| http://lists.gnu.org/archive/html/bug-bash/2012-11/msg00034.html |
| |
| From 530d4988afd68ea9d2cf1b0267d4dc821d0d204f Mon Sep 17 00:00:00 2001 |
| From: Mike Frysinger <vapier@gentoo.org> |
| Date: Mon, 19 Nov 2012 17:58:51 -0500 |
| Subject: [PATCH] bash: speed up `read -N` |
| |
| Rather than using 1 byte reads, use the existing cache read logic. |
| This could be sped up more, but this change is not as invasive and |
| should (hopefully) be fairly safe. |
| |
| Signed-off-by: Mike Frysinger <vapier@gentoo.org> |
| --- |
| builtins/read.def | 21 ++++++++++++++++----- |
| externs.h | 1 + |
| lib/sh/zread.c | 15 +++++++++++++-- |
| 3 files changed, 30 insertions(+), 7 deletions(-) |
| |
| diff --git a/builtins/read.def b/builtins/read.def |
| index e32dec7..81a1b3f 100644 |
| --- a/builtins/read.def |
| +++ b/builtins/read.def |
| @@ -457,7 +457,10 @@ read_builtin (list) |
| interrupt_immediately++; |
| terminate_immediately++; |
| |
| - unbuffered_read = (nchars > 0) || (delim != '\n') || input_is_pipe; |
| + if ((nchars > 0) && !input_is_tty && ignore_delim) |
| + unbuffered_read = 2; |
| + else if ((nchars > 0) || (delim != '\n') || input_is_pipe) |
| + unbuffered_read = 1; |
| |
| if (prompt && edit == 0) |
| { |
| @@ -505,10 +508,18 @@ read_builtin (list) |
| print_ps2 = 0; |
| } |
| |
| - if (unbuffered_read) |
| - retval = zread (fd, &c, 1); |
| - else |
| - retval = zreadc (fd, &c); |
| + switch (unbuffered_read) |
| + { |
| + case 2: |
| + retval = zreadcn (fd, &c, nchars - nr); |
| + break; |
| + case 1: |
| + retval = zread (fd, &c, 1); |
| + break; |
| + default: |
| + retval = zreadc (fd, &c); |
| + break; |
| + } |
| |
| if (retval <= 0) |
| { |
| diff --git a/externs.h b/externs.h |
| index 09244fa..a5ad645 100644 |
| --- a/externs.h |
| +++ b/externs.h |
| @@ -479,6 +479,7 @@ extern ssize_t zread __P((int, char *, size_t)); |
| extern ssize_t zreadretry __P((int, char *, size_t)); |
| extern ssize_t zreadintr __P((int, char *, size_t)); |
| extern ssize_t zreadc __P((int, char *)); |
| +extern ssize_t zreadcn __P((int, char *, int)); |
| extern ssize_t zreadcintr __P((int, char *)); |
| extern void zreset __P((void)); |
| extern void zsyncfd __P((int)); |
| diff --git a/lib/sh/zread.c b/lib/sh/zread.c |
| index 5db21a9..af7d02b 100644 |
| --- a/lib/sh/zread.c |
| +++ b/lib/sh/zread.c |
| @@ -101,15 +101,18 @@ static char lbuf[128]; |
| static size_t lind, lused; |
| |
| ssize_t |
| -zreadc (fd, cp) |
| +zreadcn (fd, cp, len) |
| int fd; |
| char *cp; |
| + int len; |
| { |
| ssize_t nr; |
| |
| if (lind == lused || lused == 0) |
| { |
| - nr = zread (fd, lbuf, sizeof (lbuf)); |
| + if (len > sizeof (lbuf)) |
| + len = sizeof (lbuf); |
| + nr = zread (fd, lbuf, len); |
| lind = 0; |
| if (nr <= 0) |
| { |
| @@ -123,6 +126,14 @@ zreadc (fd, cp) |
| return 1; |
| } |
| |
| +ssize_t |
| +zreadc (fd, cp) |
| + int fd; |
| + char *cp; |
| +{ |
| + return zreadcn (fd, cp, sizeof (lbuf)); |
| +} |
| + |
| /* Don't mix calls to zreadc and zreadcintr in the same function, since they |
| use the same local buffer. */ |
| ssize_t |
| -- |
| 1.7.12.4 |
| |