fix: use unlock notify also on sqlite3_exec (launchbadge#2021)

sqlx-core/src/sqlite/connection/handle.rs

@@ -3,9 +3,12 @@ use std::ptr;
 use std::ptr::NonNull;
 
 use crate::error::Error;
-use libsqlite3_sys::{sqlite3, sqlite3_close, sqlite3_exec, sqlite3_last_insert_rowid, SQLITE_OK};
+use libsqlite3_sys::{
+    sqlite3, sqlite3_close, sqlite3_exec, sqlite3_last_insert_rowid, SQLITE_LOCKED_SHAREDCACHE,
+    SQLITE_OK,
+};
 
-use crate::sqlite::SqliteError;
+use crate::sqlite::{statement::unlock_notify, SqliteError};
 
 /// Managed handle to the raw SQLite3 database handle.
 /// The database handle will be closed when this is dropped and no `ConnectionHandleRef`s exist.
@@ -61,21 +64,23 @@ impl ConnectionHandle {
 
         // SAFETY: we have exclusive access to the database handle
         unsafe {
-            let status = sqlite3_exec(
-                self.as_ptr(),
-                query.as_ptr(),
-                // callback if we wanted result rows
-                None,
-                // callback data
-                ptr::null_mut(),
-                // out-pointer for the error message, we just use `SqliteError::new()`
-                ptr::null_mut(),
-            );
-
-            if status == SQLITE_OK {
-                Ok(())
-            } else {
-                Err(SqliteError::new(self.as_ptr()).into())
+            loop {
+                let status = sqlite3_exec(
+                    self.as_ptr(),
+                    query.as_ptr(),
+                    // callback if we wanted result rows
+                    None,
+                    // callback data
+                    ptr::null_mut(),
+                    // out-pointer for the error message, we just use `SqliteError::new()`
+                    ptr::null_mut(),
+                );
+
+                match status {
+                    SQLITE_OK => return Ok(()),
+                    SQLITE_LOCKED_SHAREDCACHE => unlock_notify::wait(self.as_ptr())?,
+                    _ => return Err(SqliteError::new(self.as_ptr()).into()),
+                }
             }
         }
     }

sqlx-core/src/sqlite/statement/handle.rs

@@ -6,7 +6,6 @@ use std::ptr;
 use std::ptr::NonNull;
 use std::slice::from_raw_parts;
 use std::str::{from_utf8, from_utf8_unchecked};
-use std::sync::{Condvar, Mutex};
 
 use libsqlite3_sys::{
     sqlite3, sqlite3_bind_blob64, sqlite3_bind_double, sqlite3_bind_int, sqlite3_bind_int64,
@@ -17,14 +16,16 @@ use libsqlite3_sys::{
     sqlite3_column_name, sqlite3_column_origin_name, sqlite3_column_table_name,
     sqlite3_column_type, sqlite3_column_value, sqlite3_db_handle, sqlite3_finalize, sqlite3_reset,
     sqlite3_sql, sqlite3_step, sqlite3_stmt, sqlite3_stmt_readonly, sqlite3_table_column_metadata,
-    sqlite3_unlock_notify, sqlite3_value, SQLITE_DONE, SQLITE_LOCKED_SHAREDCACHE, SQLITE_MISUSE,
-    SQLITE_OK, SQLITE_ROW, SQLITE_TRANSIENT, SQLITE_UTF8,
+    sqlite3_value, SQLITE_DONE, SQLITE_LOCKED_SHAREDCACHE, SQLITE_MISUSE, SQLITE_OK, SQLITE_ROW,
+    SQLITE_TRANSIENT, SQLITE_UTF8,
 };
 
 use crate::error::{BoxDynError, Error};
 use crate::sqlite::type_info::DataType;
 use crate::sqlite::{SqliteError, SqliteTypeInfo};
 
+use super::unlock_notify;
+
 #[derive(Debug)]
 pub(crate) struct StatementHandle(NonNull<sqlite3_stmt>);
 
@@ -314,7 +315,7 @@ impl StatementHandle {
                     SQLITE_LOCKED_SHAREDCACHE => {
                         // The shared cache is locked by another connection. Wait for unlock
                         // notification and try again.
-                        wait_for_unlock_notify(self.db_handle())?;
+                        unlock_notify::wait(self.db_handle())?;
                         // Need to reset the handle after the unlock
                         // (https://www.sqlite.org/unlock_notify.html)
                         sqlite3_reset(self.0.as_ptr());
@@ -344,55 +345,3 @@ impl Drop for StatementHandle {
         }
     }
 }
-
-unsafe fn wait_for_unlock_notify(conn: *mut sqlite3) -> Result<(), SqliteError> {
-    let notify = Notify::new();
-
-    if sqlite3_unlock_notify(
-        conn,
-        Some(unlock_notify_cb),
-        &notify as *const Notify as *mut Notify as *mut _,
-    ) != SQLITE_OK
-    {
-        return Err(SqliteError::new(conn));
-    }
-
-    notify.wait();
-
-    Ok(())
-}
-
-unsafe extern "C" fn unlock_notify_cb(ptr: *mut *mut c_void, len: c_int) {
-    let ptr = ptr as *mut &Notify;
-    let slice = from_raw_parts(ptr, len as usize);
-
-    for notify in slice {
-        notify.fire();
-    }
-}
-
-struct Notify {
-    mutex: Mutex<bool>,
-    condvar: Condvar,
-}
-
-impl Notify {
-    fn new() -> Self {
-        Self {
-            mutex: Mutex::new(false),
-            condvar: Condvar::new(),
-        }
-    }
-
-    fn wait(&self) {
-        let _ = self
-            .condvar
-            .wait_while(self.mutex.lock().unwrap(), |fired| !*fired)
-            .unwrap();
-    }
-
-    fn fire(&self) {
-        *self.mutex.lock().unwrap() = true;
-        self.condvar.notify_one();
-    }
-}

sqlx-core/src/sqlite/statement/mod.rs

@@ -9,6 +9,7 @@ use std::borrow::Cow;
 use std::sync::Arc;
 
 mod handle;
+pub(super) mod unlock_notify;
 mod r#virtual;
 
 pub(crate) use handle::StatementHandle;

sqlx-core/src/sqlite/statement/unlock_notify.rs

@@ -0,0 +1,61 @@
+use std::ffi::c_void;
+use std::os::raw::c_int;
+use std::slice;
+use std::sync::{Condvar, Mutex};
+
+use libsqlite3_sys::{sqlite3, sqlite3_unlock_notify, SQLITE_OK};
+
+use crate::sqlite::SqliteError;
+
+// Wait for unlock notification (https://www.sqlite.org/unlock_notify.html)
+pub unsafe fn wait(conn: *mut sqlite3) -> Result<(), SqliteError> {
+    let notify = Notify::new();
+
+    if sqlite3_unlock_notify(
+        conn,
+        Some(unlock_notify_cb),
+        &notify as *const Notify as *mut Notify as *mut _,
+    ) != SQLITE_OK
+    {
+        return Err(SqliteError::new(conn));
+    }
+
+    notify.wait();
+
+    Ok(())
+}
+
+unsafe extern "C" fn unlock_notify_cb(ptr: *mut *mut c_void, len: c_int) {
+    let ptr = ptr as *mut &Notify;
+    let slice = slice::from_raw_parts(ptr, len as usize);
+
+    for notify in slice {
+        notify.fire();
+    }
+}
+
+struct Notify {
+    mutex: Mutex<bool>,
+    condvar: Condvar,
+}
+
+impl Notify {
+    fn new() -> Self {
+        Self {
+            mutex: Mutex::new(false),
+            condvar: Condvar::new(),
+        }
+    }
+
+    fn wait(&self) {
+        let _ = self
+            .condvar
+            .wait_while(self.mutex.lock().unwrap(), |fired| !*fired)
+            .unwrap();
+    }
+
+    fn fire(&self) {
+        *self.mutex.lock().unwrap() = true;
+        self.condvar.notify_one();
+    }
+}