fn enter
Start of step k (0-based) with the value v of the previous one: stops (Timeout) when the saga was cancelled or is being
compensated from this step on, records the cursor, and sets the idempotency key of the step to sagaId#(k+1).
Example:
@error data Boom { m: str }
service Bank {
@public @idempotent rpc hold(n: u64) -> u64
@public @idempotent rpc unhold(n: u64) -> () | Boom
@public @idempotent rpc refuse(n: u64) -> u64 | Boom
}
impl Bank {
rpc hold(n) => n
rpc unhold(n) { fail Boom{ m: "bank is down" } }
rpc refuse(n) { fail Boom{ m: "no" } }
}
// the second step fails and its compensation never succeeds: the saga becomes stuck
saga pay(n: u64) -> u64 {
Bank.hold(n) undo h => Bank.unhold(h)
-> Bank.refuse(n)
}
fn main() io, net, time, db {
match pay(1) {
u64 v => print("done {v}")
Boom b => print("step failed: {b.m}")
CompensationFailed c => print("stuck at step {c.step}")
NetError e => print("net error")
}
}Output
stuck at step 1
pub(api) fn enter<T>(k: i64, v: T) -> T | Timeout net, db, timeSince. 1.0.0-beta
Parameters
| Name | Type |
|---|---|
k | i64 |
v | T |
Returns
T
Errors
Timeout@error- `Timeout` when the caller's deadline passed and the saga is being cancelled.
Effects
net, db, time
Defined in: std/saga/saga.oxl:437