Class DataBlockView

Inheritance Relationships

Base Type

Class Documentation

class DataBlockView : public ska::pst::smrb::DataBlockAccessor

Object Oriented interface to view to a PSRDADA Shared Memory Ring Buffer (SMRB).

Public Functions

explicit DataBlockView(const std::string &key)

Construct a new Data Block View object for the SMRB identified by the key.

Parameters

key – four-character hexidecimal key that identifies the SMRB in shared memory

~DataBlockView()

Destroy the Data Block View object. Closes the access to the SMRB if required.

virtual void open() override

Open the SMRB for viewing.

virtual void close() override

Clear the information last parsed from the header block.

It is not necessary to close the SMRB when only viewing.

virtual void lock() override

Effectively does nothing.

Although viewers need not necessarily lock exclusive access to the ring buffer in shared memory, the assumptions built into DataBlockAccessor base class dictate that the locked flag must be set; therefore, it is necessary to call this method after calling open().

virtual void unlock() override

Effectively does nothing (see note on lock() method)

virtual char *open_block() override

Open the current viewing buffer in the data block.

Returns

pointer to the current viewing buffer in the data block

virtual ssize_t close_block(uint64_t bytes) override

Internally flag the current data block buffer as viewed.

Parameters

bytes – effective ignored

Returns

ssize_t the number of bytes passed as an argument

ssize_t read_data(char *ptr, size_t bytes)

Read the specified amount of data from the SMRB data block.

Parameters

  • ptr – pointer to buffer where the data will be stored

  • bytes – size of buffer

Returns

ssize_t number of bytes read from the data block

void read_config()

Read the scan configuration from the header_block.

void read_header()

Read the full header from the header_block.

int seek_to_end(uint64_t byte_resolution = 0)

Go to the end of the SMRB data block.

Parameters

byte_resolution – how large of a chunck of data to allow for.

Returns

int Return 0 on success, -1 on failure

ssize_t seek(int64_t offset, int whence)

Move the view to a particular part of the data block.

Parameters

  • offset – the offset to apply in bytes

  • whence – from where to apply the offset

char *get_curr_buf()

Get the current buffer of the SMRB data_block.

size_t get_current_buffer_index() const

Get the index of the current buffer of the SMRB data_block.

void seek_to_buffer_index(size_t buffer_index)

Go to the specified buffer of the SMRB data block.

Parameters

buffer_index – ring buffer index in the data block