From 9364a2d01d3c37b9ade7ee04d180dd5c51b3ecc3 Mon Sep 17 00:00:00 2001
From: Arvid Norberg <arvid@libtorrent.org>
Date: Sun, 16 Sep 2007 01:34:06 +0000
Subject: [PATCH] added priority to disk io jobs

---
 include/libtorrent/disk_io_thread.hpp | 7 +++++++
 include/libtorrent/storage.hpp        | 3 ++-
 src/disk_io_thread.cpp                | 7 +++++++
 src/storage.cpp                       | 4 +++-
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/include/libtorrent/disk_io_thread.hpp b/include/libtorrent/disk_io_thread.hpp
index 16ee0bca4..e9103b9e4 100644
--- a/include/libtorrent/disk_io_thread.hpp
+++ b/include/libtorrent/disk_io_thread.hpp
@@ -50,6 +50,7 @@ namespace libtorrent
 			, buffer_size(0)
 			, piece(0)
 			, offset(0)
+			, priority(0)
 		{}
 
 		enum action_t
@@ -72,6 +73,12 @@ namespace libtorrent
 		// to the error message
 		std::string str;
 
+		// priority decides whether or not this
+		// job will skip entries in the queue or
+		// not. It always skips in front of entries
+		// with lower priority
+		int priority;
+
 		// this is called when operation completes
 		boost::function<void(int, disk_io_job const&)> callback;
 	};
diff --git a/include/libtorrent/storage.hpp b/include/libtorrent/storage.hpp
index e52196c76..505be8b6c 100755
--- a/include/libtorrent/storage.hpp
+++ b/include/libtorrent/storage.hpp
@@ -202,7 +202,8 @@ namespace libtorrent
 		void async_read(
 			peer_request const& r
 			, boost::function<void(int, disk_io_job const&)> const& handler
-			, char* buffer = 0);
+			, char* buffer = 0
+			, int priority = 0);
 
 		void async_write(
 			peer_request const& r
diff --git a/src/disk_io_thread.cpp b/src/disk_io_thread.cpp
index e07a884cf..9096cff0e 100644
--- a/src/disk_io_thread.cpp
+++ b/src/disk_io_thread.cpp
@@ -89,8 +89,15 @@ namespace libtorrent
 	
 	namespace
 	{
+		// The semantic of this operator is:
+		// shouls lhs come before rhs in the job queue
 		bool operator<(disk_io_job const& lhs, disk_io_job const& rhs)
 		{
+			// NOTE: comparison inverted to make higher priority
+			// skip _in_front_of_ lower priority
+			if (lhs.priority > rhs.priority) return true;
+			if (lhs.priority < rhs.priority) return false;
+
 			if (lhs.storage.get() < rhs.storage.get()) return true;
 			if (lhs.storage.get() > rhs.storage.get()) return false;
 			if (lhs.piece < rhs.piece) return true;
diff --git a/src/storage.cpp b/src/storage.cpp
index e1ddd20ae..7124fab96 100755
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -1084,7 +1084,8 @@ namespace libtorrent
 	void piece_manager::async_read(
 		peer_request const& r
 		, boost::function<void(int, disk_io_job const&)> const& handler
-		, char* buffer)
+		, char* buffer
+		, int priority)
 	{
 		disk_io_job j;
 		j.storage = this;
@@ -1093,6 +1094,7 @@ namespace libtorrent
 		j.offset = r.start;
 		j.buffer_size = r.length;
 		j.buffer = buffer;
+		j.priority = priority;
 		// if a buffer is not specified, only one block can be read
 		// since that is the size of the pool allocator's buffers
 		assert(r.length <= 16 * 1024 || buffer != 0);