Enhance error handling and simplify Result type usage in the library

.github/workflows/rust.yml

@@ -16,7 +16,9 @@ jobs:
     - uses: actions/checkout@v3
     - name: Fetch library
       run: |
-          wget https://github.com/chdb-io/chdb/releases/latest/download/linux-x86_64-libchdb.tar.gz
+          #wget https://github.com/chdb-io/chdb/releases/latest/download/linux-x86_64-libchdb.tar.gz
+          #Fix libchdb version to v2.1.1 until libchdb v3 based chdb-rust refactor
+          wget https://github.com/chdb-io/chdb/releases/download/v2.1.1/linux-x86_64-libchdb.tar.gz
           tar -xzf linux-x86_64-libchdb.tar.gz
           sudo mv libchdb.so /usr/lib/libchdb.so
           sudo ldconfig

Cargo.toml

@@ -9,3 +9,6 @@ thiserror = "1"
 
 [build-dependencies]
 bindgen = "0.70.1"
+
+[dev-dependencies]
+tempdir = "0.3.7"

src/error.rs

@@ -1,9 +1,12 @@
 use std::ffi::NulError;
+use std::string::FromUtf8Error;
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
     #[error("An unknown error has occurred")]
     Unknown,
+    #[error("No result")]
+    NoResult,
     #[error("Invalid data: {0}")]
     InvalidData(String),
     #[error("Invalid path")]
@@ -15,7 +18,9 @@ pub enum Error {
     #[error("Insufficient dir permissions")]
     InsufficientPermissions,
     #[error("Non UTF-8 sequence: {0}")]
-    NonUtf8Sequence(String),
+    NonUtf8Sequence(FromUtf8Error),
     #[error("{0}")]
     QueryError(String),
 }
+
+pub type Result<T, Err = Error> = std::result::Result<T, Err>;

src/lib.rs

@@ -17,9 +17,10 @@ use std::ffi::{c_char, CString};
 
 use crate::arg::Arg;
 use crate::error::Error;
+use crate::error::Result;
 use crate::query_result::QueryResult;
 
-pub fn execute(query: &str, query_args: Option<&[Arg]>) -> Result<Option<QueryResult>, Error> {
+pub fn execute(query: &str, query_args: Option<&[Arg]>) -> Result<QueryResult> {
     let mut argv = Vec::with_capacity(query_args.as_ref().map_or(0, |v| v.len()) + 2);
     argv.push(arg_clickhouse()?.into_raw());
 
@@ -33,26 +34,28 @@ pub fn execute(query: &str, query_args: Option<&[Arg]>) -> Result<Option<QueryRe
     call_chdb(argv)
 }
 
-fn call_chdb(mut argv: Vec<*mut c_char>) -> Result<Option<QueryResult>, Error> {
+fn call_chdb(mut argv: Vec<*mut c_char>) -> Result<QueryResult> {
     let argc = argv.len() as i32;
     let argv = argv.as_mut_ptr();
     let result_ptr = unsafe { bindings::query_stable_v2(argc, argv) };
 
     if result_ptr.is_null() {
-        return Ok(None);
+        return Err(Error::NoResult);
     }
+    let result = QueryResult::new(result_ptr);
+    let result = result.check_error()?;
 
-    Ok(Some(QueryResult(result_ptr).check_error()?))
+    Ok(result)
 }
 
-fn arg_clickhouse() -> Result<CString, Error> {
+fn arg_clickhouse() -> Result<CString> {
     Ok(CString::new("clickhouse")?)
 }
 
-fn arg_data_path(value: &str) -> Result<CString, Error> {
+fn arg_data_path(value: &str) -> Result<CString> {
     Ok(CString::new(format!("--path={}", value))?)
 }
 
-fn arg_query(value: &str) -> Result<CString, Error> {
+fn arg_query(value: &str) -> Result<CString> {
     Ok(CString::new(format!("--query={}", value))?)
 }

src/query_result.rs

@@ -5,17 +5,23 @@ use std::time::Duration;
 
 use crate::bindings;
 use crate::error::Error;
-
+use crate::error::Result;
 #[derive(Clone)]
-pub struct QueryResult(pub(crate) *mut bindings::local_result_v2);
+pub struct QueryResult {
+    inner: *mut bindings::local_result_v2,
+}
 
 impl QueryResult {
-    pub fn data_utf8(&self) -> Result<String, Error> {
-        String::from_utf8(self.data_ref().to_vec())
-            .map_err(|e| Error::NonUtf8Sequence(e.to_string()))
+    pub(crate) fn new(inner: *mut bindings::local_result_v2) -> Self {
+        Self { inner }
     }
+    pub fn data_utf8(&self) -> Result<String> {
+        let buf = self.data_ref();
 
-    pub fn data_utf8_lossy<'a>(&'a self) -> Cow<'a, str> {
+        String::from_utf8(buf.to_vec()).map_err(Error::NonUtf8Sequence)
+    }
+
+    pub fn data_utf8_lossy(&self) -> Cow<str> {
         String::from_utf8_lossy(self.data_ref())
     }
 
@@ -24,30 +30,37 @@ impl QueryResult {
     }
 
     pub fn data_ref(&self) -> &[u8] {
-        let buf = unsafe { (*self.0).buf };
-        let len = unsafe { (*self.0).len };
+        let inner = self.inner;
+        let buf = unsafe { (*inner).buf };
+        let len = unsafe { (*inner).len };
         let bytes: &[u8] = unsafe { slice::from_raw_parts(buf as *const u8, len) };
         bytes
     }
 
     pub fn rows_read(&self) -> u64 {
-        (unsafe { *self.0 }).rows_read
+        let inner = self.inner;
+        unsafe { *inner }.rows_read
     }
 
     pub fn bytes_read(&self) -> u64 {
-        unsafe { (*self.0).bytes_read }
+        let inner = self.inner;
+        unsafe { *inner }.bytes_read
     }
 
     pub fn elapsed(&self) -> Duration {
-        let elapsed = unsafe { (*self.0).elapsed };
+        let elapsed = unsafe { (*self.inner).elapsed };
         Duration::from_secs_f64(elapsed)
     }
 
-    pub(crate) fn check_error(self) -> Result<Self, Error> {
-        let err_ptr = unsafe { (*self.0).error_message };
+    pub(crate) fn check_error(self) -> Result<Self> {
+        self.check_error_ref()?;
+        Ok(self)
+    }
+    pub(crate) fn check_error_ref(&self) -> Result<()> {
+        let err_ptr = unsafe { (*self.inner).error_message };
 
         if err_ptr.is_null() {
-            return Ok(self);
+            return Ok(());
         }
 
         Err(Error::QueryError(unsafe {
@@ -58,6 +71,6 @@ impl QueryResult {
 
 impl Drop for QueryResult {
     fn drop(&mut self) {
-        unsafe { bindings::free_result_v2(self.0) };
+        unsafe { bindings::free_result_v2(self.inner) };
     }
 }

src/session.rs

@@ -82,11 +82,7 @@ impl<'a> Default for SessionBuilder<'a> {
 }
 
 impl Session {
-    pub fn execute(
-        &self,
-        query: &str,
-        query_args: Option<&[Arg]>,
-    ) -> Result<Option<QueryResult>, Error> {
+    pub fn execute(&self, query: &str, query_args: Option<&[Arg]>) -> Result<QueryResult, Error> {
         let mut argv = Vec::with_capacity(
             self.default_args.len() + query_args.as_ref().map_or(0, |v| v.len()) + 1,
         );

tests/examples.rs

@@ -1,68 +1,65 @@
 use chdb_rust::arg::Arg;
+use chdb_rust::error::Result;
 use chdb_rust::execute;
 use chdb_rust::format::InputFormat;
 use chdb_rust::format::OutputFormat;
 use chdb_rust::log_level::LogLevel;
 use chdb_rust::session::SessionBuilder;
 
 #[test]
-fn stateful() {
+fn test_stateful() -> Result<()> {
     //
     // Create session.
     //
-
+    let tmp = tempdir::TempDir::new("chdb-rust")?;
     let session = SessionBuilder::new()
-        .with_data_path("/tmp/chdb")
+        .with_data_path(tmp.path())
         .with_arg(Arg::LogLevel(LogLevel::Debug))
         .with_arg(Arg::Custom("priority".into(), Some("1".into())))
         .with_auto_cleanup(true)
-        .build()
-        .unwrap();
+        .build()?;
 
     //
     // Create database.
     //
 
-    session
-        .execute("CREATE DATABASE demo; USE demo", Some(&[Arg::MultiQuery]))
-        .unwrap();
+    session.execute("CREATE DATABASE demo; USE demo", Some(&[Arg::MultiQuery]))?;
 
     //
     // Create table.
     //
 
-    session
-        .execute(
-            "CREATE TABLE logs (id UInt64, msg String) ENGINE = MergeTree ORDER BY id",
-            None,
-        )
-        .unwrap();
+    session.execute(
+        "CREATE TABLE logs (id UInt64, msg String) ENGINE = MergeTree() ORDER BY id",
+        None,
+    )?;
 
     //
     // Insert into table.
     //
 
-    session
-        .execute("INSERT INTO logs (id, msg) VALUES (1, 'test')", None)
-        .unwrap();
+    session.execute("INSERT INTO logs (id, msg) VALUES (1, 'test')", None)?;
 
     //
     // Select from table.
     //
+    let len = session.execute(
+        "SELECT COUNT(*) FROM logs",
+        Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)]),
+    )?;
 
-    let result = session
-        .execute(
-            "SELECT * FROM logs",
-            Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)]),
-        )
-        .unwrap()
-        .unwrap();
+    assert_eq!(len.data_utf8_lossy(), "{\"COUNT()\":1}\n");
 
+    let result = session.execute(
+        "SELECT * FROM logs",
+        Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)]),
+    )?;
     assert_eq!(result.data_utf8_lossy(), "{\"id\":1,\"msg\":\"test\"}\n");
+    Ok(())
 }
 
 #[test]
-fn stateless() {
+fn test_stateless() -> Result<()> {
     let query = format!(
         "SELECT * FROM file('tests/logs.csv', {})",
         InputFormat::CSV.as_str()
@@ -71,9 +68,8 @@ fn stateless() {
     let result = execute(
         &query,
         Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)]),
-    )
-    .unwrap()
-    .unwrap();
+    )?;
 
     assert_eq!(result.data_utf8_lossy(), "{\"id\":1,\"msg\":\"test\"}\n");
+    Ok(())
 }