forked from extern/nushell
Box ShellError in Value::Error (#8375)
# Description Our `ShellError` at the moment has a `std::mem::size_of<ShellError>` of 136 bytes (on AMD64). As a result `Value` directly storing the struct also required 136 bytes (thanks to alignment requirements). This change stores the `Value::Error` `ShellError` on the heap. Pro: - Value now needs just 80 bytes - Should be 1 cacheline less (still at least 2 cachelines) Con: - More small heap allocations when dealing with `Value::Error` - More heap fragmentation - Potential for additional required memcopies # Further code changes Includes a small refactor of `try` due to a type mismatch in its large match. # User-Facing Changes None for regular users. Plugin authors may have to update their matches on `Value` if they use `nu-protocol` Needs benchmarking to see if there is a benefit in real world workloads. **Update** small improvements in runtime for workloads with high volume of values. Significant reduction in maximum resident set size, when many values are held in memory. # Tests + Formatting
This commit is contained in:
Stefan Holderbach
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GitHub
GitHub
parent
c26d91fb61
commit
a52386e837
@ -57,66 +57,29 @@ impl Command for Try {
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let result = eval_block(engine_state, stack, try_block, input, false, false);
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match result {
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Err(error) | Ok(PipelineData::Value(Value::Error { error }, ..)) => {
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if let nu_protocol::ShellError::Break(_) = error {
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return Err(error);
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} else if let nu_protocol::ShellError::Continue(_) = error {
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return Err(error);
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} else if let nu_protocol::ShellError::Return(_, _) = error {
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return Err(error);
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}
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if let Some(catch_block) = catch_block {
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let catch_block = engine_state.get_block(catch_block.block_id);
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let err_value = Value::Error { error };
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// Put the error value in the positional closure var
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if let Some(var) = catch_block.signature.get_positional(0) {
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if let Some(var_id) = &var.var_id {
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stack.add_var(*var_id, err_value.clone());
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}
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}
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eval_block(
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engine_state,
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stack,
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catch_block,
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// Make the error accessible with $in, too
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err_value.into_pipeline_data(),
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false,
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false,
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)
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} else {
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Ok(PipelineData::empty())
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}
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Err(error) => {
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let error = intercept_block_control(error)?;
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let err_value = Value::Error {
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error: Box::new(error),
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};
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handle_catch(err_value, catch_block, engine_state, stack)
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}
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Ok(PipelineData::Value(Value::Error { error }, ..)) => {
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let error = intercept_block_control(*error)?;
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let err_value = Value::Error {
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error: Box::new(error),
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};
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handle_catch(err_value, catch_block, engine_state, stack)
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}
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// external command may fail to run
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Ok(pipeline) => {
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let (pipeline, external_failed) = pipeline.is_external_failed();
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if external_failed {
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if let Some(catch_block) = catch_block {
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let catch_block = engine_state.get_block(catch_block.block_id);
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if let Some(var) = catch_block.signature.get_positional(0) {
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if let Some(var_id) = &var.var_id {
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// Because external command errors aren't "real" errors,
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// (unless do -c is in effect)
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// they can't be passed in as Nushell values.
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let err_value = Value::nothing(call.head);
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stack.add_var(*var_id, err_value);
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}
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}
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eval_block(
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engine_state,
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stack,
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catch_block,
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// The same null as in the above block is set as the $in value.
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Value::nothing(call.head).into_pipeline_data(),
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false,
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false,
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)
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} else {
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Ok(PipelineData::empty())
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}
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// Because external command errors aren't "real" errors,
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// (unless do -c is in effect)
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// they can't be passed in as Nushell values.
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let err_value = Value::nothing(call.head);
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handle_catch(err_value, catch_block, engine_state, stack)
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} else {
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Ok(pipeline)
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}
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@ -140,6 +103,48 @@ impl Command for Try {
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}
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}
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fn handle_catch(
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err_value: Value,
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catch_block: Option<Closure>,
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engine_state: &EngineState,
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stack: &mut Stack,
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) -> Result<PipelineData, ShellError> {
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if let Some(catch_block) = catch_block {
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let catch_block = engine_state.get_block(catch_block.block_id);
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// Put the error value in the positional closure var
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if let Some(var) = catch_block.signature.get_positional(0) {
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if let Some(var_id) = &var.var_id {
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stack.add_var(*var_id, err_value.clone());
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}
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}
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eval_block(
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engine_state,
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stack,
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catch_block,
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// Make the error accessible with $in, too
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err_value.into_pipeline_data(),
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false,
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false,
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)
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} else {
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Ok(PipelineData::empty())
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}
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}
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/// The flow control commands `break`/`continue`/`return` emit their own [`ShellError`] variants
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/// We need to ignore those in `try` and bubble them through
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///
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/// `Err` when flow control to bubble up with `?`
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fn intercept_block_control(error: ShellError) -> Result<ShellError, ShellError> {
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match error {
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nu_protocol::ShellError::Break(_) => Err(error),
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nu_protocol::ShellError::Continue(_) => Err(error),
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nu_protocol::ShellError::Return(_, _) => Err(error),
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_ => Ok(error),
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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