From c7bcfaead179bfa9470ed0eff3673a15ac3ba12c Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Wed, 29 Aug 2018 08:48:57 +0200
Subject: [PATCH] SDRdaemon: channel source data read queue: scale max length
 to sample rate

---
 sdrdaemon/channel/sdrdaemonchannelsource.cpp | 13 ++++++++++++-
 sdrdaemon/channel/sdrdaemonchannelsource.h   |  1 +
 sdrdaemon/channel/sdrdaemondatareadqueue.cpp | 18 +++++++++++++-----
 sdrdaemon/channel/sdrdaemondatareadqueue.h   |  6 ++++--
 4 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/sdrdaemon/channel/sdrdaemonchannelsource.cpp b/sdrdaemon/channel/sdrdaemonchannelsource.cpp
index 8d6131eae..d51ca6680 100644
--- a/sdrdaemon/channel/sdrdaemonchannelsource.cpp
+++ b/sdrdaemon/channel/sdrdaemonchannelsource.cpp
@@ -265,8 +265,10 @@ void SDRDaemonChannelSource::handleDataBlock(SDRDaemonDataBlock* dataBlock)
                         m_deviceAPI->getSampleSink()->setCenterFrequency(metaData->m_centerFrequency);
                     }
 
-                    if (m_currentMeta.m_sampleRate != metaData->m_sampleRate) {
+                    if (m_currentMeta.m_sampleRate != metaData->m_sampleRate)
+                    {
                         m_channelizer->configure(m_channelizer->getInputMessageQueue(), metaData->m_sampleRate, 0);
+                        m_dataReadQueue.setSize(calculateDataReadQueueSize(metaData->m_sampleRate));
                     }
                 }
 
@@ -304,3 +306,12 @@ void SDRDaemonChannelSource::printMeta(const QString& header, SDRDaemonMetaDataF
             << ":" << metaData->m_tv_usec
             << "|";
 }
+
+uint32_t SDRDaemonChannelSource::calculateDataReadQueueSize(int sampleRate)
+{
+    // scale for 20 blocks at 48 kS/s. Take next even number.
+    uint32_t maxSize = sampleRate / 2400;
+    maxSize = (maxSize % 2 == 0) ? maxSize : maxSize + 1;
+    qDebug("SDRDaemonChannelSource::calculateDataReadQueueSize: set max queue size to %u blocks", maxSize);
+    return maxSize;
+}
diff --git a/sdrdaemon/channel/sdrdaemonchannelsource.h b/sdrdaemon/channel/sdrdaemonchannelsource.h
index f61c5cca1..e743b3418 100644
--- a/sdrdaemon/channel/sdrdaemonchannelsource.h
+++ b/sdrdaemon/channel/sdrdaemonchannelsource.h
@@ -106,6 +106,7 @@ private:
     void applySettings(const SDRDaemonChannelSourceSettings& settings, bool force = false);
     void handleDataBlock(SDRDaemonDataBlock *dataBlock);
     void printMeta(const QString& header, SDRDaemonMetaDataFEC *metaData);
+    uint32_t calculateDataReadQueueSize(int sampleRate);
 
 private slots:
     void handleData();
diff --git a/sdrdaemon/channel/sdrdaemondatareadqueue.cpp b/sdrdaemon/channel/sdrdaemondatareadqueue.cpp
index 7081ee569..7dc92be51 100644
--- a/sdrdaemon/channel/sdrdaemondatareadqueue.cpp
+++ b/sdrdaemon/channel/sdrdaemondatareadqueue.cpp
@@ -23,10 +23,11 @@
 #include "channel/sdrdaemondatablock.h"
 #include "channel/sdrdaemondatareadqueue.h"
 
-const uint32_t SDRDaemonDataReadQueue::MaxSize = 20;
+const uint32_t SDRDaemonDataReadQueue::MinimumMaxSize = 10;
 
 SDRDaemonDataReadQueue::SDRDaemonDataReadQueue() :
         m_dataBlock(0),
+        m_maxSize(MinimumMaxSize),
         m_blockIndex(1),
         m_sampleIndex(0),
         m_full(false)
@@ -45,7 +46,7 @@ SDRDaemonDataReadQueue::~SDRDaemonDataReadQueue()
 
 void SDRDaemonDataReadQueue::push(SDRDaemonDataBlock* dataBlock)
 {
-    if (size() >= MaxSize)
+    if (size() >= m_maxSize)
     {
         qWarning("SDRDaemonDataReadQueue::push: queue is full");
         m_full = true; // stop filling the queue
@@ -54,7 +55,7 @@ void SDRDaemonDataReadQueue::push(SDRDaemonDataBlock* dataBlock)
     }
 
     if (m_full) {
-        m_full = (size() > MaxSize/2); // do not fill queue again before queue is half size
+        m_full = (size() > m_maxSize/2); // do not fill queue again before queue is half size
     }
 
     if (!m_full) {
@@ -77,17 +78,24 @@ SDRDaemonDataBlock* SDRDaemonDataReadQueue::pop()
     }
 }
 
-uint32_t SDRDaemonDataReadQueue::size()
+uint32_t SDRDaemonDataReadQueue::size() const
 {
     return m_dataReadQueue.size();
 }
 
+void SDRDaemonDataReadQueue::setSize(uint32_t size)
+{
+    if (size != m_maxSize) {
+        m_maxSize = size < MinimumMaxSize ? MinimumMaxSize : size;
+    }
+}
+
 void SDRDaemonDataReadQueue::readSample(Sample& s)
 {
     // depletion/repletion state
     if (m_dataBlock == 0)
     {
-        if (size() >= MaxSize/2)
+        if (size() >= m_maxSize/2)
         {
             qDebug("SDRDaemonDataReadQueue::readSample: initial pop new block: queue size: %u", size());
             m_blockIndex = 1;
diff --git a/sdrdaemon/channel/sdrdaemondatareadqueue.h b/sdrdaemon/channel/sdrdaemondatareadqueue.h
index 7caa3e5e6..fe9a88edc 100644
--- a/sdrdaemon/channel/sdrdaemondatareadqueue.h
+++ b/sdrdaemon/channel/sdrdaemondatareadqueue.h
@@ -37,13 +37,15 @@ public:
     void push(SDRDaemonDataBlock* dataBlock); //!< push block on the queue
     SDRDaemonDataBlock* pop();                //!< Pop block from the queue
     void readSample(Sample& s);               //!< Read sample from queue
-    uint32_t size();                          //!< Returns queue size
+    uint32_t size() const;                    //!< Returns queue size
+    void setSize(uint32_t size);              //!< Sets the queue size
 
-    static const uint32_t MaxSize;
+    static const uint32_t MinimumMaxSize;
 
 private:
     QQueue<SDRDaemonDataBlock*> m_dataReadQueue;
     SDRDaemonDataBlock *m_dataBlock;
+    uint32_t m_maxSize;
     uint32_t m_blockIndex;
     uint32_t m_sampleIndex;
     bool m_full; //!< full condition was hit