(re)introduce timeout in HardwareSerial::readBytes(buffer, size) (#5558)

(re)introduce timeout in HardwareSerial::readBytes(buffer, size), add HardwareSerial::read(buffer, size) + visual test

cores/esp8266/HardwareSerial.cpp

@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <inttypes.h>
+#include <PolledTimeout.h>
 #include "Arduino.h"
 #include "HardwareSerial.h"
 #include "Esp.h"
@@ -132,6 +133,22 @@ unsigned long HardwareSerial::detectBaudrate(time_t timeoutMillis)
     return detectedBaudrate;
 }
 
+size_t HardwareSerial::readBytes(char* buffer, size_t size)
+{
+    size_t got = 0;
+
+    while (got < size)
+    {
+        esp8266::polledTimeout::oneShot timeOut(_timeout);
+        size_t avail;
+        while ((avail = available()) == 0 && !timeOut);
+        if (avail == 0)
+            break;
+        got += read(buffer + got, std::min(size - got, avail));
+    }
+    return got;
+}
+
 #if !defined(NO_GLOBAL_INSTANCES) && !defined(NO_GLOBAL_SERIAL)
 HardwareSerial Serial(UART0);
 #endif

cores/esp8266/HardwareSerial.h

@@ -132,13 +132,15 @@ public:
         // return -1 when data is unvailable (arduino api)
         return uart_read_char(_uart);
     }
-    size_t readBytes(char* buffer, size_t size) override
+    // ::read(buffer, size): same as readBytes without timeout
+    size_t read(char* buffer, size_t size)
     {
         return uart_read(_uart, buffer, size);
     }
+    size_t readBytes(char* buffer, size_t size) override;
     size_t readBytes(uint8_t* buffer, size_t size) override
     {
-        return uart_read(_uart, (char*)buffer, size);
+        return readBytes((char*)buffer, size);
     }
     int availableForWrite(void)
     {

libraries/esp8266/examples/SerialStress/SerialStress.ino

@@ -16,12 +16,15 @@
 #define BUFFER_SIZE     4096    // may be useless to use more than 2*SERIAL_SIZE_RX
 #define SERIAL_SIZE_RX  1024    // Serial.setRxBufferSize()
 
+#define FAKE_INCREASED_AVAILABLE 100 // test readBytes's timeout
+
 #define TIMEOUT 5000
 #define DEBUG(x...) //x
 
 uint8_t buf [BUFFER_SIZE];
 uint8_t temp [BUFFER_SIZE];
 bool reading = true;
+size_t testReadBytesTimeout = 0;
 
 static size_t out_idx = 0, in_idx = 0;
 static size_t local_receive_size = 0;
@@ -83,6 +86,7 @@ void setup() {
   size_for_1sec = baud / 10; // 8n1=10baudFor8bits
   logger->printf("led changes state every %zd bytes (= 1 second)\n", size_for_1sec);
   logger->printf("press 's' to stop reading, not writing (induces overrun)\n");
+  logger->printf("press 't' to toggle timeout testing on readBytes\n");
 
   // prepare send/compare buffer
   for (size_t i = 0; i < sizeof buf; i++) {
@@ -136,7 +140,7 @@ void loop() {
 
   if (reading) {
     // receive data
-    maxlen = Serial.available();
+    maxlen = Serial.available() + testReadBytesTimeout;
     if (maxlen > maxavail) {
       maxavail = maxlen;
     }
@@ -180,8 +184,16 @@ void loop() {
     timeout = (last_ms = now_ms) + TIMEOUT;
   }
 
-  if (logger->read() == 's') {
+  if (logger->available())
+    switch (logger->read()) {
+      case 's':
         logger->println("now stopping reading, keeping writing");
         reading = false;
+        break;
+      case 't':
+        testReadBytesTimeout ^= FAKE_INCREASED_AVAILABLE;
+        logger->printf("testing readBytes timeout: %d\n", !!testReadBytesTimeout);
+        break;
+      default:;
     }
 }

tests/host/common/MockSerial.cpp

@@ -30,6 +30,7 @@
 */
 
 #include <Arduino.h>
+#include <PolledTimeout.h>
 
 #include <unistd.h> // write
 
@@ -64,6 +65,22 @@ void HardwareSerial::flush ()
 	fflush(stdout);
 }
 
+size_t HardwareSerial::readBytes(char* buffer, size_t size)
+{
+    size_t got = 0;
+
+    while (got < size)
+    {
+        esp8266::polledTimeout::oneShot timeOut(_timeout);
+        size_t avail;
+        while ((avail = available()) == 0 && !timeOut);
+        if (avail == 0)
+            break;
+        got += read(buffer + got, std::min(size - got, avail));
+    }
+    return got;
+}
+
 // uart.c
 
 extern "C"