I have big big data in form of bytes around 5GB.
I need to store this data in a file ServerData.xml. This data should be first converted into string and then should be saved to file so that we can perform operation on the file.
I used below code to convert stream of bytes to string and then to save the same in a file.
private const string fileName = "ServerData.xml";
public void ProcessBuffer(byte[] receiveBuffer, int bytes)
{
if (!File.Exists(fileName))
{
using (File.Create(fileName)) { };
}
TextWriter tw = new StreamWriter(fileName, true);
tw.Write(Encoding.UTF8.GetString(receiveBuffer).TrimEnd((Char)0));
tw.Close();
}
Is it the right way ?
or please suggest better way so that there should not be any memory issue if any in future ?
The code in your question can only work if ProcessBuffer is always called with a UTF-8 encoded text that is broken on code point boundaries. That seems pretty unlikely to me, so I would expect that you encounter errors when decoding to text.
However, decoding to text and then writing, is rather pointless and indeed counter-productive. The bytes are already UTF-8 encoded. Write them directly to file as they arrive from the socket. Don't perform any processing of them. When you come to read the XML using XmlReader, the parser will read the encoding as UTF-8 from the document's XML declaration, and be able to decode the rest of the document. I am assuming that the document's XML declaration specifies UTF-8 but that seems highly likely. You should check.
You should get rid of the text writer which is no use to you for writing bytes. Write the bytes directly to a file stream. And try to avoid opening and closing the file repeatedly. That's very inefficient. Open and close the file exactly once.
Why do you need to convert it to a string?
using System.IO;
public static void WriteBytes(byte[] bytes, string filename)
{
using (FileStream fs = new FileStream(filename, FileMode.OpenOrCreate))
using (BinaryWriter writer = new BinaryWriter(fs, Encoding.UTF8))
{
writer.Write(bytes);
}
}
You can simply write these bytes to a file using FileStream:
public void ProcessBuffer(byte[] receivedBuffer, int bytes)
{
using (var fileStream = new FileStream(fileName, FileMode.Create)) // overwrites file
{
fileStream.Write(receivedBuffer, 0, bytes);
}
}
Update: You won't be able to work with such a big XML document if you don't have enough resources. I would suggest reformatting this file. For example, I would parse this XML and insert data into a SQL database. Then, you can easily operate with such amounts of data.
I would prefer that I write all bytes to file. And when reading, convert it to string and then convert to XML using XDocument, XElement etc. By writing bytes in file you will save space, and it is efficient,
Instead of using FileStream, I will prefer File.WriteAllBytes method.
private const string fileName = "ServerData.xml";
public void ProcessBuffer(byte[] receiveBuffer, int bytes)
{
File.WriteAllBytes(filename, bytes);
// And when reading
var bytes = File.ReadAllBytes(filename);
var binaryReader = new BinaryReader(new MemoryStream(bytes));
// Parse strings and make xml,
binaryReader.ReadString();
}
I got a file stream which has content read from a disk.
Stream input = new FileStream("filename");
This stream is to be passed to a third party library which after reading the stream, keeps the Stream's position pointer at the end of the file (as ususal).
My requirement is not to load the file from the desk everytime, instead I want to maintain MemoryStream, which will be used everytime.
public static void CopyStream(Stream input, Stream output)
{
byte[] buffer = new byte[32768];
int read;
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{
output.Write(buffer, 0, read);
}
}
I have tried the above code. It works for the first very time to copy the input stream to output stream, but subsequent calls to CopyStream will not work as the source's Position will be at the end of the stream after the first call.
Are there other alternatives which copy the content of the source stream to another stream irrespective of the source stream's current Position.
And this code needs to run in thread safe manner in a multi threaded environment.
You can use .NET 4.0 Stream.CopyTo to copy your steam to a MemoryStream. The MemoryStream has a Position property you can use to move its postition to the beginning.
var ms = new MemoryStream();
using (Stream file = File.OpenRead(#"filename"))
{
file.CopyTo(ms);
}
ms.Position = 0;
To make a thread safe solution, you can copy the content to a byte array, and make a new MemoryStream wrapping the byte array for each thread that need access:
byte[] fileBytes = ms.ToArray();
var ms2 = new MemoryStream(fileBytes);
You should check the input stream's CanSeek property. If that returns false, you can only read it once anyway. If CanSeek returns true, you can set the position to zero and copy away.
if (input.CanSeek)
{
input.Position = 0;
}
You may also want to store the old position and restore it after copying.
ETA: Passing the same instance of a Stream around is not the safest thing to do. E.g. you can't be sure the Stream wasn't disposed when you get it back. I'd suggest to copy the FileStream to a MemoryStream in the beginning, but only store the byte content of the latter by calling ToArray(). When you need to pass a Stream somewhere, just create a new one each time with new MemoryStream(byte[]).
I am in a situation where i need to write to same file stream from different threads. The problem is that i cannot find any clear explanation whether i need to handle current stream position between writes ?
I open stream with FileOptions.Asynchronous option thus have an overlapped IO.
All write requests are coming in sequentially with buffers for next offset and from my test everything working fine and data is written correctly at file offsets.
But really can someone answer if there is no implications with this approach.
You can pass a FileStream to another method through the parameter. For example:
public void FirstMethod(){
FileStream filestream = new FileStream();
//fill filestream
SecondMethod(filestream);
}
public void SecondMethod(FileStream filestream)
filestream.//do whatever you want with it
}
Or you can make a method return the filestream:
public FileStream FirstMethod() {
FileStream filestream = new FileStream();
//fill filestream
}
public void SecondMethod() {
FileStream filestream = FirstMethod();
//do what you want with it
}
If you could show us what you did, we can give you an answer that suits your situation.
I've got a method that streams files by returning a System.IO.FileStream pointing to a file opened for reading. What I want to do at this point is store the stream into a System.IO.MemoryStream as well.
The simplest option would be to first read the FileStream into the MemoryStream, and then return the MemoryStream to the caller. However this means that I'll have to buffer the entire file into memory before returning, thereby delaying the streaming response to the caller.
What I'd like to do (if possible) is read the FileStream into a MemoryStream and also stream it to the caller simultaneously. This way, the file doesn't have to be buffered before being returned, and still ends up getting stored into a MemoryStream.
You can create a custom implementation of the Stream class in which you write away the data red to a memory stream, or use my version of that which can be found at: http://upreader.codeplex.com/SourceControl/changeset/view/d287ca854370#src%2fUpreader.Usenet.Nntp%2fEncodings%2fRecordStream.cs
This can be used in the following way:
using (FileStream fileStream = File.Open("test.txt", FileMode.Open))
using (RecordStream recordStream = new RecordStream(fileStream))
{
// make sure we record incoming data
recordStream.Record();
// do something with the data
StreamReader reader = new StreamReader(recordStream);
string copy1 = reader.ReadToEnd();
// now reset
recordStream.Playback();
// do something with the data again
StreamReader reader = new StreamReader(recordStream);
string copy2 = reader.ReadToEnd();
Assert.AreEqual(cop1, copy2);
}
I Built this class particularly for Network stream but it works equally well with a fileStream and it only reads the file once without buffering it first before returning
A simple implementation would be
class RecordStream : Stream
{
public Stream BaseStream { get; }
public MemoryStream Record { get; }
....
public override int Read(byte[] buffer, int offset, int count)
{
int result = BaseStream.Read(buffer, offset, count);
// store it
Record.Write(buffer, offset, count);
return result;
}
}
What is the best way to copy the contents of one stream to another? Is there a standard utility method for this?
From .NET 4.5 on, there is the Stream.CopyToAsync method
input.CopyToAsync(output);
This will return a Task that can be continued on when completed, like so:
await input.CopyToAsync(output)
// Code from here on will be run in a continuation.
Note that depending on where the call to CopyToAsync is made, the code that follows may or may not continue on the same thread that called it.
The SynchronizationContext that was captured when calling await will determine what thread the continuation will be executed on.
Additionally, this call (and this is an implementation detail subject to change) still sequences reads and writes (it just doesn't waste a threads blocking on I/O completion).
From .NET 4.0 on, there's is the Stream.CopyTo method
input.CopyTo(output);
For .NET 3.5 and before
There isn't anything baked into the framework to assist with this; you have to copy the content manually, like so:
public static void CopyStream(Stream input, Stream output)
{
byte[] buffer = new byte[32768];
int read;
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{
output.Write (buffer, 0, read);
}
}
Note 1: This method will allow you to report on progress (x bytes read so far ...)
Note 2: Why use a fixed buffer size and not input.Length? Because that Length may not be available! From the docs:
If a class derived from Stream does not support seeking, calls to Length, SetLength, Position, and Seek throw a NotSupportedException.
MemoryStream has .WriteTo(outstream);
and .NET 4.0 has .CopyTo on normal stream object.
.NET 4.0:
instream.CopyTo(outstream);
I use the following extension methods. They have optimized overloads for when one stream is a MemoryStream.
public static void CopyTo(this Stream src, Stream dest)
{
int size = (src.CanSeek) ? Math.Min((int)(src.Length - src.Position), 0x2000) : 0x2000;
byte[] buffer = new byte[size];
int n;
do
{
n = src.Read(buffer, 0, buffer.Length);
dest.Write(buffer, 0, n);
} while (n != 0);
}
public static void CopyTo(this MemoryStream src, Stream dest)
{
dest.Write(src.GetBuffer(), (int)src.Position, (int)(src.Length - src.Position));
}
public static void CopyTo(this Stream src, MemoryStream dest)
{
if (src.CanSeek)
{
int pos = (int)dest.Position;
int length = (int)(src.Length - src.Position) + pos;
dest.SetLength(length);
while(pos < length)
pos += src.Read(dest.GetBuffer(), pos, length - pos);
}
else
src.CopyTo((Stream)dest);
}
.NET Framework 4 introduce new "CopyTo" method of Stream Class of System.IO namespace. Using this method we can copy one stream to another stream of different stream class.
Here is example for this.
FileStream objFileStream = File.Open(Server.MapPath("TextFile.txt"), FileMode.Open);
Response.Write(string.Format("FileStream Content length: {0}", objFileStream.Length.ToString()));
MemoryStream objMemoryStream = new MemoryStream();
// Copy File Stream to Memory Stream using CopyTo method
objFileStream.CopyTo(objMemoryStream);
Response.Write("<br/><br/>");
Response.Write(string.Format("MemoryStream Content length: {0}", objMemoryStream.Length.ToString()));
Response.Write("<br/><br/>");
There is actually, a less heavy-handed way of doing a stream copy. Take note however, that this implies that you can store the entire file in memory. Don't try and use this if you are working with files that go into the hundreds of megabytes or more, without caution.
public static void CopySmallTextStream(Stream input, Stream output)
{
using (StreamReader reader = new StreamReader(input))
using (StreamWriter writer = new StreamWriter(output))
{
writer.Write(reader.ReadToEnd());
}
}
NOTE: There may also be some issues concerning binary data and character encodings.
The basic questions that differentiate implementations of "CopyStream" are:
size of the reading buffer
size of the writes
Can we use more than one thread (writing while we are reading).
The answers to these questions result in vastly different implementations of CopyStream and are dependent on what kind of streams you have and what you are trying to optimize. The "best" implementation would even need to know what specific hardware the streams were reading and writing to.
Unfortunately, there is no really simple solution. You can try something like that:
Stream s1, s2;
byte[] buffer = new byte[4096];
int bytesRead = 0;
while (bytesRead = s1.Read(buffer, 0, buffer.Length) > 0) s2.Write(buffer, 0, bytesRead);
s1.Close(); s2.Close();
But the problem with that that different implementation of the Stream class might behave differently if there is nothing to read. A stream reading a file from a local harddrive will probably block until the read operaition has read enough data from the disk to fill the buffer and only return less data if it reaches the end of file. On the other hand, a stream reading from the network might return less data even though there are more data left to be received.
Always check the documentation of the specific stream class you are using before using a generic solution.
There may be a way to do this more efficiently, depending on what kind of stream you're working with. If you can convert one or both of your streams to a MemoryStream, you can use the GetBuffer method to work directly with a byte array representing your data. This lets you use methods like Array.CopyTo, which abstract away all the issues raised by fryguybob. You can just trust .NET to know the optimal way to copy the data.
if you want a procdure to copy a stream to other the one that nick posted is fine but it is missing the position reset, it should be
public static void CopyStream(Stream input, Stream output)
{
byte[] buffer = new byte[32768];
long TempPos = input.Position;
while (true)
{
int read = input.Read (buffer, 0, buffer.Length);
if (read <= 0)
return;
output.Write (buffer, 0, read);
}
input.Position = TempPos;// or you make Position = 0 to set it at the start
}
but if it is in runtime not using a procedure you shpuld use memory stream
Stream output = new MemoryStream();
byte[] buffer = new byte[32768]; // or you specify the size you want of your buffer
long TempPos = input.Position;
while (true)
{
int read = input.Read (buffer, 0, buffer.Length);
if (read <= 0)
return;
output.Write (buffer, 0, read);
}
input.Position = TempPos;// or you make Position = 0 to set it at the start
Since none of the answers have covered an asynchronous way of copying from one stream to another, here is a pattern that I've successfully used in a port forwarding application to copy data from one network stream to another. It lacks exception handling to emphasize the pattern.
const int BUFFER_SIZE = 4096;
static byte[] bufferForRead = new byte[BUFFER_SIZE];
static byte[] bufferForWrite = new byte[BUFFER_SIZE];
static Stream sourceStream = new MemoryStream();
static Stream destinationStream = new MemoryStream();
static void Main(string[] args)
{
// Initial read from source stream
sourceStream.BeginRead(bufferForRead, 0, BUFFER_SIZE, BeginReadCallback, null);
}
private static void BeginReadCallback(IAsyncResult asyncRes)
{
// Finish reading from source stream
int bytesRead = sourceStream.EndRead(asyncRes);
// Make a copy of the buffer as we'll start another read immediately
Array.Copy(bufferForRead, 0, bufferForWrite, 0, bytesRead);
// Write copied buffer to destination stream
destinationStream.BeginWrite(bufferForWrite, 0, bytesRead, BeginWriteCallback, null);
// Start the next read (looks like async recursion I guess)
sourceStream.BeginRead(bufferForRead, 0, BUFFER_SIZE, BeginReadCallback, null);
}
private static void BeginWriteCallback(IAsyncResult asyncRes)
{
// Finish writing to destination stream
destinationStream.EndWrite(asyncRes);
}
For .NET 3.5 and before try :
MemoryStream1.WriteTo(MemoryStream2);
Easy and safe - make new stream from original source:
MemoryStream source = new MemoryStream(byteArray);
MemoryStream copy = new MemoryStream(byteArray);
The following code to solve the issue copy the Stream to MemoryStream using CopyTo
Stream stream = new MemoryStream();
//any function require input the stream. In mycase to save the PDF file as stream
document.Save(stream);
MemoryStream newMs = (MemoryStream)stream;
byte[] getByte = newMs.ToArray();
//Note - please dispose the stream in the finally block instead of inside using block as it will throw an error 'Access denied as the stream is closed'