C++ session::write_data方法代码示例

static void test_cache_timestamp(session &sess)
{
	argument_data data("this is a timestamp test");

	key k("this is a timestamp test key");
	sess.transform(k);

	dnet_io_control ctl;
	memset(&ctl, 0, sizeof(ctl));

	ctl.data = data.data();

	dnet_current_time(&ctl.io.timestamp);
	ctl.io.flags = DNET_IO_FLAGS_CACHE;
	ctl.io.start = 5;
	ctl.io.size = data.size();

	memcpy(&ctl.id, &k.id(), sizeof(dnet_id));
	ctl.fd = -1;

	ELLIPTICS_REQUIRE(write_result, sess.write_data(ctl));

	sleep(ctl.io.start + 2);

	ELLIPTICS_REQUIRE(read_result, sess.read_data(k, 0, 0));
	auto io = read_result.get_one().io_attribute();

	BOOST_REQUIRE_EQUAL(io->timestamp.tsec, ctl.io.timestamp.tsec);
	BOOST_REQUIRE_EQUAL(io->timestamp.tnsec, ctl.io.timestamp.tnsec);
}

/*
 * After writing of a key to cache, keys data will be synced to disk cache_sync_timeout seconds later.
 * Before syncing a key, dnet_oplock() taken for this key. After syncing a key, key's oplock released.
 *
 * Following test checks this mechanics by calling write_data(key, data) multiple times with the same data,
 * then writing to cache by calling write_cache(key, cache_data) cache data, waiting cache_sync_timeout seconds
 * until cache is synced back to disk (backend), thereby taking oplock. Then called write_data(key, result_data).
 * If last write_data() operation timeouted, then dnet_opunlock() (after cache sync) is not properly realeased key's oplock.
 */
static void test_oplock(session &sess)
{
	const key id(std::string("oplock_key"));
	const std::string data = "some_data";
	const std::string cache_data = "cache_data";
	const std::string result_data = "result_data";

	const size_t num_writes = 10;
	std::unique_ptr<async_write_result[]> results(new async_write_result[num_writes]);

	for (size_t i = 0; i < num_writes; ++i) {
		results[i] = std::move(sess.write_data(id, data, 0));
	}
	for (size_t i = 0; i < num_writes; ++i) {
		results[i].wait();
	}
	ELLIPTICS_COMPARE_REQUIRE(read_data_result, sess.read_data(id, 0, 0), data);

	ELLIPTICS_REQUIRE(async_cache_write, sess.write_cache(id, cache_data, 0));
	sleep(cache_sync_timeout + 1);
	ELLIPTICS_COMPARE_REQUIRE(read_cache_result, sess.read_data(id, 0, 0), cache_data);
	ELLIPTICS_REQUIRE(async_write, sess.write_data(id, result_data, 0));
	ELLIPTICS_COMPARE_REQUIRE(read_result, sess.read_data(id, 0, 0), result_data);
}

/*
 * Multiple writes with same key must be processed in the same order as
 * they were initiated by client.
 *
 * Following test checks this mechanics by calling write_cas() with data containing
 * counter that is incremented after every write_cas() and checking that previosly stored
 * counter is one unit less than current counter. Also this test writes multiple different
 * keys (with repetitions) in different order, thereby modelling real workload case.
 */
static void test_write_order_execution(session &sess)
{
	const int num_write_repetitions = 5;
	const int num_different_keys = 10;
	std::vector<std::pair<key, int>> keys;
	for (int i = 0; i < num_different_keys; ++i) {
		key id(std::to_string(static_cast<unsigned long long>(i)));
		for (int j = 0; j < num_write_repetitions; ++j) {
			keys.push_back(std::make_pair(id, i));
		}
	}

	std::unique_ptr<async_write_result[]> results(new async_write_result[keys.size()]);
	dnet_id old_csum;

	const int num_iterations = 30;
	for (int i = 0; i < num_iterations; ++i) {
		// every key is associated with counter, which is initialized by zero
		std::vector<int> write_counter(num_different_keys, 0);

		std::random_shuffle(keys.begin(), keys.end());

		for (size_t j = 0; j < keys.size(); ++j) {
			// increment counter associated with key identified by key_id
			const int key_id = keys[j].second;
			const int new_value = write_counter[key_id]++;
			if (new_value > 0) {
				const int prev_value = new_value - 1;
				memset(&old_csum, 0, sizeof(old_csum));
				sess.transform(std::to_string(static_cast<unsigned long long>(prev_value)), old_csum);
				results[j] = std::move(sess.write_cas(keys[j].first, std::to_string(static_cast<unsigned long long>(new_value)), old_csum, 0));
			} else {
				// first write
				results[j] = std::move(sess.write_data(keys[j].first, std::to_string(static_cast<unsigned long long>(new_value)), 0));
			}
		}

		for (size_t j = 0; j < keys.size(); ++j) {
			results[j].wait();
			const int err = results[j].error().code();
			BOOST_REQUIRE_MESSAGE(err == 0,
					      "write_cas() failed (err=" + std::to_string(static_cast<unsigned long long>(err)) + "): "
					      "multiple consecutive writes are executed out-of-order "
					      "or overlapped. Oplock mechanism of backend's request queue is broken.");
		}
	}
}

// Writing of keys to all groups updates backend weights for every backend they
// were written. Writes to slow backend leads to significant reduction of this
// backend weigth comparing to faster ones.
// read_data() uses backend weights to choose fastest group via dnet_mix_states().
//
// Following test checks this mechanics by reading of previously written keys and
// checking read distribution among backends. Slow backend simulated by setting artificial delay.
// Expected outcome should be that reads would be rarely sent to that slow backend.
//
// We define "rarely" as no more than 1% of total reads. This value was empirically found.
static void test_backend_weights(session &sess)
{
	// set backends delay to simulate slow backends i/o behaviour for particular group
	set_backends_delay_for_group(sess, slow_group_id, backend_delay);

	const int num_keys = 10;
	for (int i = 0; i < num_keys; ++i) {
		const key id = std::string("key_") + std::to_string(static_cast<long long>(i));
		const std::string data = "some_data";
		ELLIPTICS_REQUIRE(async_write, sess.write_data(id, data, 0));
	}

	const int num_reads = 1000;
	int num_slow_group_reads = 0;
	for (int i = 0; i < num_reads; ++i) {
		const key id = std::string("key_") + std::to_string(static_cast<long long>(i % num_keys));
		auto async_result = sess.read_data(id, 0, 0);
		async_result.wait();

		read_result_entry read_result;
		async_result.get(read_result);

		const dnet_cmd *cmd = read_result.command();
		const int group_id = cmd->id.group_id;
		if ( group_id == slow_group_id )
			++num_slow_group_reads;
	}

	const int max_reads_from_slow_group = 10;
	BOOST_REQUIRE_MESSAGE(num_slow_group_reads < max_reads_from_slow_group,
			      "Too much reads from slow group (it means that backend weights are not working or backend hardware is extremely slow): "
			      "num_slow_group_reads: " + std::to_string(static_cast<long long>(num_slow_group_reads)) +
			      ", max_reads_from_slow_group: " + std::to_string(static_cast<long long>(max_reads_from_slow_group)));

	set_backends_delay_for_group(sess, slow_group_id, 0);
}