geomyidae

commit bbda3db127acc7e916bdd1668edb00ca7235ad02
parent 4481c2cbcf4bb258d8f06785528c0387386064ca
Author: Christoph Lohmann <20h@r-36.net>
Date:   Sat, 30 Jan 2021 18:28:55 +0100

Add the story of xsendfile to the source.

Diffstat:
ind.c
 | 
21
++++++++++++++++++++-

1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/ind.c b/ind.c
@@ -116,9 +116,27 @@ xsendfile(int fd, int sock)
 
 	USED(optval);
 
-	if (fstat(fd, &st) >= 0)
+	/*
+	 * The story of xsendfile.
+	 *
+	 * Once upon a time, here you saw a big #ifdef switch source of
+	 * many ways how to send files with special functions on
+	 * different operating systems. All of this was removed, because
+	 * operating systems and kernels got better over time,
+	 * simplifying what you need and reducing corner cases.
+	 *
+	 * For example Linux sendfile(2) sounds nice and faster, but
+	 * the function is different on every OS and slower to the now
+	 * used approach of read(2) and write(2).
+	 *
+	 * If you ever consider changing this to some "faster" approach,
+	 * consider benchmarks on all platforms.
+	 */
+
+	if (fstat(fd, &st) >= 0) {
 		if ((bufsiz = st.st_blksize) < BUFSIZ)
 			bufsiz = BUFSIZ;
+	}
 
 	sendb = xmalloc(bufsiz);
 	while ((len = read(fd, sendb, bufsiz)) > 0) {
@@ -133,6 +151,7 @@ xsendfile(int fd, int sock)
 		}
 	}
 	free(sendb);
+
 	return 0;
 }