deprecate explicit cache feature

docs/tuning.rst

@@ -238,42 +238,17 @@ In order to increase the possibility of read cache hits, set the
 ``session_settings::cache_expiry`` to a large number. This won't degrade anything as
 long as the client is only seeding, and not downloading any torrents.
 
-In order to increase the disk cache hit rate, you can enable suggest messages based on
+There's a *guided cache* mode. This means the size of the read cache line that's
-what's in the read cache. To do this, set ``session_settings::suggest_mode`` to
+stored in the cache is determined based on the upload rate to the peer that
-``session_settings::suggest_read_cache``. This will send suggest messages to peers
+triggered the read operation. The idea being that slow peers don't use up a
-for the most recently used pieces in the read cache. This is especially useful if you
+disproportional amount of space in the cache. This is enabled through
-also enable explicit read cache, by settings ``session_settings::explicit_read_cache``
+``session_settings::guided_read_cache``.
-to the number of pieces to keep in the cache. The explicit read cache will make the
-disk read cache stick, and not be evicted by cache misses. The explicit read cache
-will automatically pull in the rarest pieces in the read cache.
-
-Assuming that you seed much more data than you can keep in the cache, to a large
-numbers of peers (so that the read cache wouldn't be useful anyway), this may be a
-good idea.
-
-When peers first connect, libtorrent will send them a number of allow-fast messages,
-which lets the peers download certain pieces even when they are choked, since peers
-are choked by default, this often triggers immediate requests for those pieces. In the
-case of using explicit read cache and suggesting those pieces, allowing fast pieces
-should be disabled, to not systematically trigger requests for pieces that are not cached
-for all peers. You can turn off allow-fast by settings ``session_settings::allowed_fast_set_size``
-to 0.
-
-As an alternative to the explicit cache and suggest messages, there's a *guided cache*
-mode. This means the size of the read cache line that's stored in the cache is determined
-based on the upload rate to the peer that triggered the read operation. The idea being
-that slow peers don't use up a disproportional amount of space in the cache. This
-is enabled through ``session_settings::guided_read_cache``.
 
 In cases where the assumption is that the cache is only used as a read-ahead, and that no
 other peer will ever request the same block while it's still in the cache, the read
 cache can be set to be *volatile*. This means that every block that is requested out of
 the read cache is removed immediately. This saves a significant amount of cache space
-which can be used as read-ahead for other peers. This mode should **never** be combined
+which can be used as read-ahead for other peers. To enable volatile read cache, set
-with either ``explicit_read_cache`` or ``suggest_read_cache``, since those uses opposite
-strategies for the read cache. You don't want to on one hand attract peers to request
-the same pieces, and on the other hand assume that they won't request the same pieces
-and drop them when the first peer requests it. To enable volatile read cache, set
 ``session_settings::volatile_read_cache`` to true.
 
 SSD as level 2 cache

include/libtorrent/aux_/session_impl.hpp

@@ -933,6 +933,7 @@ namespace libtorrent
 			// torrents.
 			int m_auto_scrape_time_scaler;
 
+#ifndef TORRENT_NO_DEPRECATED
 			// the index of the torrent that we'll
 			// refresh the next time
 			int m_next_explicit_cache_torrent;
@@ -941,6 +942,7 @@ namespace libtorrent
 			// the next time the read cache is rotated, if we're
 			// using an explicit read read cache.
 			int m_cache_rotation_timer;
+#endif
 
 			// the index of the torrent that we'll
 			// refresh the next time

include/libtorrent/session_settings.hpp

@@ -451,6 +451,7 @@ namespace libtorrent
 		// once we want to calculate the piece hash
 		bool dont_flush_write_cache;
 
+#ifndef TORRENT_NO_DEPRECATE
 		// defaults to 0. If set to something greater than 0, the disk read cache
 		// will not be evicted by cache misses and will explicitly be controlled
 		// based on the rarity of pieces. Rare pieces are more likely to be
@@ -468,6 +469,7 @@ namespace libtorrent
 		// the cache, so that subsequent refreshes only swaps in pieces that are
 		// rarer than whatever is in the cache at the time.
 		int explicit_cache_interval;
+#endif
 
 		// the buffer modes to use for reading and writing. Set
 		// session_settings::disk_io_read_mode and disk_io_write_mode to one of

include/libtorrent/settings_pack.hpp

@@ -275,6 +275,7 @@ namespace libtorrent
 			// hash
 			dont_flush_write_cache,
 
+#ifndef TORRENT_NO_DEPRECATED
 			// ``explicit_read_cache`` defaults to 0. If set to something greater
 			// than 0, the disk read cache will not be evicted by cache misses and
 			// will explicitly be controlled based on the rarity of pieces. Rare
@@ -284,6 +285,9 @@ namespace libtorrent
 			// actual read cache can't fit as many, it will essentially be
 			// clamped.
 			explicit_read_cache,
+#else
+			deprecated10,
+#endif
 
 			// allocate separate, contiguous, buffers for read and write calls.
 			// Only used where writev/readv cannot be used will use more RAM but
@@ -924,6 +928,7 @@ namespace libtorrent
 			cache_buffer_chunk_size,
 			cache_expiry,
 
+#ifndef TORRENT_NO_DEPRECATED
 			// ``explicit_cache_interval`` is the number of seconds in between
 			// each refresh of a part of the explicit read cache. Torrents take
 			// turns in refreshing and this is the time in between each torrent
@@ -933,6 +938,9 @@ namespace libtorrent
 			// subsequent refreshes only swaps in pieces that are rarer than
 			// whatever is in the cache at the time.
 			explicit_cache_interval,
+#else
+			deprecated11,
+#endif
 
 			// determines how files are opened when they're in read only mode
 			// versus read and write mode. The options are:

include/libtorrent/torrent.hpp

@@ -676,14 +676,16 @@ namespace libtorrent
 		void get_peer_info(std::vector<peer_info>& v);
 		void get_download_queue(std::vector<partial_piece_info>* queue) const;
 
+#ifndef TORRENT_NO_DEPRECATED
 		void refresh_explicit_cache(int cache_size);
+#endif
 
 		void add_suggest_piece(int piece);
 		void update_suggest_piece(int index, int change);
 		void update_auto_sequential();
+
 		void refresh_suggest_pieces();
 		void do_refresh_suggest_pieces();
-		void on_cache_info(disk_io_job const* j);
 
 // --------------------------------------------
 		// TRACKER MANAGEMENT

src/session.cpp

@@ -231,7 +231,6 @@ namespace libtorrent
 		// download rate
 		set.set_int(settings_pack::max_queued_disk_bytes, 7 * 1024 * 1024);
 
-		set.set_bool(settings_pack::explicit_read_cache, false);
 		// prevent fast pieces to interfere with suggested pieces
 		// since we unchoke everyone, we don't need fast pieces anyway
 		set.set_int(settings_pack::allowed_fast_set_size, 0);

src/session_impl.cpp

@@ -393,8 +393,10 @@ namespace aux {
 		, m_optimistic_unchoke_time_scaler(0)
 		, m_disconnect_time_scaler(90)
 		, m_auto_scrape_time_scaler(180)
+#ifndef TORRENT_NO_DEPRECATED
 		, m_next_explicit_cache_torrent(0)
 		, m_cache_rotation_timer(0)
+#endif
 		, m_next_suggest_torrent(0)
 		, m_suggest_timer(0)
 		, m_peak_up_rate(0)
@@ -3333,6 +3335,7 @@ retry:
 			++m_next_suggest_torrent;
 		}
 
+#ifndef TORRENT_NO_DEPRECATED
 		// --------------------------------------------------------------
 		// refresh explicit disk read cache
 		// --------------------------------------------------------------
@@ -3368,6 +3371,7 @@ retry:
 				least_recently_refreshed->second->refresh_explicit_cache(cache_size);
 			++m_next_explicit_cache_torrent;
 		}
+#endif
 
 		// --------------------------------------------------------------
 		// connect new peers

src/settings_pack.cpp

@@ -152,7 +152,7 @@ namespace libtorrent
 		SET(use_read_cache, true, 0),
 		DEPRECATED_SET(use_write_cache, true, 0),
 		SET(dont_flush_write_cache, false, 0),
-		SET(explicit_read_cache, false, 0),
+		DEPRECATED_SET(explicit_read_cache, false, 0),
 		SET(coalesce_reads, false, 0),
 		SET(coalesce_writes, false, 0),
 		SET(auto_manage_prefer_seeds, false, 0),
@@ -251,7 +251,7 @@ namespace libtorrent
 		SET(cache_size, 1024, 0),
 		SET(cache_buffer_chunk_size, 0, &session_impl::update_cache_buffer_chunk_size),
 		SET(cache_expiry, 300, 0),
-		SET(explicit_cache_interval, 30, 0),
+		DEPRECATED_SET(explicit_cache_interval, 30, 0),
 		SET(disk_io_write_mode, settings_pack::enable_os_cache, 0),
 		SET(disk_io_read_mode, settings_pack::enable_os_cache, 0),
 		SET(outgoing_port, 0, 0),

src/torrent.cpp

@@ -10576,6 +10576,7 @@ namespace libtorrent
 		update_want_peers();
 	}
 
+#ifndef TORRENT_NO_DEPRECATED
 	// TODO: 2 this should probably be removed
 	void torrent::refresh_explicit_cache(int cache_size)
 	{
@@ -10674,6 +10675,7 @@ namespace libtorrent
 			}
 		}
 	}
+#endif
 
 	void torrent::sent_bytes(int bytes_payload, int bytes_protocol)
 	{

test/swarm_suite.cpp

@@ -48,13 +48,12 @@ void test_swarm(int flags)
 	using namespace libtorrent;
 	namespace lt = libtorrent;
 
-	fprintf(stderr, "\n\n ==== TEST SWARM === %s%s%s%s%s%s ===\n\n\n"
+	fprintf(stderr, "\n\n ==== TEST SWARM === %s%s%s%s%s ===\n\n\n"
 		, (flags & super_seeding) ? "super-seeding ": ""
 		, (flags & strict_super_seeding) ? "strict-super-seeding ": ""
 		, (flags & seed_mode) ? "seed-mode ": ""
 		, (flags & time_critical) ? "time-critical ": ""
 		, (flags & suggest) ? "suggest ": ""
-		, (flags & explicit_cache) ? "explicit-cache ": ""
 		);
 
 	// in case the previous run was terminated
@@ -89,15 +88,6 @@ void test_swarm(int flags)
 	if (flags & suggest)
 		pack.set_int(settings_pack::suggest_mode, settings_pack::suggest_read_cache);
 
-	if (flags & explicit_cache)
-		pack.set_bool(settings_pack::explicit_read_cache, true);
-
-	if (flags & explicit_cache)
-	{
-		pack.set_bool(settings_pack::explicit_read_cache, true);
-		pack.set_int(settings_pack::explicit_cache_interval, 5);
-	}
-
 	// this is to avoid everything finish from a single peer
 	// immediately. To make the swarm actually connect all
 	// three peers before finishing.

test/swarm_suite.hpp

@@ -39,7 +39,6 @@ enum test_flags_t
 	seed_mode = 4,
 	time_critical = 8,
 	suggest = 16,
-	explicit_cache = 32
 };
 
 void EXPORT test_swarm(int flags = 0);