Move pg_pwritev_with_retry() to src/common/file_utils.c

This commit moves pg_pwritev_with_retry(), a convenience wrapper of
pg_writev() able to handle partial writes, to common/file_utils.c so
that the frontend code is able to use it.  A first use-case targetted
for this routine is pg_basebackup and pg_receivewal, for the
zero-padding of a newly-initialized WAL segment.  This is used currently
in the backend when the GUC wal_init_zero is enabled (default).

Author: Bharath Rupireddy
Reviewed-by: Nathan Bossart, Thomas Munro
Discussion: https://postgr.es/m/CALj2ACUq7nAb7=bJNbK3yYmp-SZhJcXFR_pLk8un6XgDzDF3OA@mail.gmail.com

1 files changed, 0 insertions, 65 deletions

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index e4d954578c8..4151cafec54 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -93,7 +93,6 @@
 #include "common/pg_prng.h"
 #include "miscadmin.h"
 #include "pgstat.h"
-#include "port/pg_iovec.h"
 #include "portability/mem.h"
 #include "postmaster/startup.h"
 #include "storage/fd.h"
@@ -3738,67 +3737,3 @@ data_sync_elevel(int elevel)
 {
 	return data_sync_retry ? elevel : PANIC;
 }
-
-/*
- * A convenience wrapper for pg_pwritev() that retries on partial write.  If an
- * error is returned, it is unspecified how much has been written.
- */
-ssize_t
-pg_pwritev_with_retry(int fd, const struct iovec *iov, int iovcnt, off_t offset)
-{
-	struct iovec iov_copy[PG_IOV_MAX];
-	ssize_t		sum = 0;
-	ssize_t		part;
-
-	/* We'd better have space to make a copy, in case we need to retry. */
-	if (iovcnt > PG_IOV_MAX)
-	{
-		errno = EINVAL;
-		return -1;
-	}
-
-	for (;;)
-	{
-		/* Write as much as we can. */
-		part = pg_pwritev(fd, iov, iovcnt, offset);
-		if (part < 0)
-			return -1;
-
-#ifdef SIMULATE_SHORT_WRITE
-		part = Min(part, 4096);
-#endif
-
-		/* Count our progress. */
-		sum += part;
-		offset += part;
-
-		/* Step over iovecs that are done. */
-		while (iovcnt > 0 && iov->iov_len <= part)
-		{
-			part -= iov->iov_len;
-			++iov;
-			--iovcnt;
-		}
-
-		/* Are they all done? */
-		if (iovcnt == 0)
-		{
-			/* We don't expect the kernel to write more than requested. */
-			Assert(part == 0);
-			break;
-		}
-
-		/*
-		 * Move whatever's left to the front of our mutable copy and adjust
-		 * the leading iovec.
-		 */
-		Assert(iovcnt > 0);
-		memmove(iov_copy, iov, sizeof(*iov) * iovcnt);
-		Assert(iov->iov_len > part);
-		iov_copy[0].iov_base = (char *) iov_copy[0].iov_base + part;
-		iov_copy[0].iov_len -= part;
-		iov = iov_copy;
-	}
-
-	return sum;
-}