optimize disk buffer allocation when seeding

include/libtorrent/block_cache.hpp

@@ -345,9 +345,6 @@ namespace libtorrent
 		int pad_job(disk_io_job const* j, int blocks_in_piece
 			, int read_ahead) const;
 
-		int allocate_iovec(file::iovec_t* iov, int iov_len);
-		void free_iovec(file::iovec_t* iov, int iov_len);
-
 		void reclaim_block(block_cache_reference const& ref);
 
 		// returns a range of all pieces. This migh be a very

include/libtorrent/disk_buffer_pool.hpp

@@ -38,6 +38,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/config.hpp"
 #include "libtorrent/thread.hpp"
 #include "libtorrent/io_service_fwd.hpp"
+#include "libtorrent/file.hpp" // for iovec_t
 #include <vector>
 #include <boost/shared_ptr.hpp>
 #include <boost/function.hpp>
@@ -73,13 +74,18 @@ namespace libtorrent
 
 		// tries to allocate a disk buffer. If the cache is full, this function will
 		// return NULL and call the disk_observer once a buffer becomes available
-		char* async_allocate_buffer(char const* category, boost::function<void(char*)> const& handler);
+		char* async_allocate_buffer(char const* category
+			, boost::function<void(char*)> const& handler);
 
 		char* allocate_buffer(char const* category);
-		char* allocate_buffer(bool& exceeded, boost::shared_ptr<disk_observer> o, char const* category);
+		char* allocate_buffer(bool& exceeded, boost::shared_ptr<disk_observer> o
+			, char const* category);
 		void free_buffer(char* buf);
 		void free_multiple_buffers(char** bufvec, int numbufs);
 
+		int allocate_iovec(file::iovec_t* iov, int iov_len);
+		void free_iovec(file::iovec_t* iov, int iov_len);
+
 		int block_size() const { return m_block_size; }
 
 		void release_memory();

src/block_cache.cpp

@@ -1109,33 +1109,6 @@ int block_cache::pad_job(disk_io_job const* j, int blocks_in_piece
 	return end - start;
 }
 
-// this function allocates buffers and
-// fills in the iovec array with the buffers
-int block_cache::allocate_iovec(file::iovec_t* iov, int iov_len)
-{
-	for (int i = 0; i < iov_len; ++i)
-	{
-		iov[i].iov_base = allocate_buffer("pending read");
-		iov[i].iov_len = block_size();
-		if (iov[i].iov_base == NULL)
-		{
-			// uh oh. We failed to allocate the buffer!
-			// we need to roll back and free all the buffers
-			// we've already allocated
-			for (int j = 0; j < i; ++j)
-				free_buffer((char*)iov[j].iov_base);
-			return -1;
-		}
-	}
-	return 0;
-}
-
-void block_cache::free_iovec(file::iovec_t* iov, int iov_len)
-{
-	for (int i = 0; i < iov_len; ++i)
-		free_buffer((char*)iov[i].iov_base);
-}
-
 void block_cache::insert_blocks(cached_piece_entry* pe, int block, file::iovec_t *iov
 	, int iov_len, disk_io_job* j, int flags)
 {

src/disk_buffer_pool.cpp

@@ -302,6 +302,37 @@ namespace libtorrent
 		return ret;
 	}
 
+// this function allocates buffers and
+// fills in the iovec array with the buffers
+	int disk_buffer_pool::allocate_iovec(file::iovec_t* iov, int iov_len)
+	{
+		mutex::scoped_lock l(m_pool_mutex);
+		for (int i = 0; i < iov_len; ++i)
+		{
+			iov[i].iov_base = allocate_buffer_impl(l, "pending read");
+			iov[i].iov_len = block_size();
+			if (iov[i].iov_base == NULL)
+			{
+				// uh oh. We failed to allocate the buffer!
+				// we need to roll back and free all the buffers
+				// we've already allocated
+				for (int j = 0; j < i; ++j)
+					free_buffer_impl((char*)iov[j].iov_base, l);
+				return -1;
+			}
+		}
+		return 0;
+	}
+
+	void disk_buffer_pool::free_iovec(file::iovec_t* iov, int iov_len)
+	{
+		// TODO: perhaps we should sort the buffers here?
+		mutex::scoped_lock l(m_pool_mutex);
+		for (int i = 0; i < iov_len; ++i)
+			free_buffer_impl((char*)iov[i].iov_base, l);
+		check_buffer_level(l);
+	}
+
 	char* disk_buffer_pool::allocate_buffer_impl(mutex::scoped_lock& l, char const* category)
 	{
 		TORRENT_ASSERT(m_settings_set);
@@ -311,7 +342,8 @@ namespace libtorrent
 #if TORRENT_HAVE_MMAP
 		if (m_cache_pool)
 		{
-			if (m_free_list.size() <= (m_max_use - m_low_watermark) / 2 && !m_exceeded_max_size)
+			if (m_free_list.size() <= (m_max_use - m_low_watermark)
+				/ 2 && !m_exceeded_max_size)
 			{
 				m_exceeded_max_size = true;
 				m_trigger_cache_trim();
@@ -368,7 +400,8 @@ namespace libtorrent
 #endif
 
 		++m_in_use;
-		if (m_in_use >= m_low_watermark + (m_max_use - m_low_watermark) / 2 && !m_exceeded_max_size)
+		if (m_in_use >= m_low_watermark + (m_max_use - m_low_watermark)
+			/ 2 && !m_exceeded_max_size)
 		{
 			m_exceeded_max_size = true;
 			m_trigger_cache_trim();
@@ -409,7 +442,6 @@ namespace libtorrent
 	{
 		mutex::scoped_lock l(m_pool_mutex);
 		free_buffer_impl(buf, l);
-
 		check_buffer_level(l);
 	}