README
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qcache
qcache
Documentation
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Index ¶
- Variables
- type Consumer
- type MmapQueue
- func (q *MmapQueue) Close() error
- func (q *MmapQueue) Dequeue() ([]byte, error)
- func (q *MmapQueue) DequeueString() (string, error)
- func (q *MmapQueue) Enqueue(message []byte) error
- func (q *MmapQueue) EnqueueString(message string) error
- func (q *MmapQueue) Flush() error
- func (q *MmapQueue) FromConsumer(name string, from *Consumer) (*Consumer, error)
- func (q *MmapQueue) IsEmpty() bool
- func (q *MmapQueue) NewConsumer(name string) (*Consumer, error)
- type Option
Constants ¶
This section is empty.
Variables ¶
var ( // ErrTooSmallArenaSize is returned when arena size is smaller than OS page size. ErrTooSmallArenaSize = errors.New("too small arena size") // ErrTooFewInMemArenas is returned when number of arenas allowed in memory < 3. ErrTooFewInMemArenas = errors.New("too few in memory arenas") )
var ( // ErrInvalidArenaSize is returned when persisted arena size // doesn't match with desired arena size. ErrInvalidArenaSize = errors.New("mismatch in arena size") // ErrDifferentQueues is returned when caller wants to copy // offsets from a consumer from a different queue. ErrDifferentQueues = errors.New("consumers from different queues") )
var ( // ErrEmptyQueue is returned when dequeue is performed on an empty queue. ErrEmptyQueue = errors.New("queue is empty") )
var ( // ErrIncompatibleVersion is returned when file format is older/newer. ErrIncompatibleVersion = errors.New("incompatible format of the code and data") )
Functions ¶
This section is empty.
Types ¶
type Consumer ¶
type Consumer struct {
// contains filtered or unexported fields
}
Consumer is a bigqueue consumer that allows reading data from bigqueue. A consumer is represented using just a base offset into the metadata
func (*Consumer) DequeueString ¶
DequeueString removes a string element from the queue and returns it.
type MmapQueue ¶
type MmapQueue struct {
// contains filtered or unexported fields
}
MmapQueue implements Queue interface.
func NewMmapQueue ¶
NewMmapQueue constructs a new persistent queue.
func (*MmapQueue) Dequeue ¶
Dequeue removes an element from the queue and returns it. This function uses the default consumer to consume from the queue.
func (*MmapQueue) DequeueString ¶
DequeueString removes a string element from the queue and returns it. This function uses the default consumer to consume from the queue.
func (*MmapQueue) EnqueueString ¶
EnqueueString adds a new string element to the tail of the queue.
func (*MmapQueue) FromConsumer ¶
FromConsumer creates a new consumer or finds an existing one with same name. It also copies the offsets from the given consumer to this consumer.
type Option ¶
type Option func(*bqConfig) error
Option is function type that takes a bqConfig object and sets various config parameters in the object.
func SetArenaSize ¶
SetArenaSize returns an Option closure that sets the arena size.
func SetMaxInMemArenas ¶
SetMaxInMemArenas returns an Option closure that sets maximum number of Arenas that could reside in memory (RAM) at any time. By default, all the arenas reside in memory and Operating System takes care of memory by paging in and out the pages from disk. A recommended value of maximum arenas that should be in memory should be chosen such that:
maxInMemArenas > (# of consumers) * 2 + 1
func SetPeriodicFlushDuration ¶
SetPeriodicFlushDuration returns an Option that sets a periodic flush every given duration after which the queue's in-memory changes will be flushed to disk. This is a best effort flush and elapsed time is checked upon an enqueue/dequeue only. If the value is set to <= 0, no periodic flush will be performed.
For durability this value should be low. For performance this value should be high.
func SetPeriodicFlushOps ¶
SetPeriodicFlushOps returns an Option that sets the number of mutate operations (enqueue/dequeue) after which the queue's in-memory changes will be flushed to disk. This is a best effort flush and number of mutate operations is checked upon an enqueue/dequeue. If the value is set to <= 0, no periodic flush will be performed.
For durability this value should be low. For performance this value should be high.
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