Struct caffe2_db::DBReader

pub struct DBReader { /* private fields */ }

| A reader wrapper for DB that also allows | us to serialize it. |

Implementations

impl DBReader

pub fn new( db_type: &String, source: &String, num_shards: i32, shard_id: i32 ) -> Self

pub fn open( &mut self, db_type: &String, source: &String, num_shards: Option<i32>, shard_id: Option<i32> )

pub fn open_with_db( &mut self, db: Box<dyn DB>, num_shards: Option<i32>, shard_id: Option<i32> )

pub fn read(&self, key: *mut String, value: *mut String)

| Read a set of key and value from the db | and move to next. Thread safe. | | The string objects key and value must | be created by the caller and explicitly | passed in to this function. This saves | one additional object copy. | | If the cursor reaches its end, the reader | will go back to the head of the db. This | function can be used to enable multiple | input ops to read the same db. | | Note(jiayq): we loosen the definition | of a const function here a little bit: | the state of the cursor is actually changed. | However, this allows us to pass in a DBReader | to an Operator without the need of a duplicated | output blob. |

pub fn seek_to_first(&self)

| ———– | @brief | | Seeks to the first key. Thread safe. |

pub fn cursor(&self) -> *mut dyn Cursor

| Returns the underlying cursor of the | db reader. | | ———– | @note | | if you directly use the cursor, the read | will not be thread safe, because there | is no mechanism to stop multiple threads | from accessing the same cursor. You | should consider using Read() explicitly. |

pub fn initialize_cursor(&mut self, num_shards: i32, shard_id: i32)

pub fn move_to_beginning(&self)

Trait Implementations

impl From<&DBReaderProto> for DBReader

fn from(proto: &DBReaderProto) -> Self

Converts to this type from the input type.

impl From<Box<dyn DB + 'static, Global>> for DBReader

fn from(db: Box<dyn DB>) -> Self

Converts to this type from the input type.