module Aws::MachineLearning::Waiters
Waiters
are utility methods that poll for a particular state to occur on a client. Waiters
can fail after a number of attempts at a polling interval defined for the service client.
For a list of operations that can be waited for and the client methods called for each operation, see the table below or the {Client#wait_until} field documentation for the {Client}.
# Invoking a Waiter To invoke a waiter, call wait_until on a {Client}. The first parameter is the waiter name, which is specific to the service client and indicates which operation is being waited for. The second parameter is a hash of parameters that are passed to the client method called by the waiter, which varies according to the waiter name.
# Wait Failures To catch errors in a waiter, use WaiterFailed, as shown in the following example.
rescue rescue Aws::Waiters::Errors::WaiterFailed => error puts "failed waiting for instance running: #{error.message} end
# Configuring a Waiter Each waiter has a default polling interval and a maximum number of attempts it will make before returning control to your program. To set these values, use the `max_attempts` and `delay` parameters in your `#wait_until` call. The following example waits for up to 25 seconds, polling every five seconds.
client.wait_until(...) do |w| w.max_attempts = 5 w.delay = 5 end
To disable wait failures, set the value of either of these parameters to `nil`.
# Extending a Waiter To modify the behavior of waiters, you can register callbacks that are triggered before each polling attempt and before waiting.
The following example implements an exponential backoff in a waiter by doubling the amount of time to wait on every attempt.
client.wait_until(...) do |w| w.interval = 0 # disable normal sleep w.before_wait do |n, resp| sleep(n ** 2) end end
# Available Waiters
The following table lists the valid waiter names, the operations they call, and the default `:delay` and `:max_attempts` values.
| waiter_name | params | :delay | :max_attempts | | ————————– | ———————————– | ——– | ————- | | batch_prediction_available | {Client#describe_batch_predictions} | 30 | 60 | | data_source_available | {Client#describe_data_sources} | 30 | 60 | | evaluation_available | {Client#describe_evaluations} | 30 | 60 | | ml_model_available | {Client#describe_ml_models} | 30 | 60 |