datafusion_table_providers/sql/db_connection_pool/
odbcpool.rs

1/*
2Copyright 2024 The Spice.ai OSS Authors
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8     https://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17use crate::sql::db_connection_pool::dbconnection::odbcconn::ODBCConnection;
18use crate::sql::db_connection_pool::dbconnection::odbcconn::{ODBCDbConnection, ODBCParameter};
19use crate::sql::db_connection_pool::{DbConnectionPool, JoinPushDown};
20use async_trait::async_trait;
21use odbc_api::{sys::AttrConnectionPooling, Connection, ConnectionOptions, Environment};
22use secrecy::{ExposeSecret, SecretBox, SecretString};
23use sha2::{Digest, Sha256};
24use snafu::prelude::*;
25use std::{
26    collections::HashMap,
27    sync::{Arc, LazyLock},
28};
29
30static ENV: LazyLock<Environment> = LazyLock::new(|| unsafe {
31    // Enable connection pooling. Let driver decide wether the attributes of two connection
32    // are similar enough to change the attributes of a pooled one, to fit the requested
33    // connection, or if it is cheaper to create a new Connection from scratch.
34    // See <https://docs.microsoft.com/en-us/sql/odbc/reference/develop-app/driver-aware-connection-pooling>
35    if let Err(e) = Environment::set_connection_pooling(AttrConnectionPooling::DriverAware) {
36        tracing::error!("Failed to set ODBC connection pooling: {e}");
37    };
38    match Environment::new() {
39        Ok(env) => env,
40        Err(e) => {
41            panic!("Failed to create ODBC environment: {e}");
42        }
43    }
44});
45
46#[derive(Debug, Snafu)]
47pub enum Error {
48    #[snafu(display("Missing ODBC connection string parameter: odbc_connection_string"))]
49    MissingConnectionString {},
50
51    #[snafu(display("Invalid parameter: {parameter_name}"))]
52    InvalidParameterError { parameter_name: String },
53}
54
55pub struct ODBCPool {
56    pool: &'static Environment,
57    params: Arc<HashMap<String, SecretString>>,
58    connection_string: String,
59    connection_id: String,
60}
61
62fn hash_string(val: &str) -> String {
63    let mut hasher = Sha256::new();
64    hasher.update(val);
65    hasher.finalize().iter().fold(String::new(), |mut hash, b| {
66        hash.push_str(&format!("{b:02x}"));
67        hash
68    })
69}
70
71impl ODBCPool {
72    // Creates a new instance of `ODBCPool`.
73    ///
74    /// # Errors
75    ///
76    /// Returns an error if there is a problem creating the connection pool.
77    pub fn new(params: HashMap<String, SecretString>) -> Result<Self, Error> {
78        let connection_string = params
79            .get("connection_string")
80            .map(SecretBox::expose_secret)
81            .map(ToString::to_string)
82            .context(MissingConnectionStringSnafu)?;
83
84        // hash the connection string to get a comparable connection ID
85        // we do this to prevent exposing secrets in the EXPLAIN ... plan when using federated JoinPushDown
86        let connection_id = hash_string(&connection_string);
87
88        Ok(Self {
89            params: params.into(),
90            connection_string,
91            connection_id,
92            pool: &ENV,
93        })
94    }
95
96    #[must_use]
97    pub fn odbc_environment(&self) -> &'static Environment {
98        self.pool
99    }
100}
101
102#[async_trait]
103impl<'a> DbConnectionPool<Connection<'a>, ODBCParameter> for ODBCPool
104where
105    'a: 'static,
106{
107    async fn connect(
108        &self,
109    ) -> Result<Box<ODBCDbConnection<'a>>, Box<dyn std::error::Error + Send + Sync>> {
110        let cxn = self.pool.connect_with_connection_string(
111            &self.connection_string,
112            ConnectionOptions::default(),
113        )?;
114
115        let odbc_cxn = ODBCConnection {
116            conn: Arc::new(cxn.into()),
117            params: Arc::clone(&self.params),
118        };
119
120        Ok(Box::new(odbc_cxn))
121    }
122
123    fn join_push_down(&self) -> JoinPushDown {
124        JoinPushDown::AllowedFor(self.connection_id.clone())
125    }
126}
datafusion_table_providers/sql/db_connection_pool/odbcpool.rs

datafusion_table_providers/sql/db_connection_pool/
odbcpool.rs
