Adding Snappy. Workaround for check_library_exists() not working and …

…conditional defines in port_stdcxx.h now working.

CMakeLists.txt

@@ -44,6 +44,9 @@ check_library_exists(snappy snappy_compress "" HAVE_SNAPPY)
 check_library_exists(zstd zstd_compress "" HAVE_ZSTD)
 check_library_exists(tcmalloc malloc "" HAVE_TCMALLOC)
 
+#remove when check_library_exits starts working
+set(HAVE_SNAPPY ON)
+
 include(CheckCXXSymbolExists)
 # Using check_cxx_symbol_exists() instead of check_c_symbol_exists() because
 # we're including the header from C++, and feature detection should use the same
@@ -284,7 +287,7 @@ endif(HAVE_TCMALLOC)
 
 # Needed by port_stdcxx.h
 find_package(Threads REQUIRED)
-target_link_libraries(leveldb PUBLIC Threads::Threads zlibstaticleveldb)
+target_link_libraries(leveldb Threads::Threads zlibstaticleveldb)
 
 add_executable(leveldbutil
  "db/leveldbutil.cc"

port/port_stdcxx.h

@@ -25,9 +25,9 @@
 #if HAVE_CRC32C
 #include <crc32c/crc32c.h>
 #endif // HAVE_CRC32C
-#if HAVE_SNAPPY
+//#if HAVE_SNAPPY
 #include <snappy.h>
-#endif // HAVE_SNAPPY
+//#endif // HAVE_SNAPPY
 #if HAVE_ZSTD
 #define ZSTD_STATIC_LINKING_ONLY // For ZSTD_compressionParameters.
 #include <zstd.h>
@@ -90,45 +90,48 @@ class CondVar {
 
 inline bool Snappy_Compress(const char* input, size_t length,
  std::string* output) {
-#if HAVE_SNAPPY
+//#if HAVE_SNAPPY
  output->resize(snappy::MaxCompressedLength(length));
  size_t outlen;
  snappy::RawCompress(input, length, &(*output)[0], &outlen);
  output->resize(outlen);
  return true;
-#else
- // Silence compiler warnings about unused arguments.
+/*#else
+ //Silence compiler warnings about unused arguments.
  (void)input;
  (void)length;
  (void)output;
 #endif // HAVE_SNAPPY
 
  return false;
+ */
 }
 
 inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
  size_t* result) {
-#if HAVE_SNAPPY
+//#if HAVE_SNAPPY
  return snappy::GetUncompressedLength(input, length, result);
-#else
+/*#else
  // Silence compiler warnings about unused arguments.
  (void)input;
  (void)length;
  (void)result;
  return false;
 #endif // HAVE_SNAPPY
+*/
 }
 
 inline bool Snappy_Uncompress(const char* input, size_t length, char* output) {
-#if HAVE_SNAPPY
+//#if HAVE_SNAPPY
  return snappy::RawUncompress(input, length, output);
-#else
+/*#else
  // Silence compiler warnings about unused arguments.
  (void)input;
  (void)length;
  (void)output;
  return false;
 #endif // HAVE_SNAPPY
+*/
 }
 
 inline bool Zstd_Compress(int level, const char* input, size_t length,