigned len;
if (check_signature16(xstate, src_fd, BZIP2_MAGIC))
if (check_signature16(xstate, BZIP2_MAGIC))
return -1;
outbuf = xmalloc(IOBUF_SIZE);
len = 0;
while (1) { /* "Process one BZ... stream" loop */
i = start_bunzip(&bd, src_fd, outbuf + 2, len);
i = start_bunzip(&bd, xstate->src_fd, outbuf + 2, len);
if (i == 0) {
while (1) { /* "Produce some output bytes" loop */
@@ -756,8 +756,7 @@ unpack_bz2_stream(transformer_state_t *xstate, int src_fd, int dst_fd)
i = IOBUF_SIZE - i; /* number of bytes produced */
if (i == 0) /* EOF? */
break;
if (i != full_write(dst_fd, outbuf, i)) {
bb_error_msg("short write");
if (i != transformer_write(xstate, outbuf, i)) {
i = RETVAL_SHORT_WRITE;
goto release_mem;
}
@@ -790,7 +789,7 @@ unpack_bz2_stream(transformer_state_t *xstate, int src_fd, int dst_fd)
len = bd->inbufCount - bd->inbufPos;
memcpy(outbuf, &bd->inbuf[bd->inbufPos], len);
if (len < 2) {
if (safe_read(src_fd, outbuf + len, 2 - len) != 2 - len)
if (safe_read(xstate->src_fd, outbuf + len, 2 - len) != 2 - len)
break;
len = 2;
}