fix: use wait condition to rewrite datarequest (#1015)

* fix: use wait condition for datarequest

* fix: rewrite byteAvailable

* [autofix.ci] apply automated fixes

* fix: rewrite qwaitcondition

* [autofix.ci] apply automated fixes

* opt: wait condition

* [autofix.ci] apply automated fixes

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/article_netmgr.cc

@@ -406,15 +406,17 @@ qint64 ArticleResourceReply::bytesAvailable() const
   if ( avail < 0 )
     return 0;
 
+  if ( !req->isFinished() ) {
+    return 65536;
+  }
+
   return avail - alreadyRead + QNetworkReply::bytesAvailable();
 }
 
+
 bool ArticleResourceReply::atEnd() const
 {
-  // QWebEngineUrlRequestJob finishes and is destroyed as soon as QIODevice::atEnd() returns true.
-  // QNetworkReply::atEnd() returns true while bytesAvailable() returns 0.
-  // Return false if the data request is not finished to work around always-blank web page.
-  return req->isFinished() && QNetworkReply::atEnd();
+  return req->isFinished() && bytesAvailable() == 0;
 }
 
 qint64 ArticleResourceReply::readData( char * out, qint64 maxSize )
@@ -431,20 +433,12 @@ qint64 ArticleResourceReply::readData( char * out, qint64 maxSize )
   if ( avail < 0 )
     return finished ? -1 : 0;
 
+
   qint64 left = avail - alreadyRead;
 
-  if ( left == 0 && !finished ) {
-    // Work around endlessly repeated useless calls to readData(). The sleep duration is a tradeoff.
-    // On the one hand, lowering the duration reduces CPU usage. On the other hand, overly long
-    // sleep duration reduces page content update frequency in the web view.
-    // Waiting on a condition variable is more complex and actually works worse than
-    // simple fixed-duration sleeping, because the web view is not updated until
-    // the data request is finished if readData() returns only when new data arrives.
-    QThread::msleep( 30 );
-    return 0;
-  }
-
   qint64 toRead = maxSize < left ? maxSize : left;
+  if ( !toRead && finished )
+    return -1;
   GD_DPRINTF( "====reading  %d of (%lld) bytes . Finished: %d", (int)toRead, avail, finished );
 
   try {

src/article_netmgr.hh

@@ -180,7 +180,7 @@ public:
 protected:
 
   virtual qint64 bytesAvailable() const;
-  bool atEnd() const override;
+  bool atEnd() const;
   virtual void abort() {}
   virtual qint64 readData( char * data, qint64 maxSize );
 

src/dict/dictionary.cc

@@ -32,16 +32,19 @@ bool Request::isFinished()
 
 void Request::update()
 {
-  if ( !Utils::AtomicInt::loadAcquire( isFinishedFlag ) )
+  if ( !Utils::AtomicInt::loadAcquire( isFinishedFlag ) ) {
     emit updated();
+  }
 }
 
 void Request::finish()
 {
   if ( !Utils::AtomicInt::loadAcquire( isFinishedFlag ) ) {
     isFinishedFlag.ref();
-
     emit finished();
+
+    QMutexLocker _( &dataMutex );
+    cond.wakeAll();
   }
 }
 
@@ -103,8 +106,13 @@ void WordSearchRequest::addMatch( WordMatch const & match )
 long DataRequest::dataSize()
 {
   QMutexLocker _( &dataMutex );
+  long size = hasAnyData ? (long)data.size() : -1;
 
-  return hasAnyData ? (long)data.size() : -1;
+  if ( size == 0 && !isFinished() ) {
+    cond.wait( &dataMutex );
+    size = hasAnyData ? (long)data.size() : -1;
+  }
+  return size;
 }
 
 void DataRequest::appendDataSlice( const void * buffer, size_t size )
@@ -116,6 +124,7 @@ void DataRequest::appendDataSlice( const void * buffer, size_t size )
   data.resize( data.size() + size );
 
   memcpy( &data.front() + offset, buffer, size );
+  cond.wakeAll();
 }
 
 void DataRequest::appendString( std::string_view str )
@@ -123,13 +132,14 @@ void DataRequest::appendString( std::string_view str )
   QMutexLocker _( &dataMutex );
   data.reserve( data.size() + str.size() );
   data.insert( data.end(), str.begin(), str.end() );
+  cond.wakeAll();
 }
 
 void DataRequest::getDataSlice( size_t offset, size_t size, void * buffer )
 {
-  if ( size == 0 )
+  if ( size == 0 ) {
     return;
-
+  }
   QMutexLocker _( &dataMutex );
 
   if ( !hasAnyData )
@@ -178,7 +188,7 @@ sptr< WordSearchRequest > Class::findHeadwordsForSynonym( wstring const & )
 
 vector< wstring > Class::getAlternateWritings( wstring const & ) noexcept
 {
-  return vector< wstring >();
+  return {};
 }
 
 QString Class::getContainingFolder() const
@@ -190,7 +200,7 @@ QString Class::getContainingFolder() const
     return fileInfo.absolutePath();
   }
 
-  return QString();
+  return {};
 }
 
 sptr< DataRequest > Class::getResource( string const & /*name*/ )
@@ -211,7 +221,7 @@ QString const & Class::getDescription()
 
 QString Class::getMainFilename()
 {
-  return QString();
+  return {};
 }
 
 QIcon const & Class::getIcon() noexcept

src/dict/dictionary.hh

@@ -104,7 +104,6 @@ signals:
   void matchCount( int );
 
 protected:
-
   /// Called by derivatives to signal update().
   void update();
 
@@ -113,6 +112,10 @@ protected:
 
   /// Sets the error string to be returned by getErrorString().
   void setErrorString( QString const & );
+  QWaitCondition cond;
+  // Subclasses should be filling up the 'data' array, locking the mutex when
+  // whey work with it.
+  QMutex dataMutex;
 
 private:
 
@@ -225,11 +228,6 @@ public:
   }
 
 protected:
-
-  // Subclasses should be filling up the 'data' array, locking the mutex when
-  // whey work with it.
-  QMutex dataMutex;
-
   bool hasAnyData; // With this being false, dataSize() always returns -1
   vector< char > data;
 };