Callbacks

Callbacks allow user code to run at specific points during time integration — after every step, at fixed simulation-time intervals, or on a wall-clock schedule. They are passed to init or solve via the callback keyword argument.

Core Types

DiscreteCallback is the primitive: a condition/action pair checked after every integrator step. CallbackSet groups multiple callbacks.

ClimaTimeSteppers.DiscreteCallback — Type

DiscreteCallback(condition, affect!; initialize, finalize)

A callback checked after each integrator step.

Arguments

condition: function (u, t, integrator) -> Bool
affect!: function (integrator) -> nothing, called when condition returns true

Keyword Arguments

initialize: function (cb, u, t, integrator) called at integrator startup
finalize: function (cb, u, t, integrator) called when solve! finishes

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ClimaTimeSteppers.CallbackSet — Type

CallbackSet(callbacks...)

A collection of DiscreteCallbacks applied after each step. Accepts nothing, individual DiscreteCallbacks, or nested CallbackSets.

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Pre-Built Callbacks

The ClimaTimeSteppers.Callbacks module provides convenience constructors for common triggering patterns. Import them with:

using ClimaTimeSteppers: Callbacks
using .Callbacks

ClimaTimeSteppers.Callbacks — Module

ClimaTimeSteppers.Callbacks

Pre-built DiscreteCallback constructors for common triggering patterns: wall-clock time, simulation time, and step count.

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ClimaTimeSteppers.Callbacks.EveryXWallTimeSeconds — Function

EveryXWallTimeSeconds(f!, Δwt, comm_ctx; atinit=false)

Trigger f!(integrator) every Δwt wall-clock seconds.

Timing is synchronized across all MPI ranks via comm_ctx (ClimaComms context).

Arguments

f!: callable f!(integrator) to execute
Δwt: wall-clock interval in seconds
comm_ctx: a ClimaComms.AbstractCommsContext

Keyword Arguments

atinit: if true, also trigger at initialization (default false)

Callbacks.initialize! and Callbacks.finalize! can be extended for typeof(f!) to add setup/teardown behavior.

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ClimaTimeSteppers.Callbacks.EveryXSimulationTime — Function

EveryXSimulationTime(f!, Δt; atinit=false)

Trigger f!(integrator) every Δt simulation time units.

Arguments

f!: callable f!(integrator) to execute
Δt: simulation time interval

Keyword Arguments

atinit: if true, also trigger at initialization (default false)

Callbacks.initialize! and Callbacks.finalize! can be extended for typeof(f!) to add setup/teardown behavior.

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ClimaTimeSteppers.Callbacks.EveryXSimulationSteps — Function

EveryXSimulationSteps(f!, Δsteps; atinit=false)

Trigger f!(integrator) every Δsteps simulation steps.

Arguments

f!: callable f!(integrator) to execute
Δsteps: number of steps between triggers

Keyword Arguments

atinit: if true, also trigger at initialization (default false)

Callbacks.initialize! and Callbacks.finalize! can be extended for typeof(f!) to add setup/teardown behavior.

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Extension Points

Define methods on initialize! and finalize! for your callback's f! type to run setup/teardown code when the integrator starts and finishes.

ClimaTimeSteppers.Callbacks.initialize! — Function

Callbacks.initialize!(f!, integrator)

Called when the integrator starts. Extend this for your callback type f! to perform setup (e.g. open files, record initial state). Default: no-op.

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ClimaTimeSteppers.Callbacks.finalize! — Function

Callbacks.finalize!(f!, integrator)

Called when ClimaTimeSteppers.solve! completes. Extend this for your callback type f! to perform teardown (e.g. close files, flush buffers). Default: no-op.

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