Restart the device automatically if stuck with read stream errors

src/audio/AudioThread.cpp

@@ -84,7 +84,7 @@ static int audioCallback(void *outputBuffer, void * /* inputBuffer */, unsigned
     }
 
     if (status) {
-       std::cout << "Audio buffer underflow.." << (src->underflowCount++) << std::endl;
+       std::cout << "Audio buffer underflow.." << (src->underflowCount++) << std::endl << std::flush;
     }
 
     if (src->boundThreads.empty()) {

src/sdr/SoapySDRThread.cpp

@@ -8,6 +8,7 @@
 #include <string>
 #include <algorithm>
 #include <SoapySDR/Logger.h>
+#include <chrono>
 
 #define TARGET_DISPLAY_FPS 60
 
@@ -191,7 +192,7 @@ void SDRThread::assureBufferMinSize(SDRThreadIQData * dataOut, size_t minSize) {
 //Called in an infinite loop, read SaopySDR device to build 
 // a 'this.numElems' sized batch of samples (SDRThreadIQData) and push it into  iqDataOutQueue.
 //this batch of samples is built to represent 1 frame / TARGET_DISPLAY_FPS.
-void SDRThread::readStream(SDRThreadIQDataQueuePtr iqDataOutQueue) {
+int SDRThread::readStream(SDRThreadIQDataQueuePtr iqDataOutQueue) {
     int flags;
     long long timeNs;
 
@@ -234,6 +235,8 @@ void SDRThread::readStream(SDRThreadIQDataQueuePtr iqDataOutQueue) {
         }
     } //end if numOverflow > 0
     
+    int readStreamCode = 0;
+
     //2. attempt readStream() at most nElems, by mtElems-sized chunks, append in dataOut->data directly.
     while (n_read < nElems && !stopping) {
         
@@ -241,6 +244,8 @@ void SDRThread::readStream(SDRThreadIQDataQueuePtr iqDataOutQueue) {
         //from which SoapySDR effectively returns n_stream_read.
         int n_stream_read = device->readStream(stream, buffs, mtElems, flags, timeNs);
         
+        readStreamCode = n_stream_read;
+
         //if the n_stream_read <= 0, bail out from reading. 
         if (n_stream_read == 0) {
              std::cout << "SDRThread::readStream(): 2. SoapySDR read blocking..." << std::endl;
@@ -362,10 +367,15 @@ void SDRThread::readStream(SDRThreadIQDataQueuePtr iqDataOutQueue) {
         //saturation, let a chance to the other threads to consume the existing samples
         std::this_thread::yield();
     }
+
+    return readStreamCode;
 }
 
+
 void SDRThread::readLoop() {
 
+    #define STREAM_READ_WATCHDOG_S (2)
+    
     SDRThreadIQDataQueuePtr iqDataOutQueue = std::static_pointer_cast<SDRThreadIQDataQueue>( getOutputQueue("IQDataOutput"));
     
     if (iqDataOutQueue == nullptr) {
@@ -374,10 +384,35 @@ void SDRThread::readLoop() {
     
     updateGains();
     
+    auto streamWatchDog = std::chrono::steady_clock::now();
+
     while (!stopping.load()) {
+
         updateSettings();
-        readStream(iqDataOutQueue);
+
+        if (readStream(iqDataOutQueue) > 0) {
+            // record the date of the last good read.
+            streamWatchDog = std::chrono::steady_clock::now();
         }
+
+        auto now = std::chrono::steady_clock::now();
+
+        //check watchdog value: if the date is too old, deinit end init the device.
+        std::chrono::duration<double> diff = now - streamWatchDog;
+
+        if (diff.count() > STREAM_READ_WATCHDOG_S) {
+            
+            std::cout << "SDRThread::readStream(): Restarting stream after too many read erros..." << std::endl << std::flush;
+            
+            deinit();
+            init();
+
+            streamWatchDog = std::chrono::steady_clock::now();
+
+            std::cout << "SDRThread::readStream(): stream restarted." << std::endl << std::flush;
+        }
+    } //End while
+
     iqDataOutQueue->flush();
 }
 

src/sdr/SoapySDRThread.h

@@ -47,12 +47,17 @@ class SDRThread : public IOThread {
 private:
     bool init();
     void deinit();
-    void readStream(SDRThreadIQDataQueuePtr iqDataOutQueue);
+    
+    //returns the SoapyDevice readStream return value,
+    //i.e if >= 0 the numbre of samples read, else if < 0 an error code.
+    int readStream(SDRThreadIQDataQueuePtr iqDataOutQueue);
+
     void readLoop();
 
 public:
     SDRThread();
     ~SDRThread();
+
     enum SDRThreadState { SDR_THREAD_MESSAGE, SDR_THREAD_INITIALIZED, SDR_THREAD_FAILED};
     
     virtual void run();