datafusion_physical_expr/
async_scalar_function.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use crate::ScalarFunctionExpr;
19use arrow::array::RecordBatch;
20use arrow::compute::concat;
21use arrow::datatypes::{DataType, Field, FieldRef, Schema};
22use datafusion_common::Result;
23use datafusion_common::config::ConfigOptions;
24use datafusion_common::{internal_err, not_impl_err};
25use datafusion_expr::ScalarFunctionArgs;
26use datafusion_expr::async_udf::AsyncScalarUDF;
27use datafusion_expr_common::columnar_value::ColumnarValue;
28use datafusion_physical_expr_common::physical_expr::PhysicalExpr;
29use std::any::Any;
30use std::fmt::Display;
31use std::hash::{Hash, Hasher};
32use std::sync::Arc;
33
34/// Wrapper around a scalar function that can be evaluated asynchronously
35#[derive(Debug, Clone, Eq)]
36pub struct AsyncFuncExpr {
37    /// The name of the output column this function will generate
38    pub name: String,
39    /// The actual function (always `ScalarFunctionExpr`)
40    pub func: Arc<dyn PhysicalExpr>,
41    /// The field that this function will return
42    return_field: FieldRef,
43}
44
45impl Display for AsyncFuncExpr {
46    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
47        write!(f, "async_expr(name={}, expr={})", self.name, self.func)
48    }
49}
50
51impl PartialEq for AsyncFuncExpr {
52    fn eq(&self, other: &Self) -> bool {
53        self.name == other.name && self.func == Arc::clone(&other.func)
54    }
55}
56
57impl Hash for AsyncFuncExpr {
58    fn hash<H: Hasher>(&self, state: &mut H) {
59        self.name.hash(state);
60        self.func.as_ref().hash(state);
61    }
62}
63
64impl AsyncFuncExpr {
65    /// create a new AsyncFuncExpr
66    pub fn try_new(
67        name: impl Into<String>,
68        func: Arc<dyn PhysicalExpr>,
69        schema: &Schema,
70    ) -> Result<Self> {
71        let Some(_) = func.as_any().downcast_ref::<ScalarFunctionExpr>() else {
72            return internal_err!(
73                "unexpected function type, expected ScalarFunctionExpr, got: {:?}",
74                func
75            );
76        };
77
78        let return_field = func.return_field(schema)?;
79        Ok(Self {
80            name: name.into(),
81            func,
82            return_field,
83        })
84    }
85
86    /// return the name of the output column
87    pub fn name(&self) -> &str {
88        &self.name
89    }
90
91    /// Return the output field generated by evaluating this function
92    pub fn field(&self, input_schema: &Schema) -> Result<Field> {
93        Ok(Field::new(
94            &self.name,
95            self.func.data_type(input_schema)?,
96            self.func.nullable(input_schema)?,
97        ))
98    }
99
100    /// Return the ideal batch size for this function
101    pub fn ideal_batch_size(&self) -> Result<Option<usize>> {
102        if let Some(expr) = self.func.as_any().downcast_ref::<ScalarFunctionExpr>()
103            && let Some(udf) =
104                expr.fun().inner().as_any().downcast_ref::<AsyncScalarUDF>()
105        {
106            return Ok(udf.ideal_batch_size());
107        }
108        not_impl_err!("Can't get ideal_batch_size from {:?}", self.func)
109    }
110
111    /// This (async) function is called for each record batch to evaluate the LLM expressions
112    ///
113    /// The output is the output of evaluating the async expression and the input record batch
114    pub async fn invoke_with_args(
115        &self,
116        batch: &RecordBatch,
117        config_options: Arc<ConfigOptions>,
118    ) -> Result<ColumnarValue> {
119        let Some(scalar_function_expr) =
120            self.func.as_any().downcast_ref::<ScalarFunctionExpr>()
121        else {
122            return internal_err!(
123                "unexpected function type, expected ScalarFunctionExpr, got: {:?}",
124                self.func
125            );
126        };
127
128        let Some(async_udf) = scalar_function_expr
129            .fun()
130            .inner()
131            .as_any()
132            .downcast_ref::<AsyncScalarUDF>()
133        else {
134            return not_impl_err!(
135                "Don't know how to evaluate async function: {:?}",
136                scalar_function_expr
137            );
138        };
139
140        let arg_fields = scalar_function_expr
141            .args()
142            .iter()
143            .map(|e| e.return_field(batch.schema_ref()))
144            .collect::<Result<Vec<_>>>()?;
145
146        let mut result_batches = vec![];
147        if let Some(ideal_batch_size) = self.ideal_batch_size()? {
148            let mut remainder = batch.clone();
149            while remainder.num_rows() > 0 {
150                let size = if ideal_batch_size > remainder.num_rows() {
151                    remainder.num_rows()
152                } else {
153                    ideal_batch_size
154                };
155
156                let current_batch = remainder.slice(0, size); // get next 10 rows
157                remainder = remainder.slice(size, remainder.num_rows() - size);
158                let args = scalar_function_expr
159                    .args()
160                    .iter()
161                    .map(|e| e.evaluate(&current_batch))
162                    .collect::<Result<Vec<_>>>()?;
163                result_batches.push(
164                    async_udf
165                        .invoke_async_with_args(ScalarFunctionArgs {
166                            args,
167                            arg_fields: arg_fields.clone(),
168                            number_rows: current_batch.num_rows(),
169                            return_field: Arc::clone(&self.return_field),
170                            config_options: Arc::clone(&config_options),
171                        })
172                        .await?,
173                );
174            }
175        } else {
176            let args = scalar_function_expr
177                .args()
178                .iter()
179                .map(|e| e.evaluate(batch))
180                .collect::<Result<Vec<_>>>()?;
181
182            result_batches.push(
183                async_udf
184                    .invoke_async_with_args(ScalarFunctionArgs {
185                        args: args.to_vec(),
186                        arg_fields,
187                        number_rows: batch.num_rows(),
188                        return_field: Arc::clone(&self.return_field),
189                        config_options: Arc::clone(&config_options),
190                    })
191                    .await?,
192            );
193        }
194
195        let datas = result_batches
196            .into_iter()
197            .map(|cv| match cv {
198                ColumnarValue::Array(arr) => Ok(arr),
199                ColumnarValue::Scalar(scalar) => Ok(scalar.to_array_of_size(1)?),
200            })
201            .collect::<Result<Vec<_>>>()?;
202
203        // Get references to the arrays as dyn Array to call concat
204        let dyn_arrays = datas
205            .iter()
206            .map(|arr| arr as &dyn arrow::array::Array)
207            .collect::<Vec<_>>();
208        let result_array = concat(&dyn_arrays)?;
209        Ok(ColumnarValue::Array(result_array))
210    }
211}
212
213impl PhysicalExpr for AsyncFuncExpr {
214    fn as_any(&self) -> &dyn Any {
215        self
216    }
217
218    fn data_type(&self, input_schema: &Schema) -> Result<DataType> {
219        self.func.data_type(input_schema)
220    }
221
222    fn nullable(&self, input_schema: &Schema) -> Result<bool> {
223        self.func.nullable(input_schema)
224    }
225
226    fn evaluate(&self, _batch: &RecordBatch) -> Result<ColumnarValue> {
227        // TODO: implement this for scalar value input
228        not_impl_err!("AsyncFuncExpr.evaluate")
229    }
230
231    fn children(&self) -> Vec<&Arc<dyn PhysicalExpr>> {
232        self.func.children()
233    }
234
235    fn with_new_children(
236        self: Arc<Self>,
237        children: Vec<Arc<dyn PhysicalExpr>>,
238    ) -> Result<Arc<dyn PhysicalExpr>> {
239        let new_func = Arc::clone(&self.func).with_new_children(children)?;
240        Ok(Arc::new(AsyncFuncExpr {
241            name: self.name.clone(),
242            func: new_func,
243            return_field: Arc::clone(&self.return_field),
244        }))
245    }
246
247    fn fmt_sql(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
248        write!(f, "{}", self.func)
249    }
250}
datafusion_physical_expr/async_scalar_function.rs

datafusion_physical_expr/
async_scalar_function.rs
