Ring buffer. At last.

kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/Matrix.kt

@@ -2,6 +2,7 @@ package scientifik.kmath.linear
 
 import scientifik.kmath.operations.RealField
 import scientifik.kmath.operations.Ring
+import scientifik.kmath.operations.sum
 import scientifik.kmath.structures.*
 import scientifik.kmath.structures.Buffer.Companion.DoubleBufferFactory
 import scientifik.kmath.structures.Buffer.Companion.boxing
@@ -69,7 +70,7 @@ interface GenericMatrixContext<T : Any, R : Ring<T>> : MatrixContext<T> {
             val row = rows[i]
             val column = other.columns[j]
             with(elementContext) {
-                row.asSequence().zip(column.asSequence(), ::multiply).sum()
+                sum(row.asSequence().zip(column.asSequence(), ::multiply))
             }
         }
     }
@@ -80,7 +81,7 @@ interface GenericMatrixContext<T : Any, R : Ring<T>> : MatrixContext<T> {
         return point(rowNum) { i ->
             val row = rows[i]
             with(elementContext) {
-                row.asSequence().zip(vector.asSequence(), ::multiply).sum()
+                sum(row.asSequence().zip(vector.asSequence(), ::multiply))
             }
         }
     }

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt

@@ -77,7 +77,7 @@ interface MutableBuffer<T> : Buffer<T> {
         /**
          * Create a boxing mutable buffer of given type
          */
-        inline fun <T : Any> boxing(size: Int, initializer: (Int) -> T): MutableBuffer<T> =
+        inline fun <T> boxing(size: Int, initializer: (Int) -> T): MutableBuffer<T> =
             MutableListBuffer(MutableList(size, initializer))
 
         /**

kmath-sequential/src/commonMain/kotlin/scientifik/kmath/sequential/Cumulative.kt

@@ -1,5 +1,6 @@
 package scientifik.kmath.sequential
 
+import scientifik.kmath.operations.Space
 import kotlin.jvm.JvmName
 
 
@@ -32,6 +33,10 @@ fun <T, R> List<T>.cumulative(initial: R, operation: (T, R) -> R): List<R> =
 
 //Cumulative sum
 
+fun <T> Iterable<T>.cumulativeSum(space: Space<T>) = with(space) {
+    cumulative(zero) { element: T, sum: T -> sum + element }
+}
+
 @JvmName("cumulativeSumOfDouble")
 fun Iterable<Double>.cumulativeSum() = this.cumulative(0.0) { element, sum -> sum + element }
 
@@ -41,6 +46,10 @@ fun Iterable<Int>.cumulativeSum() = this.cumulative(0) { element, sum -> sum + e
 @JvmName("cumulativeSumOfLong")
 fun Iterable<Long>.cumulativeSum() = this.cumulative(0L) { element, sum -> sum + element }
 
+fun <T> Sequence<T>.cumulativeSum(space: Space<T>) = with(space) {
+    cumulative(zero) { element: T, sum: T -> sum + element }
+}
+
 @JvmName("cumulativeSumOfDouble")
 fun Sequence<Double>.cumulativeSum() = this.cumulative(0.0) { element, sum -> sum + element }
 
@@ -50,6 +59,10 @@ fun Sequence<Int>.cumulativeSum() = this.cumulative(0) { element, sum -> sum + e
 @JvmName("cumulativeSumOfLong")
 fun Sequence<Long>.cumulativeSum() = this.cumulative(0L) { element, sum -> sum + element }
 
+fun <T> List<T>.cumulativeSum(space: Space<T>) = with(space) {
+    cumulative(zero) { element: T, sum: T -> sum + element }
+}
+
 @JvmName("cumulativeSumOfDouble")
 fun List<Double>.cumulativeSum() = this.cumulative(0.0) { element, sum -> sum + element }
 

kmath-sequential/src/commonMain/kotlin/scientifik/kmath/sequential/DoubleStreaming.kt

@@ -0,0 +1,136 @@
+package scientifik.kmath.sequential
+
+import kotlinx.atomicfu.atomic
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.channels.*
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Mutex
+
+interface DoubleProducer : Producer<Double> {
+    suspend fun receiveArray(): DoubleArray
+}
+
+interface DoubleConsumer : Consumer<Double> {
+    suspend fun sendArray(array: DoubleArray)
+}
+
+abstract class AbstractDoubleProducer(scope: CoroutineScope) : AbstractProducer<Double>(scope), DoubleProducer {
+
+    override fun connectOutput(consumer: Consumer<Double>) {
+        if (consumer is DoubleConsumer) {
+            launch {
+                while (this.isActive) {
+                    consumer.sendArray(receiveArray())
+                }
+            }
+        } else {
+            super.connectOutput(consumer)
+        }
+    }
+}
+
+abstract class AbstractDoubleConsumer(scope: CoroutineScope) : AbstractConsumer<Double>(scope), DoubleConsumer {
+    override fun connectInput(producer: Producer<Double>) {
+        if (producer is DoubleProducer) {
+            launch {
+                while (isActive) {
+                    sendArray(producer.receiveArray())
+                }
+            }
+        } else {
+            super.connectInput(producer)
+        }
+    }
+}
+
+abstract class AbstractDoubleProcessor(scope: CoroutineScope) : AbstractProcessor<Double, Double>(scope),
+    DoubleProducer, DoubleConsumer {
+
+    override fun connectOutput(consumer: Consumer<Double>) {
+        if (consumer is DoubleConsumer) {
+            launch {
+                while (this.isActive) {
+                    consumer.sendArray(receiveArray())
+                }
+            }
+        } else {
+            super.connectOutput(consumer)
+        }
+    }
+
+    override fun connectInput(producer: Producer<Double>) {
+        if (producer is DoubleProducer) {
+            launch {
+                while (isActive) {
+                    sendArray(producer.receiveArray())
+                }
+            }
+        } else {
+            super.connectInput(producer)
+        }
+    }
+}
+
+/**
+ * The basic [Double] producer supporting both arrays and element-by-element simultaneously
+ */
+class BasicDoubleProducer(
+    scope: CoroutineScope,
+    capacity: Int = Channel.UNLIMITED,
+    block: suspend ProducerScope<DoubleArray>.() -> Unit
+) : AbstractDoubleProducer(scope) {
+
+
+    private val currentArray = atomic<ReceiveChannel<Double>?>(null)
+    private val channel: ReceiveChannel<DoubleArray> by lazy { produce(capacity = capacity, block = block) }
+    private val cachingChannel by lazy {
+        channel.map {
+            it.also { doubles -> currentArray.lazySet(doubles.asChannel()) }
+        }
+    }
+
+    private fun DoubleArray.asChannel() = produce {
+        for (value in this@asChannel) {
+            send(value)
+        }
+    }
+
+    override suspend fun receiveArray(): DoubleArray = cachingChannel.receive()
+
+    override suspend fun receive(): Double = (currentArray.value ?: cachingChannel.receive().asChannel()).receive()
+}
+
+
+class DoubleReducer<S>(
+    scope: CoroutineScope,
+    initialState: S,
+    val fold: suspend (S, DoubleArray) -> S
+) : AbstractDoubleConsumer(scope) {
+
+    var state: S = initialState
+        private set
+
+    private val mutex = Mutex()
+
+    override suspend fun sendArray(array: DoubleArray) {
+        state = fold(state, array)
+    }
+
+    override suspend fun send(value: Double) = sendArray(doubleArrayOf(value))
+}
+
+/**
+ * Convert an array to single element producer, splitting it in chunks if necessary
+ */
+fun DoubleArray.produce(scope: CoroutineScope = GlobalScope, chunkSize: Int = Int.MAX_VALUE) = if (size < chunkSize) {
+    BasicDoubleProducer(scope) { send(this@produce) }
+} else {
+    BasicDoubleProducer(scope) {
+        //TODO optimize this!
+        asSequence().chunked(chunkSize).forEach {
+            send(it.toDoubleArray())
+        }
+    }
+}

kmath-sequential/src/commonMain/kotlin/scientifik/kmath/sequential/RingBuffer.kt

@@ -0,0 +1,89 @@
+package scientifik.kmath.sequential
+
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import scientifik.kmath.structures.Buffer
+import scientifik.kmath.structures.MutableBuffer
+import scientifik.kmath.structures.VirtualBuffer
+
+/**
+ * Thread-safe ring buffer
+ */
+internal class RingBuffer<T>(
+    private val buffer: MutableBuffer<T>,
+    private var startIndex: Int = 0,
+    size: Int = 0
+) : Buffer<T> {
+
+    private val mutex = Mutex()
+
+    override var size: Int = size
+        private set
+
+    override fun get(index: Int): T {
+        require(index >= 0) { "Index must be positive" }
+        require(index < size) { "Index $index is out of circular buffer size $size" }
+        return buffer[startIndex.forward(index)]
+    }
+
+    fun isFull() = size == buffer.size
+
+    /**
+     * Iterator could provide wrong results if buffer is changed in initialization (iteration is safe)
+     */
+    override fun iterator(): Iterator<T> = object : AbstractIterator<T>() {
+        private var count = size
+        private var index = startIndex
+        val copy = buffer.copy()
+
+        override fun computeNext() {
+            if (count == 0) {
+                done()
+            } else {
+                setNext(copy[index])
+                index = index.forward(1)
+                count--
+            }
+        }
+    }
+
+    /**
+     * A safe snapshot operation
+     */
+    suspend fun snapshot(): Buffer<T> {
+        mutex.withLock {
+            val copy = buffer.copy()
+            return VirtualBuffer(size) { i -> copy[startIndex.forward(i)] }
+        }
+    }
+
+    suspend fun push(element: T) {
+        mutex.withLock {
+            buffer[startIndex.forward(size)] = element
+            if (isFull()) {
+                startIndex++
+            } else {
+                size++
+            }
+        }
+    }
+
+
+    @Suppress("NOTHING_TO_INLINE")
+    private inline fun Int.forward(n: Int): Int = (this + n) % (buffer.size)
+
+    companion object {
+        inline fun <reified T : Any> build(size: Int, empty: T): RingBuffer<T> {
+            val buffer = MutableBuffer.auto(size) { empty }
+            return RingBuffer(buffer)
+        }
+
+        /**
+         * Slow yet universal buffer
+         */
+        fun <T> boxing(size: Int): RingBuffer<T?> {
+            val buffer: MutableBuffer<T?> = MutableBuffer.boxing(size) { null }
+            return RingBuffer(buffer)
+        }
+    }
+}

kmath-sequential/src/commonMain/kotlin/scientifik/kmath/sequential/SpecializedStreamingBlocks.kt

@@ -1,79 +0,0 @@
-package scientifik.kmath.sequential
-
-import kotlinx.atomicfu.atomic
-import kotlinx.atomicfu.update
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.channels.*
-import kotlinx.coroutines.launch
-
-interface DoubleProducer : Producer<Double> {
-    suspend fun receiveArray(): DoubleArray
-}
-
-interface DoubleConsumer : Consumer<Double> {
-    suspend fun sendArray(): DoubleArray
-}
-
-
-abstract class AbstractDoubleProducer(scope: CoroutineScope) : AbstractProducer<Double>(scope), DoubleProducer {
-    override suspend fun connectOutput(consumer: Consumer<Double>) {
-        if (consumer is DoubleConsumer) {
-            arrayOutput.toChannel(consumer.arrayInput)
-        } else {
-            connectOutput(super, consumer)
-        }
-    }
-}
-
-abstract class AbstractDoubleConsumer(scope: CoroutineScope) : AbstractConsumer<Double>(scope), DoubleConsumer {
-    override suspend fun connectInput(producer: Producer<Double>) {
-        if (producer is DoubleProducer) {
-            producer.arrayOutput.toChannel(arrayInput)
-        } else {
-            super.connectInput(producer)
-        }
-    }
-}
-
-abstract class AbstractDoubleProcessor(scope: CoroutineScope) : AbstractProcessor<Double, Double>(scope),
-    DoubleProducer, DoubleConsumer {
-
-    override suspend fun connectOutput(consumer: Consumer<Double>) {
-        if (consumer is DoubleConsumer) {
-            arrayOutput.toChannel(consumer.arrayInput)
-        } else {
-            connectOutput(super, consumer)
-        }
-    }
-
-    override suspend fun connectInput(producer: Producer<Double>) {
-        if (producer is DoubleProducer) {
-            producer.arrayOutput.toChannel(arrayInput)
-        } else {
-            super.connectInput(producer)
-        }
-    }
-}
-
-class DoubleReducer<S>(
-    scope: CoroutineScope,
-    initialState: S,
-    fold: suspend (S, DoubleArray) -> S
-) : AbstractDoubleConsumer(scope) {
-    private val state = atomic(initialState)
-
-    val value: S = state.value
-
-    override val arrayInput: SendChannel<DoubleArray> by lazy {
-        //create a channel and start process of reading all elements into aggregator
-        Channel<DoubleArray>(capacity = Channel.RENDEZVOUS).also {
-            launch {
-                it.consumeEach { value -> state.update { fold(it, value) } }
-            }
-        }
-    }
-
-    override val input: SendChannel<DoubleArray> = object :Abstr
-
-
-}

kmath-sequential/src/commonMain/kotlin/scientifik/kmath/sequential/Streaming.kt

@@ -1,7 +1,5 @@
 package scientifik.kmath.sequential
 
-import kotlinx.atomicfu.atomic
-import kotlinx.atomicfu.update
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.channels.*
@@ -9,6 +7,7 @@ import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
+import scientifik.kmath.structures.Buffer
 import kotlin.coroutines.CoroutineContext
 
 /**
@@ -172,7 +171,7 @@ class PipeProcessor<T, R>(
 }
 
 /**
- * A [Processor] that splits the input in fixed chunk size and transforms each chunk
+ * A [Processor] that splits the input in fixed chunked size and transforms each chunked
  */
 class ChunkProcessor<T, R>(
     scope: CoroutineScope,
@@ -205,47 +204,44 @@ class ChunkProcessor<T, R>(
 class WindowedProcessor<T, R>(
     scope: CoroutineScope,
     window: Int,
-    process: suspend (List<T>) -> R
+    val process: suspend (Buffer<T?>) -> R
 ) : AbstractProcessor<T, R>(scope) {
 
+    private val ringBuffer = RingBuffer.boxing<T>(window)
+
+    private val channel = Channel<R>(Channel.RENDEZVOUS)
+
     override suspend fun receive(): R {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+        return channel.receive()
     }
 
     override suspend fun send(value: T) {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+        ringBuffer.push(value)
+        channel.send(process(ringBuffer.snapshot()))
     }
-
-
 }
 
 /**
  * Thread-safe aggregator of values from input. The aggregator does not store all incoming values, it uses fold procedure
  * to incorporate them into state on-arrival.
- * The current aggregated state could be accessed by [value]. The input channel is inactive unless requested
+ * The current aggregated state could be accessed by [state]. The input channel is inactive unless requested
  * @param T - the type of the input element
  * @param S - the type of the aggregator
  */
 class Reducer<T, S>(
     scope: CoroutineScope,
     initialState: S,
-    fold: suspend (S, T) -> S
+    val fold: suspend (S, T) -> S
 ) : AbstractConsumer<T>(scope) {
 
-    private val state = atomic(initialState)
+    var state: S = initialState
+        private set
 
-    val value: S = state.value
+    private val mutex = Mutex()
 
-    private val input: SendChannel<T> by lazy {
+    override suspend fun send(value: T) = mutex.withLock {
-        //create a channel and start process of reading all elements into aggregator
+        state = fold(state, value)
-        Channel<T>(capacity = Channel.RENDEZVOUS).also {
-            launch {
-                it.consumeEach { value -> state.update { fold(it, value) } }
     }
-        }
-    }
-
-    override suspend fun send(value: T) = input.send(value)
 }
 
 /**
@@ -257,20 +253,11 @@ class Collector<T>(scope: CoroutineScope) : AbstractConsumer<T>(scope) {
     private val mutex = Mutex()
     val list: List<T> get() = _list
 
-    private val input: SendChannel<T> by lazy {
+    override suspend fun send(value: T) {
-        //create a channel and start process of reading all elements into aggregator
-        Channel<T>(capacity = Channel.RENDEZVOUS).also {
-            launch {
-                it.consumeEach { value ->
         mutex.withLock {
             _list.add(value)
         }
     }
-            }
-        }
-    }
-
-    override suspend fun send(value: T) = input.send(value)
 }
 
 /**
@@ -285,6 +272,10 @@ fun <T> Sequence<T>.produce(scope: CoroutineScope = GlobalScope) =
 fun <T> ReceiveChannel<T>.produce(scope: CoroutineScope = GlobalScope) =
     GenericProducer<T>(scope) { for (e in this@produce) send(e) }
 
+
+fun <T, C : Consumer<T>> Producer<T>.consumer(consumerFactory: () -> C): C =
+    consumerFactory().also { connect(it) }
+
 /**
  * Create a reducer and connect this producer to reducer
  */
@@ -297,8 +288,13 @@ fun <T, S> Producer<T>.reduce(initialState: S, fold: suspend (S, T) -> S) =
 fun <T> Producer<T>.collect() =
     Collector<T>(this).also { connect(it) }
 
-fun <T, R> Producer<T>.process(capacity: Int = Channel.RENDEZVOUS, process: suspend (T) -> R) =
+fun <T, R, P : Processor<T, R>> Producer<T>.process(processorBuilder: () -> P): P =
-    PipeProcessor(this, capacity, process)
+    processorBuilder().also { connect(it) }
 
-fun <T, R> Producer<T>.chunk(chunkSize: Int, process: suspend (List<T>) -> R) =
+fun <T, R> Producer<T>.process(capacity: Int = Channel.RENDEZVOUS, process: suspend (T) -> R) =
-    ChunkProcessor(this, chunkSize, process)
+    PipeProcessor<T, R>(this, capacity, process).also { connect(it) }
+
+fun <T, R> Producer<T>.chunked(chunkSize: Int, process: suspend (List<T>) -> R) =
+    ChunkProcessor(this, chunkSize, process).also { connect(it) }
+
+fun <T> Producer<T>.chunked(chunkSize: Int) = chunked(chunkSize) { it }

kmath-sequential/src/commonTest/kotlin/scientifik/kmath/sequential/CumulativeKtTest.kt

@@ -1,5 +1,6 @@
 package scientifik.kmath.misc
 
+import scientifik.kmath.sequential.cumulativeSum
 import kotlin.test.Test
 import kotlin.test.assertEquals
 

kmath-sequential/src/commonTest/kotlin/scientifik/kmath/sequential/RingBufferTest.kt

@@ -0,0 +1,19 @@
+package scientifik.kmath.sequential
+
+import scientifik.kmath.structures.asSequence
+import scientifik.kmath.structures.runBlocking
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class RingBufferTest {
+    @Test
+    fun testPush() {
+        val buffer = RingBuffer.build(20, Double.NaN)
+        runBlocking {
+            for (i in 1..30) {
+                buffer.push(i.toDouble())
+            }
+            assertEquals(410.0, buffer.asSequence().sum())
+        }
+    }
+}

kmath-sequential/src/jvmMain/kotlin/scientifik/kmath/sequential/AccumulatorsExt.kt

@@ -1,33 +0,0 @@
-package scientifik.kmath.sequential
-
-import kotlinx.coroutines.channels.Channel
-import kotlinx.coroutines.channels.ReceiveChannel
-import kotlinx.coroutines.sync.Mutex
-import kotlinx.coroutines.sync.withLock
-import scientifik.kmath.operations.Space
-import scientifik.kmath.structures.runBlocking
-import java.util.*
-
-/**
- * A moving average with fixed window
- */
-class MovingAverage<T : Any>(val window: Int, val context: Space<T>) : Accumulator<T> {
-    private val outputChannel = Channel<T>()
-    private val queue = ArrayDeque<T>(window)
-    private val mutex = Mutex()
-
-    override suspend fun send(value: T) {
-        mutex.withLock {
-            queue.add(value)
-            if (queue.size == window) {
-                val sum = queue.fold(context.zero) { a, b -> context.run { a + b } }
-                outputChannel.send(context.run { sum / window })
-                queue.pop()
-            }
-        }
-    }
-
-    override fun push(value: T) = runBlocking { send(value) }
-
-    val output: ReceiveChannel<T> = outputChannel
-}

settings.gradle.kts

@@ -20,7 +20,7 @@ pluginManagement {
 rootProject.name = "kmath"
 include(
     ":kmath-core",
-    ":kmath-io",
+//    ":kmath-io",
     ":kmath-coroutines",
     ":kmath-commons",
     ":kmath-koma",