/* =========================================================================================
* Copyright © 2013-2018 the kamon project <http://kamon.io/>
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
* =========================================================================================
*/
package kamon
package context
import java.io.{ByteArrayInputStream, ByteArrayOutputStream, InputStream, OutputStream}
import com.typesafe.config.Config
import kamon.context.BinaryPropagation.{ByteStreamReader, ByteStreamWriter}
import kamon.context.generated.binary.context.{Context => ColferContext, Entry => ColferEntry}
import org.slf4j.LoggerFactory
import scala.reflect.ClassTag
import scala.util.control.NonFatal
import scala.util.{Failure, Success, Try}
/**
* Context propagation that uses byte stream abstractions as the transport medium. The Binary propagation uses
* instances of [[ByteStreamReader]] and [[ByteStreamWriter]] to decode and encode Context instances, respectively.
*
* Binary propagation uses the [[ByteStreamReader]] and [[ByteStreamWriter]] abstraction which closely model the APIs
* from [[InputStream]] and [[OutputStream]], but without exposing additional functionality that wouldn't have any
* well defined behavior for Context propagation, e.g. flush or close functions on OutputStreams.
*/
object BinaryPropagation {
/**
* Represents a readable stream of bytes. This interface closely resembles [[InputStream]], minus the functionality
* that wouldn't have a clearly defined behavior in the context of Context propagation.
*/
trait ByteStreamReader {
/**
* Number of available bytes on the ByteStream.
*/
def available(): Int
/**
* Reads as many bytes as possible into the target byte array.
*
* @param target Target buffer in which the read bytes will be written.
* @return The number of bytes written into the target buffer.
*/
def read(target: Array[Byte]): Int
/**
* Reads a specified number of bytes into the target buffer, starting from the offset position.
*
* @param target Target buffer in which read bytes will be written.
* @param offset Offset index in which to start writing bytes on the target buffer.
* @param count Number of bytes to be read.
* @return The number of bytes written into the target buffer.
*/
def read(target: Array[Byte], offset: Int, count: Int): Int
/**
* Reads all available bytes into a newly created byte array.
*
* @return All bytes read.
*/
def readAll(): Array[Byte]
}
object ByteStreamReader {
/**
* Creates a new [[ByteStreamReader]] that reads data from a byte array.
*/
def of(bytes: Array[Byte]): ByteStreamReader = new ByteArrayInputStream(bytes) with ByteStreamReader {
override def readAll(): Array[Byte] = {
val target = Array.ofDim[Byte](available())
read(target, 0, available())
target
}
}
}
/**
* Represents a writable stream of bytes. This interface closely resembles [[OutputStream]], minus the functionality
* that wouldn't have a clearly defined behavior in the context of Context propagation.
*/
trait ByteStreamWriter {
/**
* Writes all bytes into the stream.
*/
def write(bytes: Array[Byte]): Unit
/**
* Writes a portion of the provided bytes into the stream.
*
* @param bytes Buffer from which data will be selected.
* @param offset Starting index on the buffer.
* @param count Number of bytes to write into the stream.
*/
def write(bytes: Array[Byte], offset: Int, count: Int): Unit
/**
* Write a single byte into the stream.
*/
def write(byte: Int): Unit
}
object ByteStreamWriter {
/**
* Creates a new [[ByteStreamWriter]] from an OutputStream.
*/
def of(outputStream: OutputStream): ByteStreamWriter = new ByteStreamWriter {
override def write(bytes: Array[Byte]): Unit =
outputStream.write(bytes)
override def write(bytes: Array[Byte], offset: Int, count: Int): Unit =
outputStream.write(bytes, offset, count)
override def write(byte: Int): Unit =
outputStream.write(byte)
}
}
/**
* Create a new default Binary Propagation instance from the provided configuration.
*
* @param config Binary Propagation channel configuration
* @return A newly constructed HttpPropagation instance.
*/
def from(config: Config, classLoading: ClassLoading): Propagation[ByteStreamReader, ByteStreamWriter] = {
new BinaryPropagation.Default(Settings.from(config, classLoading))
}
/**
* Default Binary propagation in Kamon. This implementation uses Colfer to read and write the context tags and
* entries. Entries are represented as simple pairs of entry name and bytes, which are then processed by the all
* configured entry readers and writers.
*/
class Default(settings: Settings) extends Propagation[ByteStreamReader, ByteStreamWriter] {
private val _log = LoggerFactory.getLogger(classOf[BinaryPropagation.Default])
private val _streamPool = new ThreadLocal[Default.ReusableByteStreamWriter] {
override def initialValue(): Default.ReusableByteStreamWriter = new Default.ReusableByteStreamWriter(128)
}
private val _contextBufferPool = new ThreadLocal[Array[Byte]] {
override def initialValue(): Array[Byte] = Array.ofDim[Byte](settings.maxOutgoingSize)
}
override def read(reader: ByteStreamReader): Context = {
if(reader.available() > 0) {
val contextData = Try {
val cContext = new ColferContext()
cContext.unmarshal(reader.readAll(), 0)
cContext
}
contextData.failed.foreach {
case NonFatal(t) => _log.warn("Failed to read Context from ByteStreamReader", t)
}
contextData.map { colferContext =>
// Context tags
var tagSectionsCount = colferContext.tags.length
if (tagSectionsCount > 0 && tagSectionsCount % 2 != 0) {
_log.warn("Malformed Context tags found, tags consistency might be compromised")
tagSectionsCount -= 1
}
val tags = if (tagSectionsCount > 0) {
val tagsBuilder = Map.newBuilder[String, String]
var tagIndex = 0
while (tagIndex < tagSectionsCount) {
tagsBuilder += (colferContext.tags(tagIndex) -> colferContext.tags(tagIndex + 1))
tagIndex += 2
}
tagsBuilder.result()
} else Map.empty[String, String]
// Only reads the entries for which there is a registered reader
colferContext.entries.foldLeft(Context.of(tags)) {
case (context, entryData) =>
settings.incomingEntries.get(entryData.name).map { entryReader =>
var contextWithEntry = context
try {
contextWithEntry = entryReader.read(ByteStreamReader.of(entryData.content), context)
} catch {
case NonFatal(t) => _log.warn("Failed to read entry [{}]", entryData.name.asInstanceOf[Any], t)
}
contextWithEntry
}.getOrElse(context)
}
} getOrElse(Context.Empty)
} else Context.Empty
}
override def write(context: Context, writer: ByteStreamWriter): Unit = {
if (context.nonEmpty()) {
val contextData = new ColferContext()
val output = _streamPool.get()
val contextOutgoingBuffer = _contextBufferPool.get()
if (context.tags.nonEmpty) {
val tags = Array.ofDim[String](context.tags.size * 2)
var tagIndex = 0
context.tags.foreach {
case (key, value) =>
tags.update(tagIndex, key)
tags.update(tagIndex + 1, value)
tagIndex += 2
}
contextData.tags = tags
}
if (context.entries.nonEmpty) {
val entries = settings.outgoingEntries.collect {
case (entryName, entryWriter) if context.entries.contains(entryName) =>
val colferEntry = new ColferEntry()
try {
output.reset()
entryWriter.write(context, output)
colferEntry.name = entryName
colferEntry.content = output.toByteArray()
} catch {
case NonFatal(t) => _log.warn("Failed to write entry [{}]", entryName.asInstanceOf[Any], t)
}
colferEntry
}
contextData.entries = entries.toArray
}
try {
val contextSize = contextData.marshal(contextOutgoingBuffer, 0)
writer.write(contextOutgoingBuffer, 0, contextSize)
} catch {
case NonFatal(t) => _log.warn("Failed to write Context to ByteStreamWriter", t)
}
}
}
}
object Default {
private class ReusableByteStreamWriter(size: Int) extends ByteArrayOutputStream(size) with ByteStreamWriter {
def underlying(): Array[Byte] = this.buf
}
}
case class Settings(
maxOutgoingSize: Int,
incomingEntries: Map[String, Propagation.EntryReader[ByteStreamReader]],
outgoingEntries: Map[String, Propagation.EntryWriter[ByteStreamWriter]]
)
object Settings {
private val log = LoggerFactory.getLogger(classOf[BinaryPropagation.Settings])
def from(config: Config, classLoading: ClassLoading): BinaryPropagation.Settings = {
def buildInstances[ExpectedType : ClassTag](mappings: Map[String, String]): Map[String, ExpectedType] = {
val instanceMap = Map.newBuilder[String, ExpectedType]
mappings.foreach {
case (contextKey, componentClass) => classLoading.createInstance[ExpectedType](componentClass, Nil) match {
case Success(componentInstance) => instanceMap += (contextKey -> componentInstance)
case Failure(exception) => log.warn("Failed to instantiate {} [{}] due to []",
implicitly[ClassTag[ExpectedType]].runtimeClass.getName, componentClass, exception)
}
}
instanceMap.result()
}
Settings(
config.getBytes("max-outgoing-size").toInt,
buildInstances[Propagation.EntryReader[ByteStreamReader]](config.getConfig("entries.incoming").pairs),
buildInstances[Propagation.EntryWriter[ByteStreamWriter]](config.getConfig("entries.outgoing").pairs)
)
}
}
}
