From 42dbb827fc8340e7d1d12ab317b3841275c187e9 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Jos=C3=A9=20Fonseca?= <jfonseca@vmware.com>
Date: Thu, 1 Sep 2011 13:47:14 +0100
Subject: [PATCH] Add a usedCacheSize() method.

Simplifies things a little, and makes the code slightly more robust,
as I trying to figure out why sometimes I get traces with trailing
garbagge.
---
 trace_snappyfile.cpp | 17 +++++++++++------
 trace_snappyfile.hpp | 15 ++++++++++++---
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/trace_snappyfile.cpp b/trace_snappyfile.cpp
index 7678401..7e70725 100644
--- a/trace_snappyfile.cpp
+++ b/trace_snappyfile.cpp
@@ -190,14 +190,19 @@ void SnappyFile::rawFlush()
 void SnappyFile::flushCache()
 {
     if (m_mode == File::Write) {
-        size_t compressedLength;
+        size_t inputLength = usedCacheSize();
+
+        if (inputLength) {
+            size_t compressedLength;
 
-        ::snappy::RawCompress(m_cache, SNAPPY_CHUNK_SIZE - freeCacheSize(),
-                              m_compressedCache, &compressedLength);
+            ::snappy::RawCompress(m_cache, inputLength,
+                                  m_compressedCache, &compressedLength);
 
-        writeCompressedLength(compressedLength);
-        m_stream.write(m_compressedCache, compressedLength);
-        m_cachePtr = m_cache;
+            writeCompressedLength(compressedLength);
+            m_stream.write(m_compressedCache, compressedLength);
+            m_cachePtr = m_cache;
+        }
+        assert(m_cachePtr == m_cache);
     } else if (m_mode == File::Read) {
         //assert(m_cachePtr == m_cache + m_cacheSize);
         size_t compressedLength;
diff --git a/trace_snappyfile.hpp b/trace_snappyfile.hpp
index 393fe02..61b7ab1 100644
--- a/trace_snappyfile.hpp
+++ b/trace_snappyfile.hpp
@@ -27,6 +27,8 @@
 #ifndef TRACE_SNAPPYFILE_HPP
 #define TRACE_SNAPPYFILE_HPP
 
+#include <assert.h>
+
 #include "trace_file.hpp"
 
 #include <string>
@@ -59,12 +61,19 @@ protected:
     virtual void rawFlush();
 
 private:
+    inline size_t usedCacheSize() const
+    {
+        assert(m_cachePtr >= m_cache);
+        return m_cachePtr - m_cache;
+    }
     inline size_t freeCacheSize() const
     {
-        if (m_cacheSize > 0)
-            return m_cacheSize - (m_cachePtr - m_cache);
-        else
+        assert(m_cacheSize >= usedCacheSize());
+        if (m_cacheSize > 0) {
+            return m_cacheSize - usedCacheSize();
+        } else {
             return 0;
+        }
     }
     inline bool endOfData() const
     {
-- 
2.43.0