Answer Posted / raj kumar

Readers: read data, never modify it
Writers: read data and modify it
criteria:
– Each read or write of the shared data must happen within
a critical section.
– Guarantee mutual exclusion for writers.
– Allow multiple readers to execute in the critical section
at once.
In this example, semaphores are used to prevent any writing
processes from changing information in the database while
other processes are reading from the database.
semaphore mutex = 1; // Controls access to
the reader count
semaphore db = 1; // Controls access to
the database
int reader_count; // The number of
reading processes accessing the data

Reader()
{
while (TRUE) { // loop forever
down(&mutex); // gain access
to reader_count
reader_count = reader_count + 1; // increment the
reader_count
if (reader_count == 1)
down(&db); // if this is
the first process to read the database,
// a down on db
is executed to prevent access to the
// database by a
writing process
up(&mutex); // allow other
processes to access reader_count
read_db(); // read the database
down(&mutex); // gain access
to reader_count
reader_count = reader_count - 1; // decrement
reader_count
if (reader_count == 0)
up(&db); // if there are
no more processes reading from the
// database,
allow writing process to access the data
up(&mutex); // allow other
processes to access reader_countuse_data();
// use the data
read from the database (non-critical)
}

Writer()
{
while (TRUE) { // loop forever
create_data(); // create data
to enter into database (non-critical)
down(&db); // gain access
to the database
write_db(); // write
information to the database
up(&db); // release
exclusive access to the database
}

can you please write a program for deadlock that can detect deadlock and to prevent deadlock.

3183

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Code for Method of Handling Factorials of Any Size?

2428

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U hv to enter a range from a and b and search hw many no. of times a pattern n. occurs between the range a and b. Eg :i/p:enter range :0 100 Enter pattern: 13 o/p: the no. times 13 occurred betwwn 0 to 100:1 Eg :i/p:enter range :100 1000 Enter pattern: 13 o/p: the no. times 13 occurred betwwn 100 to 1000: (in this 13,113,131,132,133…139,213,313,…913 all these will be counted)

2470

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How to swap two ASCII numbers?

2967

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write a program that can LOCATE and INSERT elements in array using c++ programming languages.

3966

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What output does this program generate as shown? Why? class A { A() { cout << "A::A()" << endl; } ~A() { cout << "A::~A()" << endl; throw "A::exception"; } }; class B { B() { cout << "B::B()" << endl; throw "B::exception"; } ~B() { cout << "B::~B()"; } }; int main(int, char**) { try { cout << "Entering try...catch block" << endl; A objectA; B objectB; cout << "Exiting try...catch block" << endl; } catch (char* ex) { cout << ex << endl; } return 0; }

988

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how to diplay a external image of output on winxp by using c & c++,

3402

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Performance Algorithm A performs 10n2 basic operations and algorithm B performs 300 lg n basic operations. For what value of n does algorithm B start to show its better performance?

7780

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Write a program that print in screen a tree with its height taken from user by entering number of 4 digits and find the odd numbers then calculate the sum of odd numbers so he get the height of tree?

3314

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How to Split Strings with Regex in Managed C++ Applications?

3599

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Given a table of the form: Product Sold on A 1/1/1980 B 1/1/1980 C 1/1/1980 A 1/1/1980 B 1/1/1980 C 2/1/1980 A 2/1/1980 There are 30 products and 10,000 records of such type. Also the month period during which sales happened is given to u. Write the program to display the result as: Product Month No. of copies A January 12 A February 15 A March 27 B January 54 B February 15 B March 10 C January 37

2637

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write a program to convert temperature from fa height into celcius and vise versa,use modular programming

2984

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Implement a command console for changing settings on a particular object. The command console should allow you to enter a string and will return the response (very similar to a terminal session). The commands are as follows: SET propertyname=newvalue will change the target object’s member named “propertyname” to have a value equal to “newvalue”. If the input value is incompatible (i.e. an int being set to a string), print out an appropriate error message. GET propertyname will print out the current value of the target object’s member named “propertyname”. GET * will print out a list of all target object members and their current values. The system should be extensible for future commands and should accept an arbitrary object, such that another developer could insert another object into the system and rely on the command console to get and set the properties correctly.

3895

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write a program that reverses the input number of n.Formulate an equation to come up with the answer.

7636

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How can I Draw an ellipse in 3d space and color it by using graph3d?

2557

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