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06f59e9f5d
This patch arose from a discussion started by Jim Meyering's patch whose intention was to provide better diagnostics for failed writes. Linus proposed a better way to do things, which also had the added benefit that adding a fflush() to git-log-* operations and incremental git-blame operations could improve interactive respose time feel, at the cost of making things a bit slower when we aren't piping the output to a downstream program. This patch skips the fflush() calls when stdout is a regular file, or if the environment variable GIT_FLUSH is set to "0". This latter can speed up a command such as: GIT_FLUSH=0 strace -c -f -e write time git-rev-list HEAD | wc -l a tiny amount. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
112 lines
2.3 KiB
C
112 lines
2.3 KiB
C
#include "cache.h"
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/*
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* Some cases use stdio, but want to flush after the write
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* to get error handling (and to get better interactive
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* behaviour - not buffering excessively).
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*
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* Of course, if the flush happened within the write itself,
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* we've already lost the error code, and cannot report it any
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* more. So we just ignore that case instead (and hope we get
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* the right error code on the flush).
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*
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* If the file handle is stdout, and stdout is a file, then skip the
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* flush entirely since it's not needed.
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*/
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void maybe_flush_or_die(FILE *f, const char *desc)
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{
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static int skip_stdout_flush = -1;
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struct stat st;
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char *cp;
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if (f == stdout) {
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if (skip_stdout_flush < 0) {
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cp = getenv("GIT_FLUSH");
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if (cp)
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skip_stdout_flush = (atoi(cp) == 0);
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else if ((fstat(fileno(stdout), &st) == 0) &&
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S_ISREG(st.st_mode))
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skip_stdout_flush = 1;
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else
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skip_stdout_flush = 0;
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}
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if (skip_stdout_flush && !ferror(f))
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return;
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}
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if (fflush(f)) {
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if (errno == EPIPE)
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exit(0);
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die("write failure on %s: %s", desc, strerror(errno));
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}
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}
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int read_in_full(int fd, void *buf, size_t count)
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{
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char *p = buf;
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ssize_t total = 0;
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while (count > 0) {
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ssize_t loaded = xread(fd, p, count);
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if (loaded <= 0)
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return total ? total : loaded;
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count -= loaded;
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p += loaded;
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total += loaded;
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}
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return total;
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}
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int write_in_full(int fd, const void *buf, size_t count)
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{
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const char *p = buf;
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ssize_t total = 0;
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while (count > 0) {
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ssize_t written = xwrite(fd, p, count);
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if (written < 0)
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return -1;
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if (!written) {
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errno = ENOSPC;
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return -1;
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}
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count -= written;
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p += written;
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total += written;
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}
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return total;
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}
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void write_or_die(int fd, const void *buf, size_t count)
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{
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if (write_in_full(fd, buf, count) < 0) {
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if (errno == EPIPE)
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exit(0);
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die("write error (%s)", strerror(errno));
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}
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}
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int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
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{
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if (write_in_full(fd, buf, count) < 0) {
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if (errno == EPIPE)
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exit(0);
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fprintf(stderr, "%s: write error (%s)\n",
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msg, strerror(errno));
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return 0;
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}
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return 1;
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}
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int write_or_whine(int fd, const void *buf, size_t count, const char *msg)
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{
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if (write_in_full(fd, buf, count) < 0) {
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fprintf(stderr, "%s: write error (%s)\n",
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msg, strerror(errno));
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return 0;
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}
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return 1;
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}
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