wip

[tripe-android] / peers.scala

package uk.org.distorted.tripe; package object peers {

import java.io.{BufferedReader, File, FileReader, Reader};
import java.net.{InetAddress, Inet4Address, Inet6Address,
		 UnknownHostException};

import scala.collection.mutable.{HashMap, HashSet};
import scala.concurrent.Channel;
import scala.util.control.Breaks;
import scala.util.matching.Regex;

val RX_COMMENT = """(?x) ^ \s* (?: [;\#] .* )? $""".r;
val RX_GRPHDR = """(?x) ^ \s* \[ (.*) \] \s* $""".r;
val RX_ASSGN = """(?x) ^
	([^\s:=] (?: [^:=]* [^\s:=])?)
	\s* [:=] \s*
	(| [^\s\#;]\S* (?: \s+ [^\s\#;]\S*)*)
	(?: \s+ (?: [;\#].*)? )? $""".r;
val RX_CONT = """(?x) ^ \s+
	(| [^\s\#;]\S* (?: \s+ [^\s\#;]\S*)*)
	(?: \s+ (?: [;\#].*)? )? $""".r;
val RX_REF = """(?x) \$ \( ([^)]+) \)""".r;
val RX_RESOLVE = """(?x) \$ ([46*]*) \[ ([^\]]+) \]""".r;
val RX_PARENT = """(?x) [^\s,]+""".r

def with_cleaner[T](body: Cleaner => T): T = {
  val cleaner = new Cleaner;
  try { body(cleaner) }
  finally { cleaner.cleanup(); }
}

class Cleaner {
  var cleanups: List[() => Unit] = Nil;
  def apply(cleanup: => Unit) { cleanups +:= { () => cleanup; } }
  def cleanup() { cleanups foreach { _() } }
}

def lines(r: Reader) = new Traversable[String] {
  val in: BufferedReader = new BufferedReader(r);
  override def foreach[T](f: String => T) {
    while (true) in.readLine match {
      case null => return;
      case line => f(line);
    }
  }
}

def thread(name: String, run: Boolean = true, daemon: Boolean = true)
	  (body: => Unit): Thread = {
  val t = new Thread(new Runnable { override def run() { body } }, name);
  t.setDaemon(daemon);
  if (run) t.start();
  t
}

object BulkResolver {
  val BREAK = new Breaks;
}

class BulkResolver(val nthreads: Int = 8) {
  import BulkResolver.BREAK._;
  class Host(val name: String) {
    var a4, a6: Seq[InetAddress] = Seq.empty;

    def addaddr(a: InetAddress) { a match {
      case _: Inet4Address => a4 +:= a;
      case _: Inet6Address => a6 +:= a;
      case _ => ();
    } }

    def get(flags: String): Seq[InetAddress] = {
      var wanta4, wanta6, any, all = false;
      var b = Seq.newBuilder[InetAddress];
      for (ch <- flags) ch match {
	case '*' => all = true;
	case '4' => wanta4 = true; any = true;
	case '6' => wanta6 = true; any = true;
	case _ => ???
      }
      if (!any) { wanta4 = true; wanta6 = true; }
      if (wanta4) b ++= a4;
      if (wanta6) b ++= a6;
      (all, b.result) match {
	case (true, aa) => aa
	case (false, aa@(Nil | Seq(_))) => aa
	case (false, Seq(a, _*)) => Seq(a)
      }
    }
  }
  val ch = new Channel[Host];
  val map = HashMap[String, Host]();
  var preparing = true;

  val workers = Array.tabulate(nthreads) { i =>
    thread(s"resolver worker #$i") {
      breakable {
	while (true) {
	  val host = ch.read; if (host == null) break;
println(s";; ${Thread.currentThread.getName} resolving `${host.name}'");
	  try {
	    for (a <- InetAddress.getAllByName(host.name)) host.addaddr(a);
	  } catch { case e: UnknownHostException => () }
	}
      }
println(s";; ${Thread.currentThread.getName} done'");
      ch.write(null);
    }
  }

  def prepare(name: String) {
println(s";; prepare host `$name'");
    assert(preparing);
    if (!(map contains name)) {
      val host = new Host(name);
      map(name) = host;
      ch.write(host);
    }
  }

  def finish() {
    assert(preparing);
    preparing = false;
    ch.write(null);
    for (t <- workers) t.join();
  }

  def resolve(name: String, flags: String): Seq[InetAddress] =
    map(name).get(flags);
}

def fmtpath(path: Seq[String]) =
  path.reverse map { i => s"`$i'" } mkString " -> ";

class ConfigSyntaxError(val file: File, val lno: Int, val msg: String)
	extends Exception {
  override def getMessage(): String = s"$file:$lno: $msg";
}
class MissingConfigSection(val sect: String) extends Exception {
  override def getMessage(): String =
    s"missing configuration section `$sect'";
}
class MissingConfigItem(val sect: String, val key: String,
			val path: Seq[(String)]) extends Exception {
  override def getMessage(): String = {
    val msg = s"missing configuration item `$key' in section `$sect'";
    if (path == Nil) msg
    else msg + s" (wanted while expanding ${fmtpath(path)})"
  }
}
class AmbiguousConfig(val key: String,
		      val v0: String, val p0: Seq[String],
		      val v1: String, val p1: Seq[String])
	extends Exception {
  override def getMessage(): String =
    s"ambiguous answer resolving key `$key': " +
    s"path ${fmtpath(p0)} yields `$v0', but ${fmtpath(p1)} yields `$v1'";
}

class ConfigCycle(val key: String, path: Seq[String]) extends Exception {
  override def getMessage(): String =
    s"found a cycle ${fmtpath(path)} looking up key `$key'";
}
class NoHostAddresses(val sect: String, val key: String, val host: String)
	extends Exception {
  override def getMessage(): String =
    s"no addresses found for `$host' (key `$key' in section `$sect')";
}

object Config {
  sealed abstract class ConfigCacheEntry;
  case object StillLooking extends ConfigCacheEntry;
  case object NotFound extends ConfigCacheEntry;
  case class Found(value: String, path: Seq[String])
    extends ConfigCacheEntry;
}

class Config { conf =>
  import Config._;
  class Section(val name: String) {
    val itemmap = HashMap[String, String]();
    val cache = HashMap[String, ConfigCacheEntry]();
    override def toString: String = s"${getClass.getName}($name)";
    def parents: Seq[Section] =
      (itemmap.get("@inherit")
       map { pp => (RX_PARENT.findAllIn(pp) map { conf.section _ }).toList }
       getOrElse Nil);

    def get_internal(key: String, path: Seq[String] = Nil):
	      Option[(String, Seq[String])] = {
      val incpath = name +: path;

      for (r <- cache.get(key)) r match {
	case StillLooking => throw new ConfigCycle(key, incpath)
	case NotFound => return None
	case Found(v, p) => return Some((v, p ++ path));
      }

      for (v <- itemmap.get(key)) {
	cache(key) = Found(v, Seq(name));
	return Some((v, incpath));
      }

      cache(key) = StillLooking;

      ((None: Option[(String, Seq[String])]) /: parents) { (st, parent) =>
	parent.get_internal(key, incpath) match {
	  case None => st;
	  case newst@Some((v, p)) => st match {
	    case None => newst
	    case Some((vv, _)) if v == vv => st
	    case Some((vv, pp)) =>
	      throw new AmbiguousConfig(key, v, p, vv, pp)
	  }
	}
      } match {
	case None => cache(key) = NotFound; None
	case Some((v, p)) =>
	  cache(key) = Found(v, p dropRight path.length);
	  Some((v, p))
      }
    }

    def get(key: String, resolve: Boolean = true,
	    path: Seq[String] = Nil): String = {
      val v0 = key match {
	case "name" => itemmap.getOrElse("name", name)
	case _ => get_internal(key).
	  getOrElse(throw new MissingConfigItem(name, key, path))._1
      }
      expand(key, v0, resolve, path)
    }

    def expand(key: String, value: String, resolve: Boolean,
	       path: Seq[String]): String = {
      val v1 = RX_REF.replaceAllIn(value, { m =>
	Regex.quoteReplacement(get(m.group(1), resolve, path))
      });
      val v2 = if (!resolve) v1
	       else RX_RESOLVE.replaceAllIn(v1, { m =>
		 resolver.resolve(m.group(2), m.group(1)) match {
		   case Nil =>
		     throw new NoHostAddresses(name, key, m.group(2));
		   case addrs =>
		     Regex.quoteReplacement((addrs map { _.getHostAddress }).
					    mkString(" "));
		 }
	       })
      v2
    }

    def items: Seq[String] = {
      val b = Seq.newBuilder[String];
      val seen = HashSet[String]();
      val visiting = HashSet[String](name);
      var stack = List(this);

      while (stack != Nil) {
	val sect = stack.head; stack = stack.tail;
	for (k <- sect.itemmap.keys)
	  if (!(seen contains k)) { b += k; seen += k; }
	for (p <- sect.parents)
	  if (!(visiting contains p.name))
	    { stack ::= p; visiting += p.name; }
      }
      b.result
    }
  }
  val sectmap = new HashMap[String, Section];
  def sections: Iterator[Section] = sectmap.values.iterator;
  def section(name: String): Section =
    sectmap.getOrElse(name, throw new MissingConfigSection(name));

  val resolver = new BulkResolver;

  def parseFile(path: File): this.type = {
println(s";; parse ${path.getPath}");
    with_cleaner { clean =>
      val in = new FileReader(path); clean { in.close(); }

      val lno = 1;
      val b = new StringBuilder;
      var key: String = null;
      var sect: Section = null;
      def flush() {
	if (key != null) {
	  sect.itemmap(key) = b.result;
println(s";; in `${sect.name}', set `$key' to `${b.result}'");
	  b.clear();
	  key = null;
	}
      }
      for (line <- lines(in)) line match {
	case RX_COMMENT() =>
	  ();
	case RX_GRPHDR(grp) =>
	  flush();
	  sect = sectmap.getOrElseUpdate(grp, new Section(grp));
	case RX_CONT(v) =>
	  if (key == null) {
	    throw new ConfigSyntaxError(
	      path, lno, "no config value to continue");
	  }
	  b += '\n'; b ++= v;
	case RX_ASSGN(k, v) =>
	  if (sect == null) {
	    throw new ConfigSyntaxError(
	      path, lno, "no active section to update");
	  }
	  flush();
	  key = k; b ++= v;
	case _ =>
	  throw new ConfigSyntaxError(path, lno, "incomprehensible line");
      }
      flush();
    }
    this
  }
  def parse(path: File): this.type = {
    if (!path.isDirectory) parseFile(path);
    else for {
      f <- path.listFiles sortBy { _.getName };
      name = f.getName;
      if name.length > 0;
      tail = name(name.length - 1);
      if tail != '#' && tail != '~'
    } parseFile(f);
    this
  }
  def parse(path: String): this.type = parse(new File(path));

  def analyse() {
println(";; resolving all...");
    for ((_, sect) <- sectmap) {
println(s";; resolving in section `${sect.name}'...");
      for (key <- sect.items) {
println(s";;	resolving in key `$key'...");
	val mm = RX_RESOLVE.findAllIn(sect.get(key, false));
	for (host <- mm) { resolver.prepare(mm.group(2)); }
      }
    }
    resolver.finish();

    def dumpsect(sect: Section) {
      for (k <- sect.items.filterNot(_.startsWith("@")).sorted)
	println(s";;	`$k' -> `${sect.get(k)}'")
    }
    for (sect <- sectmap.values.toSeq sortBy { _.name })
      if (sect.name.startsWith("@")) ();
      else if (sect.name.startsWith("$")) {
	println(s";; special section `${sect.name}'");
	dumpsect(sect);
      } else {
	println(s";; peer section `${sect.name}'");
	dumpsect(sect);
      }
  }
}

}