[[user-comments:osrf-devel:persist-queue|User Comments]]

**QUEUE API-Namespace Slot methods**

Uses the Slot in FIFO mode, pushing values onto one end an pulling them off the other.  The QUEUE API-Namespace is useful for creating an ordered message passing access point.

===== opensrf.persist.queue.push( slot_name, object ) =====

Adds an object to a Slot in FIFO order.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot to use for storing the object.
    * //object//\\ The object that should be pushed onto the front of the QUEUE.
  * **Returns:**
    * //Success//\\ The name of the Slot that was used.
    * //Failure//\\ An empty (NULL) result.


===== opensrf.persist.queue.pop( slot_name ) =====

Removes and returns the next value in a QUEUE type Slot.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot from which an object should be retrieved.
  * **Returns:**
    * //Success//\\ The next object on the QUEUE Slot, or an empty (NULL) result if the Slot is empty.
    * //Failure//\\ An empty (NULL) result.


===== opensrf.persist.queue.peek( slot_name ) =====

Returns the next value in a QUEUE type Slot __without__ removing it.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot from which an object should be retrieved.
  * **Returns:**
    * //Success//\\ The next object on the QUEUE Slot, or an empty (NULL) result if the Slot is empty.
    * //Failure//\\ An empty (NULL) result.


===== opensrf.persist.queue.peek.all( slot_name ) =====

Returns all values in a QUEUE type Slot __without__ removing them.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot from which the objects should be retrieved.
  * **Returns:**
    * //Success//\\ A stream of all objects on the QUEUE Slot, or an empty (NULL) result if the Slot is empty.
    * //Failure//\\ An empty (NULL) result.


===== opensrf.persist.queue.peek.all.atomic( slot_name )=====

Returns all values in a QUEUE type Slot __without__ removing them.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot from which the objects should be retrieved.
  * **Returns:**
    * //Success//\\ A single array of all objects on the QUEUE Slot, or an empty array if the Slot is empty.
    * //Failure//\\ An empty (NULL) result.


===== opensrf.persist.queue.length( slot_name ) =====

Returns the number of objects in the QUEUE type Slot.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot in question.
  * **Returns:**
    * //Success//\\ The number of objects in the Persistence Slot.
    * //Failure//\\ An empty (NULL) result.


===== opensrf.persist.queue.size( slot_name ) =====

Returns the number bytes taken up by the JSON encoded version of the objects in the QUEUE type Slot.

  * **Parameters:**
    * //slot_name//\\ The name of the Persistence Slot in question.
  * **Returns:**
    * //Success//\\ The space, in bytes, used by the JSON encoded objects in the Persistence Slot.
    * //Failure//\\ An empty (NULL) result.