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com.twitter.finagle.memcached.protocol.text.client.Decoder.scala Maven / Gradle / Ivy
package com.twitter.finagle.memcached.protocol.text.client
import com.twitter.finagle.memcached.protocol.ServerError
import com.twitter.finagle.memcached.protocol.text._
import com.twitter.finagle.memcached.util.ChannelBufferUtils._
import com.twitter.finagle.memcached.util.ParserUtils
import com.twitter.finagle.netty3.ChannelBufferBuf
import com.twitter.util.StateMachine
import org.jboss.netty.buffer.ChannelBuffer
import org.jboss.netty.channel._
object Decoder {
private val END = "END": ChannelBuffer
private val ITEM = "ITEM": ChannelBuffer
private val STAT = "STAT": ChannelBuffer
private val VALUE = "VALUE": ChannelBuffer
private val EmptyValueLines = ValueLines(Seq.empty)
private val NeedMoreData: Decoding = null
}
class Decoder extends AbstractDecoder with StateMachine {
import Decoder._
case object AwaitingResponse extends State
case class AwaitingResponseOrEnd(valuesSoFar: Seq[TokensWithData]) extends State
case class AwaitingStatsOrEnd(valuesSoFar: Seq[Tokens]) extends State
case class AwaitingData(
valuesSoFar: Seq[TokensWithData],
tokens: Seq[ChannelBuffer],
bytesNeeded: Int)
extends State
final protected[memcached] def start() {
state = AwaitingResponse
}
private[this] val awaitingResponseContinue: Seq[ChannelBuffer] => Decoding = { tokens =>
if (isEnd(tokens)) {
EmptyValueLines
} else if (isStats(tokens)) {
awaitStatsOrEnd(Seq(Tokens(tokens.map(ChannelBufferBuf.Owned(_)))))
NeedMoreData
} else {
Tokens(tokens.map(ChannelBufferBuf.Owned(_)))
}
}
def decode(ctx: ChannelHandlerContext, channel: Channel, buffer: ChannelBuffer): Decoding = {
state match {
case AwaitingResponse =>
decodeLine(buffer, needsData)(awaitingResponseContinue)
case AwaitingStatsOrEnd(linesSoFar) =>
decodeLine(buffer, needsData) { tokens =>
if (isEnd(tokens)) {
StatLines(linesSoFar)
} else if (isStats(tokens)) {
awaitStatsOrEnd(linesSoFar :+ Tokens(tokens.map(ChannelBufferBuf.Owned(_))))
NeedMoreData
} else {
throw new ServerError("Invalid reply from STATS command")
}
}
case AwaitingData(valuesSoFar, tokens, bytesNeeded) =>
decodeData(bytesNeeded, buffer) { data =>
awaitResponseOrEnd(
valuesSoFar :+
TokensWithData(tokens.map(ChannelBufferBuf.Owned(_)), ChannelBufferBuf.Owned(data))
)
NeedMoreData
}
case AwaitingResponseOrEnd(valuesSoFar) =>
decodeLine(buffer, needsData) { tokens =>
if (isEnd(tokens)) {
ValueLines(valuesSoFar)
} else NeedMoreData
}
}
}
final protected[memcached] def awaitData(tokens: Seq[ChannelBuffer], bytesNeeded: Int): Unit = {
state match {
case AwaitingResponse =>
awaitData(Nil, tokens, bytesNeeded)
case AwaitingResponseOrEnd(valuesSoFar) =>
awaitData(valuesSoFar, tokens, bytesNeeded)
}
}
private[this] def awaitData(
valuesSoFar: Seq[TokensWithData],
tokens: Seq[ChannelBuffer],
bytesNeeded: Int
): Unit = {
state = AwaitingData(valuesSoFar, tokens, bytesNeeded)
}
private[this] def awaitResponseOrEnd(valuesSoFar: Seq[TokensWithData]): Unit = {
state = AwaitingResponseOrEnd(valuesSoFar)
}
private[this] def awaitStatsOrEnd(valuesSoFar: Seq[Tokens]): Unit = {
state = AwaitingStatsOrEnd(valuesSoFar)
}
private[this] def isEnd(tokens: Seq[ChannelBuffer]) =
tokens.length == 1 && tokens.head == END
private[this] def isStats(tokens: Seq[ChannelBuffer]) =
tokens.nonEmpty && (tokens.head == STAT || tokens.head == ITEM)
private[this] val needsData: Seq[ChannelBuffer] => Int = { tokens =>
val responseName = tokens.head
if (responseName == VALUE) {
validateValueResponse(tokens)
tokens(3).toInt
} else -1
}
private[this] def validateValueResponse(args: Seq[ChannelBuffer]) {
if (args.length < 4) throw new ServerError("Too few arguments")
if (args.length > 5) throw new ServerError("Too many arguments")
if (args.length == 5 && !ParserUtils.isDigits(args(4))) throw new ServerError("CAS must be a number")
if (!ParserUtils.isDigits(args(3))) throw new ServerError("Bytes must be number")
}
}