https://github.com/raftlib/shm
https://github.com/raftlib/shm
Last synced: about 1 year ago
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- Host: GitHub
- URL: https://github.com/raftlib/shm
- Owner: RaftLib
- Created: 2015-06-18T21:02:20.000Z (almost 11 years ago)
- Default Branch: master
- Last Pushed: 2024-12-22T14:53:27.000Z (over 1 year ago)
- Last Synced: 2025-04-14T17:43:34.425Z (about 1 year ago)
- Language: C++
- Size: 1.02 MB
- Stars: 9
- Watchers: 5
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Description
Easy SHM library for C++, still a work in progress but it's
a easier way to code up an anonymous SHM mapping, protect
the last page and generate a key to access it....I've used
similar code quite a bit and was tired of re-coding it. If
I find time I'll make it a bit more advanced, like adding
a monitor process to cleanup if for some reason the code
crashes (you know, things happen right?). I've tested the
code on OS X and Linux, but as usual your mileage may vary
greatly.
# Build Status
# Important Notes
So I've checked the functions found in the testsuite. I've
used the code quite a bit in various forms so it should work
rather well...however if you find bugs please submit a pull
request and I'll get it fixed ASAP.
# Compilation Notes
To build this library on OS X you'll need to run:
```bash
mkdir build
cd build
cmake ../build -G -DCMAKE_BUILD_TYPE=Release
[make | ninja]
[make | ninja] test
```
## Build options
* There are the usual options (e.g., Release/Debug), there's also...
* ```-DUSE_SYSV_MEMORY=1``` which will build the library using the SystemV SHM interface
* ```-DUSE_POSIX_SHM=1``` which will build the library using the POSIX SHM interface
* ```-DCPP_EXCEPTIONS=0``` which will remove the use of CPP exceptions, the return
values in this case must be checked (e.g., check for _nullptr_ vs. waiting for the
cpp exception.
# Install
* Just run ```[make | ninja] install```
# Usage
To use this library, simply:
```cpp
#include
```
When compiling your code that uses it, link with -lshm. On
Linux you'll have to compile with the -lrt, -lpthread and
-lnuma in order to fully utilize all the features. In
the future I might add a flag to compile without the NUMA
features so that you can use the library without having
to install libnuma.
## Two process example
```cpp
shm_key_t key;
shm::gen_key( key, 42);
using type_t = std::uint32_t;
type_t *ptr( nullptr );
/**
* NOTE: you can compile with or without CPP exceptions.
*/
try
{
ptr = reinterpret_cast< type_t* >( shm::init( key, 0x1000, false, nullptr ) );
}
catch( bad_shm_alloc ex )
{
std::cerr << ex.what() << "\n";
exit( EXIT_FAILURE );
}
auto child = fork();
switch( child )
{
case( 0 /** child **/ ):
{
try
{
ptr = shm::eopen< type_t >( key );
}
catch( bad_shm_alloc ex )
{
std::cerr << ex.what() << "\n";
exit( EXIT_FAILURE );
}
*ptr = 0x1137;
shm::close( key,
reinterpret_cast( &ptr),
0x1000,
false /** don't zero **/,
false /** don't unlink **/ );
}
break;
case( -1 /** error, back to parent **/ ):
{
exit( EXIT_FAILURE );
}
break;
default:
{
/**
* spin on value being written from child
* process.
*/
while( *ptr != 0x1137 );
std::fprintf( stdout, "leet\n" );
int status = 0;
waitpid( -1, &status, 0 );
shm::close( key,
reinterpret_cast( &ptr),
0x1000,
true /** zero **/,
true /** unlink **/ );
}
}
```