From 8ae6051e97f728569c526d5e53fa195bd7ddac49 Mon Sep 17 00:00:00 2001
From: Petr Baudis <pasky@ucw.cz>
Date: Thu, 8 Dec 2011 02:01:56 +0100
Subject: [PATCH] Support reconnecting to agents

Agents do not die immediately on disconnect anymore. Instead, agent_id
is sent at birth and can be sent during negotiation to attach to a
disconnected agent.
---
 README            | 19 ++++++++++++++++---
 agent.cc          |  1 -
 client/example.pl | 11 ++++++++---
 connection.cc     | 28 ++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/README b/README
index 6dd7123..d637647 100644
--- a/README
+++ b/README
@@ -20,6 +20,9 @@ CRLF ("\r\n"), not just LF ("\n")!
 
 The following inputs (in no particular order) are supported:
 
+	agent_id <id>
+		unique id of agent; may be sent only once at the beginning
+		(you can use it to reconnect to the same agent later)
 	tick <ticknum>
 	BUMP
 		if received, the agent's move failed
@@ -62,9 +65,10 @@ The following outputs are supported:
 		energy required is proportional to phintensity
 
 
-After connecting, the client specifies its desired attributes,
-in the same format as in normal output (line-based, terminated
-by empty line), but with these commands instead:
+When new agent connects, the client first enters the "negotiation"
+phase, specifying its desired attributes, in the same format as in
+normal output (line-based, terminated by empty line), but with
+these commands instead:
 
 	move <rate>
 		<rate> between 0 and 1, describing probability
@@ -76,3 +80,12 @@ by empty line), but with these commands instead:
 
 In general, higher rate means higher energy maintenance of the
 appropriate actuators.
+
+Alternately, the client may send a single command in the negotiation
+phase:
+
+	agent_id <id>
+
+If the id corresponds to a disconnected agent, the connection
+is immediately attached to that agent. Combining this with other
+negotiation commands is undefined.
diff --git a/agent.cc b/agent.cc
index da51732..43e6891 100644
--- a/agent.cc
+++ b/agent.cc
@@ -126,7 +126,6 @@ agent::on_action_takes(void)
 		return;
 
 	if (conn->error) {
-		if (!dead) die();
 		conn->cancel();
 		conn = NULL;
 		return;
diff --git a/client/example.pl b/client/example.pl
index 6e852a5..e4abe45 100755
--- a/client/example.pl
+++ b/client/example.pl
@@ -143,9 +143,14 @@ $socket = IO::Socket::INET->new(
 print "[ii] connected\r\n";
 
 # negotiate attributs
-print $socket "move 1.0\r\n";
-print $socket "attack 1.0\r\n";
-print $socket "defense 1.0\r\n";
+if ($ARGV[1]) {
+	print "[ii] recovering agent $ARGV[1]\r\n";
+	print $socket "agent_id $ARGV[1]\r\n";
+} else {
+	print $socket "move 1.0\r\n";
+	print $socket "attack 1.0\r\n";
+	print $socket "defense 1.0\r\n";
+}
 print $socket "\r\n";
 print "[ii] agent created\r\n";
 
diff --git a/connection.cc b/connection.cc
index e91f914..99cf31e 100644
--- a/connection.cc
+++ b/connection.cc
@@ -2,6 +2,7 @@
 #include <cstdio>
 #include <cstring>
 #include <iostream>
+#include <sstream>
 
 #include <sys/select.h>
 #include <pthread.h>
@@ -9,6 +10,7 @@
 
 #include "agent.h"
 #include "connection.h"
+#include "main.h"
 
 #define buf_incomplete(buf) \
 	(buf.find("\r\n") == std::string::npos || (buf.find("\r\n") > 0 && buf.find("\r\n\r\n") == std::string::npos))
@@ -120,6 +122,28 @@ connection::actions(class agent &agent)
 			if (rate >= 0 && rate <= 1)
 				agent.attr.defense = rate;
 
+		} else if (negotiation && !cmd.compare("agent_id")) {
+			int id = -1;
+			sscanf(line.c_str(), "%d", &id);
+			if (id < 0) {
+bump_negot:
+				bump(); out_buf.append("\r\n");
+			} else {
+				class agent *a2 = NULL;
+				for (std::list<class agent *>::iterator ai = agents.begin(); ai != agents.end(); ai++) {
+					if ((*ai)->id == id) {
+						a2 = *ai;
+						break;
+					}
+				}
+				if (!a2 || a2->conn || !a2->tile || (dynamic_cast<herb *> (a2)))
+					goto bump_negot;
+				/* Round and round she goes, where she stops, nobody knows. */
+				a2->conn = this;
+				agent.conn = NULL;
+				negotiation = false;
+			}
+
 		} else if (!negotiation && !cmd.compare("move_dir") && !(mask & 1)) {
 			int x = 0, y = 0;
 			sscanf(line.c_str(), "%d %d", &x, &y);
@@ -154,6 +178,10 @@ connection::actions(class agent &agent)
 	if (negotiation) {
 		negotiation = false;
 		agent.spawn();
+
+		std::stringstream s;
+		s << "agent_id " << agent.id << "\r\n";
+		out_buf.append(s.str());
 	}
 
 	pthread_mutex_unlock(&buf_lock);