compress: add benchmark-style test

This is useful to test the behaviour of the compressor for various buffer
sizes.

Time is limited to a minute per compression, since otherwise, when LZ4
takes more than a second which is necessary to reduce the noise, XZ
takes more than 10 minutes.

% build/test-compress-benchmark (without time limit)
XZ: compressed & decompressed 2535300963 bytes in 794.57s (3.04MiB/s), mean compresion 99.95%, skipped 3570 bytes
LZ4: compressed & decompressed 2535303543 bytes in 1.56s (1550.07MiB/s), mean compresion 99.60%, skipped 990 bytes

% build/test-compress-benchmark (with time limit)
XZ: compressed & decompressed 174321481 bytes in 60.02s (2.77MiB/s), mean compresion 99.76%, skipped 3570 bytes
LZ4: compressed & decompressed 2535303543 bytes in 1.63s (1480.83MiB/s), mean compresion 99.60%, skipped 990 bytes

 It appears that there's a bug in lzma_end where it leaks 32 bytes.

1 files changed, 113 insertions, 0 deletions

diff --git a/src/journal/test-compress-benchmark.c b/src/journal/test-compress-benchmark.c
new file mode 100644
index 0000000000..0a23bd1e13
--- /dev/null
+++ b/src/journal/test-compress-benchmark.c
@@ -0,0 +1,113 @@
+/***
+  This file is part of systemd
+
+  Copyright 2014 Zbigniew Jędrzejewski-Szmek
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "compress.h"
+#include "util.h"
+#include "macro.h"
+
+typedef int (compress_t)(const void *src, uint64_t src_size, void *dst, uint64_t *dst_size);
+typedef int (decompress_t)(const void *src, uint64_t src_size,
+                           void **dst, uint64_t *dst_alloc_size, uint64_t* dst_size, uint64_t dst_max);
+
+#define MAX_SIZE (1024*1024LU)
+
+static char* make_buf(size_t count) {
+        char *buf;
+        size_t i;
+
+        buf = malloc(count);
+        assert(buf);
+
+        for (i = 0; i < count; i++)
+                buf[i] = 'a' + i % ('z' - 'a' + 1);
+
+        return buf;
+}
+
+static void test_compress_decompress(const char* label,
+                                     compress_t compress, decompress_t decompress) {
+        usec_t n, n2;
+        float dt;
+
+        _cleanup_free_ char *text, *buf;
+        _cleanup_free_ void *buf2 = NULL;
+        size_t buf2_allocated = 0;
+        size_t skipped = 0, compressed = 0, total = 0;
+
+        text = make_buf(MAX_SIZE);
+        buf = calloc(MAX_SIZE + 1, 1);
+        assert(text && buf);
+
+        n = now(CLOCK_MONOTONIC);
+
+        for (size_t i = 1; i <= MAX_SIZE; i += (i < 2048 ? 1 : 217)) {
+                size_t j = 0, k = 0;
+                int r;
+
+                r = compress(text, i, buf, &j);
+                /* assume compresion must be succesful except for small inputs */
+                assert(r == 0 || (i < 2048 && r == -ENOBUFS));
+                /* check for overwrites */
+                assert(buf[i] == 0);
+                if (r != 0) {
+                        skipped += i;
+                        continue;
+                }
+
+                assert(j > 0);
+                if (j >= i)
+                        log_error("%s \"compressed\" %zu -> %zu", label, i, j);
+
+                r = decompress(buf, j, &buf2, &buf2_allocated, &k, 0);
+                assert(r == 0);
+                assert(buf2_allocated >= k);
+                assert(k == i);
+
+                assert(memcmp(text, buf2, i) == 0);
+
+                total += i;
+                compressed += j;
+
+                n2 = now(CLOCK_MONOTONIC);
+                if (n2 - n > 60 * USEC_PER_SEC)
+                        break;
+        }
+
+        dt = (n2-n) / 1e6;
+
+        log_info("%s: compressed & decompressed %zu bytes in %.2fs (%.2fMiB/s), "
+                 "mean compresion %.2f%%, skipped %zu bytes",
+                 label, total, dt,
+                 total / 1024. / 1024 / dt,
+                 100 - compressed * 100. / total,
+                 skipped);
+}
+
+int main(int argc, char *argv[]) {
+
+        log_set_max_level(LOG_DEBUG);
+
+#ifdef HAVE_XZ
+        test_compress_decompress("XZ", compress_blob_xz, decompress_blob_xz);
+#endif
+#ifdef HAVE_LZ4
+        test_compress_decompress("LZ4", compress_blob_lz4, decompress_blob_lz4);
+#endif
+        return 0;
+}