Programming

Hello everyone,

How to connect hash table with shared memory?.I need to update and retrieve data from the shared memory through hash table.

Thanks in advance

You put a hash table in shared memory the same way you put a hash table in other memory -- you write to the memory. What does your existing code look like? Maybe it can be adapted.

Of course, you'll also need a mutex of some sort to prevent writers from messing up the table while readers are trying to use it.

I am using linux operating system.I need to create one hash table and need to point that hash table to shared memory.The database data that we are entering from the server program.

So the hash table isn't in shared memory, just points to it? What do your current data structures look like?

The hash table should consist of one primary key of database(key) and the value is the address of the corresponding shared memory.................

So the table isn't shared, but the data it holds is shared?

Using the mmap system call you can map a file into shared memory. After you map it, the file effectively "is" memory; reads from the memory read from the file, writes to the memory write to the file. The OS only loads the parts you use. When you map it, it gives you a pointer; the pointer plus an offset gives you a particular location in that file.

The hashit library is a generic hash table that stores pointers. Pointers to shared memory aren't special, so it'll hold those too.

If you need more help you're going to have to stop the monosyllabic nonanswers and explain your data structures and modes of access in detail.

hai,
The hash table which consist of one key and data.The data it should pointing to shared memory.In shared memory(shmid) we are storing the database.(eg:- employee details).So by specifying the key i need to access the "data base" details from the shared memory.I wrote hash table program for storing the key and data.The key i am specifying the database name(there are n number of databases),but i am confused with the shared memory accessing?????