using
System.Runtime.InteropServices;
using System.Diagnostics;
using
Microsoft.Win32;
namespace Org.Mentalis.Utilities {
/// <summary>
/// Defines an abstract base class for implementations of CPU usage
counters.
/// </summary>
public abstract class CpuUsage {
/// <summary>
/// Creates and returns a CpuUsage instance that can
be used to query the CPU time on this operating system.
///
</summary>
/// <returns>An instance of the CpuUsage
class.</returns>
/// <exception
cref="NotSupportedException">This platform is not supported -or-
initialization of the CPUUsage object failed.</exception>
public
static CpuUsage Create() {
if (m_CpuUsage == null) {
if
(Environment.OSVersion.Platform == PlatformID.Win32NT)
m_CpuUsage =
new CpuUsageNt();
else if (Environment.OSVersion.Platform ==
PlatformID.Win32Windows)
m_CpuUsage = new CpuUsage9x();
else
throw new NotSupportedException();
}
return
m_CpuUsage;
}
/// <summary>
/// Determines the
current average CPU load.
/// </summary>
///
<returns>An integer that holds the CPU load percentage.</returns>
/// <exception cref="NotSupportedException">One of the system calls
fails. The CPU time can not be obtained.</exception>
public
abstract int Query();
/// <summary>
/// Holds an instance of
the CPUUsage class.
/// </summary>
private static CpuUsage
m_CpuUsage= null;
}
instantiate a CPUUsage object.</p>
///
</remarks>
internal sealed class CpuUsage9x : CpuUsage {
///
<summary>
/// Initializes a new CPUUsage9x instance.
///
</summary>
/// <exception cref="NotSupportedException">One of
the system calls fails.</exception>
public CpuUsage9x() {
try {
// start the counter by reading the value of the
'StartStat' key
RegistryKey startKey =
Registry.DynData.OpenSubKey(@"PerfStats\StartStat", false);
if
(startKey == null)
throw new NotSupportedException();
startKey.GetValue(@"KERNEL\CPUUsage");
startKey.Close();
//
open the counter's value key
m_StatData =
Registry.DynData.OpenSubKey(@"PerfStats\StatData", false);
if
(m_StatData == null)
throw new NotSupportedException();
}
catch (NotSupportedException e) {
throw e;
} catch (Exception
e) {
throw new NotSupportedException("Error while querying the system
information.", e);
}
}
/// <summary>
///
Determines the current average CPU load.
/// </summary>
///
<returns>An integer that holds the CPU load percentage.</returns>
/// <exception cref="NotSupportedException">One of the system calls
fails. The CPU time can not be obtained.</exception>
public
override int Query() {
try {
return
(int)m_StatData.GetValue(@"KERNEL\CPUUsage");
} catch (Exception e) {
throw new NotSupportedException("Error while querying the system
information.", e);
}
}
/// <summary>
///
Closes the allocated resources.
/// </summary>
~CpuUsage9x()
{
try {
m_StatData.Close();
} catch {}
//
stopping the counter
try {
RegistryKey stopKey =
Registry.DynData.OpenSubKey(@"PerfStats\StopStat", false);
stopKey.GetValue(@"KERNEL\CPUUsage", false);
stopKey.Close();
}
catch {}
}
/// <summary>Holds the registry key that's used
to read the CPU load.</summary>
private RegistryKey m_StatData;
}
internal sealed class CpuUsageNt : CpuUsage {
///
<summary>
/// Initializes a new CpuUsageNt instance.
///
</summary>
/// <exception cref="NotSupportedException">One of
the system calls fails.</exception>
public CpuUsageNt() {
byte[] timeInfo = new byte[32]; // SYSTEM_TIME_INFORMATION structure
byte[] perfInfo = new byte[312]; // SYSTEM_PERFORMANCE_INFORMATION
structure
byte[] baseInfo = new byte[44]; // SYSTEM_BASIC_INFORMATION
structure
int ret;
// get new system time
ret =
NtQuerySystemInformation(SYSTEM_TIMEINFORMATION, timeInfo, timeInfo.Length,
IntPtr.Zero);
if (ret != NO_ERROR)
throw new
NotSupportedException();
// get new CPU's idle time
ret =
NtQuerySystemInformation(SYSTEM_PERFORMANCEINFORMATION, perfInfo,
perfInfo.Length, IntPtr.Zero);
if (ret != NO_ERROR)
throw new
NotSupportedException();
// get number of processors in the system
ret = NtQuerySystemInformation(SYSTEM_BASICINFORMATION, baseInfo,
baseInfo.Length, IntPtr.Zero);
if (ret != NO_ERROR )
throw new
NotSupportedException();
// store new CPU's idle and system time and
number of processors
oldIdleTime = BitConverter.ToInt64(perfInfo, 0); //
SYSTEM_PERFORMANCE_INFORMATION.liIdleTime
oldSystemTime =
BitConverter.ToInt64(timeInfo, 8); // SYSTEM_TIME_INFORMATION.liKeSystemTime
processorCount = baseInfo[40];
}
/// <summary>
/// Determines the current average CPU load.
/// </summary>
/// <returns>An integer that holds the CPU load
percentage.</returns>
/// <exception
cref="NotSupportedException">One of the system calls fails. The CPU time can
not be obtained.</exception>
public override int Query() {
byte[] timeInfo = new byte[32]; // SYSTEM_TIME_INFORMATION structure
byte[] perfInfo = new byte[312]; // SYSTEM_PERFORMANCE_INFORMATION
structure
double dbIdleTime, dbSystemTime;
int ret;
//
get new system time
ret =
NtQuerySystemInformation(SYSTEM_TIMEINFORMATION, timeInfo, timeInfo.Length,
IntPtr.Zero);
if (ret != NO_ERROR)
throw new
NotSupportedException();
// get new CPU's idle time
ret =
NtQuerySystemInformation(SYSTEM_PERFORMANCEINFORMATION, perfInfo,
perfInfo.Length, IntPtr.Zero);
if (ret != NO_ERROR)
throw new
NotSupportedException();
// CurrentValue = NewValue - OldValue
dbIdleTime = BitConverter.ToInt64(perfInfo, 0) - oldIdleTime;
dbSystemTime = BitConverter.ToInt64(timeInfo, 8) - oldSystemTime;
// CurrentCpuIdle = IdleTime / SystemTime
if (dbSystemTime != 0)
dbIdleTime = dbIdleTime / dbSystemTime;
// CurrentCpuUsage% =
100 - (CurrentCpuIdle * 100) / NumberOfProcessors
dbIdleTime = 100.0 -
dbIdleTime * 100.0 / processorCount + 0.5;
// store new CPU's idle and
system time
oldIdleTime = BitConverter.ToInt64(perfInfo, 0); //
SYSTEM_PERFORMANCE_INFORMATION.liIdleTime
oldSystemTime =
BitConverter.ToInt64(timeInfo, 8); // SYSTEM_TIME_INFORMATION.liKeSystemTime
return (int)dbIdleTime;
}
/// <summary>
///
NtQuerySystemInformation is an internal Windows function that retrieves various
kinds of system information.
/// </summary>
/// <param
name="dwInfoType">One of the values enumerated in SYSTEM_INFORMATION_CLASS,
indicating the kind of system information to be retrieved.</param>
/// <param name="lpStructure">Points to a buffer where the requested
information is to be returned. The size and structure of this information varies
depending on the value of the SystemInformationClass parameter.</param>
/// <param name="dwSize">Length of the buffer pointed to by the
SystemInformation parameter.</param>
/// <param
name="returnLength">Optional pointer to a location where the function writes
the actual size of the information requested.</param>
///
<returns>Returns a success NTSTATUS if successful, and an NTSTATUS error
code otherwise.</returns>
[DllImport("ntdll",
EntryPoint="NtQuerySystemInformation")]
private static extern int
NtQuerySystemInformation(int dwInfoType, byte[] lpStructure, int dwSize, IntPtr
returnLength);
/// <summary>Returns the number of processors in the
system in a SYSTEM_BASIC_INFORMATION structure.</summary>
private
const int SYSTEM_BASICINFORMATION = 0;
/// <summary>Returns an
opaque SYSTEM_PERFORMANCE_INFORMATION structure.</summary>
private
const int SYSTEM_PERFORMANCEINFORMATION = 2;
/// <summary>Returns
an opaque SYSTEM_TIMEOFDAY_INFORMATION structure.</summary>
private
const int SYSTEM_TIMEINFORMATION = 3;
/// <summary>The value
returned by NtQuerySystemInformation is no error occurred.</summary>
private const int NO_ERROR = 0;
/// <summary>Holds the old
idle time.</summary>
private long oldIdleTime;
///
<summary>Holds the old system time.</summary>
private long
oldSystemTime;
/// <summary>Holds the number of processors in the
system.</summary>
private double processorCount;
}
}