artdaq_core  v3_04_09
SharedMemoryManager.hh
1 #ifndef artdaq_core_Core_SharedMemoryManager_hh
2 #define artdaq_core_Core_SharedMemoryManager_hh 1
3 
4 #include <atomic>
5 #include <string>
6 #include <deque>
7 #include "artdaq-core/Utilities/TimeUtils.hh"
8 #include <mutex>
9 #include <vector>
10 #include <list>
11 
12 namespace artdaq
13 {
19  {
20  public:
21 
26  {
27  Empty,
28  Writing,
29  Full,
30  Reading
31  };
32 
38  static inline std::string FlagToString(BufferSemaphoreFlags flag)
39  {
40  switch (flag)
41  {
43  return "Empty";
45  return "Writing";
47  return "Full";
49  return "Reading";
50  }
51  return "Unknown";
52  }
53 
63  SharedMemoryManager(uint32_t shm_key, size_t buffer_count = 0, size_t buffer_size = 0, uint64_t buffer_timeout_us = 100 * 1000000, bool destructive_read_mode = true);
64 
68  virtual ~SharedMemoryManager() noexcept;
69 
70 
74  void Attach();
75 
80  int GetBufferForReading();
81 
87  int GetBufferForWriting(bool overwrite);
88 
93  bool ReadyForRead();
94 
100  virtual bool ReadyForWrite(bool overwrite);
101 
106  size_t ReadReadyCount();
107 
113  size_t WriteReadyCount(bool overwrite);
114 
120  std::deque<int> GetBuffersOwnedByManager(bool locked = true);
121 
127  size_t BufferDataSize(int buffer);
128 
132  size_t BufferSize() {return (shm_ptr_ != nullptr ? shm_ptr_->buffer_size : 0);}
133 
138  void ResetReadPos(int buffer);
139 
144  void ResetWritePos(int buffer);
150  void IncrementReadPos(int buffer, size_t read);
151 
158  bool IncrementWritePos(int buffer, size_t written);
159 
165  bool MoreDataInBuffer(int buffer);
166 
173  bool CheckBuffer(int buffer, BufferSemaphoreFlags flags);
174 
180  void MarkBufferFull(int buffer, int destination = -1);
181 
187  void MarkBufferEmpty(int buffer, bool force = false);
188 
195  bool ResetBuffer(int buffer);
196 
200  void GetNewId() { if (manager_id_ < 0 && IsValid()) manager_id_ = shm_ptr_->next_id.fetch_add(1); }
201 
206  uint16_t GetAttachedCount() const;
207 
211  void ResetAttachedCount() const { if (manager_id_ == 0 && IsValid()) shm_ptr_->next_id = 1; }
212 
217  int GetMyId() const { return manager_id_; }
218 
223  int GetRank()const { return IsValid() ? shm_ptr_->rank : -1; }
224 
229  void SetRank(int rank) { if (manager_id_ == 0 && IsValid()) shm_ptr_->rank = rank; }
230 
235  bool IsValid() const { return shm_ptr_ ? true : false; }
236 
240  bool IsEndOfData() const;
241 
246  size_t size() const { return IsValid() ? shm_ptr_->buffer_count : 0; }
247 
255  size_t Write(int buffer, void* data, size_t size);
256 
264  bool Read(int buffer, void* data, size_t size);
265 
270  virtual std::string toString();
271 
276  uint32_t GetKey() const { return shm_key_; }
277 
283  void* GetReadPos(int buffer);
284 
290  void* GetWritePos(int buffer);
291 
297  void* GetBufferStart(int buffer);
298 
306  void Detach(bool throwException = false, std::string category = "", std::string message = "", bool force = false);
307 
312  uint64_t GetBufferTimeout() const { return IsValid() ? shm_ptr_->buffer_timeout_us : 0; }
313 
318  size_t GetBufferCount() const { return IsValid() ? shm_ptr_->next_sequence_id : 0; }
319 
324  size_t GetLastSeenBufferID() const { return last_seen_id_; }
325 
329  size_t GetLowestSeqIDRead() const { return IsValid() ? shm_ptr_->lowest_seq_id_read : 0; }
330 
335  void SetMinWriteSize(size_t size) { min_write_size_ = size; }
336 
341  std::list<std::pair<int, BufferSemaphoreFlags>> GetBufferReport();
342 
346  void TouchBuffer(int buffer) { return touchBuffer_(getBufferInfo_(buffer)); }
347  private:
348  struct ShmBuffer
349  {
350  size_t writePos;
351  size_t readPos;
352  std::atomic<BufferSemaphoreFlags> sem;
353  std::atomic<int16_t> sem_id;
354  std::atomic<size_t> sequence_id;
355  std::atomic<uint64_t> last_touch_time;
356  };
357 
358  struct ShmStruct
359  {
360  std::atomic<unsigned int> reader_pos;
361  std::atomic<unsigned int> writer_pos;
362  int buffer_count;
363  size_t buffer_size;
364  size_t buffer_timeout_us;
365  size_t next_sequence_id;
366  size_t lowest_seq_id_read;
367  bool destructive_read_mode;
368 
369  std::atomic<int> next_id;
370  int rank;
371  unsigned ready_magic;
372  };
373 
374  uint8_t* dataStart_() const;
375  uint8_t* bufferStart_(int buffer);
376  ShmBuffer* getBufferInfo_(int buffer);
377  bool checkBuffer_(ShmBuffer* buffer, BufferSemaphoreFlags flags, bool exceptions = true);
378  void touchBuffer_(ShmBuffer* buffer);
379 
380  ShmStruct requested_shm_parameters_;
381 
382  int shm_segment_id_;
383  ShmStruct* shm_ptr_;
384  uint32_t shm_key_;
385  int manager_id_;
386  mutable std::vector<std::mutex> buffer_mutexes_;
387  mutable std::mutex search_mutex_;
388 
389  std::atomic<size_t> last_seen_id_;
390  size_t min_write_size_;
391  };
392 
393 }
394 
395 #endif // artdaq_core_Core_SharedMemoryManager_hh
void TouchBuffer(int buffer)
Touch the given buffer (update its last_touch_time)
bool Read(int buffer, void *data, size_t size)
Read size bytes of data from buffer into the given pointer.
void IncrementReadPos(int buffer, size_t read)
Increment the read position for a given buffer.
void ResetAttachedCount() const
Reset the attached manager count to 0.
bool IsValid() const
Is the shared memory pointer valid?
std::deque< int > GetBuffersOwnedByManager(bool locked=true)
Get the list of all buffers currently owned by this manager instance.
void ResetReadPos(int buffer)
Set the read position of the given buffer to the beginning of the buffer.
static std::string FlagToString(BufferSemaphoreFlags flag)
Convert a BufferSemaphoreFlags variable to its string represenatation.
bool MoreDataInBuffer(int buffer)
Determine if more data is available to be read, based on the read position and data size...
virtual std::string toString()
Write information about the SharedMemory to a string.
void GetNewId()
Assign a new ID to the current SharedMemoryManager, if one has not yet been assigned.
std::list< std::pair< int, BufferSemaphoreFlags > > GetBufferReport()
Get a report on the status of each buffer.
The buffer is full, and waiting for a reader.
BufferSemaphoreFlags
The BufferSemaphoreFlags enumeration represents the different possible &quot;states&quot; of a given shared mem...
size_t BufferDataSize(int buffer)
Get the current size of the buffer&#39;s data.
size_t BufferSize()
Get the size of of a single buffer.
void Attach()
Reconnect to the shared memory segment.
void Detach(bool throwException=false, std::string category="", std::string message="", bool force=false)
Detach from the Shared Memory segment, optionally throwing a cet::exception with the specified proper...
virtual ~SharedMemoryManager() noexcept
SharedMemoryManager Destructor.
The buffer is currently being read from.
The buffer is currently being written to.
The SharedMemoryManager creates a Shared Memory area which is divided into a number of fixed-size buf...
The buffer is empty, and waiting for a writer.
size_t ReadReadyCount()
Count the number of buffers that are ready for reading.
bool ResetBuffer(int buffer)
Resets the buffer from Reading to Full. This operation will only have an effect if performed by the o...
int GetRank() const
Get the rank of the owner of the Shared Memory (artdaq assigns rank to each artdaq process for data f...
size_t GetLowestSeqIDRead() const
Gets the lowest sequence ID that has been read by any reader, as reported by the readers.
size_t size() const
Get the number of buffers in the shared memory segment.
bool IncrementWritePos(int buffer, size_t written)
Increment the write position for a given buffer.
bool IsEndOfData() const
Determine whether the Shared Memory is marked for destruction (End of Data)
bool CheckBuffer(int buffer, BufferSemaphoreFlags flags)
Check both semaphore conditions (Mode flag and manager ID) for a given buffer.
size_t GetLastSeenBufferID() const
Gets the highest buffer number either written or read by this SharedMemoryManager.
uint32_t GetKey() const
Get the key of the shared memory attached to this SharedMemoryManager.
void MarkBufferFull(int buffer, int destination=-1)
Release a buffer from a writer, marking it Full and ready for a reader.
void MarkBufferEmpty(int buffer, bool force=false)
Release a buffer from a reader, marking it Empty and ready to accept more data.
uint64_t GetBufferTimeout() const
Gets the configured timeout for buffers to be declared &quot;stale&quot;.
void ResetWritePos(int buffer)
Set the write position of the given buffer to the beginning of the buffer.
void SetMinWriteSize(size_t size)
Sets the threshold after which a buffer should be considered &quot;non-empty&quot; (in case of default headers)...
size_t GetBufferCount() const
Gets the number of buffers which have been processed through the Shared Memory.
void * GetWritePos(int buffer)
Get a pointer to the current write position of the buffer.
size_t Write(int buffer, void *data, size_t size)
Write size bytes of data from the given pointer to a buffer.
void * GetReadPos(int buffer)
Get a pointer to the current read position of the buffer.
void * GetBufferStart(int buffer)
Get a pointer to the start position of the buffer.
SharedMemoryManager(uint32_t shm_key, size_t buffer_count=0, size_t buffer_size=0, uint64_t buffer_timeout_us=100 *1000000, bool destructive_read_mode=true)
SharedMemoryManager Constructor.
bool ReadyForRead()
Whether any buffer is ready for read.
void SetRank(int rank)
Set the rank stored in the Shared Memory, if the current instance is the owner of the shared memory...
int GetBufferForWriting(bool overwrite)
Finds a buffer that is ready to be written to, and reserves it for the calling manager.
uint16_t GetAttachedCount() const
Get the number of attached SharedMemoryManagers.
size_t WriteReadyCount(bool overwrite)
Count the number of buffers that are ready for writing.
int GetMyId() const
Get the ID number of the current SharedMemoryManager.
int GetBufferForReading()
Finds a buffer that is ready to be read, and reserves it for the calling manager. ...
virtual bool ReadyForWrite(bool overwrite)
Whether any buffer is available for write.