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use quote::{quote_spanned, ToTokens};
use super::{
DelayType, OpInstGenerics, OperatorCategory, OperatorConstraints,
OperatorInstance, OperatorWriteOutput, Persistence, WriteContextArgs, RANGE_1,
};
use crate::diagnostic::{Diagnostic, Level};
/// > 1 input stream of type `(K, V)`, 1 output stream of type `(K, V)`.
/// > The output will have one tuple for each distinct `K`, with an accumulated (reduced) value of
/// > type `V`.
///
/// If you need the accumulated value to have a different type than the input, use [`fold_keyed`](#keyed_fold).
///
/// > Arguments: one Rust closures. The closure takes two arguments: an `&mut` 'accumulator', and
/// > an element. Accumulator should be updated based on the element.
///
/// A special case of `reduce`, in the spirit of SQL's GROUP BY and aggregation constructs. The input
/// is partitioned into groups by the first field, and for each group the values in the second
/// field are accumulated via the closures in the arguments.
///
/// > Note: The closures have access to the [`context` object](surface_flows.mdx#the-context-object).
///
/// `reduce_keyed` can also be provided with one generic lifetime persistence argument, either
/// `'tick` or `'static`, to specify how data persists. With `'tick`, values will only be collected
/// within the same tick. With `'static`, values will be remembered across ticks and will be
/// aggregated with pairs arriving in later ticks. When not explicitly specified persistence
/// defaults to `'tick`.
///
/// `reduce_keyed` can also be provided with two type arguments, the key and value type. This is
/// required when using `'static` persistence if the compiler cannot infer the types.
///
/// ```dfir
/// source_iter([("toy", 1), ("toy", 2), ("shoe", 11), ("shoe", 35), ("haberdashery", 7)])
/// -> reduce_keyed(|old: &mut u32, val: u32| *old += val)
/// -> assert_eq([("toy", 3), ("shoe", 46), ("haberdashery", 7)]);
/// ```
///
/// Example using `'tick` persistence and type arguments:
/// ```rustbook
/// let (input_send, input_recv) = dfir_rs::util::unbounded_channel::<(&str, &str)>();
/// let mut flow = dfir_rs::dfir_syntax! {
/// source_stream(input_recv)
/// -> reduce_keyed::<'tick, &str>(|old: &mut _, val| *old = std::cmp::max(*old, val))
/// -> for_each(|(k, v)| println!("({:?}, {:?})", k, v));
/// };
///
/// input_send.send(("hello", "oakland")).unwrap();
/// input_send.send(("hello", "berkeley")).unwrap();
/// input_send.send(("hello", "san francisco")).unwrap();
/// flow.run_available();
/// // ("hello", "oakland, berkeley, san francisco, ")
///
/// input_send.send(("hello", "palo alto")).unwrap();
/// flow.run_available();
/// // ("hello", "palo alto, ")
/// ```
pub const REDUCE_KEYED: OperatorConstraints = OperatorConstraints {
name: "reduce_keyed",
categories: &[OperatorCategory::KeyedFold],
hard_range_inn: RANGE_1,
soft_range_inn: RANGE_1,
hard_range_out: RANGE_1,
soft_range_out: RANGE_1,
num_args: 1,
persistence_args: &(0..=1),
type_args: &(0..=2),
is_external_input: false,
// If this is set to true, the state will need to be cleared using `#context.set_state_tick_hook`
// to prevent reading uncleared data if this subgraph doesn't run.
// https://github.com/hydro-project/hydro/issues/1298
has_singleton_output: false,
flo_type: None,
ports_inn: None,
ports_out: None,
input_delaytype_fn: |_| Some(DelayType::Stratum),
write_fn: |wc @ &WriteContextArgs {
hydroflow,
context,
op_span,
ident,
inputs,
is_pull,
root,
op_inst:
OperatorInstance {
generics:
OpInstGenerics {
persistence_args,
type_args,
..
},
..
},
arguments,
..
},
diagnostics| {
assert!(is_pull);
let persistence = match persistence_args[..] {
[] => Persistence::Tick,
[a] => a,
_ => unreachable!(),
};
let generic_type_args = [
type_args
.first()
.map(ToTokens::to_token_stream)
.unwrap_or(quote_spanned!(op_span=> _)),
type_args
.get(1)
.map(ToTokens::to_token_stream)
.unwrap_or(quote_spanned!(op_span=> _)),
];
let input = &inputs[0];
let aggfn = &arguments[0];
let (write_prologue, write_iterator, write_iterator_after) = match persistence {
Persistence::Tick => {
let groupbydata_ident = wc.make_ident("groupbydata");
let hashtable_ident = wc.make_ident("hashtable");
(
quote_spanned! {op_span=>
let #groupbydata_ident = #hydroflow.add_state(::std::cell::RefCell::new(#root::rustc_hash::FxHashMap::<#( #generic_type_args ),*>::default()));
},
quote_spanned! {op_span=>
let mut #hashtable_ident = #context.state_ref(#groupbydata_ident).borrow_mut();
{
#[inline(always)]
fn check_input<Iter: ::std::iter::Iterator<Item = (A, B)>, A: ::std::clone::Clone, B: ::std::clone::Clone>(iter: Iter)
-> impl ::std::iter::Iterator<Item = (A, B)> { iter }
#[inline(always)]
/// A: accumulator type
/// O: output type
fn call_comb_type<A, O>(acc: &mut A, item: A, f: impl Fn(&mut A, A) -> O) -> O {
f(acc, item)
}
for kv in check_input(#input) {
match #hashtable_ident.entry(kv.0) {
::std::collections::hash_map::Entry::Vacant(vacant) => {
vacant.insert(kv.1);
}
::std::collections::hash_map::Entry::Occupied(mut occupied) => {
#[allow(clippy::redundant_closure_call)] call_comb_type(occupied.get_mut(), kv.1, #aggfn);
}
}
}
}
let #ident = #hashtable_ident.drain();
},
Default::default(),
)
}
Persistence::Static => {
let groupbydata_ident = wc.make_ident("groupbydata");
let hashtable_ident = wc.make_ident("hashtable");
(
quote_spanned! {op_span=>
let #groupbydata_ident = #hydroflow.add_state(::std::cell::RefCell::new(#root::rustc_hash::FxHashMap::<#( #generic_type_args ),*>::default()));
},
quote_spanned! {op_span=>
let mut #hashtable_ident = #context.state_ref(#groupbydata_ident).borrow_mut();
{
#[inline(always)]
fn check_input<Iter: ::std::iter::Iterator<Item = (A, B)>, A: ::std::clone::Clone, B: ::std::clone::Clone>(iter: Iter)
-> impl ::std::iter::Iterator<Item = (A, B)> { iter }
#[inline(always)]
/// A: accumulator type
/// O: output type
fn call_comb_type<A, O>(acc: &mut A, item: A, f: impl Fn(&mut A, A) -> O) -> O {
f(acc, item)
}
for kv in check_input(#input) {
match #hashtable_ident.entry(kv.0) {
::std::collections::hash_map::Entry::Vacant(vacant) => {
vacant.insert(kv.1);
}
::std::collections::hash_map::Entry::Occupied(mut occupied) => {
#[allow(clippy::redundant_closure_call)] call_comb_type(occupied.get_mut(), kv.1, #aggfn);
}
}
}
}
let #ident = #context.is_first_run_this_tick()
.then_some(#hashtable_ident.iter())
.into_iter()
.flatten()
.map(
// TODO(mingwei): remove `unknown_lints` when `suspicious_double_ref_op` is stabilized.
#[allow(unknown_lints, suspicious_double_ref_op, clippy::clone_on_copy)]
|(k, v)| (
::std::clone::Clone::clone(k),
::std::clone::Clone::clone(v),
)
);
},
quote_spanned! {op_span=>
#context.schedule_subgraph(#context.current_subgraph(), false);
},
)
}
Persistence::Mutable => {
diagnostics.push(Diagnostic::spanned(
op_span,
Level::Error,
"An implementation of 'mutable does not exist",
));
return Err(());
}
};
Ok(OperatorWriteOutput {
write_prologue,
write_iterator,
write_iterator_after,
})
},
};