Merge pull request #1550 from terrelln/cparams-cdict

[libzstd] Allow compression parameters to be set with a cdict

lib/compress/zstd_compress.c

@@ -450,11 +450,12 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value)
 
     switch(param)
     {
-    case ZSTD_c_compressionLevel:
+    case ZSTD_c_nbWorkers:
-        RETURN_ERROR_IF(cctx->cdict, stage_wrong,
+        RETURN_ERROR_IF((value!=0) && cctx->staticSize, parameter_unsupported,
-                        "compression level is configured in cdict");
+                        "MT not compatible with static alloc");
         break;
 
+    case ZSTD_c_compressionLevel:
     case ZSTD_c_windowLog:
     case ZSTD_c_hashLog:
     case ZSTD_c_chainLog:
@@ -462,20 +463,7 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value)
     case ZSTD_c_minMatch:
     case ZSTD_c_targetLength:
     case ZSTD_c_strategy:
-        RETURN_ERROR_IF(cctx->cdict, stage_wrong,
-                        "cparams are configured in cdict");
-        break;
-
-    case ZSTD_c_nbWorkers:
-        RETURN_ERROR_IF((value!=0) && cctx->staticSize, parameter_unsupported,
-                        "MT not compatible with static alloc");
-        break;
-
     case ZSTD_c_ldmHashRateLog:
-        RETURN_ERROR_IF(cctx->cdict, stage_wrong,
-                        "LDM hash rate log is configured in cdict");
-        break;
-
     case ZSTD_c_format:
     case ZSTD_c_contentSizeFlag:
     case ZSTD_c_checksumFlag:

lib/zstd.h

@@ -503,7 +503,10 @@ typedef enum { ZSTD_fast=1,
 
 typedef enum {
 
-    /* compression parameters */
+    /* compression parameters
+     * Note: When compressing with a ZSTD_CDict these parameters are superseded
+     * by the parameters used to construct the ZSTD_CDict. See ZSTD_CCtx_refCDict()
+     * for more info (superseded-by-cdict). */
     ZSTD_c_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
                               * Default level is ZSTD_CLEVEL_DEFAULT==3.
                               * Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.
@@ -705,7 +708,9 @@ ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, s
 /*! ZSTD_CCtx_refCDict() :
  *  Reference a prepared dictionary, to be used for all next compressed frames.
  *  Note that compression parameters are enforced from within CDict,
- *  and supercede any compression parameter previously set within CCtx.
+ *  and supersede any compression parameter previously set within CCtx.
+ *  The parameters ignored are labled as "superseded-by-cdict" in the ZSTD_cParameter enum docs.
+ *  The ignored parameters will be used again if the CCtx is returned to no-dictionary mode.
  *  The dictionary will remain valid for future compressed frames using same CCtx.
  * @result : 0, or an error code (which can be tested with ZSTD_isError()).
  *  Special : Referencing a NULL CDict means "return to no-dictionary mode".

tests/fuzzer.c

@@ -1294,6 +1294,17 @@ static int basicUnitTests(U32 seed, double compressibility)
         }
         DISPLAYLEVEL(3, "OK \n");
 
+        DISPLAYLEVEL(3, "test%3i : ZSTD_CCtx_refCDict() then set parameters : ", testNb++);
+        {   ZSTD_CDict* const cdict = ZSTD_createCDict(CNBuffer, dictSize, 1);
+            CHECK_Z( ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, 1) );
+            CHECK_Z( ZSTD_CCtx_setParameter(cctx, ZSTD_c_hashLog, 12 ));
+            CHECK_Z( ZSTD_CCtx_refCDict(cctx, cdict) );
+            CHECK_Z( ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, 1) );
+            CHECK_Z( ZSTD_CCtx_setParameter(cctx, ZSTD_c_hashLog, 12 ));
+            ZSTD_freeCDict(cdict);
+        }
+        DISPLAYLEVEL(3, "OK \n");
+
         DISPLAYLEVEL(3, "test%3i : Dictionary with non-default repcodes : ", testNb++);
         { U32 u; for (u=0; u<nbSamples; u++) samplesSizes[u] = sampleUnitSize; }
         dictSize = ZDICT_trainFromBuffer(dictBuffer, dictSize,

tests/zstreamtest.c

@@ -1930,16 +1930,6 @@ static int fuzzerTests_newAPI(U32 seed, int nbTests, int startTest,
                     } else {
                         CHECK_Z( ZSTD_CCtx_loadDictionary_byReference(zc, dict, dictSize) );
                     }
-                    if (dict && dictSize) {
-                        /* test that compression parameters are rejected (correctly) after loading a non-NULL dictionary */
-                        if (opaqueAPI) {
-                            size_t const setError = ZSTD_CCtx_setParametersUsingCCtxParams(zc, cctxParams);
-                            CHECK(!ZSTD_isError(setError), "ZSTD_CCtx_setParametersUsingCCtxParams should have failed");
-                        } else {
-                            size_t const setError = ZSTD_CCtx_setParameter(zc, ZSTD_c_windowLog, cParams.windowLog-1);
-                            CHECK(!ZSTD_isError(setError), "ZSTD_CCtx_setParameter should have failed");
-                        }
-                    }
                 } else {
                     CHECK_Z( ZSTD_CCtx_refPrefix(zc, dict, dictSize) );
                 }