Improve performance of --reorder by emulating move semantics

Author: ch4rr0

hit.h

@@ -565,7 +565,8 @@ class HitSink {
 			ThreadSafe _ts(&mutex_); // flush
 			if (reorder_) {
 				nchars += ptBufs_[threadId].length();
-				batch b = {ptBufs_[threadId], batchIds_[threadId], false};
+				batch b = { .batchId = batchIds_[threadId], .isWritten = false };
+				ptBufs_[threadId].moveTo(b.btString);
 				unwrittenBatches_.push_back(b);
 				// consider writing if we have enough data to fill the buffer
 				// or we're ready to output the final batch
@@ -634,10 +635,19 @@ class HitSink {
 		size_t batchId;
 		bool isWritten;
 
-		bool operator< (const batch& other) const {
+		bool operator<(const batch& other) const {
 			return batchId < other.batchId;
 		}
 
+		batch& operator=(batch& other) {
+			if (&other != *this) {
+				batchId = other.batchId;
+				isWritten = other.isWritten;
+				other.btString.moveTo(btString);
+			}
+			return *this;
+		}
+
 		static bool remove_written_batches(const batch& b) {
 			return b.isWritten;
 		}

sstring.h

@@ -2075,6 +2075,15 @@ class SStringExpandable {
 	 */
 	T* wbuf() { return cs_; }
 
+	void moveTo(SStringExpandable<T,S>& o) {
+		if (&o != this) {
+			o.sz_ = sz_; sz_ = 0;
+			o.cs_ = cs_; cs_ = NULL;
+			o.len_ = len_; len_ = 0;
+			o.printcs_ = printcs_; printcs_ = NULL;
+		}
+	}
+
 protected:
 	/**
 	 * Allocate new, bigger buffer and copy old contents into it.  If