artdaq_core  v3_02_01
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 <unordered_map>
10 #include <set>
11 
12 namespace artdaq
13 {
19  {
20  public:
21 
26  {
27  Empty,
28  Writing,
29  Full,
30  Reading
31  };
32 
38  static 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() { return ReadReadyCount() > 0; }
94 
100  virtual bool ReadyForWrite(bool overwrite) { return WriteReadyCount(overwrite) > 0; }
101 
106  size_t ReadReadyCount();
107 
114  size_t WriteReadyCount(bool overwrite);
115 
121  std::deque<int> GetBuffersOwnedByManager(bool locked = true);
122 
128  size_t BufferDataSize(int buffer);
129 
134  void ResetReadPos(int buffer);
135 
140  void ResetWritePos(int buffer);
146  void IncrementReadPos(int buffer, size_t read);
147 
153  void IncrementWritePos(int buffer, size_t written);
154 
160  bool MoreDataInBuffer(int buffer);
161 
168  bool CheckBuffer(int buffer, BufferSemaphoreFlags flags);
169 
175  void MarkBufferFull(int buffer, int destination = -1);
176 
182  void MarkBufferEmpty(int buffer, bool force = false);
183 
190  bool ResetBuffer(int buffer);
191 
195  void GetNewId() { if (manager_id_ < 0 && IsValid()) manager_id_ = shm_ptr_->next_id.fetch_add(1); }
196 
201  uint16_t GetAttachedCount() const;
202 
206  void ResetAttachedCount() const { if (manager_id_ == 0 && IsValid()) shm_ptr_->next_id = 1; }
207 
212  int GetMyId() const { return manager_id_; }
213 
218  int GetRank()const { return IsValid() ? shm_ptr_->rank : -1; }
219 
224  void SetRank(int rank) { if (manager_id_ == 0 && IsValid()) shm_ptr_->rank = rank; }
225 
230  bool IsValid() const { return shm_ptr_ ? true : false; }
231 
235  bool IsEndOfData() const;
236 
241  size_t size() const { return IsValid() ? shm_ptr_->buffer_count : 0; }
242 
250  size_t Write(int buffer, void* data, size_t size);
251 
259  bool Read(int buffer, void* data, size_t size);
260 
265  virtual std::string toString();
266 
271  uint32_t GetKey() const { return shm_key_; }
272 
278  void* GetReadPos(int buffer);
279 
285  void* GetWritePos(int buffer);
286 
292  void* GetBufferStart(int buffer);
293 
301  void Detach(bool throwException = false, std::string category = "", std::string message = "", bool force = false);
302 
307  uint64_t GetBufferTimeout() const { return IsValid() ? shm_ptr_->buffer_timeout_us : 0; }
308 
313  size_t GetBufferCount() const { return IsValid() ? shm_ptr_->next_sequence_id : 0; }
314 
319  size_t GetLastSeenBufferID() const { return last_seen_id_; }
320 
324  size_t GetLowestSeqIDRead() const { return IsValid() ? shm_ptr_->lowest_seq_id_read : 0; }
325 
330  void SetMinWriteSize(size_t size) { min_write_size_ = size; }
331  private:
332  struct ShmBuffer
333  {
334  size_t writePos;
335  size_t readPos;
336  std::atomic<BufferSemaphoreFlags> sem;
337  std::atomic<int16_t> sem_id;
338  std::atomic<size_t> sequence_id;
339  std::atomic<uint64_t> last_touch_time;
340  };
341 
342  struct ShmStruct
343  {
344  std::atomic<unsigned int> reader_pos;
345  std::atomic<unsigned int> writer_pos;
346  int buffer_count;
347  size_t buffer_size;
348  size_t buffer_timeout_us;
349  size_t next_sequence_id;
350  size_t lowest_seq_id_read;
351  bool destructive_read_mode;
352 
353  std::atomic<int> next_id;
354  int rank;
355  unsigned ready_magic;
356  };
357 
358  uint8_t* dataStart_() const;
359  uint8_t* bufferStart_(int buffer);
360  ShmBuffer* getBufferInfo_(int buffer);
361  bool checkBuffer_(ShmBuffer* buffer, BufferSemaphoreFlags flags, bool exceptions = true);
362  void touchBuffer_(ShmBuffer* buffer);
363 
364  ShmStruct requested_shm_parameters_;
365 
366  int shm_segment_id_;
367  ShmStruct* shm_ptr_;
368  uint32_t shm_key_;
369  int manager_id_;
370  mutable std::unordered_map<int, std::mutex> buffer_mutexes_;
371  mutable std::mutex search_mutex_;
372 
373  size_t last_seen_id_;
374  size_t min_write_size_;
375  };
376 
377 }
378 
379 #endif // artdaq_core_Core_SharedMemoryManager_hh
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.
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.
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.
virtual bool ReadyForWrite(bool overwrite)
Whether any buffer is available for write.
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 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 IncrementWritePos(int buffer, size_t written)
Increment the write position for a given buffer.
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. ...