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authorJunio C Hamano <gitster@pobox.com>2016-07-28 11:26:02 -0700
committerJunio C Hamano <gitster@pobox.com>2016-07-28 11:26:02 -0700
commit8e4571e57a1a3cc6f1318b3da8612b2e3c8e1252 (patch)
tree62c096209932596087c620dc7057378534895e27
parentc81d2836753a268be07346d362ffab3c6a5e14a9 (diff)
parentd751dd11ae16fd4e2410d3a32c8e2d951fafc923 (diff)
downloadgit-8e4571e57a1a3cc6f1318b3da8612b2e3c8e1252.tar.gz
Merge branch 'sb/submodule-parallel-fetch' into maint
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
-rw-r--r--wrapper.c43
1 files changed, 27 insertions, 16 deletions
diff --git a/wrapper.c b/wrapper.c
index 5dc4e15aa9..26db215f0c 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -227,6 +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 +260,8 @@ ssize_t xread(int fd, void *buf, size_t len)
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 +279,13 @@ ssize_t xwrite(int fd, const void *buf, size_t len)
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;
}
}