offset_clock.go

// Copyright (c) 2021 Uber Technologies, Inc.
//
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// of this software and associated documentation files (the "Software"), to deal
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// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// THE SOFTWARE.

package clock

import (
	"time"
)

// OffsetClock represents offset clock which returns current time from the initial seed time value.
type OffsetClock struct {
	timeDelta time.Duration
	nowFn     NowFn
}

// NewOffsetClock returns new offset clock.
func NewOffsetClock(offsetTime time.Time, nowFn NowFn) OffsetClock {
	return OffsetClock{nowFn: nowFn, timeDelta: offsetTime.Sub(nowFn())}
}

// NewOffsetClockFromTimeDelta returns new offset clock that has time shifted by timeDelta duration.
func NewOffsetClockFromTimeDelta(timeDelta time.Duration, nowFn NowFn) OffsetClock {
	return OffsetClock{nowFn: nowFn, timeDelta: timeDelta}
}

// Now returns current time with time offset taken into account.
func (c OffsetClock) Now() time.Time {
	now := c.nowFn()
	return now.Add(c.timeDelta)
}