Rewrite BBR handling of limited applications

UnitTest1/unittest1.cpp

@@ -523,6 +523,13 @@ namespace UnitTest1
             Assert::AreEqual(ret, 0);
         }
 
+        TEST_METHOD(datagram_small_packet)
+        {
+            int ret = datagram_small_packet_test();
+
+            Assert::AreEqual(ret, 0);
+        }
+
         TEST_METHOD(datagram_wifi)
         {
             int ret = datagram_wifi_test();

picoquic/bbr.c

@@ -526,27 +526,35 @@ void BBRUpdateBtlBw(picoquic_bbr_state_t* bbr_state, picoquic_path_t* path_x, ui
     BBRltbwSampling(bbr_state, path_x, current_time);
 
     if (bbr_state->round_start) {
-        /* Forget the oldest BW round, shift by 1, compute the max BTL_BW for
-         * the remaining rounds, set current round max to current value */
-
-        bbr_state->btl_bw = 0;
-
-        for (int i = BBR_BTL_BW_FILTER_LENGTH - 2; i >= 0; i--) {
-            uint64_t b = bbr_state->btl_bw_filter[i];
-            bbr_state->btl_bw_filter[i + 1] = b;
-            if (b > bbr_state->btl_bw) {
-                bbr_state->btl_bw = b;
+        if (bandwidth_estimate > bbr_state->btl_bw ||
+            !path_x->last_bw_estimate_path_limited) {
+            /* Forget the oldest BW round, shift by 1, compute the max BTL_BW for
+            * the remaining rounds, set current round max to current value */
+            bbr_state->btl_bw = 0;
+            for (int i = BBR_BTL_BW_FILTER_LENGTH - 2; i >= 0; i--) {
+                uint64_t b = bbr_state->btl_bw_filter[i];
+                bbr_state->btl_bw_filter[i + 1] = b;
+                if (b > bbr_state->btl_bw) {
+                    bbr_state->btl_bw = b;
+                }
+            }
+            bbr_state->btl_bw_increased |= (bandwidth_estimate > bbr_state->btl_bw_filter[0]);
+            bbr_state->btl_bw_filter[0] = bandwidth_estimate;
+            if (bandwidth_estimate > bbr_state->btl_bw) {
+                bbr_state->btl_bw = bandwidth_estimate;
             }
         }
-
-        bbr_state->btl_bw_filter[0] = 0;
+        else {
+            bbr_state->btl_bw_increased = 0;
+        }
     }
-
-    if (bandwidth_estimate > bbr_state->btl_bw_filter[0]) {
-        bbr_state->btl_bw_filter[0] =bandwidth_estimate;
-        if (bandwidth_estimate > bbr_state->btl_bw) {
-            bbr_state->btl_bw = bandwidth_estimate;
-            bbr_state->btl_bw_increased = 1;
+    else {
+        if (bandwidth_estimate > bbr_state->btl_bw_filter[0]) {
+            bbr_state->btl_bw_filter[0] =bandwidth_estimate;
+            if (bandwidth_estimate > bbr_state->btl_bw) {
+                bbr_state->btl_bw = bandwidth_estimate;
+                bbr_state->btl_bw_increased = 1;
+            }
         }
     }
 }

picoquic_t/picoquic_t.c

@@ -124,6 +124,7 @@ static const picoquic_test_def_t test_table[] = {
     { "datagram_size", datagram_size_test },
     { "datagram_small", datagram_small_test },
     { "datagram_small_new", datagram_small_new_test },
+    { "datagram_small_packet", datagram_small_packet_test },
     { "datagram_wifi", datagram_wifi_test },
     { "ddos_amplification", ddos_amplification_test },
     { "ddos_amplification_0rtt", ddos_amplification_0rtt_test },

picoquictest/datagram_tests.c

@@ -92,7 +92,7 @@ int test_datagram_send(picoquic_cnx_t* cnx, uint64_t unique_path_id,
         skipping = 1;
         if (dg_ctx->use_extended_provider_api) {
             is_active = test_datagram_check_ready(dg_ctx, cnx->client_mode, current_time);
-            (void)picoquic_provide_datagram_buffer_ex(bytes, 0, is_active);
+            (void)picoquic_provide_datagram_buffer_ex(bytes, 0, (is_active && !dg_ctx->one_datagram_per_packet));
         }
     }
     else if (!dg_ctx->is_ready[cnx->client_mode] || (dg_ctx->test_affinity && unique_path_id != 0)) {
@@ -119,7 +119,9 @@ int test_datagram_send(picoquic_cnx_t* cnx, uint64_t unique_path_id,
             if (dg_ctx->test_affinity) {
                 is_active = picoquic_datagram_active_this_path_only;
             }
+            is_active &= !dg_ctx->one_datagram_per_packet;
             buffer = picoquic_provide_datagram_buffer_ex(bytes, available, is_active);
+            dg_ctx->is_ready[cnx->client_mode] = is_active;
         }
         else {
             buffer = picoquic_provide_datagram_buffer(bytes, available);
@@ -269,6 +271,10 @@ int datagram_test_one(uint8_t test_id, test_datagram_send_recv_ctx_t *dg_ctx, ui
             test_ctx->c_to_s_link->microsec_latency = dg_ctx->link_latency;
             test_ctx->s_to_c_link->microsec_latency = dg_ctx->link_latency;
         }
+        if (dg_ctx->picosec_per_byte != 0) {
+            test_ctx->c_to_s_link->picosec_per_byte = dg_ctx->picosec_per_byte;
+            test_ctx->s_to_c_link->picosec_per_byte = dg_ctx->picosec_per_byte;
+        }
         /* Set parameters */
         picoquic_init_transport_parameters(&client_parameters, 1);
         client_parameters.max_datagram_frame_size = dg_ctx->dg_max_size;
@@ -602,3 +608,24 @@ int datagram_wifi_test()
 
     return datagram_test_one(8, &dg_ctx, 0);
 }
+
+int datagram_small_packet_test()
+{
+    test_datagram_send_recv_ctx_t dg_ctx = { 0 };
+    dg_ctx.dg_max_size = 512;
+    dg_ctx.dg_small_size = 64;
+    dg_ctx.dg_target[0] = 100;
+    dg_ctx.dg_target[1] = 20000;
+    dg_ctx.send_delay = 100;
+    dg_ctx.next_gen_time[0] = 50000;
+    dg_ctx.next_gen_time[1] = 50000;
+    dg_ctx.link_latency = 10000;
+    dg_ctx.picosec_per_byte = 20000; /* 400 Mbps */
+    dg_ctx.dg_latency_target[0] = 100000;
+    dg_ctx.dg_latency_target[1] = 100000;
+    dg_ctx.use_extended_provider_api = 1;
+    dg_ctx.one_datagram_per_packet = 1;
+    dg_ctx.nb_trials_max = 200000;
+
+    return datagram_test_one(9, &dg_ctx, 0);
+}

picoquictest/picoquictest.h

@@ -322,6 +322,7 @@ int datagram_loss_test();
 int datagram_size_test();
 int datagram_small_test();
 int datagram_small_new_test();
+int datagram_small_packet_test();
 int datagram_wifi_test();
 int ddos_amplification_test();
 int ddos_amplification_0rtt_test();

picoquictest/picoquictest_internal.h

@@ -69,6 +69,7 @@ typedef struct st_test_datagram_send_recv_ctx_t {
     uint64_t dg_latency_target[2];
     uint64_t dg_number_delta_target[2];
     uint64_t link_latency;
+    uint64_t picosec_per_byte;
     uint64_t send_delay;
     uint64_t next_gen_time[2];
     int is_ready[2];
@@ -82,6 +83,7 @@ typedef struct st_test_datagram_send_recv_ctx_t {
     unsigned int is_skipping[2];
     unsigned int test_affinity;
     unsigned int test_wifi;
+    unsigned int one_datagram_per_packet;
 
 } test_datagram_send_recv_ctx_t;