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Fix #124391: crash in complex node setup with multi-threading

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The lazy-function for a logical-or made the wrong assumption that
`try_get_input_data_ptr_or_request` returns null when `try_get_input_data_ptr`
returns null for the same input right before that. That's not true, because the
input might have been computed by another thread in the mean-time.

This wrong assumption lead to a bug because lazy-functions are always assumed to
either request more unavailable inputs, or compute all requested outputs. Here,
the lazy-function did neither. It wanted to request a new input, but it was
available already.

The solution is to handle the return value of
`try_get_input_data_ptr_or_request` properly.

Pull Request: https://projects.blender.org/blender/blender/pulls/124465
This commit is contained in:
Jacques Lucke
2024-07-10 18:00:48 +02:00
parent e02c6fd130
commit 6390f2e4c6
1 changed files with 21 additions and 4 deletions
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25
source/blender/nodes/intern/geometry_nodes_lazy_function.cc
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@@ -1142,7 +1142,9 @@ class LazyFunctionForLogicalOr : public lf::LazyFunction {
void execute_impl(lf::Params &params, const lf::Context & /*context*/) const override
{
int first_unavailable_input = -1;
Vector<int, 16> unavailable_inputs;
/* First check all inputs for available values without requesting more inputs. If any of the
* available inputs is true already, the others don't have to be requested anymore. */
for (const int i : inputs_.index_range()) {
if (const bool *value = params.try_get_input_data_ptr<bool>(i)) {
if (*value) {
@@ -1151,14 +1153,29 @@ class LazyFunctionForLogicalOr : public lf::LazyFunction {
}
}
else {
first_unavailable_input = i;
unavailable_inputs.append(i);
}
}
if (first_unavailable_input == -1) {
if (unavailable_inputs.is_empty()) {
params.set_output(0, false);
return;
}
params.try_get_input_data_ptr_or_request(first_unavailable_input);
/* Request the next unavailable input. Note that a value might be available now even if it was
* not available before, because it might have been computed in the mean-time. */
for (const int i : unavailable_inputs) {
if (const bool *value = params.try_get_input_data_ptr_or_request<bool>(i)) {
if (*value) {
params.set_output(0, true);
return;
}
}
else {
/* The input has been requested and it's not available yet, so wait until it is ready. */
return;
}
}
/* All inputs were available now and all of them were false, so the final output is false. */
params.set_output(0, false);
}
};