From e3c42c739b3e4e7541b9c9f6d063231819e866d3 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 7 Jun 2018 13:53:30 -0700
Subject: [PATCH] clean ZSTD_compress() initialization

The (pretty old) code inside ZSTD_compress()
was making some pretty bold assumptions
on what's inside a CCtx and how to init it.

This is pretty fragile by design.
CCtx content evolve.
Knowledge of how to handle that should be concentrate in one place.

A side effect of this strategy
is that ZSTD_compress() wouldn't check for BMI2 capability,
and is therefore missing out some potential speed opportunity.

This patch makes ZSTD_compress() use
the same initialization and release functions
as the normal creator / destructor ones.

Measured on my laptop, with a custom version of bench
manually modified to use ZSTD_compress() (instead of the advanced API) :
This patch :
 1#silesia.tar       : 211984896 ->  73651053 (2.878), 312.2 MB/s , 723.8 MB/s
 2#silesia.tar       : 211984896 ->  70163650 (3.021), 226.2 MB/s , 649.8 MB/s
 3#silesia.tar       : 211984896 ->  66996749 (3.164), 169.4 MB/s , 636.7 MB/s
 4#silesia.tar       : 211984896 ->  65998319 (3.212), 136.7 MB/s , 619.2 MB/s
dev branch :
 1#silesia.tar       : 211984896 ->  73651053 (2.878), 291.7 MB/s , 727.5 MB/s
 2#silesia.tar       : 211984896 ->  70163650 (3.021), 216.2 MB/s , 655.7 MB/s
 3#silesia.tar       : 211984896 ->  66996749 (3.164), 162.2 MB/s , 633.1 MB/s
 4#silesia.tar       : 211984896 ->  65998319 (3.212), 130.6 MB/s , 618.6 MB/s
---
 lib/compress/zstd_compress.c | 41 ++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 7a30d5525..fe4d65b66 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -64,19 +64,26 @@ ZSTD_CCtx* ZSTD_createCCtx(void)
     return ZSTD_createCCtx_advanced(ZSTD_defaultCMem);
 }
 
+static void ZSTD_initCCtx(ZSTD_CCtx* cctx, ZSTD_customMem memManager)
+{
+    assert(cctx != NULL);
+    memset(cctx, 0, sizeof(*cctx));
+    cctx->customMem = memManager;
+    cctx->bmi2 = ZSTD_cpuid_bmi2(ZSTD_cpuid());
+    {   size_t const err = ZSTD_CCtx_resetParameters(cctx);
+        assert(!ZSTD_isError(err));
+        (void)err;
+    }
+}
+
 ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem)
 {
     ZSTD_STATIC_ASSERT(zcss_init==0);
     ZSTD_STATIC_ASSERT(ZSTD_CONTENTSIZE_UNKNOWN==(0ULL - 1));
     if (!customMem.customAlloc ^ !customMem.customFree) return NULL;
-    {   ZSTD_CCtx* const cctx = (ZSTD_CCtx*)ZSTD_calloc(sizeof(ZSTD_CCtx), customMem);
+    {   ZSTD_CCtx* const cctx = (ZSTD_CCtx*)ZSTD_malloc(sizeof(ZSTD_CCtx), customMem);
         if (!cctx) return NULL;
-        cctx->customMem = customMem;
-        cctx->bmi2 = ZSTD_cpuid_bmi2(ZSTD_cpuid());
-        {   size_t const err = ZSTD_CCtx_resetParameters(cctx);
-            assert(!ZSTD_isError(err));
-            (void)err;
-        }
+        ZSTD_initCCtx(cctx, customMem);
         return cctx;
     }
 }
@@ -104,17 +111,24 @@ ZSTD_CCtx* ZSTD_initStaticCCtx(void *workspace, size_t workspaceSize)
     return cctx;
 }
 
-size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx)
+static void ZSTD_freeCCtxContent(ZSTD_CCtx* cctx)
 {
-    if (cctx==NULL) return 0;   /* support free on NULL */
-    if (cctx->staticSize) return ERROR(memory_allocation);   /* not compatible with static CCtx */
+    assert(cctx != NULL);
+    assert(cctx->staticSize == 0);
     ZSTD_free(cctx->workSpace, cctx->customMem); cctx->workSpace = NULL;
     ZSTD_freeCDict(cctx->cdictLocal); cctx->cdictLocal = NULL;
 #ifdef ZSTD_MULTITHREAD
     ZSTDMT_freeCCtx(cctx->mtctx); cctx->mtctx = NULL;
 #endif
+}
+
+size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx)
+{
+    if (cctx==NULL) return 0;   /* support free on NULL */
+    if (cctx->staticSize) return ERROR(memory_allocation);   /* not compatible with static CCtx */
+    ZSTD_freeCCtxContent(cctx);
     ZSTD_free(cctx, cctx->customMem);
-    return 0;   /* reserved as a potential error code in the future */
+    return 0;
 }
 
 
@@ -2963,10 +2977,9 @@ size_t ZSTD_compress(void* dst, size_t dstCapacity, const void* src, size_t srcS
 {
     size_t result;
     ZSTD_CCtx ctxBody;
-    memset(&ctxBody, 0, sizeof(ctxBody));
-    ctxBody.customMem = ZSTD_defaultCMem;
+    ZSTD_initCCtx(&ctxBody, ZSTD_defaultCMem);
     result = ZSTD_compressCCtx(&ctxBody, dst, dstCapacity, src, srcSize, compressionLevel);
-    ZSTD_free(ctxBody.workSpace, ZSTD_defaultCMem);  /* can't free ctxBody itself, as it's on stack; free only heap content */
+    ZSTD_freeCCtxContent(&ctxBody);   /* can't free ctxBody itself, as it's on stack; free only heap content */
     return result;
 }
 
-- 
2.47.2