isle/go/toolkit/toolkit.go

// Package toolkit contains useful utilities which are not specific to any
// specific part of isle.
package toolkit

import (
	"context"
	"reflect"
	"time"

	"dev.mediocregopher.com/mediocre-go-lib.git/mctx"
	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

// IsZero returns true if the value is equal to its zero value according to
// reflect.DeepEqual.
func IsZero[T any](v T) bool {
	var zero T
	return reflect.DeepEqual(v, zero)
}

// Ptr returns a pointer to the given value.
func Ptr[T any](v T) *T {
	return &v
}

// UntilTrue will repeatedly call the given callback, waiting the given duration
// between calls until:
// - The context is canceled, returning the context's error
// - The callback returns an error, returning that error
// - The callback returns true, returning nil
func UntilTrue(
	ctx context.Context,
	logger *mlog.Logger,
	period time.Duration,
	fn func() (bool, error),
) error {
	ctx = mctx.Annotate(ctx, "retryAfter", period)

	for {
		if ok, err := fn(); err != nil {
			return err
		} else if ok {
			return nil
		}

		logger.Info(ctx, "Waiting before retrying")

		select {
		case <-time.After(period):
		case <-ctx.Done():
			return ctx.Err()
		}
	}
}