relay: Reduce streaming compression ratio from HIGH to LOW (70d8fb3e) · Commits · The Tor Project / Core / Tor

changes/ticket40301

0 → 100644

+4 −0

Original line number	Original line	Diff line number	Diff line
			o Minor bugfixes (relay):
			- Reduce the compression level for data streaming from HIGH to LOW. Fixes
			bug 40301; bugfix on 0.3.5.1-alpha.

src/feature/dircache/dircache.c

+20 −17

Original line number	Original line	Diff line number	Diff line
	@@ -296,19 +296,22 @@ client_likes_consensus(const struct consensus_cache_entry_t *ent,
	/** Return the compression level we should use for sending a compressed		/** Return the compression level we should use for sending a compressed
	* response of size <b>n_bytes</b>. */		* response of size <b>n_bytes</b>. */
	STATIC compression_level_t		STATIC compression_level_t
	choose_compression_level(ssize_t n_bytes)		choose_compression_level(void)
	{		{
	if (! have_been_under_memory_pressure()) {		/* This is the compression level choice for a stream.
	return HIGH_COMPRESSION; /* we have plenty of RAM. */		*
	} else if (n_bytes < 0) {		* We always return LOW because this compression is done in the main thread
	return HIGH_COMPRESSION; /* unknown; might be big. */		* thus we save CPU time as much as possible, and it is also done more than
	} else if (n_bytes < 1024) {		* background compression for document we serve pre-compressed.
			*
			* GZip highest compression level (9) gives us a ratio of 49.72%
			* Zstd lowest compression level (1) gives us a ratio of 47.38%
			*
			* Thus, as the network moves more and more to use Zstd when requesting
			* directory documents that are not pre-cached, even at the
			* lowest level, we still gain over GZip and thus help with load and CPU
			* time on the network. */
	return LOW_COMPRESSION;		return LOW_COMPRESSION;
	} else if (n_bytes < 2048) {
	return MEDIUM_COMPRESSION;
	} else {
	return HIGH_COMPRESSION;
	}
	}		}

	/** Information passed to handle a GET request. */		/** Information passed to handle a GET request. */
	@@ -1078,7 +1081,7 @@ handle_get_status_vote(dir_connection_t conn, const get_handler_args_t args)
	if (smartlist_len(items)) {		if (smartlist_len(items)) {
	if (compress_method != NO_METHOD) {		if (compress_method != NO_METHOD) {
	conn->compress_state = tor_compress_new(1, compress_method,		conn->compress_state = tor_compress_new(1, compress_method,
	choose_compression_level(estimated_len));		choose_compression_level());
	}		}

	SMARTLIST_FOREACH(items, const char *, c,		SMARTLIST_FOREACH(items, const char *, c,
	@@ -1141,7 +1144,7 @@ handle_get_microdesc(dir_connection_t conn, const get_handler_args_t args)

	if (compress_method != NO_METHOD)		if (compress_method != NO_METHOD)
	conn->compress_state = tor_compress_new(1, compress_method,		conn->compress_state = tor_compress_new(1, compress_method,
	choose_compression_level(size_guess));		choose_compression_level());

	const int initial_flush_result = connection_dirserv_flushed_some(conn);		const int initial_flush_result = connection_dirserv_flushed_some(conn);
	tor_assert_nonfatal(initial_flush_result == 0);		tor_assert_nonfatal(initial_flush_result == 0);
	@@ -1236,7 +1239,7 @@ handle_get_descriptor(dir_connection_t conn, const get_handler_args_t args)
	write_http_response_header(conn, -1, compress_method, cache_lifetime);		write_http_response_header(conn, -1, compress_method, cache_lifetime);
	if (compress_method != NO_METHOD)		if (compress_method != NO_METHOD)
	conn->compress_state = tor_compress_new(1, compress_method,		conn->compress_state = tor_compress_new(1, compress_method,
	choose_compression_level(size_guess));		choose_compression_level());
	clear_spool = 0;		clear_spool = 0;
	/* Prime the connection with some data. */		/* Prime the connection with some data. */
	int initial_flush_result = connection_dirserv_flushed_some(conn);		int initial_flush_result = connection_dirserv_flushed_some(conn);
	@@ -1332,7 +1335,7 @@ handle_get_keys(dir_connection_t conn, const get_handler_args_t args)
	60*60);		60*60);
	if (compress_method != NO_METHOD) {		if (compress_method != NO_METHOD) {
	conn->compress_state = tor_compress_new(1, compress_method,		conn->compress_state = tor_compress_new(1, compress_method,
	choose_compression_level(len));		choose_compression_level());
	}		}

	SMARTLIST_FOREACH(certs, authority_cert_t *, c,		SMARTLIST_FOREACH(certs, authority_cert_t *, c,
	@@ -1484,7 +1487,7 @@ handle_get_next_bandwidth(dir_connection_t *conn,
	compress_method, BANDWIDTH_CACHE_LIFETIME);		compress_method, BANDWIDTH_CACHE_LIFETIME);
	if (compress_method != NO_METHOD) {		if (compress_method != NO_METHOD) {
	conn->compress_state = tor_compress_new(1, compress_method,		conn->compress_state = tor_compress_new(1, compress_method,
	choose_compression_level(len/2));		choose_compression_level());
	log_debug(LD_DIR, "Compressing bandwidth file.");		log_debug(LD_DIR, "Compressing bandwidth file.");
	} else {		} else {
	log_debug(LD_DIR, "Not compressing bandwidth file.");		log_debug(LD_DIR, "Not compressing bandwidth file.");

src/feature/dircache/dircache.h

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -26,7 +26,7 @@ MOCK_DECL(STATIC int, directory_handle_command_post,(dir_connection_t *conn,

	STATIC int handle_post_hs_descriptor(const char url, const char body);		STATIC int handle_post_hs_descriptor(const char url, const char body);
	enum compression_level_t;		enum compression_level_t;
	STATIC enum compression_level_t choose_compression_level(ssize_t n_bytes);		STATIC enum compression_level_t choose_compression_level(void);

	struct get_handler_args_t;		struct get_handler_args_t;
	STATIC int handle_get_hs_descriptor_v3(dir_connection_t *conn,		STATIC int handle_get_hs_descriptor_v3(dir_connection_t *conn,

src/lib/compress/compress_zstd.c

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -49,8 +49,8 @@ memory_level(compression_level_t level)
	default:		default:
	case BEST_COMPRESSION:		case BEST_COMPRESSION:
	case HIGH_COMPRESSION: return 9;		case HIGH_COMPRESSION: return 9;
	case MEDIUM_COMPRESSION: return 8;		case MEDIUM_COMPRESSION: return 3;
	case LOW_COMPRESSION: return 7;		case LOW_COMPRESSION: return 1;
	}		}
	}		}
	#endif /* defined(HAVE_ZSTD) */		#endif /* defined(HAVE_ZSTD) */

src/test/test_dir.c

+0 −26

Original line number	Original line	Diff line number	Diff line
	@@ -5495,31 +5495,6 @@ dir_tests_directory_initiate_request(directory_request_t *req)
	dir_tests_directory_initiate_request_called++;		dir_tests_directory_initiate_request_called++;
	}		}

	static void
	test_dir_choose_compression_level(void* data)
	{
	(void)data;

	/* It starts under_memory_pressure */
	tt_int_op(have_been_under_memory_pressure(), OP_EQ, 1);

	tt_assert(HIGH_COMPRESSION == choose_compression_level(-1));
	tt_assert(LOW_COMPRESSION == choose_compression_level(1024-1));
	tt_assert(MEDIUM_COMPRESSION == choose_compression_level(2048-1));
	tt_assert(HIGH_COMPRESSION == choose_compression_level(2048));

	/* Reset under_memory_pressure timer */
	cell_queues_check_size();
	tt_int_op(have_been_under_memory_pressure(), OP_EQ, 0);

	tt_assert(HIGH_COMPRESSION == choose_compression_level(-1));
	tt_assert(HIGH_COMPRESSION == choose_compression_level(1024-1));
	tt_assert(HIGH_COMPRESSION == choose_compression_level(2048-1));
	tt_assert(HIGH_COMPRESSION == choose_compression_level(2048));

	done: ;
	}

	/*		/*
	* Mock check_private_dir(), and always succeed - no need to actually		* Mock check_private_dir(), and always succeed - no need to actually
	* look at or create anything on the filesystem.		* look at or create anything on the filesystem.
	@@ -7325,7 +7300,6 @@ struct testcase_t dir_tests[] = {
	DIR(should_not_init_request_to_ourselves, TT_FORK),		DIR(should_not_init_request_to_ourselves, TT_FORK),
	DIR(should_not_init_request_to_dir_auths_without_v3_info, 0),		DIR(should_not_init_request_to_dir_auths_without_v3_info, 0),
	DIR(should_init_request_to_dir_auths, 0),		DIR(should_init_request_to_dir_auths, 0),
	DIR(choose_compression_level, 0),
	DIR(dump_unparseable_descriptors, 0),		DIR(dump_unparseable_descriptors, 0),
	DIR(populate_dump_desc_fifo, 0),		DIR(populate_dump_desc_fifo, 0),
	DIR(populate_dump_desc_fifo_2, 0),		DIR(populate_dump_desc_fifo_2, 0),