Develop Reference

filesystemwatcher waiting for file to complete writing

I have an issue with a file system watcher application I am working on. It seems to run fine with a single file but not with multiple files or a folder with files inside.
in the code below, I call IsFileReady to determine if the file has completed writing before trying to copy it to the other folder. However, when a new folder is created with files inside, for some reason it's hanging and not continuing.
I think it's because multiple files are being written at the same time and my code is referencing just a single file, but I am unsure of how to correct this.
Any assistance is appreciated and thank you.
static void Init()
{
string directory = watch_path;
Program._watcher = new FileSystemWatcher(directory);
Program._watcher.Created +=
new FileSystemEventHandler(Program._watcher_Changed);
Program._watcher.EnableRaisingEvents = true;
Program._watcher.IncludeSubdirectories = true;
}
static void _watcher_Changed(object sender, FileSystemEventArgs e)
{
Console.WriteLine("CHANGED, NAME: " + e.Name);
Console.WriteLine("CHANGED, FULLPATH: " + e.FullPath);
try
{
Console.WriteLine("Checking If File Exists at copy location");
if (!File.Exists(copy_path + "\\" + e.Name))
{
Console.WriteLine("Waiting for File to complete write");
WaitForFile(e.FullPath);
Console.WriteLine("Copying file to remote folder");
File.Copy(e.FullPath, copy_path + "\\" + e.Name);
Console.WriteLine("Copy Completed writing to log");
error_handling("File Copy Completed : ", copy_path + "\\" + e.Name, e.FullPath);
}
else
{
Console.WriteLine("Copy Failed Writing to Log");
error_handling("File Copy Skipped, File exists at destination : ", copy_path + "\\" + e.Name, e.FullPath);
}
}
catch (Exception error)
{
Console.WriteLine("Copy process totally failed" + error.Message);
error_handling("File Copy Failed ", "Exception: " + error.Message, "00");
}
}
public static void WaitForFile(string filename)
{
while (!IsFileReady(filename)) { }
}
public static bool IsFileReady(string filename)
{
try
{
using (FileStream inputStream = File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.None))
return inputStream.Length > 0;
}
catch (Exception)
{
return false;
}
*Edit
When it hangs, it seems that the WaitForFile never actually finishes up. When copying a single file, it finishes no problem, but I think when there are multiple files it get stuck somehow and it will not go past the
WaitForFile(e.FullPath);
I am intentionally hooking the Created event. the use of this application is to monitor a folder that needs to be identical between multiple web servers. the sync process needs to be as fast as possible as the web servers are load balanced.
the Call to error_handling is just a write to log function as seen below:
public static void error_handling(string message, string fileident, string source)
{
using (System.IO.StreamWriter myFile = new System.IO.StreamWriter(log_folder + "\\" + log_file, true))
{
string finalMessage = string.Format("{0}: {1} SOURCE: {3} - DEST: {2}", DateTime.Now, message, fileident, source, Environment.NewLine);
myFile.WriteLine(finalMessage);
myFile.Close();
}
}

IOException: The process cannot access the file 'file path' because it is being used by another process in Console Application in C#

I am running Console_Application-A in which I am calling another Console_Application-B (in which I am creating log file for Error/Exception).
But when I am running Console_Application-B individually its working properly but when I am running Console_Application-A at that time I am getting an Exception when Application need to write an Error in log file.(Error.txt).
IOException: The process cannot access the file 'Error.txt' because it
is being used by another process
please guide me in this issue.
Code for Writing Error log
public static bool IsFileLocked(FileInfo file)
{
FileStream stream = null;
try
{
stream = file.Open(FileMode.Open, FileAccess.Read, FileShare.None);
}
catch (IOException)
{
return true;
}
finally
{
if (stream != null)
stream.Close();
}
return false;
}
catch (Exception e)
{
string filePath =Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + "\\Error.txt";
FileInfo FInfo = new FileInfo(filePath);
var FileState = IsFileLocked(FInfo);
while (FileState){
FileState = IsFileLocked(FInfo);
}
if (!FileState){
using (StreamWriter writer = new StreamWriter(filePath, true))
{
writer.WriteLine("Message :" + e.Message + "<br/>" + Environment.NewLine + "StackTrace :" + e.StackTrace +"" + Environment.NewLine + "Date :" + DateTime.Now.ToString());
writer.WriteLine(Environment.NewLine + "-----------------------------------------------------------------------------" + Environment.NewLine);
writer.Dispose();
}
}
}

There is no need first to check if the file is locked and then access it, as between the check and the access some other process may still get a lock on the file.
using System;
using System.IO;
class DirAppend
{
public static void Main()
{
using (StreamWriter w = File.AppendText("log.txt"))
{
Log("Test1", w);
Log("Test2", w);
}
using (StreamReader r = File.OpenText("log.txt"))
{
DumpLog(r);
}
}
public static void Log(string logMessage, TextWriter w)
{
w.Write("\r\nLog Entry : ");
w.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(),
DateTime.Now.ToLongDateString());
w.WriteLine(" :");
w.WriteLine(" :{0}", logMessage);
w.WriteLine ("-------------------------------");
}
public static void DumpLog(StreamReader r)
{
string line;
while ((line = r.ReadLine()) != null)
{
Console.WriteLine(line);
}
}
}
Source - https://msdn.microsoft.com/en-us/library/3zc0w663(v=vs.110).aspx

Why do I have an IOException in this case?

I'm programming a video player in C# (the video works fine) and what I need now is to get the libvlc logs as well as my custom logs to print them in a file.
I use NLog which handles the libvlc logs (with nVLC) and I raise an event for my custom logs, and in buth cases this function is called :
private static void tracerlogs(string erreur, VLCControl.ControleUtilisateurVLC.LogLevels LvLog)
{
string path = "logs.txt";//Sera redéfini dans l'appli
if (!File.Exists(path))
{
// Create a file to write to.
using (StreamWriter sw = File.CreateText(path))
{
sw.WriteLine(erreur + " " + LvLog.ToString());
sw.Close();
}
}
else
{
using (StreamWriter sw = File.AppendText(path))
{
sw.WriteLine(erreur + " " + LvLog.ToString());
sw.Close();
}
}
Console.WriteLine(erreur + " " + LvLog.ToString());
}
The problem is that I'm getting at random times a System.IO.IOException telling that "the process cannot access the file because it is being used by another process". Although I do close my StreamWriter (which should normally not be useful in a using block)... This makes my app crash. Does anyone have any idea why it does this ?

I finally solved it by adding a resource : as there was a conflict between different threads trying to access this function, I wrapped this :
private static void tracerlogs(string erreur, VLCControl.ControleUtilisateurVLC.LogLevels LvLog)
{
lock (LockLog) {
string path = "logs.txt";//Sera redéfini dans l'appli
if (!File.Exists(path))
{
// Create a file to write to.
using (StreamWriter sw = File.CreateText(path))
{
sw.WriteLine(erreur + " " + LvLog.ToString());
sw.Close();
}
}
else
{
using (StreamWriter sw = File.AppendText(path))
{
sw.WriteLine(erreur + " " + LvLog.ToString());
sw.Close();
}
}
Console.WriteLine(erreur + " " + LvLog.ToString());
}
}
And I declare a public static readonly object LockLog = new Object(); in my class. This works just fine ! Thanks to those who told me that this had to see with threading.

The process cannot access the file because it is being used by another process. (Text File will not close)

I am trying to Write to a text file after this code block checks for the last time the PC was restarted. The code below reads from a text file, the last time the PC was resarted, and from there it determines whether to show a splash-screen. However, After this method runs, i need to write to the text file what the current "System Up-Time" is. But i keep getting an error that says the text file is in use. This has driven me insane. I have made sure all StreamWriters and StreamReaders are closed. I have tried Using Statements. I have tried GC.Collect. I feel like i have tried everything.
Any help would be appreciated.
private void checkLastResart()
{
StreamReader sr = new StreamReader(Path.GetDirectoryName(Application.ExecutablePath) + #"\Settings.txt");
if (sr.ReadLine() == null)
{
sr.Close();
MessageBox.Show("There was an error loading 'System UpTime'. All settings have been restored to default.");
StreamWriter sw = new StreamWriter(Path.GetDirectoryName(Application.ExecutablePath) + #"\Settings.txt", false);
sw.WriteLine("Conversion Complete Checkbox: 0");
sw.WriteLine("Default Tool: 0");
sw.WriteLine("TimeSinceResart: 0");
sw.Flush();
sw.Close();
}
else
{
try
{
StreamReader sr2 = new StreamReader(Path.GetDirectoryName(Application.ExecutablePath) + #"\Settings.txt");
while (!sr2.EndOfStream)
{
string strSetting = sr2.ReadLine();
if (strSetting.Contains("TimeSinceResart:"))
{
double lastTimeRecorded = double.Parse(strSetting.Substring(17));
//If the lastTimeRecorded is greater than timeSinceResart (computer has been resarted) OR 2 hours have passed since LVT was last run
if (lastTimeRecorded > timeSinceRestart || lastTimeRecorded + 7200 < timeSinceRestart)
{
runSplashScreen = true;
}
else
{
runSplashScreen = false;
}
}
}
sr2.Close();
sr2.Dispose();
}
catch (Exception e) { MessageBox.Show("An error has occured loading 'System UpTime'.\r\n\r\n" + e); }
}
}
Below is a sample of writing to the Text file, after the above code has been run. It doesnt matter if i open a StreamWriter, or use File.WriteAllLines, an error is thrown immediately.
StreamWriter sw = new StreamWriter(Path.GetDirectoryName(Application.ExecutablePath) + #"\Settings.txt");
string[] lines = File.ReadAllLines(Path.GetDirectoryName(Application.ExecutablePath) + #"\Settings.txt");
lines[2] = "TimeSinceResart: " + timeSinceRestart;
foreach (string s in lines)
sw.WriteLine(s);

Your writing code should be changed in this way
string file = Path.Combine(Path.GetDirectoryName(Application.ExecutablePath),"Settings.txt");
// First read the two lines in memory
string[] lines = File.ReadAllLines(file);
// then use the StreamWriter that locks the file
using(StreamWriter sw = new StreamWriter(file))
{
lines[2] = "TimeSinceResart: " + timeSinceRestart;
foreach (string s in lines)
sw.WriteLine(s);
}
In this way the lock on the StreamWriter doesn't block the reading with FileReadAllLines.
Said that, please note a couple of things. Do not create path strings with string concatenation, use the static methods of the Path class. But most important, when you create a disposable object like a stream be sure to use the using statement to close correctly the file
To complete the answer in response to your comment. Using statement also for the first part of your code
private void checkLastResart()
{
string file = Path.Combine(Path.GetDirectoryName(Application.ExecutablePath),"Settings.txt");
using(StreamReader sr = new StreamReader(file))
{
if (sr.ReadLine() == null)
{
sr.Close();
MessageBox.Show(...)
using(StreamWriter sw = new StreamWriter(file, false))
{
sw.WriteLine("Conversion Complete Checkbox: 0");
sw.WriteLine("Default Tool: 0");
sw.WriteLine("TimeSinceResart: 0");
sw.Flush();
}
}
else
{
....
}
} // exit using block closes and disposes the stream
}

Where you create sr2, sr still has settings.txt open.

How to write log file in c#?

How would I write a log file in c#?
Currently i have a timer with this statement which ticks every 20 secs:
File.WriteAllText(filePath+"log.txt", log);
For everything that i want logged i do this:
log += "stringToBeLogged";
As you can assume the string log just grows and grows as the program runs. (I don't even know if there is a maximum chars per string?)
I assume that there must be better ways of doing this. i just thought that it would be heavy to write the whole file again and again for every time something is added to the log.

From the performance point of view your solution is not optimal. Every time you add another log entry with +=, the whole string is copied to another place in memory. I would recommend using StringBuilder instead:
StringBuilder sb = new StringBuilder();
...
sb.Append("log something");
...
// flush every 20 seconds as you do it
File.AppendAllText(filePath+"log.txt", sb.ToString());
sb.Clear();
By the way your timer event is probably executed on another thread. So you may want to use a mutex when accessing your sb object.
Another thing to consider is what happens to the log entries that were added within the last 20 seconds of the execution. You probably want to flush your string to the file right before the app exits.

create a class create a object globally and call this
using System.IO;
using System.Reflection;
public class LogWriter
{
private string m_exePath = string.Empty;
public LogWriter(string logMessage)
{
LogWrite(logMessage);
}
public void LogWrite(string logMessage)
{
m_exePath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
try
{
using (StreamWriter w = File.AppendText(m_exePath + "\\" + "log.txt"))
{
Log(logMessage, w);
}
}
catch (Exception ex)
{
}
}
public void Log(string logMessage, TextWriter txtWriter)
{
try
{
txtWriter.Write("\r\nLog Entry : ");
txtWriter.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(),
DateTime.Now.ToLongDateString());
txtWriter.WriteLine(" :");
txtWriter.WriteLine(" :{0}", logMessage);
txtWriter.WriteLine("-------------------------------");
}
catch (Exception ex)
{
}
}
}

Use File.AppendAllText instead:
File.AppendAllText(filePath + "log.txt", log);

public static void WriteLog(string strLog)
{
StreamWriter log;
FileStream fileStream = null;
DirectoryInfo logDirInfo = null;
FileInfo logFileInfo;
string logFilePath = "C:\\Logs\\";
logFilePath = logFilePath + "Log-" + System.DateTime.Today.ToString("MM-dd-yyyy") + "." + "txt";
logFileInfo = new FileInfo(logFilePath);
logDirInfo = new DirectoryInfo(logFileInfo.DirectoryName);
if (!logDirInfo.Exists) logDirInfo.Create();
if (!logFileInfo.Exists)
{
fileStream = logFileInfo.Create();
}
else
{
fileStream = new FileStream(logFilePath, FileMode.Append);
}
log = new StreamWriter(fileStream);
log.WriteLine(strLog);
log.Close();
}
Refer Link:
blogspot.in

as posted by #randymohan, with using statements instead
public static void WriteLog(string strLog)
{
string logFilePath = #"C:\Logs\Log-" + System.DateTime.Today.ToString("MM-dd-yyyy") + "." + "txt";
FileInfo logFileInfo = new FileInfo(logFilePath);
DirectoryInfo logDirInfo = new DirectoryInfo(logFileInfo.DirectoryName);
if (!logDirInfo.Exists) logDirInfo.Create();
using (FileStream fileStream = new FileStream(logFilePath, FileMode.Append))
{
using (StreamWriter log = new StreamWriter(fileStream))
{
log.WriteLine(strLog);
}
}
}

Very convenient tool for logging is http://logging.apache.org/log4net/
You can also make something of themselves less (more) powerful. You can use http://msdn.microsoft.com/ru-ru/library/system.io.filestream (v = vs.110). Aspx

Add log to file with Static Class
public static class LogWriter
{
private static string m_exePath = string.Empty;
public static void LogWrite(string logMessage)
{
m_exePath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
if (!File.Exists(m_exePath + "\\" + "log.txt"))
File.Create(m_exePath + "\\" + "log.txt");
try
{
using (StreamWriter w = File.AppendText(m_exePath + "\\" + "log.txt"))
AppendLog(logMessage, w);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
private static void AppendLog(string logMessage, TextWriter txtWriter)
{
try
{
txtWriter.Write("\r\nLog Entry : ");
txtWriter.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(),DateTime.Now.ToLongDateString());
txtWriter.WriteLine(" :");
txtWriter.WriteLine(" :{0}", logMessage);
txtWriter.WriteLine("-------------------------------");
}
catch (Exception ex)
{
}
}
}

if(!File.Exists(filename)) //No File? Create
{
fs = File.Create(filename);
fs.Close();
}
if(File.ReadAllBytes().Length >= 100*1024*1024) // (100mB) File to big? Create new
{
string filenamebase = "myLogFile"; //Insert the base form of the log file, the same as the 1st filename without .log at the end
if(filename.contains("-")) //Check if older log contained -x
{
int lognumber = Int32.Parse(filename.substring(filename.lastIndexOf("-")+1, filename.Length-4); //Get old number, Can cause exception if the last digits aren't numbers
lognumber++; //Increment lognumber by 1
filename = filenamebase + "-" + lognumber + ".log"; //Override filename
}
else
{
filename = filenamebase + "-1.log"; //Override filename
}
fs = File.Create(filename);
fs.Close();
}
Refer link:
http://www.codeproject.com/Questions/163337/How-to-write-in-log-Files-in-C

This is add new string in the file
using (var file = new StreamWriter(filePath + "log.txt", true))
{
file.WriteLine(log);
file.Close();
}

There are 2 easy ways
StreamWriter - http://www.dotnetperls.com/streamwriter
Log4Net like Log4j(Java) - http://www.codeproject.com/Articles/140911/log4net-Tutorial

If your application is multithreaded then in some environments file.appendalltext could give error like file already in use and if you skip that then you could lose important logs .
For that you can use
Lock object technique with file.append.. in that case it will wait for existing process to close and the write your log
This can also save you from adding other libraries in your source

Above code will throw: Process can't access the file because it is being used by another process error because of File.Create(m_exePath + "\" + "log.txt"); if you will comment out this it will work as expected
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
namespace SolutionLogWriter
{
public static class LogWriterClass
{
private static string m_exePath = string.Empty;
public static void LogWrite(string logMessage)
{
m_exePath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
string fullpath = m_exePath + "\\" + "log.txt";
if (File.Exists(fullpath))
{
File.Delete(fullpath);
}
// File.Create(fullpath);
try
{
FileStream fs = new FileStream(fullpath, FileMode.OpenOrCreate);
using (StreamWriter w = new StreamWriter(fs))
AppendLog(logMessage, w);
}
catch (Exception ex)
{
AppendLog(ex.ToString());
}
}
private static void AppendLog(string logMessage, TextWriter txtWriter=null)
{
try
{
txtWriter.Write("\r\nLog Entry : ");
txtWriter.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(), DateTime.Now.ToLongDateString());
txtWriter.WriteLine(" :");
txtWriter.WriteLine(" :{0}", logMessage);
txtWriter.WriteLine("-------------------------------");
}
catch (Exception ex)
{
txtWriter.Write(ex.Message);
}
}
}
}