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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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.
*/
package org.elasticsearch.monitor.os;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.lucene.util.Constants;
import org.elasticsearch.common.SuppressForbidden;
import org.elasticsearch.common.io.PathUtils;
import org.elasticsearch.monitor.Probes;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
/**
* The {@link OsProbe} class retrieves information about the physical and swap size of the machine
* memory, as well as the system load average and cpu load.
*
* In some exceptional cases, it's possible the underlying native method used by
* {@link #getFreePhysicalMemorySize()} and {@link #getTotalPhysicalMemorySize()} can return a
* negative value. Because of this, we prevent those methods from returning negative values,
* returning 0 instead.
*
* The OS can report a negative number in a number of cases:
* - Non-supported OSes (HP-UX, or AIX)
* - A failure of macOS to initialize host statistics
* - An OS that does not support the {@code _SC_PHYS_PAGES} or {@code _SC_PAGE_SIZE} flags for the {@code sysconf()} linux kernel call
* - An overflow of the product of {@code _SC_PHYS_PAGES} and {@code _SC_PAGE_SIZE}
* - An error case retrieving these values from a linux kernel
* - A non-standard libc implementation not implementing the required values
* For a more exhaustive explanation, see https://github.com/elastic/elasticsearch/pull/42725
*/
public class OsProbe {
private static final OperatingSystemMXBean osMxBean = ManagementFactory.getOperatingSystemMXBean();
private static final Method getFreePhysicalMemorySize;
private static final Method getTotalPhysicalMemorySize;
private static final Method getFreeSwapSpaceSize;
private static final Method getTotalSwapSpaceSize;
private static final Method getSystemLoadAverage;
private static final Method getSystemCpuLoad;
static {
getFreePhysicalMemorySize = getMethod("getFreePhysicalMemorySize");
getTotalPhysicalMemorySize = getMethod("getTotalPhysicalMemorySize");
getFreeSwapSpaceSize = getMethod("getFreeSwapSpaceSize");
getTotalSwapSpaceSize = getMethod("getTotalSwapSpaceSize");
getSystemLoadAverage = getMethod("getSystemLoadAverage");
getSystemCpuLoad = getMethod("getSystemCpuLoad");
}
/**
* Returns the amount of free physical memory in bytes.
*/
public long getFreePhysicalMemorySize() {
if (getFreePhysicalMemorySize == null) {
logger.warn("getFreePhysicalMemorySize is not available");
return 0;
}
try {
final long freeMem = (long) getFreePhysicalMemorySize.invoke(osMxBean);
if (freeMem < 0) {
logger.warn("OS reported a negative free memory value [{}]", freeMem);
return 0;
}
return freeMem;
} catch (Exception e) {
logger.warn("exception retrieving free physical memory", e);
return 0;
}
}
/**
* Returns the total amount of physical memory in bytes.
*/
public long getTotalPhysicalMemorySize() {
if (getTotalPhysicalMemorySize == null) {
logger.warn("getTotalPhysicalMemorySize is not available");
return 0;
}
try {
final long totalMem = (long) getTotalPhysicalMemorySize.invoke(osMxBean);
if (totalMem < 0) {
logger.warn("OS reported a negative total memory value [{}]", totalMem);
return 0;
}
return totalMem;
} catch (Exception e) {
logger.warn("exception retrieving total physical memory", e);
return 0;
}
}
/**
* Returns the amount of free swap space in bytes.
*/
public long getFreeSwapSpaceSize() {
if (getFreeSwapSpaceSize == null) {
return -1;
}
try {
return (long) getFreeSwapSpaceSize.invoke(osMxBean);
} catch (Exception e) {
return -1;
}
}
/**
* Returns the total amount of swap space in bytes.
*/
public long getTotalSwapSpaceSize() {
if (getTotalSwapSpaceSize == null) {
return -1;
}
try {
return (long) getTotalSwapSpaceSize.invoke(osMxBean);
} catch (Exception e) {
return -1;
}
}
/**
* The system load averages as an array.
*
* On Windows, this method returns {@code null}.
*
* On Linux, this method returns the 1, 5, and 15-minute load averages.
*
* On macOS, this method should return the 1-minute load average.
*
* @return the available system load averages or {@code null}
*/
final double[] getSystemLoadAverage() {
if (Constants.WINDOWS) {
return null;
} else if (Constants.LINUX) {
try {
final String procLoadAvg = readProcLoadavg();
assert procLoadAvg.matches("(\\d+\\.\\d+\\s+){3}\\d+/\\d+\\s+\\d+");
final String[] fields = procLoadAvg.split("\\s+");
return new double[]{Double.parseDouble(fields[0]), Double.parseDouble(fields[1]), Double.parseDouble(fields[2])};
} catch (final IOException e) {
if (logger.isDebugEnabled()) {
logger.debug("error reading /proc/loadavg", e);
}
return null;
}
} else {
assert Constants.MAC_OS_X;
if (getSystemLoadAverage == null) {
return null;
}
try {
final double oneMinuteLoadAverage = (double) getSystemLoadAverage.invoke(osMxBean);
return new double[]{oneMinuteLoadAverage >= 0 ? oneMinuteLoadAverage : -1, -1, -1};
} catch (IllegalAccessException | InvocationTargetException e) {
if (logger.isDebugEnabled()) {
logger.debug("error reading one minute load average from operating system", e);
}
return null;
}
}
}
/**
* The line from {@code /proc/loadavg}. The first three fields are the load averages averaged over 1, 5, and 15 minutes. The fourth
* field is two numbers separated by a slash, the first is the number of currently runnable scheduling entities, the second is the
* number of scheduling entities on the system. The fifth field is the PID of the most recently created process.
*
* @return the line from {@code /proc/loadavg} or {@code null}
*/
@SuppressForbidden(reason = "access /proc/loadavg")
String readProcLoadavg() throws IOException {
return readSingleLine(PathUtils.get("/proc/loadavg"));
}
public short getSystemCpuPercent() {
return Probes.getLoadAndScaleToPercent(getSystemCpuLoad, osMxBean);
}
/**
* Reads a file containing a single line.
*
* @param path path to the file to read
* @return the single line
* @throws IOException if an I/O exception occurs reading the file
*/
private String readSingleLine(final Path path) throws IOException {
final List lines = Files.readAllLines(path);
assert lines != null && lines.size() == 1;
return lines.get(0);
}
// this property is to support a hack to workaround an issue with Docker containers mounting the cgroups hierarchy inconsistently with
// respect to /proc/self/cgroup; for Docker containers this should be set to "/"
private static final String CONTROL_GROUPS_HIERARCHY_OVERRIDE = System.getProperty("es.cgroups.hierarchy.override");
/**
* A map of the control groups to which the Elasticsearch process belongs. Note that this is a map because the control groups can vary
* from subsystem to subsystem. Additionally, this map can not be cached because a running process can be reclassified.
*
* @return a map from subsystems to the control group for the Elasticsearch process.
* @throws IOException if an I/O exception occurs reading {@code /proc/self/cgroup}
*/
private Map getControlGroups() throws IOException {
final List lines = readProcSelfCgroup();
final Map controllerMap = new HashMap<>();
for (final String line : lines) {
/*
* The virtual file /proc/self/cgroup lists the control groups that the Elasticsearch process is a member of. Each line contains
* three colon-separated fields of the form hierarchy-ID:subsystem-list:cgroup-path. For cgroups version 1 hierarchies, the
* subsystem-list is a comma-separated list of subsystems. The subsystem-list can be empty if the hierarchy represents a cgroups
* version 2 hierarchy. For cgroups version 1
*/
final String[] fields = line.split(":");
assert fields.length == 3;
final String[] controllers = fields[1].split(",");
for (final String controller : controllers) {
final String controlGroupPath;
if (CONTROL_GROUPS_HIERARCHY_OVERRIDE != null) {
/*
* Docker violates the relationship between /proc/self/cgroup and the /sys/fs/cgroup hierarchy. It's possible that this
* will be fixed in future versions of Docker with cgroup namespaces, but this requires modern kernels. Thus, we provide
* an undocumented hack for overriding the control group path. Do not rely on this hack, it will be removed.
*/
controlGroupPath = CONTROL_GROUPS_HIERARCHY_OVERRIDE;
} else {
controlGroupPath = fields[2];
}
final String previous = controllerMap.put(controller, controlGroupPath);
assert previous == null;
}
}
return controllerMap;
}
/**
* The lines from {@code /proc/self/cgroup}. This file represents the control groups to which the Elasticsearch process belongs. Each
* line in this file represents a control group hierarchy of the form
*
* {@code \d+:([^:,]+(?:,[^:,]+)?):(/.*)}
*
* with the first field representing the hierarchy ID, the second field representing a comma-separated list of the subsystems bound to
* the hierarchy, and the last field representing the control group.
*
* @return the lines from {@code /proc/self/cgroup}
* @throws IOException if an I/O exception occurs reading {@code /proc/self/cgroup}
*/
@SuppressForbidden(reason = "access /proc/self/cgroup")
List readProcSelfCgroup() throws IOException {
final List lines = Files.readAllLines(PathUtils.get("/proc/self/cgroup"));
assert lines != null && !lines.isEmpty();
return lines;
}
/**
* The total CPU time in nanoseconds consumed by all tasks in the cgroup to which the Elasticsearch process belongs for the {@code
* cpuacct} subsystem.
*
* @param controlGroup the control group for the Elasticsearch process for the {@code cpuacct} subsystem
* @return the total CPU time in nanoseconds
* @throws IOException if an I/O exception occurs reading {@code cpuacct.usage} for the control group
*/
private long getCgroupCpuAcctUsageNanos(final String controlGroup) throws IOException {
return Long.parseLong(readSysFsCgroupCpuAcctCpuAcctUsage(controlGroup));
}
/**
* Returns the line from {@code cpuacct.usage} for the control group to which the Elasticsearch process belongs for the {@code cpuacct}
* subsystem. This line represents the total CPU time in nanoseconds consumed by all tasks in the same control group.
*
* @param controlGroup the control group to which the Elasticsearch process belongs for the {@code cpuacct} subsystem
* @return the line from {@code cpuacct.usage}
* @throws IOException if an I/O exception occurs reading {@code cpuacct.usage} for the control group
*/
@SuppressForbidden(reason = "access /sys/fs/cgroup/cpuacct")
String readSysFsCgroupCpuAcctCpuAcctUsage(final String controlGroup) throws IOException {
return readSingleLine(PathUtils.get("/sys/fs/cgroup/cpuacct", controlGroup, "cpuacct.usage"));
}
/**
* The total period of time in microseconds for how frequently the Elasticsearch control group's access to CPU resources will be
* reallocated.
*
* @param controlGroup the control group for the Elasticsearch process for the {@code cpuacct} subsystem
* @return the CFS quota period in microseconds
* @throws IOException if an I/O exception occurs reading {@code cpu.cfs_period_us} for the control group
*/
private long getCgroupCpuAcctCpuCfsPeriodMicros(final String controlGroup) throws IOException {
return Long.parseLong(readSysFsCgroupCpuAcctCpuCfsPeriod(controlGroup));
}
/**
* Returns the line from {@code cpu.cfs_period_us} for the control group to which the Elasticsearch process belongs for the {@code cpu}
* subsystem. This line represents the period of time in microseconds for how frequently the control group's access to CPU resources
* will be reallocated.
*
* @param controlGroup the control group to which the Elasticsearch process belongs for the {@code cpu} subsystem
* @return the line from {@code cpu.cfs_period_us}
* @throws IOException if an I/O exception occurs reading {@code cpu.cfs_period_us} for the control group
*/
@SuppressForbidden(reason = "access /sys/fs/cgroup/cpu")
String readSysFsCgroupCpuAcctCpuCfsPeriod(final String controlGroup) throws IOException {
return readSingleLine(PathUtils.get("/sys/fs/cgroup/cpu", controlGroup, "cpu.cfs_period_us"));
}
/**
* The total time in microseconds that all tasks in the Elasticsearch control group can run during one period as specified by {@code
* cpu.cfs_period_us}.
*
* @param controlGroup the control group for the Elasticsearch process for the {@code cpuacct} subsystem
* @return the CFS quota in microseconds
* @throws IOException if an I/O exception occurs reading {@code cpu.cfs_quota_us} for the control group
*/
private long getCgroupCpuAcctCpuCfsQuotaMicros(final String controlGroup) throws IOException {
return Long.parseLong(readSysFsCgroupCpuAcctCpuAcctCfsQuota(controlGroup));
}
/**
* Returns the line from {@code cpu.cfs_quota_us} for the control group to which the Elasticsearch process belongs for the {@code cpu}
* subsystem. This line represents the total time in microseconds that all tasks in the control group can run during one period as
* specified by {@code cpu.cfs_period_us}.
*
* @param controlGroup the control group to which the Elasticsearch process belongs for the {@code cpu} subsystem
* @return the line from {@code cpu.cfs_quota_us}
* @throws IOException if an I/O exception occurs reading {@code cpu.cfs_quota_us} for the control group
*/
@SuppressForbidden(reason = "access /sys/fs/cgroup/cpu")
String readSysFsCgroupCpuAcctCpuAcctCfsQuota(final String controlGroup) throws IOException {
return readSingleLine(PathUtils.get("/sys/fs/cgroup/cpu", controlGroup, "cpu.cfs_quota_us"));
}
/**
* The CPU time statistics for all tasks in the Elasticsearch control group.
*
* @param controlGroup the control group for the Elasticsearch process for the {@code cpuacct} subsystem
* @return the CPU time statistics
* @throws IOException if an I/O exception occurs reading {@code cpu.stat} for the control group
*/
private OsStats.Cgroup.CpuStat getCgroupCpuAcctCpuStat(final String controlGroup) throws IOException {
final List lines = readSysFsCgroupCpuAcctCpuStat(controlGroup);
long numberOfPeriods = -1;
long numberOfTimesThrottled = -1;
long timeThrottledNanos = -1;
for (final String line : lines) {
final String[] fields = line.split("\\s+");
switch (fields[0]) {
case "nr_periods":
numberOfPeriods = Long.parseLong(fields[1]);
break;
case "nr_throttled":
numberOfTimesThrottled = Long.parseLong(fields[1]);
break;
case "throttled_time":
timeThrottledNanos = Long.parseLong(fields[1]);
break;
}
}
assert numberOfPeriods != -1;
assert numberOfTimesThrottled != -1;
assert timeThrottledNanos != -1;
return new OsStats.Cgroup.CpuStat(numberOfPeriods, numberOfTimesThrottled, timeThrottledNanos);
}
/**
* Returns the lines from {@code cpu.stat} for the control group to which the Elasticsearch process belongs for the {@code cpu}
* subsystem. These lines represent the CPU time statistics and have the form
*
* nr_periods \d+
* nr_throttled \d+
* throttled_time \d+
*
* where {@code nr_periods} is the number of period intervals as specified by {@code cpu.cfs_period_us} that have elapsed, {@code
* nr_throttled} is the number of times tasks in the given control group have been throttled, and {@code throttled_time} is the total
* time in nanoseconds for which tasks in the given control group have been throttled.
*
* @param controlGroup the control group to which the Elasticsearch process belongs for the {@code cpu} subsystem
* @return the lines from {@code cpu.stat}
* @throws IOException if an I/O exception occurs reading {@code cpu.stat} for the control group
*/
@SuppressForbidden(reason = "access /sys/fs/cgroup/cpu")
List readSysFsCgroupCpuAcctCpuStat(final String controlGroup) throws IOException {
final List lines = Files.readAllLines(PathUtils.get("/sys/fs/cgroup/cpu", controlGroup, "cpu.stat"));
assert lines != null && lines.size() == 3;
return lines;
}
/**
* The maximum amount of user memory (including file cache).
* If there is no limit then some Linux versions return the maximum value that can be stored in an
* unsigned 64 bit number, and this will overflow a long, hence the result type is String.
* (The alternative would have been BigInteger but then it would not be possible to index
* the OS stats document into Elasticsearch without losing information, as BigInteger is
* not a supported Elasticsearch type.)
*
* @param controlGroup the control group for the Elasticsearch process for the {@code memory} subsystem
* @return the maximum amount of user memory (including file cache)
* @throws IOException if an I/O exception occurs reading {@code memory.limit_in_bytes} for the control group
*/
private String getCgroupMemoryLimitInBytes(final String controlGroup) throws IOException {
return readSysFsCgroupMemoryLimitInBytes(controlGroup);
}
/**
* Returns the line from {@code memory.limit_in_bytes} for the control group to which the Elasticsearch process belongs for the
* {@code memory} subsystem. This line represents the maximum amount of user memory (including file cache).
*
* @param controlGroup the control group to which the Elasticsearch process belongs for the {@code memory} subsystem
* @return the line from {@code memory.limit_in_bytes}
* @throws IOException if an I/O exception occurs reading {@code memory.limit_in_bytes} for the control group
*/
@SuppressForbidden(reason = "access /sys/fs/cgroup/memory")
String readSysFsCgroupMemoryLimitInBytes(final String controlGroup) throws IOException {
return readSingleLine(PathUtils.get("/sys/fs/cgroup/memory", controlGroup, "memory.limit_in_bytes"));
}
/**
* The total current memory usage by processes in the cgroup (in bytes).
* If there is no limit then some Linux versions return the maximum value that can be stored in an
* unsigned 64 bit number, and this will overflow a long, hence the result type is String.
* (The alternative would have been BigInteger but then it would not be possible to index
* the OS stats document into Elasticsearch without losing information, as BigInteger is
* not a supported Elasticsearch type.)
*
* @param controlGroup the control group for the Elasticsearch process for the {@code memory} subsystem
* @return the total current memory usage by processes in the cgroup (in bytes)
* @throws IOException if an I/O exception occurs reading {@code memory.limit_in_bytes} for the control group
*/
private String getCgroupMemoryUsageInBytes(final String controlGroup) throws IOException {
return readSysFsCgroupMemoryUsageInBytes(controlGroup);
}
/**
* Returns the line from {@code memory.usage_in_bytes} for the control group to which the Elasticsearch process belongs for the
* {@code memory} subsystem. This line represents the total current memory usage by processes in the cgroup (in bytes).
*
* @param controlGroup the control group to which the Elasticsearch process belongs for the {@code memory} subsystem
* @return the line from {@code memory.usage_in_bytes}
* @throws IOException if an I/O exception occurs reading {@code memory.usage_in_bytes} for the control group
*/
@SuppressForbidden(reason = "access /sys/fs/cgroup/memory")
String readSysFsCgroupMemoryUsageInBytes(final String controlGroup) throws IOException {
return readSingleLine(PathUtils.get("/sys/fs/cgroup/memory", controlGroup, "memory.usage_in_bytes"));
}
/**
* Checks if cgroup stats are available by checking for the existence of {@code /proc/self/cgroup}, {@code /sys/fs/cgroup/cpu},
* {@code /sys/fs/cgroup/cpuacct} and {@code /sys/fs/cgroup/memory}.
*
* @return {@code true} if the stats are available, otherwise {@code false}
*/
@SuppressForbidden(reason = "access /proc/self/cgroup, /sys/fs/cgroup/cpu, /sys/fs/cgroup/cpuacct and /sys/fs/cgroup/memory")
boolean areCgroupStatsAvailable() {
if (!Files.exists(PathUtils.get("/proc/self/cgroup"))) {
return false;
}
if (!Files.exists(PathUtils.get("/sys/fs/cgroup/cpu"))) {
return false;
}
if (!Files.exists(PathUtils.get("/sys/fs/cgroup/cpuacct"))) {
return false;
}
if (!Files.exists(PathUtils.get("/sys/fs/cgroup/memory"))) {
return false;
}
return true;
}
/**
* Basic cgroup stats.
*
* @return basic cgroup stats, or {@code null} if an I/O exception occurred reading the cgroup stats
*/
private OsStats.Cgroup getCgroup() {
try {
if (!areCgroupStatsAvailable()) {
return null;
} else {
final Map controllerMap = getControlGroups();
assert !controllerMap.isEmpty();
final String cpuAcctControlGroup = controllerMap.get("cpuacct");
if (cpuAcctControlGroup == null) {
logger.debug("no [cpuacct] data found in cgroup stats");
return null;
}
final long cgroupCpuAcctUsageNanos = getCgroupCpuAcctUsageNanos(cpuAcctControlGroup);
final String cpuControlGroup = controllerMap.get("cpu");
if (cpuControlGroup == null) {
logger.debug("no [cpu] data found in cgroup stats");
return null;
}
final long cgroupCpuAcctCpuCfsPeriodMicros = getCgroupCpuAcctCpuCfsPeriodMicros(cpuControlGroup);
final long cgroupCpuAcctCpuCfsQuotaMicros = getCgroupCpuAcctCpuCfsQuotaMicros(cpuControlGroup);
final OsStats.Cgroup.CpuStat cpuStat = getCgroupCpuAcctCpuStat(cpuControlGroup);
final String memoryControlGroup = controllerMap.get("memory");
if (memoryControlGroup == null) {
logger.debug("no [memory] data found in cgroup stats");
return null;
}
final String cgroupMemoryLimitInBytes = getCgroupMemoryLimitInBytes(memoryControlGroup);
final String cgroupMemoryUsageInBytes = getCgroupMemoryUsageInBytes(memoryControlGroup);
return new OsStats.Cgroup(
cpuAcctControlGroup,
cgroupCpuAcctUsageNanos,
cpuControlGroup,
cgroupCpuAcctCpuCfsPeriodMicros,
cgroupCpuAcctCpuCfsQuotaMicros,
cpuStat,
memoryControlGroup,
cgroupMemoryLimitInBytes,
cgroupMemoryUsageInBytes);
}
} catch (final IOException e) {
logger.debug("error reading control group stats", e);
return null;
}
}
private static class OsProbeHolder {
private static final OsProbe INSTANCE = new OsProbe();
}
public static OsProbe getInstance() {
return OsProbeHolder.INSTANCE;
}
OsProbe() {
}
private final Logger logger = LogManager.getLogger(getClass());
OsInfo osInfo(long refreshInterval, int allocatedProcessors) throws IOException {
return new OsInfo(
refreshInterval,
Runtime.getRuntime().availableProcessors(),
allocatedProcessors,
Constants.OS_NAME,
getPrettyName(),
Constants.OS_ARCH,
Constants.OS_VERSION);
}
private String getPrettyName() throws IOException {
// TODO: return a prettier name on non-Linux OS
if (Constants.LINUX) {
/*
* We read the lines from /etc/os-release (or /usr/lib/os-release) to extract the PRETTY_NAME. The format of this file is
* newline-separated key-value pairs. The key and value are separated by an equals symbol (=). The value can unquoted, or
* wrapped in single- or double-quotes.
*/
final List etcOsReleaseLines = readOsRelease();
final List prettyNameLines =
etcOsReleaseLines.stream().filter(line -> line.startsWith("PRETTY_NAME")).collect(Collectors.toList());
assert prettyNameLines.size() <= 1 : prettyNameLines;
final Optional maybePrettyNameLine =
prettyNameLines.size() == 1 ? Optional.of(prettyNameLines.get(0)) : Optional.empty();
if (maybePrettyNameLine.isPresent()) {
// we trim since some OS contain trailing space, for example, Oracle Linux Server 6.9 has a trailing space after the quote
final String trimmedPrettyNameLine = maybePrettyNameLine.get().trim();
final Matcher matcher = Pattern.compile("PRETTY_NAME=(\"?|'?)?([^\"']+)\\1").matcher(trimmedPrettyNameLine);
final boolean matches = matcher.matches();
assert matches : trimmedPrettyNameLine;
assert matcher.groupCount() == 2 : trimmedPrettyNameLine;
return matcher.group(2);
} else {
return Constants.OS_NAME;
}
} else {
return Constants.OS_NAME;
}
}
/**
* The lines from {@code /etc/os-release} or {@code /usr/lib/os-release} as a fallback, with an additional fallback to
* {@code /etc/system-release}. These files represent identification of the underlying operating system. The structure of the file is
* newlines of key-value pairs of shell-compatible variable assignments.
*
* @return the lines from {@code /etc/os-release} or {@code /usr/lib/os-release} or {@code /etc/system-release}
* @throws IOException if an I/O exception occurs reading {@code /etc/os-release} or {@code /usr/lib/os-release} or
* {@code /etc/system-release}
*/
@SuppressForbidden(reason = "access /etc/os-release or /usr/lib/os-release or /etc/system-release")
List readOsRelease() throws IOException {
final List lines;
if (Files.exists(PathUtils.get("/etc/os-release"))) {
lines = Files.readAllLines(PathUtils.get("/etc/os-release"));
assert lines != null && lines.isEmpty() == false;
return lines;
} else if (Files.exists(PathUtils.get("/usr/lib/os-release"))) {
lines = Files.readAllLines(PathUtils.get("/usr/lib/os-release"));
assert lines != null && lines.isEmpty() == false;
return lines;
} else if (Files.exists(PathUtils.get("/etc/system-release"))) {
// fallback for older Red Hat-like OS
lines = Files.readAllLines(PathUtils.get("/etc/system-release"));
assert lines != null && lines.size() == 1;
return Collections.singletonList("PRETTY_NAME=\"" + lines.get(0) + "\"");
} else {
return Collections.emptyList();
}
}
public OsStats osStats() {
final OsStats.Cpu cpu = new OsStats.Cpu(getSystemCpuPercent(), getSystemLoadAverage());
final OsStats.Mem mem = new OsStats.Mem(getTotalPhysicalMemorySize(), getFreePhysicalMemorySize());
final OsStats.Swap swap = new OsStats.Swap(getTotalSwapSpaceSize(), getFreeSwapSpaceSize());
final OsStats.Cgroup cgroup = Constants.LINUX ? getCgroup() : null;
return new OsStats(System.currentTimeMillis(), cpu, mem, swap, cgroup);
}
/**
* Returns a given method of the OperatingSystemMXBean, or null if the method is not found or unavailable.
*/
private static Method getMethod(String methodName) {
try {
return Class.forName("com.sun.management.OperatingSystemMXBean").getMethod(methodName);
} catch (Exception e) {
// not available
return null;
}
}
}