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// Copyright (C) by Josh Blum. See LICENSE.txt for licensing information.
#include <gras/buffer_queue.hpp>
#include <gras_impl/debug.hpp>
#include <boost/format.hpp>
#include <boost/bind.hpp>
#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/anonymous_shared_memory.hpp>
#include <boost/interprocess/mapped_region.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/thread/thread.hpp>
#include <boost/thread/mutex.hpp>
#include <ctime>
using namespace gras;
namespace ipc = boost::interprocess;
static boost::mutex alloc_mutex;
/*!
* This routine generates an incredibly unique name for the allocation.
*
* Because we are using boost IPC, and it expects that we share the memory;
* IPC allocation requires a unique name to share amongst the processes.
* Since we are not actually using IPC, the sharing aspect isnt very useful,
* but we still need a unique name for the shared memory allocation anyway.
* (I would like if a empty string would suffice as an anonymous allocation)
*/
static std::string omg_so_unique(void)
{
const std::string tid = boost::lexical_cast<std::string>(boost::this_thread::get_id());
static size_t count = 0;
return boost::str(boost::format("shmem-%s-%u-%u") % tid % count++ % clock());
}
//! Round a number (length or address) to an IPC boundary
static size_t round_up_to_ipc_page(const size_t bytes)
{
const size_t chunk = ipc::mapped_region::get_page_size();
return chunk*((bytes + chunk - 1)/chunk);
}
/*!
* OK, we need a chunk of virtual memory that can be mapped.
* But we cant actually be holding exclusive access to that memory
* until it it mapped... This is naturally a race condition.
*/
static void *probably_get_vmem(const size_t length)
{
void *addr = NULL;
/*
#if defined(linux) || defined(__linux) || defined(__linux__)
addr = mmap(NULL, length, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
munmap(addr, length);
return addr;
#endif
//*/
const std::string shm_name = omg_so_unique();
//std::cout << "make shmem 2x\n" << std::endl;
ipc::shared_memory_object shm_obj_2x(
ipc::create_only, //only create
shm_name.c_str(), //name
ipc::read_write //read-write mode
);
//std::cout << "truncate 2x\n" << std::endl;
shm_obj_2x.truncate(length);
{
//std::cout << "map region 0\n" << std::endl;
ipc::mapped_region region0(
shm_obj_2x, //Memory-mappable object
ipc::read_write, //Access mode
0, //Offset from the beginning of shm
length //Length of the region
);
//std::cout << "region0.get_address() " << size_t(region0.get_address()) << std::endl;
addr = region0.get_address();
}
ipc::shared_memory_object::remove(shm_name.c_str());
return addr;
}
struct CircularBuffer
{
CircularBuffer(const size_t);
~CircularBuffer(void)
{
ipc::shared_memory_object::remove(shm_name.c_str());
}
char *buff_addr;
const size_t actual_length;
std::string shm_name;
ipc::shared_memory_object shm_obj;
ipc::mapped_region region1;
ipc::mapped_region region2;
};
CircularBuffer::CircularBuffer(const size_t num_bytes):
buff_addr(NULL),
actual_length(round_up_to_ipc_page(num_bytes))
{
////////////////////////////////////////////////////////////////
// Step 0) Find an address that can be mapped across 2x length:
////////////////////////////////////////////////////////////////
buff_addr = (char *)probably_get_vmem(actual_length*2);
//std::cout << "reserve addr " << std::hex << size_t(buff_addr) << std::dec << std::endl;
////////////////////////////////////////////////////////////////
// Step 1) Allocate a chunk of physical memory of length bytes
////////////////////////////////////////////////////////////////
//std::cout << "make shmem\n" << std::endl;
shm_name = omg_so_unique();
shm_obj = ipc::shared_memory_object(
ipc::create_only, //only create
shm_name.c_str(), //name
ipc::read_write //read-write mode
);
//std::cout << "truncate\n" << std::endl;
shm_obj.truncate(actual_length);
////////////////////////////////////////////////////////////////
//Step 2) Remap region1 of the virtual memory space
////////////////////////////////////////////////////////////////
//std::cout << "map region 1\n" << std::endl;
region1 = ipc::mapped_region(
shm_obj, //Memory-mappable object
ipc::read_write, //Access mode
0, //Offset from the beginning of shm
actual_length, //Length of the region
buff_addr
);
//std::cout << "region1.get_address() " << size_t(region1.get_address()) << std::endl;
////////////////////////////////////////////////////////////////
//Step 3) Remap region2 of the virtual memory space
////////////////////////////////////////////////////////////////
//std::cout << "map region 2\n" << std::endl;
region2 = ipc::mapped_region(
shm_obj, //Memory-mappable object
ipc::read_write, //Access mode
0, //Offset from the beginning of shm
actual_length, //Length of the region
buff_addr + actual_length
);
//std::cout << "region2.get_address() " << size_t(region2.get_address()) << std::endl;
//std::cout << "diff " << (long(region2.get_address()) - long(region1.get_address())) << std::endl;
////////////////////////////////////////////////////////////////
//4) Self memory test
////////////////////////////////////////////////////////////////
boost::uint32_t *mem = (boost::uint32_t*)buff_addr;
for (size_t i = 0; i < actual_length/sizeof(*mem); i++)
{
const boost::uint32_t num = std::rand();
mem[i] = num;
ASSERT(mem[i+actual_length/sizeof(*mem)] == num);
}
////////////////////////////////////////////////////////////////
//5) Zero out the memory for good measure
////////////////////////////////////////////////////////////////
std::memset(buff_addr, 0, actual_length);
}
static void circular_buffer_delete(SBuffer &buff, CircularBuffer *circ_buff)
{
boost::mutex::scoped_lock lock(alloc_mutex);
delete circ_buff;
}
SBuffer make_circular_buffer(const size_t num_bytes)
{
boost::mutex::scoped_lock lock(alloc_mutex);
CircularBuffer *circ_buff = NULL;
size_t trial_count = 0;
while (circ_buff == NULL)
{
trial_count++;
try
{
circ_buff = new CircularBuffer(num_bytes);
}
catch(const boost::interprocess::interprocess_exception &ex)
{
std::cerr << boost::format(
"GRAS: make_circular_buffer threw ipc exception on attempt %u\n%s"
) % trial_count % ex.what() << std::endl;
if (trial_count == 3) throw ex;
}
catch(...)
{
throw;
}
}
SBufferDeleter deleter = boost::bind(&circular_buffer_delete, _1, circ_buff);
SBufferConfig config;
config.memory = circ_buff->buff_addr;
config.length = circ_buff->actual_length;
config.deleter = deleter;
return SBuffer(config);
}
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