journal: add LZ4 as optional compressor

Add liblz4 as an optional dependency when requested with --enable-lz4,
and use it in preference to liblzma for journal blob and coredump
compression. To retain backwards compatibility, XZ is used to
decompress old blobs.

Things will function correctly only with lz4-119.

Based on the benchmarks found on the web, lz4 seems to be the best
choice for "quick" compressors atm.

For pkg-config status, see http://code.google.com/p/lz4/issues/detail?id=135.

1 files changed, 56 insertions, 9 deletions

diff --git a/src/journal/compress.h b/src/journal/compress.h
index f25fe86ab..92621ba52 100644
--- a/src/journal/compress.h
+++ b/src/journal/compress.h
@@ -25,15 +25,62 @@
 #include <stdbool.h>
 #include <unistd.h>
 
-bool compress_blob(const void *src, uint64_t src_size, void *dst, uint64_t *dst_size);
+#include "journal-def.h"
 
-bool uncompress_blob(const void *src, uint64_t src_size,
-                     void **dst, uint64_t *dst_alloc_size, uint64_t* dst_size, uint64_t dst_max);
+const char* object_compressed_to_string(int compression);
+int object_compressed_from_string(const char *compression);
 
-bool uncompress_startswith(const void *src, uint64_t src_size,
-                           void **buffer, uint64_t *buffer_size,
-                           const void *prefix, uint64_t prefix_len,
-                           uint8_t extra);
+int compress_blob_xz(const void *src, uint64_t src_size, void *dst, uint64_t *dst_size);
+int compress_blob_lz4(const void *src, uint64_t src_size, void *dst, uint64_t *dst_size);
 
-int compress_stream(int fdf, int fdt, uint32_t preset, off_t max_size);
-int decompress_stream(int fdf, int fdt, off_t max_size);
+static inline int compress_blob(const void *src, uint64_t src_size, void *dst, uint64_t *dst_size) {
+        int r;
+#ifdef HAVE_LZ4
+        r = compress_blob_lz4(src, src_size, dst, dst_size);
+        if (r == 0)
+                return OBJECT_COMPRESSED_LZ4;
+#else
+        r = compress_blob_xz(src, src_size, dst, dst_size);
+        if (r == 0)
+                return OBJECT_COMPRESSED_XZ;
+#endif
+        return r;
+}
+
+int decompress_blob_xz(const void *src, uint64_t src_size,
+                       void **dst, uint64_t *dst_alloc_size, uint64_t* dst_size, uint64_t dst_max);
+int decompress_blob_lz4(const void *src, uint64_t src_size,
+                        void **dst, uint64_t *dst_alloc_size, uint64_t* dst_size, uint64_t dst_max);
+int decompress_blob(int compression,
+                    const void *src, uint64_t src_size,
+                    void **dst, uint64_t *dst_alloc_size, uint64_t* dst_size, uint64_t dst_max);
+
+int decompress_startswith_xz(const void *src, uint64_t src_size,
+                             void **buffer, uint64_t *buffer_size,
+                             const void *prefix, uint64_t prefix_len,
+                             uint8_t extra);
+int decompress_startswith_lz4(const void *src, uint64_t src_size,
+                              void **buffer, uint64_t *buffer_size,
+                              const void *prefix, uint64_t prefix_len,
+                              uint8_t extra);
+int decompress_startswith(int compression,
+                          const void *src, uint64_t src_size,
+                          void **buffer, uint64_t *buffer_size,
+                          const void *prefix, uint64_t prefix_len,
+                          uint8_t extra);
+
+int compress_stream_xz(int fdf, int fdt, off_t max_bytes);
+int compress_stream_lz4(int fdf, int fdt, off_t max_bytes);
+
+int decompress_stream_xz(int fdf, int fdt, off_t max_size);
+int decompress_stream_lz4(int fdf, int fdt, off_t max_size);
+
+#ifdef HAVE_LZ4
+#  define compress_stream compress_stream_lz4
+#  define COMPRESSED_EXT ".lz4"
+#else
+#  define compress_stream compress_stream_xz
+#  define COMPRESSED_EXT ".xz"
+#endif
+
+int decompress_stream(const char *filename, int fdf, int fdt, off_t max_bytes);