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author | Jim Meyering <jim@meyering.net> | 2006-11-12 17:35:38 +0000 |
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committer | Jim Meyering <jim@meyering.net> | 2006-11-12 17:35:38 +0000 |
commit | 7f01591aadb13b59cb04f9ad42400eb7ea1c6e19 (patch) | |
tree | 999bfb5f230fed1381aca5e7f5a1d72b4cb6e3f6 /lib/i-ring.h | |
parent | 42a01df09d7f13f15a54e0c4b09d121c5bf7ac66 (diff) | |
download | gnulib-7f01591aadb13b59cb04f9ad42400eb7ea1c6e19.tar.gz |
Make fts (in FTS_CWDFD mode) more efficient by caching a few open
file descriptors. This also averts a failure on systems with
native openat support when a traversed directory lacks "x" access.
* lib/fts_.h: Include "i-ring.h"
(struct FTS) [fts_fd_ring]: New member.
* lib/fts.c (RESTORE_INITIAL_CWD): Also call fd_ring_clear.
(FCHDIR): Add parentheses.
(fd_ring_check, fd_ring_print) [!FTS_DEBUG]: Define away.
(cwd_advance_fd): Add a 3rd parameter. Adjust all callers.
When descending, rather than simply closing the previous
fts_cwd_fd value, push that file descriptor onto the ring.
(same_fd, fd_ring_print, fd_ring_check) [FTS_DEBUG]: New functions.
(fts_open): Initialize the new fd_ring member.
(fts_close): Clear the ring.
(fts_safe_changedir): When possible, use our new fd_ring to skip
the diropen and fstat and dev/ino comparison that would normally
accompany a virtual `chdir ("..")'.
* modules/fts (Depends-on): Add i-ring.
* modules/i-ring: New module.
* lib/i-ring.c, lib/i-ring.h, lib/i-ring-test.c: New files.
* m4/i-ring.m4: New file.
Diffstat (limited to 'lib/i-ring.h')
-rw-r--r-- | lib/i-ring.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/lib/i-ring.h b/lib/i-ring.h new file mode 100644 index 0000000000..fadfa2b78b --- /dev/null +++ b/lib/i-ring.h @@ -0,0 +1,45 @@ +/* definitions for a simple ring buffer + Copyright (C) 2006 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +#include <stdbool.h> +#include "verify.h" + +enum { I_RING_SIZE = 4 }; +verify (1 <= I_RING_SIZE); + +/* When ir_empty is true, the ring is empty. + Otherwise, ir_data[B..F] are defined, where B..F is the contiguous + range of indices, modulo I_RING_SIZE, from back to front, inclusive. + Undefined elements of ir_data are always set to ir_default_val. + Popping from an empty ring aborts. + Pushing onto a full ring returns the displaced value. + An empty ring has F==B and ir_empty == true. + A ring with one entry still has F==B, but now ir_empty == false. */ +struct I_ring +{ + int ir_data[I_RING_SIZE]; + int ir_default_val; + unsigned int ir_front; + unsigned int ir_back; + bool ir_empty; +}; +typedef struct I_ring I_ring; + +void i_ring_init (I_ring *ir, int ir_default_val); +int i_ring_push (I_ring *ir, int val); +int i_ring_pop (I_ring *ir); +bool i_ring_empty (I_ring const *ir); |