Struct Pipeline

pub struct Pipeline { /* private fields */ }

Execution pipeline.

A pipeline follows a precise flow:

1. Client library-specified per-call policies are executed. Per-call policies can fail and bail out of the pipeline immediately.
2. User-specified per-call policies are executed.
3. Telemetry policy.
4. Retry policy. It allows to re-execute the following policies.
5. Client library-specified per-retry policies. Per-retry polices are always executed at least once but are re-executed in case of retries.
6. User-specified per-retry policies are executed.
7. Authorization policy. Authorization can depend on the HTTP headers and/or the request body so it must be executed right before sending the request to the transport. Also, the authorization can depend on the current time so it must be executed at every retry.
8. Transport policy. Transport policy is always the last policy and is the policy that actually constructs the Response to be passed up the pipeline.

A pipeline is immutable. In other words a policy can either succeed and call the following policy of fail and return to the calling policy. Arbitrary policy “skip” must be avoided (but cannot be enforced by code). All policies except Transport policy can assume there is another following policy (so self.pipeline[0] is always valid).

The C generic contains the pipeline-specific context. Different crates can pass different contexts using this generic. This way each crate can have its own specific pipeline context. For example, in CosmosDB, the generic carries the operation-specific information used by the authorization policy.

Implementations

impl Pipeline

pub fn new( crate_name: Option<&'static str>, crate_version: Option<&'static str>, options: ClientOptions, per_call_policies: Vec<Arc<dyn Policy>>, per_retry_policies: Vec<Arc<dyn Policy>>, ) -> Self

Creates a new pipeline given the client library crate name and version, alone with user-specified and client library-specified policies.

Crates can simply pass option_env!("CARGO_PKG_NAME") and option_env!("CARGO_PKG_VERSION") for the crate_name and crate_version arguments respectively.

pub fn replace_policy( &mut self, policy: Arc<dyn Policy>, position: usize, ) -> Arc<dyn Policy>

pub fn policies(&self) -> &[Arc<dyn Policy>]

pub async fn send( &self, ctx: &Context, request: &mut Request, ) -> Result<Response>

Trait Implementations

impl Clone for Pipeline

fn clone(&self) -> Pipeline

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Pipeline

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.