Speed up Snappy uncompression, new Logger interface.

- Removed one copy of an uncompressed block contents changing
  the signature of Snappy_Uncompress() so it uncompresses into a
  flat array instead of a std::string.
        
  Speeds up readrandom ~10%.

- Instead of a combination of Env/WritableFile, we now have a
  Logger interface that can be easily overridden applications
  that want to supply their own logging.

- Separated out the gcc and Sun Studio parts of atomic_pointer.h
  so we can use 'asm', 'volatile' keywords for Sun Studio.




git-svn-id: https://leveldb.googlecode.com/svn/trunk@39 62dab493-f737-651d-591e-8d6aee1b9529

1 files changed, 15 insertions, 11 deletions

diff --git a/port/port_posix.h b/port/port_posix.h
index 2995026..ef01de3 100644
--- a/port/port_posix.h
+++ b/port/port_posix.h
@@ -80,12 +80,12 @@ class CondVar {
   Mutex* mu_;
 };
 
-inline bool Snappy_Compress(const char* input, size_t input_length,
+inline bool Snappy_Compress(const char* input, size_t length,
                             ::std::string* output) {
 #ifdef SNAPPY
-  output->resize(snappy::MaxCompressedLength(input_length));
+  output->resize(snappy::MaxCompressedLength(length));
   size_t outlen;
-  snappy::RawCompress(input, input_length, &(*output)[0], &outlen);
+  snappy::RawCompress(input, length, &(*output)[0], &outlen);
   output->resize(outlen);
   return true;
 #endif
@@ -93,18 +93,22 @@ inline bool Snappy_Compress(const char* input, size_t input_length,
   return false;
 }
 
-inline bool Snappy_Uncompress(const char* input_data, size_t input_length,
-                              ::std::string* output) {
+inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
+                                         size_t* result) {
 #ifdef SNAPPY
-  size_t ulength;
-  if (!snappy::GetUncompressedLength(input_data, input_length, &ulength)) {
-    return false;
-  }
-  output->resize(ulength);
-  return snappy::RawUncompress(input_data, input_length, &(*output)[0]);
+  return snappy::GetUncompressedLength(input, length, result);
+#else
+  return false;
 #endif
+}
 
+inline bool Snappy_Uncompress(const char* input, size_t length,
+                              char* output) {
+#ifdef SNAPPY
+  return snappy::RawUncompress(input, length, output);
+#else
   return false;
+#endif
 }
 
 inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {