Struct nats::jetstream::ConsumerConfig
source · [−]pub struct ConsumerConfig {Show 22 fields
pub deliver_subject: Option<String>,
pub durable_name: Option<String>,
pub description: Option<String>,
pub deliver_group: Option<String>,
pub deliver_policy: DeliverPolicy,
pub opt_start_seq: Option<u64>,
pub opt_start_time: Option<DateTime>,
pub ack_policy: AckPolicy,
pub ack_wait: Duration,
pub max_deliver: i64,
pub filter_subject: String,
pub replay_policy: ReplayPolicy,
pub rate_limit: u64,
pub sample_frequency: u8,
pub max_waiting: i64,
pub max_ack_pending: i64,
pub headers_only: bool,
pub flow_control: bool,
pub idle_heartbeat: Duration,
pub max_batch: i64,
pub max_expires: Duration,
pub inactive_threshold: Duration,
}
Expand description
Configuration for consumers. From a high level, the
durable_name
and deliver_subject
fields have a particularly
strong influence on the consumer’s overall behavior.
Fields
deliver_subject: Option<String>
Setting deliver_subject
to Some(...)
will cause this consumer
to be “push-based”. This is analogous in some ways to a normal
NATS subscription (rather than a queue subscriber) in that the
consumer will receive all messages published to the stream that
the consumer is interested in. Acknowledgement policies such as
AckPolicy::None
and AckPolicy::All
may be enabled for such
push-based consumers, which reduce the amount of effort spent
tracking delivery. Combining AckPolicy::All
with
Consumer::process_batch
enables particularly nice throughput
optimizations.
Setting deliver_subject
to None
will cause this consumer to
be “pull-based”, and will require explicit acknowledgement of
each message. This is analogous in some ways to a normal NATS
queue subscriber, where a message will be delivered to a single
subscriber. Pull-based consumers are intended to be used for
workloads where it is desirable to have a single process receive
a message. The only valid ack_policy
for pull-based consumers
is the default of AckPolicy::Explicit
, which acknowledges each
processed message individually. Pull-based consumers may be a
good choice for work queue-like workloads where you want messages
to be handled by a single consumer process. Note that it is
possible to deliver a message to multiple consumers if the
consumer crashes or is slow to acknowledge the delivered message.
This is a fundamental behavior present in all distributed systems
that attempt redelivery when a consumer fails to acknowledge a message.
This is known as “at least once” message processing. To achieve
“exactly once” semantics, it is necessary to implement idempotent
semantics in any system that is written to as a result of processing
a message.
durable_name: Option<String>
Setting durable_name
to Some(...)
will cause this consumer
to be “durable”. This may be a good choice for workloads that
benefit from the JetStream
server or cluster remembering the
progress of consumers for fault tolerance purposes. If a consumer
crashes, the JetStream
server or cluster will remember which
messages the consumer acknowledged. When the consumer recovers,
this information will allow the consumer to resume processing
where it left off. If you’re unsure, set this to Some(...)
.
Setting durable_name
to None
will cause this consumer to
be “ephemeral”. This may be a good choice for workloads where
you don’t need the JetStream
server to remember the consumer’s
progress in the case of a crash, such as certain “high churn”
workloads or workloads where a crashed instance is not required
to recover.
description: Option<String>
A short description of the purpose of this consumer.
deliver_group: Option<String>
Deliver group to use.
deliver_policy: DeliverPolicy
Allows for a variety of options that determine how this consumer will receive messages
opt_start_seq: Option<u64>
Used in combination with DeliverPolicy::ByStartSeq
to only select messages arriving
after this sequence number.
opt_start_time: Option<DateTime>
Used in combination with DeliverPolicy::ByStartTime
to only select messages arriving
after this time.
ack_policy: AckPolicy
How messages should be acknowledged
ack_wait: Duration
How long to allow messages to remain un-acknowledged before attempting redelivery
max_deliver: i64
Maximum number of times a specific message will be delivered. Use this to avoid poison pill messages that repeatedly crash your consumer processes forever.
filter_subject: String
When consuming from a Stream with many subjects, or wildcards, this selects only specific incoming subjects. Supports wildcards.
replay_policy: ReplayPolicy
Whether messages are sent as quickly as possible or at the rate of receipt
rate_limit: u64
The rate of message delivery in bits per second
sample_frequency: u8
What percentage of acknowledgements should be samples for observability, 0-100
max_waiting: i64
The maximum number of waiting consumers.
max_ack_pending: i64
The maximum number of unacknowledged messages that may be in-flight before pausing sending additional messages to this consumer.
headers_only: bool
Only deliver headers without payloads.
flow_control: bool
Enable flow control messages
idle_heartbeat: Duration
Enable idle heartbeat messages
max_batch: i64
Maximum size of a request batch
max_expires: Duration
Maximum value for request exiration
inactive_threshold: Duration
Threshold for ephemeral consumer intactivity
Trait Implementations
sourceimpl Clone for ConsumerConfig
impl Clone for ConsumerConfig
sourcefn clone(&self) -> ConsumerConfig
fn clone(&self) -> ConsumerConfig
Returns a copy of the value. Read more
1.0.0 · sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
sourceimpl Debug for ConsumerConfig
impl Debug for ConsumerConfig
sourceimpl Default for ConsumerConfig
impl Default for ConsumerConfig
sourcefn default() -> ConsumerConfig
fn default() -> ConsumerConfig
Returns the “default value” for a type. Read more
sourceimpl<'de> Deserialize<'de> for ConsumerConfig
impl<'de> Deserialize<'de> for ConsumerConfig
sourcefn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
__D: Deserializer<'de>,
fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
__D: Deserializer<'de>,
Deserialize this value from the given Serde deserializer. Read more
sourceimpl From<&ConsumerConfig> for ConsumerConfig
impl From<&ConsumerConfig> for ConsumerConfig
sourcefn from(cc: &ConsumerConfig) -> ConsumerConfig
fn from(cc: &ConsumerConfig) -> ConsumerConfig
Converts to this type from the input type.
sourceimpl From<&str> for ConsumerConfig
impl From<&str> for ConsumerConfig
sourcefn from(s: &str) -> ConsumerConfig
fn from(s: &str) -> ConsumerConfig
Converts to this type from the input type.
sourceimpl PartialEq<ConsumerConfig> for ConsumerConfig
impl PartialEq<ConsumerConfig> for ConsumerConfig
sourcefn eq(&self, other: &ConsumerConfig) -> bool
fn eq(&self, other: &ConsumerConfig) -> bool
This method tests for self
and other
values to be equal, and is used
by ==
. Read more
sourcefn ne(&self, other: &ConsumerConfig) -> bool
fn ne(&self, other: &ConsumerConfig) -> bool
This method tests for !=
.
sourceimpl Serialize for ConsumerConfig
impl Serialize for ConsumerConfig
impl Eq for ConsumerConfig
impl StructuralEq for ConsumerConfig
impl StructuralPartialEq for ConsumerConfig
Auto Trait Implementations
impl RefUnwindSafe for ConsumerConfig
impl Send for ConsumerConfig
impl Sync for ConsumerConfig
impl Unpin for ConsumerConfig
impl UnwindSafe for ConsumerConfig
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more