posted by Brad Prendergast at 6:44:00 PM
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System Information and the PerformanceCounter Class
The objective of that post was retrieving memory information (I also retrieve disk information in my ‘AboutBox’ discussed in that post). In the 'managed codeworld' there is another way to get different information values. Using the System.Diagnostics.PerformanceCounter Class you can retrieve ‘counter’ information from a local or remote machine. Many of you may be familiar with some of the information accessible through PerformanceCounters if you run the
System.Diagnostics.PerformanceCounter perfcounter; private void cbxPerfCategories_SelectedIndexChanged(object sender, EventArgs e)
...{
cbxInstances.Enabled = true; cbxInstances.Items.Clear(); cbxCounters.Items.Clear(); lstOutput.Items.Clear(); timer1.Enabled = false; if (cbxPerfCategories.SelectedIndex != -1)
...{ if (PerformanceCounterCategory.Exists(cbxPerfCategories.Text)) ...{ PerformanceCounterCategory perfcategory = new PerformanceCounterCategory(cbxPerfCategories.Text); cbxInstances.Items.AddRange(perfcategory.GetInstanceNames()); if (cbxInstances.Items.Count == 0) ...{ cbxInstances.Enabled = false; // Get the counters for a category that has only one // instance GetCounters(perfcategory, "",cbxCounters);
} } }
} private void GetCounters(PerformanceCounterCategory perfcategory, string instancename, ComboBox combobox) ...{ System.Diagnostics.PerformanceCounter[] counters; if (instancename.Equals("")) ...{ counters = perfcategory.GetCounters(); } else ...{ counters = perfcategory.GetCounters(instancename); } for (int i = 0; i < counters.Length; i++) ...{ combobox.Items.Add(counters[i].CounterName); } } private void frmMain_Load(object sender, EventArgs e) ...{ PerformanceCounterCategory[] perfcategories; try ...{ perfcategories = PerformanceCounterCategory.GetCategories(); for (int i = 0; i < perfcategories.Length; i++) ...{ cbxPerfCategories.Items.Add(perfcategories[i].CategoryName); } } catch (Exception ex) ...{ MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error); } } private void cbxInstances_SelectedIndexChanged(object sender, EventArgs e) ...{ cbxCounters.Items.Clear(); lstOutput.Items.Clear(); timer1.Enabled = false; if (cbxInstances.SelectedIndex != -1) ...{ if (PerformanceCounterCategory.InstanceExists(cbxInstances.Text, cbxPerfCategories.Text)) ...{ PerformanceCounterCategory perfcategory = new PerformanceCounterCategory(cbxPerfCategories.Text); GetCounters(perfcategory, cbxInstances.Text, cbxCounters); } } } private void cbxCounters_SelectedIndexChanged(object sender, EventArgs e) ...{ lstOutput.Items.Clear(); if (cbxInstances.Text.Equals("")) ...{ perfcounter = new System.Diagnostics.PerformanceCounter(cbxPerfCategories.Text, cbxCounters.Text, true); } else ...{ perfcounter = new System.Diagnostics.PerformanceCounter(cbxPerfCategories.Text, cbxCounters.Text, cbxInstances.Text,true); } timer1.Enabled = true; } private void timer1_Tick(object sender, EventArgs e) ...{ float value; value = perfcounter.NextValue(); lstOutput.Items.Insert(0,value.ToString("#,##0.00")); }
Cryptography hash and a class - to goOne of the things I appreciate the most in OOP is the concept of classes. I have found that the use of classes allows for code to be easily maintained and reused. I look at classes as neat little packaged objects that can be ‘moved around’ and ‘worked with’ as their own. Another big benefit of classes is the concept of inheritance and polymorphism. In three previous posts (1, 2, 3) I discussed using the System.Security.Cryptography Namespace to calculate the hash values of text (strings) and files. I actually did create a class (that I actively use) from that sample.
using System;using System.Text;using System.Security.Cryptography;using System.IO; public class CryptoHash
...{
/**//// <summary>
/// public enum hashtypes { MD5, SHA1, SHA256, SHA384, SHA512 };
/// </summary> public enum hashtypes ...{ MD5, SHA1, SHA256, SHA384, SHA512 }; Properties#region Properties private Int64 _bytesread; /**//// <summary> /// Int64 Bytesread returns the number of bytes read when calculating the hash /// value. /// </summary> public Int64 Bytesread ...{ get ...{ return _bytesread; } } private hashtypes _hashtype; /**//// <summary> /// hashtypes Hashtype specifies the type of hash to calculate. /// </summary> public hashtypes Hashtype ...{ get ...{ return _hashtype; } set ...{ _hashtype = value; } } #endregion Constructors#region Constructors public CryptoHash() ...{ } public CryptoHash(hashtypes inhashtype) ...{ _hashtype = inhashtype; } #endregion Methods#region Methods private string GetByteString(byte[] data) ...{ StringBuilder sb = new StringBuilder(); for (int i = 0; i < data.Length; i++) ...{ sb.Append(data[i].ToString("x2")); } string bytestring = sb.ToString(); return bytestring.ToUpper(); } private string GetHash(byte[] data) ...{ HashAlgorithm ha; switch (_hashtype) ...{ case hashtypes.MD5: ha = MD5CryptoServiceProvider.Create(); break; case hashtypes.SHA1: ha = SHA1Managed.Create(); break; case hashtypes.SHA256: ha = SHA256Managed.Create(); break; case hashtypes.SHA384: ha = SHA384Managed.Create(); break; case hashtypes.SHA512: ha = SHA512Managed.Create(); break; default: ha = MD5CryptoServiceProvider.Create(); break; } _bytesread = data.Length; byte[] res = ha.ComputeHash(data); return GetByteString(res); } /**//// <summary> /// GetStringHash calculates the hash value for a string. /// </summary> /// <param name="inputtext">String value.</param> /// <returns>Returns the hash value of a file.</returns> public string GetStringHash(string inputtext) ...{ return GetHash(Encoding.Default.GetBytes(inputtext)); } /**//// <summary> /// GetFileHash calculates the hash value for a file. /// </summary> /// <param name="filename">Full file path for the file.</param> /// <returns>Returns the hash value of a file.</returns> public string GetFileHash(string filename) ...{ _bytesread = 0; byte[] filecontents; FileInfo instance = new FileInfo(filename); if (!instance.Exists) ...{ throw new FileNotFoundException(); } else ...{ try