lwip - Added windowing to tcp packet pressure tests

Despite being able to buffer an arbitrary stream of data,
TCP send is still limited by the available buffer space in the
network stack. Errors from TCP send are perfectly reasonable
and should be handled by reducing the buffer that is attempted.

Author: geky

features/FEATURE_LWIP/TESTS/mbedmicro-net/tcp_packet_pressure/main.cpp

@@ -156,29 +156,40 @@ int main() {
         RandSeq rx_seq;
         size_t rx_count = 0;
         size_t tx_count = 0;
+        size_t window = buffer_size;
 
         while (tx_count < size || rx_count < size) {
             // Send out data
             if (tx_count < size) {
                 size_t chunk_size = size - tx_count;
-                if (chunk_size > buffer_size) {
-                    chunk_size = buffer_size;
+                if (chunk_size > window) {
+                    chunk_size = window;
                 }
 
                 tx_seq.buffer(buffer, chunk_size);
                 int td = sock.send(buffer, chunk_size);
-                TEST_ASSERT(td > 0 || td == NSAPI_ERROR_WOULD_BLOCK);
+
                 if (td > 0) {
                     if (MBED_CFG_TCP_CLIENT_PACKET_PRESSURE_DEBUG) {
                         printf("TCP: tx -> %d\r\n", td);
                     }
                     tx_seq.skip(td);
                     tx_count += td;
+                } else if (td != NSAPI_ERROR_WOULD_BLOCK) {
+                    // We may fail to send because of buffering issues,
+                    // cut buffer in half
+                    if (window > MBED_CFG_TCP_CLIENT_PACKET_PRESSURE_MIN) {
+                        window /= 2;
+                    }
+
+                    if (MBED_CFG_TCP_CLIENT_PACKET_PRESSURE_DEBUG) {
+                        printf("TCP: Not sent (%d), window = %d\r\n", td, window);
+                    }
                 }
             }
 
             // Verify recieved data
-            if (rx_count < size) {
+            while (rx_count < size) {
                 int rd = sock.recv(buffer, buffer_size);
                 TEST_ASSERT(rd > 0 || rd == NSAPI_ERROR_WOULD_BLOCK);
                 if (rd > 0) {
@@ -189,6 +200,8 @@ int main() {
                     TEST_ASSERT_EQUAL(0, diff);
                     rx_seq.skip(rd);
                     rx_count += rd;
+                } else if (rd == NSAPI_ERROR_WOULD_BLOCK) {
+                    break;
                 }
             }
         }

features/FEATURE_LWIP/TESTS/mbedmicro-net/tcp_packet_pressure_parallel/main.cpp

@@ -153,18 +153,19 @@ class PressureTest {
             RandSeq rx_seq;
             size_t rx_count = 0;
             size_t tx_count = 0;
+            size_t window = buffer_size;
 
             while (tx_count < size || rx_count < size) {
                 // Send out data
                 if (tx_count < size) {
                     size_t chunk_size = size - tx_count;
-                    if (chunk_size > buffer_size) {
-                        chunk_size = buffer_size;
+                    if (chunk_size > window) {
+                        chunk_size = window;
                     }
 
                     tx_seq.buffer(buffer, chunk_size);
                     int td = sock.send(buffer, chunk_size);
-                    TEST_ASSERT(td > 0 || td == NSAPI_ERROR_WOULD_BLOCK);
+
                     if (td > 0) {
                         if (MBED_CFG_TCP_CLIENT_PACKET_PRESSURE_DEBUG) {
                             iomutex.lock();
@@ -173,11 +174,23 @@ class PressureTest {
                         }
                         tx_seq.skip(td);
                         tx_count += td;
+                    } else if (td != NSAPI_ERROR_WOULD_BLOCK) {
+                        // We may fail to send because of buffering issues,
+                        // cut buffer in half
+                        if (window > MBED_CFG_TCP_CLIENT_PACKET_PRESSURE_MIN) {
+                            window /= 2;
+                        }
+
+                        if (MBED_CFG_TCP_CLIENT_PACKET_PRESSURE_DEBUG) {
+                            iomutex.lock();
+                            printf("TCP: Not sent (%d), window = %d\r\n", td, window);
+                            iomutex.unlock();
+                        }
                     }
                 }
 
                 // Verify recieved data
-                if (rx_count < size) {
+                while (rx_count < size) {
                     int rd = sock.recv(buffer, buffer_size);
                     TEST_ASSERT(rd > 0 || rd == NSAPI_ERROR_WOULD_BLOCK);
                     if (rd > 0) {
@@ -190,6 +203,8 @@ class PressureTest {
                         TEST_ASSERT_EQUAL(0, diff);
                         rx_seq.skip(rd);
                         rx_count += rd;
+                    } else if (rd == NSAPI_ERROR_WOULD_BLOCK) {
+                        break;
                     }
                 }
             }