From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 19 Jul 2016 20:22:14 +0000 (-0700)
Subject: Merge branch 'sb/submodule-parallel-fetch'
X-Git-Tag: v2.10.0-rc0~112
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/7725bebe21dfa4877dad74b1ac3d921f26f949cf?ds=inline;hp=-c

Merge branch 'sb/submodule-parallel-fetch'

Fix recently introduced codepaths that are involved in parallel
submodule operations, which gave up on reading too early, and
could have wasted CPU while attempting to write under a corner
case condition.

* sb/submodule-parallel-fetch:
hoist out handle_nonblock function for xread and xwrite
xwrite: poll on non-blocking FDs
xread: retry after poll on EAGAIN/EWOULDBLOCK
---

7725bebe21dfa4877dad74b1ac3d921f26f949cf
diff --combined wrapper.c
index 5dc4e15aa9,a774ab7d80..26db215f0c
--- a/wrapper.c
+++ b/wrapper.c
@@@ -152,9 -152,6 +152,9 @@@ void *xcalloc(size_t nmemb, size_t size
  {
  	void *ret;
  
 +	if (unsigned_mult_overflows(nmemb, size))
 +		die("data too large to fit into virtual memory space");
 +
  	memory_limit_check(size * nmemb, 0);
  	ret = calloc(nmemb, size);
  	if (!ret && (!nmemb || !size))
@@@ -227,6 -224,24 +227,24 @@@ int xopen(const char *path, int oflag, 
  	}
  }
  
+ static int handle_nonblock(int fd, short poll_events, int err)
+ {
+ 	struct pollfd pfd;
+ 
+ 	if (err != EAGAIN && err != EWOULDBLOCK)
+ 		return 0;
+ 
+ 	pfd.fd = fd;
+ 	pfd.events = poll_events;
+ 
+ 	/*
+ 	 * no need to check for errors, here;
+ 	 * a subsequent read/write will detect unrecoverable errors
+ 	 */
+ 	poll(&pfd, 1, -1);
+ 	return 1;
+ }
+ 
  /*
   * xread() is the same a read(), but it automatically restarts read()
   * operations with a recoverable error (EAGAIN and EINTR). xread()
@@@ -242,20 -257,8 +260,8 @@@ ssize_t xread(int fd, void *buf, size_
  		if (nr < 0) {
  			if (errno == EINTR)
  				continue;
- 			if (errno == EAGAIN || errno == EWOULDBLOCK) {
- 				struct pollfd pfd;
- 				pfd.events = POLLIN;
- 				pfd.fd = fd;
- 				/*
- 				 * it is OK if this poll() failed; we
- 				 * want to leave this infinite loop
- 				 * only when read() returns with
- 				 * success, or an expected failure,
- 				 * which would be checked by the next
- 				 * call to read(2).
- 				 */
- 				poll(&pfd, 1, -1);
- 			}
+ 			if (handle_nonblock(fd, POLLIN, errno))
+ 				continue;
  		}
  		return nr;
  	}
@@@ -273,8 -276,13 +279,13 @@@ ssize_t xwrite(int fd, const void *buf
  	    len = MAX_IO_SIZE;
  	while (1) {
  		nr = write(fd, buf, len);
- 		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
- 			continue;
+ 		if (nr < 0) {
+ 			if (errno == EINTR)
+ 				continue;
+ 			if (handle_nonblock(fd, POLLOUT, errno))
+ 				continue;
+ 		}
+ 
  		return nr;
  	}
  }
@@@ -394,19 -402,6 +405,19 @@@ FILE *xfdopen(int fd, const char *mode
  	return stream;
  }
  
 +FILE *fopen_for_writing(const char *path)
 +{
 +	FILE *ret = fopen(path, "w");
 +
 +	if (!ret && errno == EPERM) {
 +		if (!unlink(path))
 +			ret = fopen(path, "w");
 +		else
 +			errno = EPERM;
 +	}
 +	return ret;
 +}
 +
  int xmkstemp(char *template)
  {
  	int fd;
@@@ -446,6 -441,23 +457,6 @@@ int git_mkstemp(char *path, size_t len
  	return mkstemp(path);
  }
  
 -/* git_mkstemps() - create tmp file with suffix honoring TMPDIR variable. */
 -int git_mkstemps(char *path, size_t len, const char *template, int suffix_len)
 -{
 -	const char *tmp;
 -	size_t n;
 -
 -	tmp = getenv("TMPDIR");
 -	if (!tmp)
 -		tmp = "/tmp";
 -	n = snprintf(path, len, "%s/%s", tmp, template);
 -	if (len <= n) {
 -		errno = ENAMETOOLONG;
 -		return -1;
 -	}
 -	return mkstemps(path, suffix_len);
 -}
 -
  /* Adapted from libiberty's mkstemp.c. */
  
  #undef TMP_MAX
@@@ -555,7 -567,7 +566,7 @@@ static int warn_if_unremovable(const ch
  	if (!rc || errno == ENOENT)
  		return 0;
  	err = errno;
 -	warning("unable to %s %s: %s", op, file, strerror(errno));
 +	warning_errno("unable to %s %s", op, file);
  	errno = err;
  	return rc;
  }
@@@ -591,7 -603,7 +602,7 @@@ int remove_or_warn(unsigned int mode, c
  
  void warn_on_inaccessible(const char *path)
  {
 -	warning(_("unable to access '%s': %s"), path, strerror(errno));
 +	warning_errno(_("unable to access '%s'"), path);
  }
  
  static int access_error_is_ok(int err, unsigned flag)
@@@ -616,6 -628,18 +627,6 @@@ int access_or_die(const char *path, in
  	return ret;
  }
  
 -struct passwd *xgetpwuid_self(void)
 -{
 -	struct passwd *pw;
 -
 -	errno = 0;
 -	pw = getpwuid(getuid());
 -	if (!pw)
 -		die(_("unable to look up current user in the passwd file: %s"),
 -		    errno ? strerror(errno) : _("no such user"));
 -	return pw;
 -}
 -
  char *xgetcwd(void)
  {
  	struct strbuf sb = STRBUF_INIT;