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SyncRoot Property:
Gets an object that can be used to synchronize access to the collection.
public virtual object SyncRoot {get;}
Property Value:
An object that can be used to synchronize access to the collection.
Synchronized Methods:
Synchronisation plays an important role in multithreaded applications where the threads are not independent of each other and share common resources. This is because if two threads share common resources and try to manipulate the resources simultaneously, the resources become inconsistent. To tackle such situations synchronisation provides a lock on the resource that is shared among threads and makes a thread wait until the other thread finishes the job with the resource. Thus synchronisation ‘locks’ the shared resource and prevents another thread from using it.
C# provides a lock keyword to lock the shared object or resource. Whatever is written inside the parenthesis following the lock keyword gets locked for the current thread and no other thread is permitted to obtain the lock on that resource or object. We can write an expression that evaluates to an object, or just the object on which we wish to have a lock, inside the parenthesis. Whatever the expression may be, the result should be a reference type. The code that uses the object to be synchronised should be written inside the block of the lock statement.
To give you a more concrete example, consider two threads working on a file. If both the threads try to open the file and write to it simultaneously, an exception is thrown. Here what we need to do is synchronise both the threads in such a way that only one thread opens the file and writes in it at any given moment.
Regards,
Satips.
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Any code snippets please?
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Now if the user supplies some number in the textbox and clicks on the purchase button, the following handler gets called:
In this Sample Code
FileInfo f;
FileStream fs;
byte total=100;
f = new FileInfo ( “C:\\log.bin” );
Thread t = new Thread (new ThreadStart(checker));
t.IsBackground = true;
t.Start();
<br />
private void purchase_Click ( object sender, System.EventArgs e )<br />
{<br />
lock ( f )<br />
{<br />
try<br />
{<br />
fs = f.OpenWrite( ) ;<br />
byte b = byte.Parse ( quantity.Text ) ;<br />
total = ( byte ) ( total - b ) ; <br />
fs.WriteByte ( total ) ;<br />
MessageBox.Show ( "Transaction Complete" + "\n" + "Item <br />
remaining: " + total ) ;<br />
fs.Close( ) ;<br />
}<br />
catch<br />
{<br />
MessageBox.Show ( "Cannot Open file" ) ;<br />
}<br />
}<br />
}<br />
Regards,
Satips.
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Synchronized returns a collection that locks on each call, i.e. while you call a method or property, no other thread may modify the collection. This is convenient, but not enough.
Imagine the following code snippet:
if (myList.Count > 0)
myList.RemoveAt(0);
In this case, you have two separate calls (querying "Count" and removing an object). However, between the calls, some other thread may access the list and e.g. clear it completely. In this case, RemoveAt will fail.
For that scenario, you get the SyncRoot:
lock(myList.SyncRoot)
{
if (myList.Count > 0)
myList.RemoveAt(0);
}
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Thanks Peter, But still i am not clear.
First point is, if we synchronize the whole method, how other thread can make calls between Count and RemoveAt?
Secondly, instead of lock(mylist.syncRoot) can't we specify lock(mylist)?
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kumar.bs wrote: if we synchronize the whole method, how other thread can make calls between Count and RemoveAt?
They can't (as long as they use the lock), and that's the whole point. because between "Count" and "RemoveAt" noone may modify the list.
Keep in mind that querying Count is usually very fast, so lock acquisition and RemoveAt will take the majority of execution time anyway.
kumar.bs wrote: lock(mylist.syncRoot) can't we specify lock(mylist)?
Two problems:
First, "List Proxies". The synchronization works correct only if all threads accessing the list use the same object to lock on. However, the List interface might not hold the data itself, but expose the interface for some underlying data. If one thread lokcs on the list proxy, and another thread locks on the underlying data, we have the concurrent access we need to avoid.
Second, Lock Order.
There is a problem wiht locking on publicly visible symbols. When you have two locking objects A and B, one thread might lock in the order A, B the other in order B,A. This leads to a deadlock situation that cannot be solved.
That's why locking on public objects is almost always a bad idea. You need to be very clear which lock objects exsit in your code (and the code you call!), and give them a definite order. SyncRoot helps here a little bit since it is a dedicated object used for locking, that is provided by the underlying data.
helped? 
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Thanks Peter, could able to understand better.
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Hi frenz,
In my application im changing formats of images...so while the process is going on i want to show the names of the images being processed in the status bar...for that i have the code...but the prob is...the for is not getting refreshed...i mean the names are not getting updated in the status bar...only the firat image's wis shown in the bar and if any messagebox pops up in between then the status bar gets updated with the latest images name...
i want to make the form get refreshed evry time the name is changed so tht the status bar gets updated with the name...
Plz help in this...
P.S writing code in C# 2005
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You should move the process to another thread, so your UI updates. Application.DoEvents() is the cheats way to try and avoid writing threaded code, you can try that first, perhaps
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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thank u for the quick reply...can u tell me in a bit detail way how to go about that...
thanx in advance...
Inder..
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The right way ? You need to read up on the BackgroundWorker class, have it do whatever your app is doing, and use the progress notifications to communicate with your main thread and update your UI.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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I want to check whether the text entered in a control, say a text box is of double or not.
How can I do it? Thanks.
Keshav Kamat
India
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Use double.TryParse(text).
Deja View - the feeling that you've seen this post before.
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I want to store more than one doc file, pdf file ,ppt file
,other file using single id.
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I have no idea what your question is
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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Do you need to convert a file into all these types that you mention?
You are being very vague and/or not making much sense.
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Hi !
i want to develop a software that must be have Math Equation.
if possible use from Math Equation of word, or no How to i have a one on my software?
beacuse i want create an editor that must be have math formula.
Thanks.![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
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Search the articles on this site, there are a few that detail what you are trying to do from what I can tell.
_____________________________________________________________________
Our developers never release
code. Rather, it tends to escape, pillaging the countryside all around.
The Enlightenment Project (paraphrased comment)
Visit Me at GISDevCafe
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I need visual studio2005 bootstrapper
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I'm sure you do....
What do you mean by bootstrapper ?
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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I dont know about .net bootstrapper.
Bootsrap loader is a program used to start up an operating system such as Windows which loads the required services and the process in the memory.
But what is .net bootstrapper.
Do you mean the installation file or something?
Keshav Kamat
India
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I suspect he wants a way to distribute a .NET app so running it installs the framework, or the framework is not required.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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initially my xml file is
<?xml version="1.0" ?>
<lasers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="laserProp.xsd">
<laser LaserName="Laser1" ModelName="Nufern v1.0" SerialNo="1" ManufacturerName="Nufern v1.0" Maximumpower="200w">
<properties>
<image>CW-Waveform.jpg</image>
<WaveTypes>
<WaveType Name="CW Waveform" url="CWwaveform.html" isavailable="true" />
<WaveType Name="Relaxation Oscillation Envelope" url="RelaxOscillation.html"
isavailable="true" />
</WaveTypes>
<tabular>
<property id="300" name="System active" currval="0" prgbar="false" selected="false" min="0"
max="100" pwd="true" units="C" gauge="true" thresholdval="10"/>
<property id="301" name="Enable laser" currval="0" prgbar="true" selected="false" min="0"
max="100" pwd="true" units="C" gauge="true" thresholdval="10"/>
</tabular>
</properties>
</laser>
</lasers>
And my xsd is
<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="lasers">
<xs:complexType>
<xs:sequence>
<xs:element name="laser">
<xs:complexType>
<xs:sequence>
<xs:element name="properties">
<xs:complexType>
<xs:sequence>
<xs:element name="image" type="xs:string" />
<xs:element name="WaveTypes">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="WaveType">
<xs:complexType>
<xs:attribute name="Name" type="xs:string" use="required" />
<xs:attribute name="url" type="xs:string" use="required" />
<xs:attribute name="isavailable" type="xs:boolean" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="tabular">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="property">
<xs:complexType>
<xs:attribute name="id" type="xs:integer" use="required" />
<xs:attribute name="name" type="xs:string" use="required" />
<xs:attribute name="currval" type="xs:integer" use="required" />
<xs:attribute name="prgbar" type="xs:boolean" use="required" />
<xs:attribute name="selected" type="xs:boolean" use="required" />
<xs:attribute name="min" type="xs:integer" use="required" />
<xs:attribute name="max" type="xs:integer" use="required" />
<xs:attribute name="pwd" type="xs:boolean" use="required" />
<xs:attribute name="units" type="xs:string" use="required" />
<xs:attribute name="gauge" type="xs:boolean" use="required" />
<xs:attribute name="thresholdval" type="xs:integer" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="LaserName" type="xs:string" use="required" />
<xs:attribute name="ModelName" type="xs:string" use="required" />
<xs:attribute name="SerialNo" type="xs:integer" use="required" />
<xs:attribute name="ManufacturerName" type="xs:string" use="required" />
<xs:attribute name="Maximumpower" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
now it is working fine, but when xml file has more than one laser(laser is child node of lasers) then it is giving validation error like
"The element lasers has invalid child element laser"
Help me on this
Thanks in advance
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<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="lasers">
<xs:complexType>
<xs:sequence>
<xs:element name="laser" maxOccurs="Unbounded">
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning." - Rick Cook www.troschuetz.de
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Thanks very much
praveenkumar Palla
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