BuildValue ExternalCommand::
getResultForOutput(Node* node, const BuildValue& value) {
// If the value was a failed or skipped command, propagate the failure.
if (value.isFailedCommand() || value.isSkippedCommand())
return BuildValue::makeFailedInput();
// Otherwise, we should have a successful command -- return the actual
// result for the output.
assert(value.isSuccessfulCommand());
// If the node is virtual, the output is always a virtual input value.
if (static_cast<BuildNode*>(node)->isVirtual()) {
return BuildValue::makeVirtualInput();
}
// Find the index of the output node.
//
// FIXME: This is O(N). We don't expect N to be large in practice, but it
// could be.
auto it = std::find(outputs.begin(), outputs.end(), node);
assert(it != outputs.end());
auto idx = it - outputs.begin();
assert(idx < value.getNumOutputs());
auto& info = value.getNthOutputInfo(idx);
if (info.isMissing())
return BuildValue::makeMissingOutput();
return BuildValue::makeExistingInput(info);
}
void ExternalCommand::providePriorValue(BuildSystemCommandInterface&,
core::Task*,
const BuildValue& value) {
if (value.isSuccessfulCommand()) {
hasPriorResult = true;
priorResultCommandSignature = value.getCommandSignature();
}
}
bool ExternalCommand::isResultValid(BuildSystem& system,
const BuildValue& value) {
// Treat the command as always out-of-date, if requested.
if (alwaysOutOfDate)
return false;
// If the prior value wasn't for a successful command, recompute.
if (!value.isSuccessfulCommand())
return false;
// If the command's signature has changed since it was built, rebuild.
if (value.getCommandSignature() != getSignature())
return false;
// Check the timestamps on each of the outputs.
for (unsigned i = 0, e = outputs.size(); i != e; ++i) {
auto* node = outputs[i];
// Ignore virtual outputs.
if (node->isVirtual())
continue;
// Rebuild if the output information has changed.
//
// We intentionally allow missing outputs here, as long as they haven't
// changed. This is under the assumption that the commands themselves are
// behaving correctly when they exit successfully, and that downstream
// commands would diagnose required missing inputs.
//
// FIXME: CONSISTENCY: One consistency issue in this model currently is that
// if the output was missing, then appears, nothing will remove it; that
// results in an inconsistent build. What would be nice if we supported
// per-edge annotations on whether an output was optional -- in that case we
// could enforce and error on the missing output if not annotated, and we
// could enable behavior to remove such output files if annotated prior to
// running the command.
auto info = node->getFileInfo(system.getDelegate().getFileSystem());
// If this output is mutated by the build, we can't rely on equivalence,
// only existence.
if (node->isMutated()) {
if (value.getNthOutputInfo(i).isMissing() != info.isMissing())
return false;
continue;
}
if (value.getNthOutputInfo(i) != info)
return false;
}
// Otherwise, the result is ok.
return true;
}