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#include <Processors/ForkProcessor.h>
namespace DB
{
ForkProcessor::Status ForkProcessor::prepare()
{
auto & input = inputs.front();
/// Check can output.
bool all_can_push = true;
size_t num_active_outputs = 0;
for (const auto & output : outputs)
{
if (!output.isFinished())
{
++num_active_outputs;
/// The order is important.
if (!output.canPush())
all_can_push = false;
}
}
if (0 == num_active_outputs)
{
input.close();
return Status::Finished;
}
if (!all_can_push)
{
input.setNotNeeded();
return Status::PortFull;
}
/// Check can input.
if (input.isFinished())
{
for (auto & output : outputs)
output.finish();
return Status::Finished;
}
input.setNeeded();
if (!input.hasData())
return Status::NeedData;
/// Move data.
auto data = input.pull();
size_t num_processed_outputs = 0;
for (auto & output : outputs)
{
if (!output.isFinished()) /// Skip finished outputs.
{
++num_processed_outputs;
if (num_processed_outputs == num_active_outputs)
output.push(std::move(data)); /// NOLINT Can push because no full or unneeded outputs.
else
output.push(data.clone()); /// NOLINT
}
}
/// Now, we pulled from input. It must be empty.
return Status::NeedData;
}
}
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