void addPreTask( TaskBatch *batch, TaskBatchPtr preTask, bool forPostTask = false )
{
TaskBatches &preTasks = batch->preTasks();
if( std::find( preTasks.begin(), preTasks.end(), preTask ) == preTasks.end() )
{
if( forPostTask )
{
// We're adding the preTask because the batch is a postTask
// of it, but the batch may already have it's own standard
// preTasks. There's no strict requirement that we separate
// out these two types of preTasks (indeed a good dispatcher might
// execute them in parallel), but for simple dispatchers
// it's more intuitive to users if we separate them so the
// standard preTasks come second.
//
// See `DispatcherTest.testPostTaskWithPreTasks()` for an
// example.
IntDataPtr postTaskIndex = batch->blindData()->member<IntData>(
g_postTaskIndexBlindDataName, /* throwExceptions = */ false, /* createIfMissing = */ true
);
preTasks.insert( preTasks.begin() + postTaskIndex->readable(), preTask );
postTaskIndex->writable()++;
}
else
{
preTasks.push_back( preTask );
}
}
}
TaskBatchPtr acquireBatch( const TaskNode::Task &task )
{
// See if we've previously visited this task, and therefore
// have placed it in a batch already, which we can return
// unchanged. The `taskToBatchMapHash` is used as the unique
// identity of a task.
MurmurHash taskToBatchMapHash = task.hash();
// Prevent identical tasks from different nodes from being
// coalesced.
taskToBatchMapHash.append( (uint64_t)task.node() );
if( task.hash() == IECore::MurmurHash() )
{
// Prevent no-ops from coalescing into a single batch, as this
// would break parallelism - see `DispatcherTest.testNoOpDoesntBreakFrameParallelism()`
taskToBatchMapHash.append( contextHash( task.context() ) );
}
const TaskToBatchMap::const_iterator it = m_tasksToBatches.find( taskToBatchMapHash );
if( it != m_tasksToBatches.end() )
{
return it->second;
}
// We haven't seen this task before, so we need to find
// an appropriate batch to put it in. This may be one of
// our current batches, or we may need to make a new one
// entirely if the current batch is full.
const bool requiresSequenceExecution = task.plug()->requiresSequenceExecution();
TaskBatchPtr batch = nullptr;
const MurmurHash batchMapHash = batchHash( task );
BatchMap::iterator bIt = m_currentBatches.find( batchMapHash );
if( bIt != m_currentBatches.end() )
{
TaskBatchPtr candidateBatch = bIt->second;
// Unfortunately we have to track batch size separately from `batch->frames().size()`,
// because no-ops don't update `frames()`, but _do_ count towards batch size.
IntDataPtr batchSizeData = candidateBatch->blindData()->member<IntData>( g_sizeBlindDataName );
const IntPlug *batchSizePlug = task.node()->dispatcherPlug()->getChild<const IntPlug>( g_batchSize );
const int batchSizeLimit = ( batchSizePlug ) ? batchSizePlug->getValue() : 1;
if( requiresSequenceExecution || ( batchSizeData->readable() < batchSizeLimit ) )
{
batch = candidateBatch;
batchSizeData->writable()++;
}
}
if( !batch )
{
batch = new TaskBatch( task.plug(), task.context() );
batch->blindData()->writable()[g_sizeBlindDataName] = new IntData( 1 );
m_currentBatches[batchMapHash] = batch;
}
// Now we have an appropriate batch, update it to include
// the frame for our task, and any other relevant information.
if( task.hash() != MurmurHash() )
{
float frame = task.context()->getFrame();
std::vector<float> &frames = batch->frames();
if( requiresSequenceExecution )
{
frames.insert( std::lower_bound( frames.begin(), frames.end(), frame ), frame );
}
else
{
frames.push_back( frame );
}
}
const BoolPlug *immediatePlug = task.node()->dispatcherPlug()->getChild<const BoolPlug>( g_immediatePlugName );
if( immediatePlug && immediatePlug->getValue() )
{
/// \todo Should we be scoping a context for this, to allow the plug to
/// have expressions on it? If so, should we be doing the same before
/// calling requiresSequenceExecution()? Or should we instead require that
/// they always be constant?
batch->blindData()->writable()[g_immediateBlindDataName] = g_trueBoolData;
}
// Remember which batch we stored this task in, for
// the next time someone asks for it.
m_tasksToBatches[taskToBatchMapHash] = batch;
return batch;
}