|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
#ifndef FWCore_SharedMemory_ReadBuffer_h
#define FWCore_SharedMemory_ReadBuffer_h
// -*- C++ -*-
//
// Package: FWCore/SharedMemory
// Class : ReadBuffer
//
/**\class ReadBuffer ReadBuffer.h " FWCore/SharedMemory/interface/ReadBuffer.h"
Description: Manages a shared memory buffer used for reading
Usage:
Handles reading from a dynamically allocatable shared memory buffer.
This works in conjunction with WriteBuffer.
*/
//
// Original Author: Chris Jones
// Created: 21/01/2020
//
// system include files
#include <array>
#include <memory>
#include <string>
#include "boost/interprocess/managed_shared_memory.hpp"
// user include files
#include "FWCore/SharedMemory/interface/buffer_names.h"
#include "FWCore/SharedMemory/interface/BufferInfo.h"
// forward declarations
namespace edm::shared_memory {
class ReadBuffer {
public:
/** iUniqueName : must be unique for all processes running on a system.
iBufferInfo : is a pointer to a shared_memory address where the same address needs to be shared by ReadBuffer and WriteBuffer.
*/
ReadBuffer(std::string const& iUniqueName, BufferInfo* iBufferInfo)
: buffer_{nullptr, 0}, bufferInfo_{iBufferInfo}, bufferOldIndex_{3} {
*bufferInfo_ = {0, 0};
bufferNames_[0] = iUniqueName + buffer_names::kBuffer0;
bufferNames_[1] = iUniqueName + buffer_names::kBuffer1;
}
ReadBuffer(const ReadBuffer&) = delete;
const ReadBuffer& operator=(const ReadBuffer&) = delete;
ReadBuffer(ReadBuffer&&) = delete;
const ReadBuffer& operator=(ReadBuffer&&) = delete;
// ---------- const member functions ---------------------
int bufferIdentifier() const { return bufferInfo_->identifier_; }
// ---------- member functions ---------------------------
std::pair<char*, std::size_t> buffer() {
if (mustGetBufferAgain()) {
using namespace boost::interprocess;
sm_ = std::make_unique<managed_shared_memory>(open_only, bufferNames_[bufferInfo_->index_].c_str());
buffer_ = sm_->find<char>(buffer_names::kBuffer);
bufferOldIndex_ = bufferInfo_->index_;
}
return buffer_;
}
private:
bool mustGetBufferAgain() const { return bufferInfo_->index_ != bufferOldIndex_; }
// ---------- member data --------------------------------
std::pair<char*, std::size_t> buffer_;
BufferInfo* bufferInfo_;
char bufferOldIndex_;
std::array<std::string, 2> bufferNames_;
std::unique_ptr<boost::interprocess::managed_shared_memory> sm_;
};
} // namespace edm::shared_memory
#endif
|