Improved seekable format ingestion speed for small frame size

As reported by @P-E-Meunier in https://github.com/facebook/zstd/issues/2662#issuecomment-1443836186,
seekable format ingestion speed can be particularly slow
when selected `FRAME_SIZE` is very small,
especially in combination with the recent row_hash compression mode.
The specific scenario mentioned was `pijul`,
using frame sizes of 256 bytes and level 10.

This is improved in this PR,
by providing approximate parameter adaptation to the compression process.

Tested locally on a M1 laptop,
ingestion of `enwik8` using `pijul` parameters
went from 35sec. (before this PR) to 2.5sec (with this PR).
For the specific corner case of a file full of zeroes,
this is even more pronounced, going from 45sec. to 0.5sec.

These benefits are unrelated to (and come on top of) other improvement efforts currently being made by @yoniko for the row_hash compression method specifically.

The `seekable_compress` test program has been updated to allows setting compression level,
in order to produce these performance results.

contrib/seekable_format/examples/parallel_compression.c

@@ -25,7 +25,7 @@
 
 #include "pool.h"      // use zstd thread pool for demo
 
-#include "zstd_seekable.h"
+#include "../zstd_seekable.h"
 
 static void* malloc_orDie(size_t size)
 {

contrib/seekable_format/examples/parallel_processing.c

@@ -29,7 +29,7 @@
 
 #include "pool.h"      // use zstd thread pool for demo
 
-#include "zstd_seekable.h"
+#include "../zstd_seekable.h"
 
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 

contrib/seekable_format/examples/seekable_compression.c

@@ -13,7 +13,7 @@
 #define ZSTD_STATIC_LINKING_ONLY
 #include <zstd.h>      // presumes zstd library is installed
 
-#include "zstd_seekable.h"
+#include "../zstd_seekable.h"
 
 static void* malloc_orDie(size_t size)
 {
@@ -112,20 +112,23 @@ static char* createOutFilename_orDie(const char* filename)
     return (char*)outSpace;
 }
 
-int main(int argc, const char** argv) {
+#define CLEVEL_DEFAULT 5
+int main(int argc, const char** argv)
+{
     const char* const exeName = argv[0];
-    if (argc!=3) {
-        printf("wrong arguments\n");
-        printf("usage:\n");
-        printf("%s FILE FRAME_SIZE\n", exeName);
+    if (argc<3 || argc>4) {
+        printf("wrong arguments \n");
+        printf("usage: \n");
+        printf("%s FILE FRAME_SIZE [LEVEL] \n", exeName);
         return 1;
     }
 
     {   const char* const inFileName = argv[1];
         unsigned const frameSize = (unsigned)atoi(argv[2]);
+        int const cLevel = (argc==4) ? atoi(argv[3]) : CLEVEL_DEFAULT;
 
         char* const outFileName = createOutFilename_orDie(inFileName);
-        compressFile_orDie(inFileName, outFileName, 5, frameSize);
+        compressFile_orDie(inFileName, outFileName, cLevel, frameSize);
         free(outFileName);
     }
 

contrib/seekable_format/examples/seekable_decompression.c

@@ -16,7 +16,7 @@
 #include <zstd.h>      // presumes zstd library is installed
 #include <zstd_errors.h>
 
-#include "zstd_seekable.h"
+#include "../zstd_seekable.h"
 
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 

contrib/seekable_format/tests/seekable_tests.c

@@ -4,7 +4,7 @@
 #include <stdio.h>
 #include <assert.h>
 
-#include "zstd_seekable.h"
+#include "../zstd_seekable.h"
 
 /* Basic unit tests for zstd seekable format */
 int main(int argc, const char** argv)

contrib/seekable_format/zstd_seekable.h

@@ -15,8 +15,8 @@ extern "C" {
 
 #define ZSTD_SEEKABLE_MAXFRAMES 0x8000000U
 
-/* Limit the maximum size to avoid any potential issues storing the compressed size */
-#define ZSTD_SEEKABLE_MAX_FRAME_DECOMPRESSED_SIZE 0x80000000U
+/* Limit maximum size to avoid potential issues storing the compressed size */
+#define ZSTD_SEEKABLE_MAX_FRAME_DECOMPRESSED_SIZE 0x40000000U
 
 /*-****************************************************************************
 *  Seekable Format

contrib/seekable_format/zstdseek_compress.c

@@ -230,6 +230,8 @@ size_t ZSTD_seekable_compressStream(ZSTD_seekable_CStream* zcs, ZSTD_outBuffer*
     const BYTE* const inBase = (const BYTE*) input->src + input->pos;
     size_t inLen = input->size - input->pos;
 
+    assert(zcs->maxFrameSize < INT_MAX);
+    ZSTD_CCtx_setParameter(zcs->cstream, ZSTD_c_srcSizeHint, (int)zcs->maxFrameSize);
     inLen = MIN(inLen, (size_t)(zcs->maxFrameSize - zcs->frameDSize));
 
     /* if we haven't finished flushing the last frame, don't start writing a new one */