gofuncy/docs/api/options.md

prev, next

prev	next
text link Map /api/map	text link Channel /api/channel

Options Reference

Options are configured via functional option constructors. Each function's API page documents which options it accepts. This page provides a consolidated overview.

Option Categories

Category	Interface	Accepted by
Shared	GoOption + GroupOption	Do, Wait, WaitWithStop, WaitWithReady, Go, Start, StartWithReady, StartWithStop, GoWithCancel, NewGroup, Group.Add
Go-only	GoOption	Do, Wait, WaitWithStop, WaitWithReady, Go, Start, StartWithReady, StartWithStop, GoWithCancel, Group.Add
Group-only	GroupOption	NewGroup, All, Map

The compiler enforces these constraints. You cannot pass a groupOnlyOpt to Go() or a goOnlyOpt to NewGroup().

Defaults

When no options are passed, the following defaults apply:

Setting	Default
Name	Function-specific (e.g. "gofuncy.go", "gofuncy.group")
Tracing	Enabled
Started counter	Enabled
Error counter	Enabled
Active counter	Enabled
Duration histogram	Disabled
Error handler (Go/Start/StartWithReady/StartWithStop/GoWithCancel only)	slog.ErrorContext
Limit	No limit
Fail-fast	Disabled
Retry	Disabled
Circuit breaker	Disabled
Fallback	Disabled

Resilience Chain Order

The framework applies resilience options in a fixed order, regardless of the order they appear in your code:

Position	Middleware	Behavior
Innermost	Timeout	Each invocation gets a fresh deadline
↑	Retry	Retries the timeout-wrapped function
↑	Circuit Breaker	Sees the final outcome after all retries
Outermost	Fallback	Last resort -- catches everything

For custom ordering, use WithMiddleware with the middleware constructors (Retry(), Fallback(), etc.) directly.

Option Merging in Group.Add

When you pass options to Group.Add, they are merged on top of the group's options using these rules:

Field type	Merge rule
string (name)	Override if non-empty
*slog.Logger	Override if non-nil
[]Middleware	Append
time.Duration	Override if > 0
bool (metrics/tracing)	OR (enable, never disable)
MeterProvider / TracerProvider	Override if non-nil
*semaphore.Weighted	Override if non-nil
*CircuitBreaker	Override if non-nil
Retry / Fallback	Override if set
limit, failFast	Not merged (group-only)