support for resident Isabelle servers;

--- a/src/Pure/System/isabelle_tool.scala	Sat Aug 05 15:48:02 2017 +0200
+++ b/src/Pure/System/isabelle_tool.scala	Sat Aug 05 20:08:41 2017 +0200
@@ -115,6 +115,7 @@
       Options.isabelle_tool,
       Profiling_Report.isabelle_tool,
       Remote_DMG.isabelle_tool,
+      Server.isabelle_tool,
       Update_Cartouches.isabelle_tool,
       Update_Header.isabelle_tool,
       Update_Then.isabelle_tool,

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/Tools/server.scala	Sat Aug 05 20:08:41 2017 +0200
@@ -0,0 +1,122 @@
+/*  Title:      Pure/Tools/server.scala
+    Author:     Makarius
+
+Resident Isabelle servers.
+*/
+
+package isabelle
+
+
+import java.util.UUID
+import java.net.{ServerSocket, InetAddress}
+
+
+object Server
+{
+  /* per-user servers */
+
+  object Data
+  {
+    val database = Path.explode("$ISABELLE_HOME_USER/server.db")
+
+    val server_name = SQL.Column.string("server_name", primary_key = true)
+    val server_port = SQL.Column.int("server_port")
+    val password = SQL.Column.string("password")
+    val table = SQL.Table("isabelle_servers", List(server_name, server_port, password))
+
+    sealed case class Entry(server_name: String, server_port: Int, password: String)
+    {
+      def address: String = "127.0.0.1:" + server_port
+    }
+  }
+
+  def list(): List[Data.Entry] =
+    using(SQLite.open_database(Data.database))(list(_))
+
+  def list(db: SQLite.Database): List[Data.Entry] =
+    if (db.tables.contains(Data.table.name)) {
+      db.using_statement(Data.table.select())(stmt =>
+        stmt.execute_query().iterator(res =>
+          Data.Entry(
+            res.string(Data.server_name),
+            res.int(Data.server_port),
+            res.string(Data.password))).toList.sortBy(_.server_name))
+    }
+    else Nil
+
+  def find(db: SQLite.Database, name: String): Option[Data.Entry] =
+    list(db).find(entry => entry.server_name == name)
+
+  def start(name: String = "", port: Int = 0): (Data.Entry, Boolean) =
+  {
+    using(SQLite.open_database(Data.database))(db =>
+      db.transaction {
+        find(db, name) match {
+          case Some(entry) => (entry, false)
+          case None =>
+            val socket = new ServerSocket(port, 50, InetAddress.getByName("127.0.0.1"))
+            val server = new Server(socket)
+            val entry = Data.Entry(name, server.port, server.password)
+
+            Isabelle_System.bash("chmod 600 " + File.bash_path(Data.database)).check
+            db.create_table(Data.table)
+            db.using_statement(Data.table.insert())(stmt =>
+            {
+              stmt.string(1) = entry.server_name
+              stmt.int(2) = entry.server_port
+              stmt.string(3) = entry.password
+              stmt.execute()
+            })
+            (entry, true)
+        }
+      })
+  }
+
+  def stop(name: String = ""): Boolean =
+  {
+    using(SQLite.open_database(Data.database))(db =>
+      db.transaction {
+        find(db, name) match {
+          case Some(entry) =>
+            // FIXME shutdown server
+            db.using_statement(Data.table.delete(Data.server_name.where_equal(name)))(_.execute)
+            true
+          case None =>
+            false
+        }
+      })
+  }
+
+
+  /* Isabelle tool wrapper */
+
+  val isabelle_tool =
+    Isabelle_Tool("server", "manage resident Isabelle servers", args =>
+    {
+      var list_servers = false
+
+      val getopts =
+        Getopts("""
+Usage: isabelle server [OPTIONS]
+
+  Options are:
+    -l           list servers
+
+  Manage resident Isabelle servers.
+""",
+          "l" -> (_ => list_servers = true))
+
+      val more_args = getopts(args)
+      if (more_args.nonEmpty || !list_servers) getopts.usage()
+
+      if (list_servers) list().foreach(entry =>
+        Console.println("server " + quote(entry.server_name) + " = " + entry.address +
+          " (password " + quote(entry.password) + ")"))
+    })
+}
+
+class Server private(val socket: ServerSocket)
+{
+  def port: Int = socket.getLocalPort
+  val password = UUID.randomUUID().toString
+}

--- a/src/Pure/build-jars	Sat Aug 05 15:48:02 2017 +0200
+++ b/src/Pure/build-jars	Sat Aug 05 20:08:41 2017 +0200
@@ -140,6 +140,7 @@
   Tools/main.scala
   Tools/print_operation.scala
   Tools/profiling_report.scala
+  Tools/server.scala
   Tools/simplifier_trace.scala
   Tools/spell_checker.scala
   Tools/task_statistics.scala