AudioGraph::Task Struct Reference

Copies from a Source to a Sink, mediated by Buffers. More...

#include <AudioGraphTask.h>

Collaboration diagram for AudioGraph::Task:

Public Types
enum class	Status { More , Done , Fail }

Public Member Functions
	Task (Source &source, Buffers &buffers, Sink &sink)
Status	RunOnce ()
	Do an increment of the copy. More...
bool	RunLoop ()
	Do the complete copy. More...

Private Attributes
Source &	mSource
Buffers &	mBuffers
Sink &	mSink
bool	mRanOnce { false }

Detailed Description

Copies from a Source to a Sink, mediated by Buffers.

Definition at line 24 of file AudioGraphTask.h.

Member Enumeration Documentation

Status

enum class AudioGraph::Task::Status

strong

Enumerator
More
Done
Fail

Definition at line 32 of file AudioGraphTask.h.

{ More, Done, Fail };

Constructor & Destructor Documentation

Task()

AudioGraph::Task::Task	(	Source &	source,
		Buffers &	buffers,
		Sink &	sink
	)

Precondition

source.AcceptsBlockSize(buffers.BlockSize())

source.AcceptsBuffers(buffers)

sink.AcceptsBuffers(buffers)

Definition at line 21 of file AudioGraphTask.cpp.

   : mSource{ source }, mBuffers{ buffers }, mSink{ sink }
{
   assert(source.AcceptsBlockSize(buffers.BlockSize()));
   assert(source.AcceptsBuffers(buffers));
   assert(sink.AcceptsBuffers(buffers));
}

References AudioGraph::Source::AcceptsBlockSize(), AudioGraph::Sink::AcceptsBuffers(), AudioGraph::Source::AcceptsBuffers(), and AudioGraph::Buffers::BlockSize().

Here is the call graph for this function:

Member Function Documentation

RunLoop()

bool AudioGraph::Task::RunLoop

(

)

Do the complete copy.

Returns

success

Precondition

mBuffers.Remaining() >= mBuffers.BlockSize()

Postcondition

result: result == Status::Fail || mBuffers.Remaining() >= mBuffers.BlockSize()

Definition at line 29 of file AudioGraphTask.cpp.

{
   // Satisfy invariant initially
   mBuffers.Rewind();
   Status status{};
   do {
      assert(mBuffers.Remaining() >= mBuffers.BlockSize());
      status = RunOnce();
   } while (status == Status::More);
   return status == Status::Done;
}

RunOnce()

auto AudioGraph::Task::RunOnce

(

)

Do an increment of the copy.

Definition at line 41 of file AudioGraphTask.cpp.

{
   const auto blockSize = mBuffers.BlockSize();
   assert(mBuffers.Remaining() >= blockSize); // pre
 
#ifndef NDEBUG
   // Variable used only for a loop termination sanity check
   std::optional<sampleCount> oldRemaining;
   if (mRanOnce)
      oldRemaining.emplace(mSource.Remaining());
   // else Remaining() may not be meaningful
#endif
 
   if (auto oCurBlockSize = mSource.Acquire(mBuffers, blockSize)) {
      const auto curBlockSize = *oCurBlockSize;
#ifndef NDEBUG
      mRanOnce = true;
      const auto remaining = mSource.Remaining();
      // Assert a post of Acquire which is part of proof of termination
      assert(!mSource.Terminates() || !oldRemaining ||
         *oldRemaining == remaining);
      oldRemaining.emplace(remaining);
      // Assert another post that guarantees progress (even if not terminating)
      assert(blockSize == 0 || remaining == 0 || curBlockSize > 0);
#endif
      if (curBlockSize == 0)
         // post (same as pre) obviously preserved
         return Status::Done;
 
      // post of source.Acquire() satisfies pre of sink.Release()
      assert(curBlockSize <= blockSize);
      if (!mSink.Release(mBuffers, curBlockSize))
         return Status::Fail;
   
      // This may break the post
      mBuffers.Advance(curBlockSize);
 
      // posts of source.Acquire() and source.Release()
      // give termination guarantee
      assert(mSource.Remaining() == 0 || curBlockSize > 0);
      if (!mSource.Release())
         return Status::Fail;
#ifndef NDEBUG
      // Assert a post of Release
      assert(!mSource.Terminates() ||
         mSource.Remaining() == remaining - curBlockSize);
#endif
 
      // Reestablish the post
      if (!mSink.Acquire(mBuffers))
         return Status::Fail;
      assert(mBuffers.Remaining() >= blockSize);
 
      return Status::More;
   }
   else
      return Status::Fail;
}

Member Data Documentation

mBuffers

Buffers& AudioGraph::Task::mBuffers

private

Definition at line 45 of file AudioGraphTask.h.

mRanOnce

bool AudioGraph::Task::mRanOnce { false }

private

Definition at line 49 of file AudioGraphTask.h.

mSink

Sink& AudioGraph::Task::mSink

private

Definition at line 46 of file AudioGraphTask.h.

mSource

Source& AudioGraph::Task::mSource

private

Definition at line 44 of file AudioGraphTask.h.

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The documentation for this struct was generated from the following files:

• AudioGraphTask.h
• AudioGraphTask.cpp