public fun addLast()

in ktor-utils/posix/src/io/ktor/util/collections/LockFreeMPSCQueueNative.kt [100:121]

• 18 lines of code
• 6 McCabe index (conditional complexity)

    public fun addLast(element: E): Int {
        _state.loop { state ->
            if (state and (FROZEN_MASK or CLOSED_MASK) != 0L) return state.addFailReason() // cannot add
            state.withState { head, tail ->
                // there could be one REMOVE element beyond head that we cannot stump up,
                // so we check for full queue with an extra margin of one element
                if ((tail + 2) and mask == head and mask) return ADD_FROZEN // overfull, so do freeze & copy
                val newTail = (tail + 1) and MAX_CAPACITY_MASK
                if (_state.compareAndSet(state, state.updateTail(newTail))) {
                    // successfully added
                    array[tail and mask].value = element
                    // could have been frozen & copied before this item was set -- correct it by filling placeholder
                    var cur = this
                    while (true) {
                        if (cur._state.value and FROZEN_MASK == 0L) break // all fine -- not frozen yet
                        cur = cur.next().fillPlaceholder(tail, element) ?: break
                    }
                    return ADD_SUCCESS // added successfully
                }
            }
        }
    }