IO: add ByteWritePacket.writePacket

Author: Sergey Mashkov

core/kotlinx-coroutines-io/src/main/kotlin/kotlinx/coroutines/experimental/io/packet/ByteWritePacket.kt

@@ -28,6 +28,8 @@ interface ByteWritePacket : Appendable {
     fun outputStream(): OutputStream
     fun writerUTF8(): Writer
 
+    fun writePacket(p: ByteReadPacket)
+
     override fun append(csq: CharSequence): ByteWritePacket {
         append(csq, 0, csq.length)
         return this

core/kotlinx-coroutines-io/src/main/kotlin/kotlinx/coroutines/experimental/io/packet/ByteWritePacketImpl.kt

@@ -83,6 +83,22 @@ internal class ByteWritePacketImpl(private val pool: ObjectPool<ByteBuffer>) : B
         return this
     }
 
+    override fun writePacket(p: ByteReadPacket) {
+        when (p) {
+            is ByteReadPacketEmpty -> {}
+            is ByteReadPacketSingle -> {
+                if (p.remaining > 0) {
+                    last(p.steal().also { it.compact() })
+                }
+            }
+            is ByteReadPacketImpl -> {
+                while (p.remaining > 0) {
+                    last(p.steal().also { it.compact() })
+                }
+            }
+        }
+    }
+
     private tailrec fun appendASCII(csq: CharSequence, start: Int, end: Int) {
         val bb = ensure()
         val limitedEnd = minOf(end, start + bb.remaining())

core/kotlinx-coroutines-io/src/main/kotlin/kotlinx/coroutines/experimental/io/packet/Packets.kt

@@ -9,6 +9,7 @@ private val PACKET_BUFFER_POOL_SIZE = getIOIntProperty("PacketBufferPoolSize", 1
 private val PacketBufferPool: ObjectPool<ByteBuffer> =
     object : ObjectPoolImpl<ByteBuffer>(PACKET_BUFFER_POOL_SIZE) {
         override fun produceInstance(): ByteBuffer = ByteBuffer.allocateDirect(PACKET_BUFFER_SIZE)
+        override fun clearInstance(instance: ByteBuffer) = instance.apply { clear() }
     }
 
 inline fun buildPacket(block: ByteWritePacket.() -> Unit): ByteReadPacket =

core/kotlinx-coroutines-io/src/test/kotlin/kotlinx/coroutines/experimental/io/BytePacketReaderWriterTest.kt

@@ -305,4 +305,34 @@ class BytePacketReaderWriterTest {
 
         assertTrue { bytes.contentEquals(copied) }
     }
+
+    @Test
+    fun testWritePacketSingle() {
+        val inner = buildPacket {
+            append("ABC")
+        }
+
+        val outer = buildPacket {
+            append("123")
+            writePacket(inner)
+            append(".")
+        }
+
+        assertEquals("123ABC.", outer.readText().toString())
+    }
+
+    @Test
+    fun testWritePacketMultiple() {
+        val inner = buildPacket {
+            append("o".repeat(100000))
+        }
+
+        val outer = buildPacket {
+            append("123")
+            writePacket(inner)
+            append(".")
+        }
+
+        assertEquals("123" + "o".repeat(100000) + ".", outer.readText().toString())
+    }
 }