func checkTruncate()

in tx.go [618:654]

• 28 lines of code
• 7 McCabe index (conditional complexity)

func checkTruncate(
	st *txAllocState,
	sz, mmapSz, maxSz int64,
	pageSize uint,
) (int64, bool) {
	if maxSz <= 0 { // file is unbounded, no truncate required
		return 0, false
	}

	expectedFileSz := mmapSz
	if expectedFileSz < maxSz {
		expectedFileSz = maxSz
	}

	if expectedFileSz >= sz {
		// Required size still surpasses the last known file size -> do not
		// truncate.
		return 0, false
	}

	lastEnd := st.data.endMarker
	if metaEnd := st.meta.endMarker; metaEnd > lastEnd {
		lastEnd = metaEnd
	}

	lastExpectedFileSz := int64(uint(lastEnd) * pageSize)
	if lastExpectedFileSz < maxSz {
		lastExpectedFileSz = maxSz
	}

	// Compute minimum required file size for the last two active transactions (maximum).
	if lastExpectedFileSz > expectedFileSz {
		expectedFileSz = lastExpectedFileSz
	}

	return expectedFileSz, expectedFileSz < sz
}