Improved memory usage while applying patch....

courgette/streams.h

Index: courgette/streams.h
===================================================================
--- courgette/streams.h	(revision 75361)
+++ courgette/streams.h	(working copy)
@@ -147,6 +147,9 @@
   // Hints that the stream will grow by an additional |length| bytes.
   void Reserve(size_t length) { buffer_.reserve(length + buffer_.length()); }
 
+  // Finished with this stream and any storage it has.
+  void Retire();
+
  private:
   std::string buffer_;  // Use a string to manage the stream's memory.
 
@@ -187,6 +190,11 @@
   DISALLOW_COPY_AND_ASSIGN(SourceStreamSet);
 };
 
+// A SinkStreamSet is a set of SinkStreams.  Data is collected by writing to the
+// component streams.  When data collection is complete, it is destructively
+// transferred, either by flattening into one stream (CopyTo), or transfering
+// data pairwise into another SinkStreamSet by calling that SinkStreamSet's
+// WriteSet method.
 class SinkStreamSet {
  public:
   SinkStreamSet();
@@ -199,8 +207,8 @@
   // Returns a pointer to a substream.
   SinkStream* stream(size_t id) { return id < count_ ? &streams_[id] : NULL; }
 
-  // CopyTo serializes the streams in the SinkStreamSet into a single target
-  // stream or file.  The serialized format may be re-read by initializing a
+  // CopyTo serializes the streams in this SinkStreamSet into a single target
+  // stream.  The serialized format may be re-read by initializing a
   // SourceStreamSet with a buffer containing the data.
   bool CopyTo(SinkStream* combined_stream);