mm-file-delay: Emulating variable-delay links

scripts/mm-delay-graph

@@ -115,7 +115,7 @@ my @signal_delay_samples = sort { $a <=> $b } keys %signal_delay;
 
 for ( my $ts = $signal_delay_samples[ -1 ]; $ts >= $signal_delay_samples[ 0 ]; $ts-- ) {
   if ( not defined $signal_delay{ $ts } ) {
-    $signal_delay{ $ts } = $signal_delay{ $ts + 1 } + 1;
+    $signal_delay{ $ts } = $signal_delay{ $ts + 1 };
   }
 }
 
@@ -135,7 +135,7 @@ my $graph_max = $signal_delays[-1] * 1.2;
 # make graph
 open GNUPLOT, q{| gnuplot} or die;
 
-my $lower_limit = min( 30, int $pp50 );
+my $lower_limit = 0;
 
 print GNUPLOT <<END;
 set xlabel "time (s)"
@@ -144,7 +144,7 @@ set logscale y
 set yrange [$lower_limit:$graph_max]
 set ytics add ($lower_limit)
 set key center outside top horizontal
-set terminal svg size 1024,560 fixed enhanced fname 'Arial' solid mouse standalone name "Delay"
+set terminal png size 1024,560
 set output "/dev/stdout"
 END
 

scripts/mm-throughput-graph

@@ -54,7 +54,10 @@ LINE: while ( <> ) {
 
   # parse and validate line
   my ( $timestamp, $event_type, $num_bytes, $delay ) = split /\s+/, $_;
-
+  if ($event_type eq q{d}){
+       $num_bytes = $delay; 
+       $delay = 0;
+  }
   if ( not defined $num_bytes ) {
     die q{Format: timestamp event_type num_bytes [delay]};
   }
@@ -110,6 +113,9 @@ LINE: while ( <> ) {
 						(defined $signal_delay{ $timestamp - $delay })
 						? $signal_delay{ $timestamp - $delay }
 						: POSIX::DBL_MAX );
+  } elsif ( $event_type eq q{d} ) {
+    $capacity{ $bin } -= $num_bits;
+    $capacity_sum -= $num_bits;
   } else {
     die qq{Unknown event type: $event_type};
   }
@@ -163,7 +169,7 @@ my @signal_delay_samples = sort { $a <=> $b } keys %signal_delay;
 
 for ( my $ts = $signal_delay_samples[ -1 ]; $ts >= $signal_delay_samples[ 0 ]; $ts-- ) {
   if ( not defined $signal_delay{ $ts } ) {
-    $signal_delay{ $ts } = $signal_delay{ $ts + 1 } + 1;
+    $signal_delay{ $ts } = $signal_delay{ $ts + 1 };
   }
 }
 
@@ -196,7 +202,7 @@ set xlabel "time (s)"
 set ylabel "throughput (Mbits/s)"
 set key center outside top horizontal
 set style fill solid 0.2 noborder
-set terminal svg size 1024,560 fixed  fname 'Arial' rounded solid mouse standalone name "Throughput"
+set terminal png size 1024,560
 set output "/dev/stdout"
 END
 

src/frontend/Makefile.am

@@ -6,6 +6,11 @@ mm_delay_SOURCES = delayshell.cc delay_queue.hh delay_queue.cc
 mm_delay_LDADD = -lrt ../util/libutil.a ../packet/libpacket.a
 mm_delay_LDFLAGS = -pthread
 
+bin_PROGRAMS += mm-file-delay
+mm_file_delay_SOURCES = filedelayshell.cc file_delay_queue.hh file_delay_queue.cc
+mm_file_delay_LDADD = -lrt ../util/libutil.a ../packet/libpacket.a
+mm_file_delay_LDFLAGS = -pthread
+
 bin_PROGRAMS += mm-loss
 mm_loss_SOURCES = lossshell.cc loss_queue.hh loss_queue.cc
 mm_loss_LDADD = -lrt ../util/libutil.a ../packet/libpacket.a
@@ -49,6 +54,8 @@ libmod_deepcgi_la_CPPFLAGS = # empty
 install-exec-hook:
 	chown root $(DESTDIR)$(bindir)/mm-delay
 	chmod u+s $(DESTDIR)$(bindir)/mm-delay
+	chown root $(DESTDIR)$(bindir)/mm-file-delay
+	chmod u+s $(DESTDIR)$(bindir)/mm-file-delay
 	chown root $(DESTDIR)$(bindir)/mm-loss
 	chmod u+s $(DESTDIR)$(bindir)/mm-loss
 	chown root $(DESTDIR)$(bindir)/mm-onoff

src/frontend/file_delay_queue.cc

@@ -0,0 +1,59 @@
+/* -*-mode:c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+#include <limits>
+#include <fstream>
+#include <iostream>
+#include "file_delay_queue.hh"
+#include "timestamp.hh"
+
+using namespace std;
+
+FileDelayQueue::FileDelayQueue(const std::string & delay_file_name, uint64_t time_res_ms) : delays_(), time_res_ms_(time_res_ms), packet_queue_() 
+{
+    ifstream delay_file(delay_file_name);
+    uint64_t delay;
+
+    if (not delay_file.good()) {
+        throw runtime_error(delay_file_name + ": error while opening for reading.");
+    }
+
+    /* Read file, line-by-line. */
+    string line;
+    while (delay_file.good() and getline(delay_file, line))
+    {
+        delay = stoi(line);
+        delays_.push_back(delay);
+    }    
+}
+
+void FileDelayQueue::read_packet( const string & contents )
+{
+    uint64_t packet_timestamp = timestamp();
+    uint64_t delay_index = packet_timestamp/time_res_ms_;
+    uint64_t delay = delays_[delay_index % delays_.size()];
+    packet_queue_.emplace(packet_timestamp + delay, contents );
+}
+
+void FileDelayQueue::write_packets( FileDescriptor & fd )
+{
+    while ( (!packet_queue_.empty())
+            && (packet_queue_.front().first <= timestamp()) ) {
+        fd.write( packet_queue_.front().second );
+        packet_queue_.pop();
+    }
+}
+
+unsigned int FileDelayQueue::wait_time( void ) const
+{
+    if ( packet_queue_.empty() ) {
+        return numeric_limits<uint16_t>::max();
+    }
+
+    const auto now = timestamp();
+
+    if ( packet_queue_.front().first <= now ) {
+        return 0;
+    } else {
+        return packet_queue_.front().first - now;
+    }
+}

src/frontend/file_delay_queue.hh

@@ -0,0 +1,34 @@
+/* -*-mode:c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+#ifndef FILE_DELAY_QUEUE_HH
+#define FILE_DELAY_QUEUE_HH
+
+#include <queue>
+#include <cstdint>
+#include <string>
+#include "file_descriptor.hh"
+
+class FileDelayQueue
+{
+private:
+    std::vector< uint64_t > delays_;
+    uint64_t time_res_ms_;
+    std::queue< std::pair<uint64_t, std::string> > packet_queue_;
+    /* release timestamp, contents */
+
+public:
+
+    FileDelayQueue(const std::string & delay_file_name, uint64_t time_res_ms);
+
+    void read_packet( const std::string & contents );
+
+    void write_packets( FileDescriptor & fd );
+
+    unsigned int wait_time( void ) const;
+
+    bool pending_output( void ) const { return wait_time() <= 0; }
+
+    static bool finished( void ) { return false; }
+};
+
+#endif /* FILE_DELAY_QUEUE_HH */

src/frontend/filedelayshell.cc

@@ -0,0 +1,48 @@
+/* -*-mode:c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+#include <vector>
+#include <string>
+
+#include "file_delay_queue.hh"
+#include "util.hh"
+#include "ezio.hh"
+#include "packetshell.cc"
+
+using namespace std;
+
+int main( int argc, char *argv[] )
+{
+    try {
+        /* clear environment while running as root */
+        char ** const user_environment = environ;
+        environ = nullptr;
+
+        check_requirements( argc, argv );
+
+        if ( argc < 3 ) {
+            throw runtime_error( "Usage: " + string( argv[ 0 ] ) + " delay_file_name time_resolution_ms [command...]" );
+        }
+
+        string delay_file = argv[1];
+        uint64_t time_res_ms = std::stoi(argv[2]);
+
+        vector< string > command;
+
+        if ( argc == 3 ) {
+            command.push_back( shell_path() );
+        } else {
+            for ( int i = 3; i < argc; i++ ) {
+                command.push_back( argv[ i ] );
+            }
+        }
+
+        PacketShell<FileDelayQueue> file_delay_shell_app( "file-delay", user_environment );
+
+        file_delay_shell_app.start_uplink( "[delay " + delay_file + "]", command, delay_file, time_res_ms);
+        file_delay_shell_app.start_downlink( delay_file, time_res_ms );
+        return file_delay_shell_app.wait_for_exit();
+    } catch ( const exception & e ) {
+        print_exception( e );
+        return EXIT_FAILURE;
+    }
+}