storaged/storaged.cpp - LeafOS-Project/android_system_core - Gitiles

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "storaged"

 #include <dirent.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <time.h>
 #include <unistd.h>
 #include <zlib.h>

 #include <chrono>
 #include <fstream>
 #include <sstream>
 #include <string>

 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/unique_fd.h>
 #include <android/hidl/manager/1.0/IServiceManager.h>
 #include <batteryservice/BatteryServiceConstants.h>
 #include <cutils/properties.h>
 #include <healthhalutils/HealthHalUtils.h>
 #include <hidl/HidlTransportSupport.h>
 #include <hwbinder/IPCThreadState.h>
 #include <log/log.h>

 #include <storaged.h>
 #include <storaged_utils.h>

 using namespace android::base;
 using namespace chrono;
 using namespace google::protobuf::io;
 using namespace storaged_proto;

 namespace {

 /*
  * The system user is the initial user that is implicitly created on first boot
  * and hosts most of the system services. Keep this in sync with
  * frameworks/base/core/java/android/os/UserManager.java
  */
 constexpr int USER_SYSTEM = 0;

 constexpr ssize_t benchmark_unit_size = 16 * 1024;  // 16KB

 constexpr ssize_t min_benchmark_size = 128 * 1024;  // 128KB

 }  // namespace

 const uint32_t storaged_t::current_version = 4;

 using android::hardware::interfacesEqual;
 using android::hardware::Return;
 using android::hardware::health::V1_0::BatteryStatus;
 using android::hardware::health::V1_0::toString;
 using android::hardware::health::V2_0::get_health_service;
 using android::hardware::health::V2_0::HealthInfo;
 using android::hardware::health::V2_0::IHealth;
 using android::hardware::health::V2_0::Result;
 using android::hidl::manager::V1_0::IServiceManager;


 inline charger_stat_t is_charger_on(BatteryStatus prop) {
     return (prop == BatteryStatus::CHARGING || prop == BatteryStatus::FULL) ?
         CHARGER_ON : CHARGER_OFF;
 }

 Return<void> storaged_t::healthInfoChanged(const HealthInfo& props) {
     mUidm.set_charger_state(is_charger_on(props.legacy.batteryStatus));
     return android::hardware::Void();
 }

 void storaged_t::init() {
     init_health_service();
     mDsm = std::make_unique<disk_stats_monitor>(health);
     storage_info.reset(storage_info_t::get_storage_info(health));
 }

 void storaged_t::init_health_service() {
     if (!mUidm.enabled())
         return;

     health = get_health_service();
     if (health == NULL) {
         LOG_TO(SYSTEM, WARNING) << "health: failed to find IHealth service";
         return;
     }

     BatteryStatus status = BatteryStatus::UNKNOWN;
     auto ret = health->getChargeStatus([&](Result r, BatteryStatus v) {
         if (r != Result::SUCCESS) {
             LOG_TO(SYSTEM, WARNING)
                 << "health: cannot get battery status " << toString(r);
             return;
         }
         if (v == BatteryStatus::UNKNOWN) {
             LOG_TO(SYSTEM, WARNING) << "health: invalid battery status";
         }
         status = v;
     });
     if (!ret.isOk()) {
         LOG_TO(SYSTEM, WARNING) << "health: get charge status transaction error "
             << ret.description();
     }

     mUidm.init(is_charger_on(status));
     // register listener after init uid_monitor
     health->registerCallback(this);
     health->linkToDeath(this, 0 /* cookie */);
 }

 void storaged_t::serviceDied(uint64_t cookie, const wp<::android::hidl::base::V1_0::IBase>& who) {
     if (health != NULL && interfacesEqual(health, who.promote())) {
         LOG_TO(SYSTEM, ERROR) << "health service died, exiting";
         android::hardware::IPCThreadState::self()->stopProcess();
         exit(1);
     } else {
         LOG_TO(SYSTEM, ERROR) << "unknown service died";
     }
 }

 void storaged_t::report_storage_info() {
     storage_info->report();
 }

 /* storaged_t */
 storaged_t::storaged_t(void) {
     mConfig.periodic_chores_interval_unit =
         property_get_int32("ro.storaged.event.interval",
                            DEFAULT_PERIODIC_CHORES_INTERVAL_UNIT);

     mConfig.event_time_check_usec =
         property_get_int32("ro.storaged.event.perf_check", 0);

     mConfig.periodic_chores_interval_disk_stats_publish =
         property_get_int32("ro.storaged.disk_stats_pub",
                            DEFAULT_PERIODIC_CHORES_INTERVAL_DISK_STATS_PUBLISH);

     mConfig.periodic_chores_interval_uid_io =
         property_get_int32("ro.storaged.uid_io.interval",
                            DEFAULT_PERIODIC_CHORES_INTERVAL_UID_IO);

     mConfig.periodic_chores_interval_flush_proto =
         property_get_int32("ro.storaged.flush_proto.interval",
                            DEFAULT_PERIODIC_CHORES_INTERVAL_FLUSH_PROTO);

     mStarttime = time(NULL);
     mTimer = 0;
 }

 void storaged_t::add_user_ce(userid_t user_id) {
     load_proto(user_id);
     proto_loaded[user_id] = true;
 }

 void storaged_t::remove_user_ce(userid_t user_id) {
     proto_loaded[user_id] = false;
     mUidm.clear_user_history(user_id);
     RemoveFileIfExists(proto_path(user_id), nullptr);
 }

 void storaged_t::load_proto(userid_t user_id) {
     string proto_file = proto_path(user_id);
     ifstream in(proto_file, ofstream::in | ofstream::binary);

     if (!in.good()) return;

     stringstream ss;
     ss << in.rdbuf();
     StoragedProto proto;
     proto.ParseFromString(ss.str());

     const UidIOUsage& uid_io_usage = proto.uid_io_usage();
     uint32_t computed_crc = crc32(current_version,
         reinterpret_cast<const Bytef*>(uid_io_usage.SerializeAsString().c_str()),
         uid_io_usage.ByteSize());
     if (proto.crc() != computed_crc) {
         LOG_TO(SYSTEM, WARNING) << "CRC mismatch in " << proto_file;
         return;
     }

     mUidm.load_uid_io_proto(user_id, proto.uid_io_usage());

     if (user_id == USER_SYSTEM) {
         storage_info->load_perf_history_proto(proto.perf_history());
     }
 }

 char* storaged_t:: prepare_proto(userid_t user_id, StoragedProto* proto) {
     proto->set_version(current_version);

     const UidIOUsage& uid_io_usage = proto->uid_io_usage();
     proto->set_crc(crc32(current_version,
         reinterpret_cast<const Bytef*>(uid_io_usage.SerializeAsString().c_str()),
         uid_io_usage.ByteSize()));

     uint32_t pagesize = sysconf(_SC_PAGESIZE);
     if (user_id == USER_SYSTEM) {
         proto->set_padding("", 1);
         vector<char> padding;
         ssize_t size = ROUND_UP(MAX(min_benchmark_size, proto->ByteSize()),
                                 pagesize);
         padding = vector<char>(size - proto->ByteSize(), 0xFD);
         proto->set_padding(padding.data(), padding.size());
         while (!IS_ALIGNED(proto->ByteSize(), pagesize)) {
             padding.push_back(0xFD);
             proto->set_padding(padding.data(), padding.size());
         }
     }

     char* data = nullptr;
     if (posix_memalign(reinterpret_cast<void**>(&data),
                        pagesize, proto->ByteSize())) {
         PLOG_TO(SYSTEM, ERROR) << "Faied to alloc aligned buffer (size: "
                                << proto->ByteSize() << ")";
         return data;
     }

     proto->SerializeToArray(data, proto->ByteSize());
     return data;
 }

 void storaged_t::flush_proto_data(userid_t user_id,
                                   const char* data, ssize_t size) {
     string proto_file = proto_path(user_id);
     string tmp_file = proto_file + "_tmp";
     unique_fd fd(TEMP_FAILURE_RETRY(open(tmp_file.c_str(),
                  O_SYNC | O_CREAT | O_TRUNC | O_WRONLY | O_CLOEXEC |
                     (user_id == USER_SYSTEM ? O_DIRECT : 0),
                  S_IRUSR | S_IWUSR)));
     if (fd == -1) {
         PLOG_TO(SYSTEM, ERROR) << "Faied to open tmp file: " << tmp_file;
         return;
     }

     if (user_id == USER_SYSTEM) {
         time_point<steady_clock> start, end;
         uint32_t benchmark_size = 0;
         uint64_t benchmark_time_ns = 0;
         ssize_t ret;
         bool first_write = true;

         while (size > 0) {
             start = steady_clock::now();
             ret = write(fd, data, MIN(benchmark_unit_size, size));
             if (ret <= 0) {
                 PLOG_TO(SYSTEM, ERROR) << "Faied to write tmp file: " << tmp_file;
                 return;
             }
             end = steady_clock::now();
             /*
             * compute bandwidth after the first write and if write returns
             * exactly unit size.
             */
             if (!first_write && ret == benchmark_unit_size) {
                 benchmark_size += benchmark_unit_size;
                 benchmark_time_ns += duration_cast<nanoseconds>(end - start).count();
             }
             size -= ret;
             data += ret;
             first_write = false;
         }

         if (benchmark_size) {
             int perf = benchmark_size * 1000000LLU / benchmark_time_ns;
             storage_info->update_perf_history(perf, system_clock::now());
         }
     } else {
         if (!WriteFully(fd, data, size)) {
             PLOG_TO(SYSTEM, ERROR) << "Faied to write tmp file: " << tmp_file;
             return;
         }
     }

     fd.reset(-1);
     rename(tmp_file.c_str(), proto_file.c_str());
 }

 void storaged_t::flush_proto(userid_t user_id, StoragedProto* proto) {
     unique_ptr<char> proto_data(prepare_proto(user_id, proto));
     if (proto_data == nullptr) return;

     flush_proto_data(user_id, proto_data.get(), proto->ByteSize());
 }

 void storaged_t::flush_protos(unordered_map<int, StoragedProto>* protos) {
     for (auto& it : *protos) {
         /*
          * Don't flush proto if we haven't attempted to load it from file.
          */
         if (proto_loaded[it.first]) {
             flush_proto(it.first, &it.second);
         }
     }
 }

 void storaged_t::event(void) {
     unordered_map<int, StoragedProto> protos;

     if (mDsm->enabled()) {
         mDsm->update();
         if (!(mTimer % mConfig.periodic_chores_interval_disk_stats_publish)) {
             mDsm->publish();
         }
     }

     if (!(mTimer % mConfig.periodic_chores_interval_uid_io)) {
         mUidm.report(&protos);
     }

     if (storage_info) {
         storage_info->refresh(protos[USER_SYSTEM].mutable_perf_history());
     }

     if (!(mTimer % mConfig.periodic_chores_interval_flush_proto)) {
         flush_protos(&protos);
     }

     mTimer += mConfig.periodic_chores_interval_unit;
 }

 void storaged_t::event_checked(void) {
     struct timespec start_ts, end_ts;
     bool check_time = true;

     if (mConfig.event_time_check_usec &&
         clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_ts) < 0) {
         check_time = false;
         PLOG_TO(SYSTEM, ERROR) << "clock_gettime() failed";
     }

     event();

     if (mConfig.event_time_check_usec && check_time) {
         if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_ts) < 0) {
             PLOG_TO(SYSTEM, ERROR) << "clock_gettime() failed";
             return;
         }
         int64_t cost = (end_ts.tv_sec - start_ts.tv_sec) * SEC_TO_USEC +
                        (end_ts.tv_nsec - start_ts.tv_nsec) / USEC_TO_NSEC;
         if (cost > mConfig.event_time_check_usec) {
             LOG_TO(SYSTEM, ERROR)
                 << "event loop spent " << cost << " usec, threshold "
                 << mConfig.event_time_check_usec << " usec";
         }
     }
 }
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "storaged"

	#include <dirent.h>
	#include <stdlib.h>
	#include <stdio.h>
	#include <time.h>
	#include <unistd.h>
	#include <zlib.h>

	#include <chrono>
	#include <fstream>
	#include <sstream>
	#include <string>

	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/unique_fd.h>
	#include <android/hidl/manager/1.0/IServiceManager.h>
	#include <batteryservice/BatteryServiceConstants.h>
	#include <cutils/properties.h>
	#include <healthhalutils/HealthHalUtils.h>
	#include <hidl/HidlTransportSupport.h>
	#include <hwbinder/IPCThreadState.h>
	#include <log/log.h>

	#include <storaged.h>
	#include <storaged_utils.h>

	using namespace android::base;
	using namespace chrono;
	using namespace google::protobuf::io;
	using namespace storaged_proto;

	namespace {

	/*
	* The system user is the initial user that is implicitly created on first boot
	* and hosts most of the system services. Keep this in sync with
	* frameworks/base/core/java/android/os/UserManager.java
	*/
	constexpr int USER_SYSTEM = 0;

	constexpr ssize_t benchmark_unit_size = 16 * 1024; // 16KB

	constexpr ssize_t min_benchmark_size = 128 * 1024; // 128KB

	} // namespace

	const uint32_t storaged_t::current_version = 4;

	using android::hardware::interfacesEqual;
	using android::hardware::Return;
	using android::hardware::health::V1_0::BatteryStatus;
	using android::hardware::health::V1_0::toString;
	using android::hardware::health::V2_0::get_health_service;
	using android::hardware::health::V2_0::HealthInfo;
	using android::hardware::health::V2_0::IHealth;
	using android::hardware::health::V2_0::Result;
	using android::hidl::manager::V1_0::IServiceManager;


	inline charger_stat_t is_charger_on(BatteryStatus prop) {
	return (prop == BatteryStatus::CHARGING \|\| prop == BatteryStatus::FULL) ?
	CHARGER_ON : CHARGER_OFF;
	}

	Return<void> storaged_t::healthInfoChanged(const HealthInfo& props) {
	mUidm.set_charger_state(is_charger_on(props.legacy.batteryStatus));
	return android::hardware::Void();
	}

	void storaged_t::init() {
	init_health_service();
	mDsm = std::make_unique<disk_stats_monitor>(health);
	storage_info.reset(storage_info_t::get_storage_info(health));
	}

	void storaged_t::init_health_service() {
	if (!mUidm.enabled())
	return;

	health = get_health_service();
	if (health == NULL) {
	LOG_TO(SYSTEM, WARNING) << "health: failed to find IHealth service";
	return;
	}

	BatteryStatus status = BatteryStatus::UNKNOWN;
	auto ret = health->getChargeStatus([&](Result r, BatteryStatus v) {
	if (r != Result::SUCCESS) {
	LOG_TO(SYSTEM, WARNING)
	<< "health: cannot get battery status " << toString(r);
	return;
	}
	if (v == BatteryStatus::UNKNOWN) {
	LOG_TO(SYSTEM, WARNING) << "health: invalid battery status";
	}
	status = v;
	});
	if (!ret.isOk()) {
	LOG_TO(SYSTEM, WARNING) << "health: get charge status transaction error "
	<< ret.description();
	}

	mUidm.init(is_charger_on(status));
	// register listener after init uid_monitor
	health->registerCallback(this);
	health->linkToDeath(this, 0 /* cookie */);
	}

	void storaged_t::serviceDied(uint64_t cookie, const wp<::android::hidl::base::V1_0::IBase>& who) {
	if (health != NULL && interfacesEqual(health, who.promote())) {
	LOG_TO(SYSTEM, ERROR) << "health service died, exiting";
	android::hardware::IPCThreadState::self()->stopProcess();
	exit(1);
	} else {
	LOG_TO(SYSTEM, ERROR) << "unknown service died";
	}
	}

	void storaged_t::report_storage_info() {
	storage_info->report();
	}

	/* storaged_t */
	storaged_t::storaged_t(void) {
	mConfig.periodic_chores_interval_unit =
	property_get_int32("ro.storaged.event.interval",
	DEFAULT_PERIODIC_CHORES_INTERVAL_UNIT);

	mConfig.event_time_check_usec =
	property_get_int32("ro.storaged.event.perf_check", 0);

	mConfig.periodic_chores_interval_disk_stats_publish =
	property_get_int32("ro.storaged.disk_stats_pub",
	DEFAULT_PERIODIC_CHORES_INTERVAL_DISK_STATS_PUBLISH);

	mConfig.periodic_chores_interval_uid_io =
	property_get_int32("ro.storaged.uid_io.interval",
	DEFAULT_PERIODIC_CHORES_INTERVAL_UID_IO);

	mConfig.periodic_chores_interval_flush_proto =
	property_get_int32("ro.storaged.flush_proto.interval",
	DEFAULT_PERIODIC_CHORES_INTERVAL_FLUSH_PROTO);

	mStarttime = time(NULL);
	mTimer = 0;
	}

	void storaged_t::add_user_ce(userid_t user_id) {
	load_proto(user_id);
	proto_loaded[user_id] = true;
	}

	void storaged_t::remove_user_ce(userid_t user_id) {
	proto_loaded[user_id] = false;
	mUidm.clear_user_history(user_id);
	RemoveFileIfExists(proto_path(user_id), nullptr);
	}

	void storaged_t::load_proto(userid_t user_id) {
	string proto_file = proto_path(user_id);
	ifstream in(proto_file, ofstream::in \| ofstream::binary);

	if (!in.good()) return;

	stringstream ss;
	ss << in.rdbuf();
	StoragedProto proto;
	proto.ParseFromString(ss.str());

	const UidIOUsage& uid_io_usage = proto.uid_io_usage();
	uint32_t computed_crc = crc32(current_version,
	reinterpret_cast<const Bytef*>(uid_io_usage.SerializeAsString().c_str()),
	uid_io_usage.ByteSize());
	if (proto.crc() != computed_crc) {
	LOG_TO(SYSTEM, WARNING) << "CRC mismatch in " << proto_file;
	return;
	}

	mUidm.load_uid_io_proto(user_id, proto.uid_io_usage());

	if (user_id == USER_SYSTEM) {
	storage_info->load_perf_history_proto(proto.perf_history());
	}
	}

	char* storaged_t:: prepare_proto(userid_t user_id, StoragedProto* proto) {
	proto->set_version(current_version);

	const UidIOUsage& uid_io_usage = proto->uid_io_usage();
	proto->set_crc(crc32(current_version,
	reinterpret_cast<const Bytef*>(uid_io_usage.SerializeAsString().c_str()),
	uid_io_usage.ByteSize()));

	uint32_t pagesize = sysconf(_SC_PAGESIZE);
	if (user_id == USER_SYSTEM) {
	proto->set_padding("", 1);
	vector<char> padding;
	ssize_t size = ROUND_UP(MAX(min_benchmark_size, proto->ByteSize()),
	pagesize);
	padding = vector<char>(size - proto->ByteSize(), 0xFD);
	proto->set_padding(padding.data(), padding.size());
	while (!IS_ALIGNED(proto->ByteSize(), pagesize)) {
	padding.push_back(0xFD);
	proto->set_padding(padding.data(), padding.size());
	}
	}

	char* data = nullptr;
	if (posix_memalign(reinterpret_cast<void**>(&data),
	pagesize, proto->ByteSize())) {
	PLOG_TO(SYSTEM, ERROR) << "Faied to alloc aligned buffer (size: "
	<< proto->ByteSize() << ")";
	return data;
	}

	proto->SerializeToArray(data, proto->ByteSize());
	return data;
	}

	void storaged_t::flush_proto_data(userid_t user_id,
	const char* data, ssize_t size) {
	string proto_file = proto_path(user_id);
	string tmp_file = proto_file + "_tmp";
	unique_fd fd(TEMP_FAILURE_RETRY(open(tmp_file.c_str(),
	O_SYNC \| O_CREAT \| O_TRUNC \| O_WRONLY \| O_CLOEXEC \|
	(user_id == USER_SYSTEM ? O_DIRECT : 0),
	S_IRUSR \| S_IWUSR)));
	if (fd == -1) {
	PLOG_TO(SYSTEM, ERROR) << "Faied to open tmp file: " << tmp_file;
	return;
	}

	if (user_id == USER_SYSTEM) {
	time_point<steady_clock> start, end;
	uint32_t benchmark_size = 0;
	uint64_t benchmark_time_ns = 0;
	ssize_t ret;
	bool first_write = true;

	while (size > 0) {
	start = steady_clock::now();
	ret = write(fd, data, MIN(benchmark_unit_size, size));
	if (ret <= 0) {
	PLOG_TO(SYSTEM, ERROR) << "Faied to write tmp file: " << tmp_file;
	return;
	}
	end = steady_clock::now();
	/*
	* compute bandwidth after the first write and if write returns
	* exactly unit size.
	*/
	if (!first_write && ret == benchmark_unit_size) {
	benchmark_size += benchmark_unit_size;
	benchmark_time_ns += duration_cast<nanoseconds>(end - start).count();
	}
	size -= ret;
	data += ret;
	first_write = false;
	}

	if (benchmark_size) {
	int perf = benchmark_size * 1000000LLU / benchmark_time_ns;
	storage_info->update_perf_history(perf, system_clock::now());
	}
	} else {
	if (!WriteFully(fd, data, size)) {
	PLOG_TO(SYSTEM, ERROR) << "Faied to write tmp file: " << tmp_file;
	return;
	}
	}

	fd.reset(-1);
	rename(tmp_file.c_str(), proto_file.c_str());
	}

	void storaged_t::flush_proto(userid_t user_id, StoragedProto* proto) {
	unique_ptr<char> proto_data(prepare_proto(user_id, proto));
	if (proto_data == nullptr) return;

	flush_proto_data(user_id, proto_data.get(), proto->ByteSize());
	}

	void storaged_t::flush_protos(unordered_map<int, StoragedProto>* protos) {
	for (auto& it : *protos) {
	/*
	* Don't flush proto if we haven't attempted to load it from file.
	*/
	if (proto_loaded[it.first]) {
	flush_proto(it.first, &it.second);
	}
	}
	}

	void storaged_t::event(void) {
	unordered_map<int, StoragedProto> protos;

	if (mDsm->enabled()) {
	mDsm->update();
	if (!(mTimer % mConfig.periodic_chores_interval_disk_stats_publish)) {
	mDsm->publish();
	}
	}

	if (!(mTimer % mConfig.periodic_chores_interval_uid_io)) {
	mUidm.report(&protos);
	}

	if (storage_info) {
	storage_info->refresh(protos[USER_SYSTEM].mutable_perf_history());
	}

	if (!(mTimer % mConfig.periodic_chores_interval_flush_proto)) {
	flush_protos(&protos);
	}

	mTimer += mConfig.periodic_chores_interval_unit;
	}

	void storaged_t::event_checked(void) {
	struct timespec start_ts, end_ts;
	bool check_time = true;

	if (mConfig.event_time_check_usec &&
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_ts) < 0) {
	check_time = false;
	PLOG_TO(SYSTEM, ERROR) << "clock_gettime() failed";
	}

	event();

	if (mConfig.event_time_check_usec && check_time) {
	if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_ts) < 0) {
	PLOG_TO(SYSTEM, ERROR) << "clock_gettime() failed";
	return;
	}
	int64_t cost = (end_ts.tv_sec - start_ts.tv_sec) * SEC_TO_USEC +
	(end_ts.tv_nsec - start_ts.tv_nsec) / USEC_TO_NSEC;
	if (cost > mConfig.event_time_check_usec) {
	LOG_TO(SYSTEM, ERROR)
	<< "event loop spent " << cost << " usec, threshold "
	<< mConfig.event_time_check_usec << " usec";
	}
	}
	}