core/src/layers/retry.rs

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

use std::fmt::Debug;
use std::fmt::Formatter;
use std::sync::Arc;
use std::time::Duration;

use backon::BlockingRetryable;
use backon::ExponentialBuilder;
use backon::Retryable;
use log::warn;

use crate::raw::*;
use crate::*;

/// Add retry for temporary failed operations.
///
/// # Notes
///
/// This layer will retry failed operations when [`Error::is_temporary`]
/// returns true. If operation still failed, this layer will set error to
/// `Persistent` which means error has been retried.
///
/// # Panics
///
/// While retrying `Reader` or `Writer` operations, please make sure either:
///
/// - All futures generated by `Reader::read` or `Writer::close` are resolved to `Ready`.
/// - Or, won't call any `Reader` or `Writer` methods after retry returns final error.
///
/// Otherwise, `RetryLayer` could panic while hitting in bad states.
///
/// For example, while composing `RetryLayer` with `TimeoutLayer`. The order of layer is sensitive.
///
/// ```no_run
/// # use std::time::Duration;
///
/// # use opendal::layers::RetryLayer;
/// # use opendal::layers::TimeoutLayer;
/// # use opendal::services;
/// # use opendal::Operator;
/// # use opendal::Result;
///
/// # fn main() -> Result<()> {
/// let op = Operator::new(services::Memory::default())?
///     // This is fine, since timeout happen during retry.
///     .layer(TimeoutLayer::new().with_io_timeout(Duration::from_nanos(1)))
///     .layer(RetryLayer::new())
///     // This is wrong. Since timeout layer will drop future, leaving retry layer in a bad state.
///     .layer(TimeoutLayer::new().with_io_timeout(Duration::from_nanos(1)))
///     .finish();
/// Ok(())
/// # }
/// ```
///
/// # Examples
///
/// ```no_run
/// # use opendal::layers::RetryLayer;
/// # use opendal::services;
/// # use opendal::Operator;
/// # use opendal::Result;
/// # use opendal::Scheme;
///
/// # fn main() -> Result<()> {
/// let _ = Operator::new(services::Memory::default())?
///     .layer(RetryLayer::new())
///     .finish();
/// Ok(())
/// # }
/// ```
///
/// ## Customize retry interceptor
///
/// RetryLayer accepts [`RetryInterceptor`] to allow users to customize
/// their own retry interceptor logic.
///
/// ```no_run
/// # use std::time::Duration;
///
/// # use opendal::layers::RetryInterceptor;
/// # use opendal::layers::RetryLayer;
/// # use opendal::services;
/// # use opendal::Error;
/// # use opendal::Operator;
/// # use opendal::Result;
/// # use opendal::Scheme;
///
/// struct MyRetryInterceptor;
///
/// impl RetryInterceptor for MyRetryInterceptor {
///     fn intercept(&self, err: &Error, dur: Duration) {
///         // do something
///     }
/// }
///
/// # fn main() -> Result<()> {
/// let _ = Operator::new(services::Memory::default())?
///     .layer(RetryLayer::new().with_notify(MyRetryInterceptor))
///     .finish();
/// Ok(())
/// # }
/// ```
pub struct RetryLayer<I: RetryInterceptor = DefaultRetryInterceptor> {
    builder: ExponentialBuilder,
    notify: Arc<I>,
}

impl<I: RetryInterceptor> Clone for RetryLayer<I> {
    fn clone(&self) -> Self {
        Self {
            builder: self.builder,
            notify: self.notify.clone(),
        }
    }
}

impl Default for RetryLayer {
    fn default() -> Self {
        Self {
            builder: ExponentialBuilder::default(),
            notify: Arc::new(DefaultRetryInterceptor),
        }
    }
}

impl RetryLayer {
    /// Create a new retry layer.
    /// # Examples
    ///
    /// ```no_run
    /// use anyhow::Result;
    /// use opendal::layers::RetryLayer;
    /// use opendal::services;
    /// use opendal::Operator;
    /// use opendal::Scheme;
    ///
    /// let _ = Operator::new(services::Memory::default())
    ///     .expect("must init")
    ///     .layer(RetryLayer::new());
    /// ```
    pub fn new() -> RetryLayer {
        Self::default()
    }
}

impl<I: RetryInterceptor> RetryLayer<I> {
    /// Set the retry interceptor as new notify.
    ///
    /// ```no_run
    /// use opendal::layers::RetryLayer;
    /// use opendal::services;
    /// use opendal::Operator;
    ///
    /// fn notify(_err: &opendal::Error, _dur: std::time::Duration) {}
    ///
    /// let _ = Operator::new(services::Memory::default())
    ///     .expect("must init")
    ///     .layer(RetryLayer::new().with_notify(notify))
    ///     .finish();
    /// ```
    pub fn with_notify<NI: RetryInterceptor>(self, notify: NI) -> RetryLayer<NI> {
        RetryLayer {
            builder: self.builder,
            notify: Arc::new(notify),
        }
    }

    /// Set jitter of current backoff.
    ///
    /// If jitter is enabled, ExponentialBackoff will add a random jitter in `[0, min_delay)
    /// to current delay.
    pub fn with_jitter(mut self) -> Self {
        self.builder = self.builder.with_jitter();
        self
    }

    /// Set factor of current backoff.
    ///
    /// # Panics
    ///
    /// This function will panic if input factor smaller than `1.0`.
    pub fn with_factor(mut self, factor: f32) -> Self {
        self.builder = self.builder.with_factor(factor);
        self
    }

    /// Set min_delay of current backoff.
    pub fn with_min_delay(mut self, min_delay: Duration) -> Self {
        self.builder = self.builder.with_min_delay(min_delay);
        self
    }

    /// Set max_delay of current backoff.
    ///
    /// Delay will not increase if current delay is larger than max_delay.
    pub fn with_max_delay(mut self, max_delay: Duration) -> Self {
        self.builder = self.builder.with_max_delay(max_delay);
        self
    }

    /// Set max_times of current backoff.
    ///
    /// Backoff will return `None` if max times is reaching.
    pub fn with_max_times(mut self, max_times: usize) -> Self {
        self.builder = self.builder.with_max_times(max_times);
        self
    }
}

impl<A: Access, I: RetryInterceptor> Layer<A> for RetryLayer<I> {
    type LayeredAccess = RetryAccessor<A, I>;

    fn layer(&self, inner: A) -> Self::LayeredAccess {
        RetryAccessor {
            inner: Arc::new(inner),
            builder: self.builder,
            notify: self.notify.clone(),
        }
    }
}

/// RetryInterceptor is used to intercept while retry happened.
pub trait RetryInterceptor: Send + Sync + 'static {
    /// Everytime RetryLayer is retrying, this function will be called.
    ///
    /// # Timing
    ///
    /// just before the retry sleep.
    ///
    /// # Inputs
    ///
    /// - err: The error that caused the current retry.
    /// - dur: The duration that will sleep before next retry.
    ///
    /// # Notes
    ///
    /// The intercept must be quick and non-blocking. No heavy IO is
    /// allowed. Otherwise, the retry will be blocked.
    fn intercept(&self, err: &Error, dur: Duration);
}

impl<F> RetryInterceptor for F
where
    F: Fn(&Error, Duration) + Send + Sync + 'static,
{
    fn intercept(&self, err: &Error, dur: Duration) {
        self(err, dur);
    }
}

/// The DefaultRetryInterceptor will log the retry error in warning level.
pub struct DefaultRetryInterceptor;

impl RetryInterceptor for DefaultRetryInterceptor {
    fn intercept(&self, err: &Error, dur: Duration) {
        warn!(
            target: "opendal::layers::retry",
            "will retry after {}s because: {}",
            dur.as_secs_f64(), err)
    }
}

pub struct RetryAccessor<A: Access, I: RetryInterceptor> {
    inner: Arc<A>,
    builder: ExponentialBuilder,
    notify: Arc<I>,
}

impl<A: Access, I: RetryInterceptor> Debug for RetryAccessor<A, I> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RetryAccessor")
            .field("inner", &self.inner)
            .finish_non_exhaustive()
    }
}

impl<A: Access, I: RetryInterceptor> LayeredAccess for RetryAccessor<A, I> {
    type Inner = A;
    type Reader = RetryWrapper<RetryReader<A, A::Reader>, I>;
    type BlockingReader = RetryWrapper<RetryReader<A, A::BlockingReader>, I>;
    type Writer = RetryWrapper<A::Writer, I>;
    type BlockingWriter = RetryWrapper<A::BlockingWriter, I>;
    type Lister = RetryWrapper<A::Lister, I>;
    type BlockingLister = RetryWrapper<A::BlockingLister, I>;
    type Deleter = RetryWrapper<A::Deleter, I>;
    type BlockingDeleter = RetryWrapper<A::BlockingDeleter, I>;

    fn inner(&self) -> &Self::Inner {
        &self.inner
    }

    async fn create_dir(&self, path: &str, args: OpCreateDir) -> Result<RpCreateDir> {
        { || self.inner.create_dir(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur: Duration| self.notify.intercept(err, dur))
            .await
            .map_err(|e| e.set_persistent())
    }

    async fn read(&self, path: &str, args: OpRead) -> Result<(RpRead, Self::Reader)> {
        let (rp, reader) = { || self.inner.read(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map_err(|e| e.set_persistent())?;

        let retry_reader = RetryReader::new(self.inner.clone(), path.to_string(), args, reader);
        let retry_wrapper = RetryWrapper::new(retry_reader, self.notify.clone(), self.builder);

        Ok((rp, retry_wrapper))
    }

    async fn write(&self, path: &str, args: OpWrite) -> Result<(RpWrite, Self::Writer)> {
        { || self.inner.write(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map(|(rp, r)| (rp, RetryWrapper::new(r, self.notify.clone(), self.builder)))
            .map_err(|e| e.set_persistent())
    }

    async fn stat(&self, path: &str, args: OpStat) -> Result<RpStat> {
        { || self.inner.stat(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map_err(|e| e.set_persistent())
    }

    async fn delete(&self) -> Result<(RpDelete, Self::Deleter)> {
        { || self.inner.delete() }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map(|(rp, r)| (rp, RetryWrapper::new(r, self.notify.clone(), self.builder)))
            .map_err(|e| e.set_persistent())
    }

    async fn copy(&self, from: &str, to: &str, args: OpCopy) -> Result<RpCopy> {
        { || self.inner.copy(from, to, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map_err(|e| e.set_persistent())
    }

    async fn rename(&self, from: &str, to: &str, args: OpRename) -> Result<RpRename> {
        { || self.inner.rename(from, to, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map_err(|e| e.set_persistent())
    }

    async fn list(&self, path: &str, args: OpList) -> Result<(RpList, Self::Lister)> {
        { || self.inner.list(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .await
            .map(|(rp, r)| (rp, RetryWrapper::new(r, self.notify.clone(), self.builder)))
            .map_err(|e| e.set_persistent())
    }

    fn blocking_create_dir(&self, path: &str, args: OpCreateDir) -> Result<RpCreateDir> {
        { || self.inner.blocking_create_dir(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map_err(|e| e.set_persistent())
    }

    fn blocking_read(&self, path: &str, args: OpRead) -> Result<(RpRead, Self::BlockingReader)> {
        let (rp, reader) = { || self.inner.blocking_read(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map_err(|e| e.set_persistent())?;

        let retry_reader = RetryReader::new(self.inner.clone(), path.to_string(), args, reader);
        let retry_wrapper = RetryWrapper::new(retry_reader, self.notify.clone(), self.builder);

        Ok((rp, retry_wrapper))
    }

    fn blocking_write(&self, path: &str, args: OpWrite) -> Result<(RpWrite, Self::BlockingWriter)> {
        { || self.inner.blocking_write(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map(|(rp, r)| (rp, RetryWrapper::new(r, self.notify.clone(), self.builder)))
            .map_err(|e| e.set_persistent())
    }

    fn blocking_stat(&self, path: &str, args: OpStat) -> Result<RpStat> {
        { || self.inner.blocking_stat(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map_err(|e| e.set_persistent())
    }

    fn blocking_delete(&self) -> Result<(RpDelete, Self::BlockingDeleter)> {
        { || self.inner.blocking_delete() }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map(|(rp, r)| (rp, RetryWrapper::new(r, self.notify.clone(), self.builder)))
            .map_err(|e| e.set_persistent())
    }

    fn blocking_copy(&self, from: &str, to: &str, args: OpCopy) -> Result<RpCopy> {
        { || self.inner.blocking_copy(from, to, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map_err(|e| e.set_persistent())
    }

    fn blocking_rename(&self, from: &str, to: &str, args: OpRename) -> Result<RpRename> {
        { || self.inner.blocking_rename(from, to, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map_err(|e| e.set_persistent())
    }

    fn blocking_list(&self, path: &str, args: OpList) -> Result<(RpList, Self::BlockingLister)> {
        { || self.inner.blocking_list(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| self.notify.intercept(err, dur))
            .call()
            .map(|(rp, p)| {
                let p = RetryWrapper::new(p, self.notify.clone(), self.builder);
                (rp, p)
            })
            .map_err(|e| e.set_persistent())
    }
}

pub struct RetryReader<A, R> {
    inner: Arc<A>,
    reader: Option<R>,

    path: String,
    args: OpRead,
}

impl<A, R> RetryReader<A, R> {
    fn new(inner: Arc<A>, path: String, args: OpRead, r: R) -> Self {
        Self {
            inner,
            reader: Some(r),

            path,
            args,
        }
    }
}

impl<A: Access> oio::Read for RetryReader<A, A::Reader> {
    async fn read(&mut self) -> Result<Buffer> {
        loop {
            match self.reader.take() {
                None => {
                    let (_, r) = self.inner.read(&self.path, self.args.clone()).await?;
                    self.reader = Some(r);
                    continue;
                }
                Some(mut reader) => {
                    let buf = reader.read().await?;
                    self.reader = Some(reader);
                    self.args.range_mut().advance(buf.len() as u64);
                    return Ok(buf);
                }
            }
        }
    }
}

impl<A: Access> oio::BlockingRead for RetryReader<A, A::BlockingReader> {
    fn read(&mut self) -> Result<Buffer> {
        loop {
            match self.reader.take() {
                None => {
                    let (_, r) = self.inner.blocking_read(&self.path, self.args.clone())?;
                    self.reader = Some(r);
                    continue;
                }
                Some(mut reader) => {
                    let buf = reader.read()?;
                    self.reader = Some(reader);
                    self.args.range_mut().advance(buf.len() as u64);
                    return Ok(buf);
                }
            }
        }
    }
}

pub struct RetryWrapper<R, I> {
    inner: Option<R>,
    notify: Arc<I>,

    builder: ExponentialBuilder,
}

impl<R, I> RetryWrapper<R, I> {
    fn new(inner: R, notify: Arc<I>, backoff: ExponentialBuilder) -> Self {
        Self {
            inner: Some(inner),
            notify,
            builder: backoff,
        }
    }

    fn take_inner(&mut self) -> Result<R> {
        self.inner.take().ok_or_else(|| {
            Error::new(
                ErrorKind::Unexpected,
                "retry layer is in bad state, please make sure future not dropped before ready",
            )
        })
    }
}

impl<R: oio::Read, I: RetryInterceptor> oio::Read for RetryWrapper<R, I> {
    async fn read(&mut self) -> Result<Buffer> {
        use backon::RetryableWithContext;

        let inner = self.take_inner()?;

        let (inner, res) = {
            |mut r: R| async move {
                let res = r.read().await;

                (r, res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context(inner)
        .notify(|err, dur| self.notify.intercept(err, dur))
        .await;

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }
}

impl<R: oio::BlockingRead, I: RetryInterceptor> oio::BlockingRead for RetryWrapper<R, I> {
    fn read(&mut self) -> Result<Buffer> {
        use backon::BlockingRetryableWithContext;

        let inner = self.take_inner()?;

        let (inner, res) = {
            |mut r: R| {
                let res = r.read();

                (r, res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context(inner)
        .notify(|err, dur| self.notify.intercept(err, dur))
        .call();

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }
}

impl<R: oio::Write, I: RetryInterceptor> oio::Write for RetryWrapper<R, I> {
    async fn write(&mut self, bs: Buffer) -> Result<()> {
        use backon::RetryableWithContext;

        let inner = self.take_inner()?;

        let ((inner, _), res) = {
            |(mut r, bs): (R, Buffer)| async move {
                let res = r.write(bs.clone()).await;

                ((r, bs), res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context((inner, bs))
        .notify(|err, dur| self.notify.intercept(err, dur))
        .await;

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }

    async fn abort(&mut self) -> Result<()> {
        use backon::RetryableWithContext;

        let inner = self.take_inner()?;

        let (inner, res) = {
            |mut r: R| async move {
                let res = r.abort().await;

                (r, res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context(inner)
        .notify(|err, dur| self.notify.intercept(err, dur))
        .await;

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }

    async fn close(&mut self) -> Result<Metadata> {
        use backon::RetryableWithContext;

        let inner = self.take_inner()?;

        let (inner, res) = {
            |mut r: R| async move {
                let res = r.close().await;

                (r, res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context(inner)
        .notify(|err, dur| self.notify.intercept(err, dur))
        .await;

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }
}

impl<R: oio::BlockingWrite, I: RetryInterceptor> oio::BlockingWrite for RetryWrapper<R, I> {
    fn write(&mut self, bs: Buffer) -> Result<()> {
        { || self.inner.as_mut().unwrap().write(bs.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| {
                self.notify.intercept(err, dur);
            })
            .call()
            .map_err(|e| e.set_persistent())
    }

    fn close(&mut self) -> Result<Metadata> {
        { || self.inner.as_mut().unwrap().close() }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| {
                self.notify.intercept(err, dur);
            })
            .call()
            .map_err(|e| e.set_persistent())
    }
}

impl<P: oio::List, I: RetryInterceptor> oio::List for RetryWrapper<P, I> {
    async fn next(&mut self) -> Result<Option<oio::Entry>> {
        use backon::RetryableWithContext;

        let inner = self.take_inner()?;

        let (inner, res) = {
            |mut p: P| async move {
                let res = p.next().await;

                (p, res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context(inner)
        .notify(|err, dur| self.notify.intercept(err, dur))
        .await;

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }
}

impl<P: oio::BlockingList, I: RetryInterceptor> oio::BlockingList for RetryWrapper<P, I> {
    fn next(&mut self) -> Result<Option<oio::Entry>> {
        { || self.inner.as_mut().unwrap().next() }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| {
                self.notify.intercept(err, dur);
            })
            .call()
            .map_err(|e| e.set_persistent())
    }
}

impl<P: oio::Delete, I: RetryInterceptor> oio::Delete for RetryWrapper<P, I> {
    fn delete(&mut self, path: &str, args: OpDelete) -> Result<()> {
        { || self.inner.as_mut().unwrap().delete(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| {
                self.notify.intercept(err, dur);
            })
            .call()
            .map_err(|e| e.set_persistent())
    }

    async fn flush(&mut self) -> Result<usize> {
        use backon::RetryableWithContext;

        let inner = self.take_inner()?;

        let (inner, res) = {
            |mut p: P| async move {
                let res = p.flush().await;

                (p, res)
            }
        }
        .retry(self.builder)
        .when(|e| e.is_temporary())
        .context(inner)
        .notify(|err, dur| self.notify.intercept(err, dur))
        .await;

        self.inner = Some(inner);
        res.map_err(|err| err.set_persistent())
    }
}

impl<P: oio::BlockingDelete, I: RetryInterceptor> oio::BlockingDelete for RetryWrapper<P, I> {
    fn delete(&mut self, path: &str, args: OpDelete) -> Result<()> {
        { || self.inner.as_mut().unwrap().delete(path, args.clone()) }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| {
                self.notify.intercept(err, dur);
            })
            .call()
            .map_err(|e| e.set_persistent())
    }

    fn flush(&mut self) -> Result<usize> {
        { || self.inner.as_mut().unwrap().flush() }
            .retry(self.builder)
            .when(|e| e.is_temporary())
            .notify(|err, dur| {
                self.notify.intercept(err, dur);
            })
            .call()
            .map_err(|e| e.set_persistent())
    }
}

#[cfg(test)]
mod tests {
    use std::mem;
    use std::sync::Arc;
    use std::sync::Mutex;

    use bytes::Bytes;
    use futures::{stream, TryStreamExt};
    use tracing_subscriber::filter::LevelFilter;

    use super::*;
    use crate::layers::LoggingLayer;

    #[derive(Default, Clone)]
    struct MockBuilder {
        attempt: Arc<Mutex<usize>>,
    }

    impl Builder for MockBuilder {
        const SCHEME: Scheme = Scheme::Custom("mock");
        type Config = ();

        fn build(self) -> Result<impl Access> {
            Ok(MockService {
                attempt: self.attempt.clone(),
            })
        }
    }

    #[derive(Debug, Clone, Default)]
    struct MockService {
        attempt: Arc<Mutex<usize>>,
    }

    impl Access for MockService {
        type Reader = MockReader;
        type Writer = MockWriter;
        type Lister = MockLister;
        type Deleter = MockDeleter;
        type BlockingReader = ();
        type BlockingWriter = ();
        type BlockingLister = ();
        type BlockingDeleter = ();

        fn info(&self) -> Arc<AccessorInfo> {
            let am = AccessorInfo::default();
            am.set_scheme(Scheme::Custom("mock"))
                .set_native_capability(Capability {
                    read: true,
                    write: true,
                    write_can_multi: true,
                    delete: true,
                    delete_max_size: Some(10),
                    stat: true,
                    list: true,
                    list_with_recursive: true,
                    ..Default::default()
                });

            am.into()
        }

        async fn stat(&self, _: &str, _: OpStat) -> Result<RpStat> {
            Ok(RpStat::new(
                Metadata::new(EntryMode::FILE).with_content_length(13),
            ))
        }

        async fn read(&self, _: &str, args: OpRead) -> Result<(RpRead, Self::Reader)> {
            Ok((
                RpRead::new(),
                MockReader {
                    buf: Bytes::from("Hello, World!").into(),
                    range: args.range(),
                    attempt: self.attempt.clone(),
                },
            ))
        }

        async fn delete(&self) -> Result<(RpDelete, Self::Deleter)> {
            Ok((
                RpDelete::default(),
                MockDeleter {
                    size: 0,
                    attempt: self.attempt.clone(),
                },
            ))
        }

        async fn write(&self, _: &str, _: OpWrite) -> Result<(RpWrite, Self::Writer)> {
            Ok((RpWrite::new(), MockWriter {}))
        }

        async fn list(&self, _: &str, _: OpList) -> Result<(RpList, Self::Lister)> {
            let lister = MockLister::default();
            Ok((RpList::default(), lister))
        }
    }

    #[derive(Debug, Clone, Default)]
    struct MockReader {
        buf: Buffer,
        range: BytesRange,
        attempt: Arc<Mutex<usize>>,
    }

    impl oio::Read for MockReader {
        async fn read(&mut self) -> Result<Buffer> {
            let mut attempt = self.attempt.lock().unwrap();
            *attempt += 1;

            match *attempt {
                1 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable_error from reader")
                        .set_temporary(),
                ),
                2 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable_error from reader")
                        .set_temporary(),
                ),
                // Should read out all data.
                3 => Ok(self.buf.slice(self.range.to_range_as_usize())),
                4 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable_error from reader")
                        .set_temporary(),
                ),
                // Should be empty.
                5 => Ok(self.buf.slice(self.range.to_range_as_usize())),
                _ => unreachable!(),
            }
        }
    }

    #[derive(Debug, Clone, Default)]
    struct MockWriter {}

    impl oio::Write for MockWriter {
        async fn write(&mut self, _: Buffer) -> Result<()> {
            Ok(())
        }

        async fn close(&mut self) -> Result<Metadata> {
            Err(Error::new(ErrorKind::Unexpected, "always close failed").set_temporary())
        }

        async fn abort(&mut self) -> Result<()> {
            Ok(())
        }
    }

    #[derive(Debug, Clone, Default)]
    struct MockLister {
        attempt: usize,
    }

    impl oio::List for MockLister {
        async fn next(&mut self) -> Result<Option<oio::Entry>> {
            self.attempt += 1;
            match self.attempt {
                1 => Err(Error::new(
                    ErrorKind::RateLimited,
                    "retryable rate limited error from lister",
                )
                .set_temporary()),
                2 => Ok(Some(oio::Entry::new(
                    "hello",
                    Metadata::new(EntryMode::FILE),
                ))),
                3 => Ok(Some(oio::Entry::new(
                    "world",
                    Metadata::new(EntryMode::FILE),
                ))),
                4 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable internal server error")
                        .set_temporary(),
                ),
                5 => Ok(Some(oio::Entry::new(
                    "2023/",
                    Metadata::new(EntryMode::DIR),
                ))),
                6 => Ok(Some(oio::Entry::new(
                    "0208/",
                    Metadata::new(EntryMode::DIR),
                ))),
                7 => Ok(None),
                _ => {
                    unreachable!()
                }
            }
        }
    }

    #[derive(Debug, Clone, Default)]
    struct MockDeleter {
        size: usize,
        attempt: Arc<Mutex<usize>>,
    }

    impl oio::Delete for MockDeleter {
        fn delete(&mut self, _: &str, _: OpDelete) -> Result<()> {
            self.size += 1;
            Ok(())
        }

        async fn flush(&mut self) -> Result<usize> {
            let mut attempt = self.attempt.lock().unwrap();
            *attempt += 1;

            match *attempt {
                1 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable_error from deleter")
                        .set_temporary(),
                ),
                2 => {
                    self.size -= 1;
                    Ok(1)
                }
                3 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable_error from deleter")
                        .set_temporary(),
                ),
                4 => Err(
                    Error::new(ErrorKind::Unexpected, "retryable_error from deleter")
                        .set_temporary(),
                ),
                5 => {
                    let s = mem::take(&mut self.size);
                    Ok(s)
                }
                _ => unreachable!(),
            }
        }
    }

    #[tokio::test]
    async fn test_retry_read() {
        let _ = tracing_subscriber::fmt()
            .with_max_level(LevelFilter::TRACE)
            .with_test_writer()
            .try_init();

        let builder = MockBuilder::default();
        let op = Operator::new(builder.clone())
            .unwrap()
            .layer(LoggingLayer::default())
            .layer(RetryLayer::new())
            .finish();

        let r = op.reader("retryable_error").await.unwrap();
        let mut content = Vec::new();
        let size = r
            .read_into(&mut content, ..)
            .await
            .expect("read must succeed");
        assert_eq!(size, 13);
        assert_eq!(content, "Hello, World!".as_bytes());
        // The error is retryable, we should request it 3 times.
        assert_eq!(*builder.attempt.lock().unwrap(), 5);
    }

    /// This test is used to reproduce the panic issue while composing retry layer with timeout layer.
    #[tokio::test]
    async fn test_retry_write_fail_on_close() {
        let _ = tracing_subscriber::fmt()
            .with_max_level(LevelFilter::TRACE)
            .with_test_writer()
            .try_init();

        let builder = MockBuilder::default();
        let op = Operator::new(builder.clone())
            .unwrap()
            .layer(
                RetryLayer::new()
                    .with_min_delay(Duration::from_millis(1))
                    .with_max_delay(Duration::from_millis(1))
                    .with_jitter(),
            )
            // Uncomment this to reproduce timeout layer panic.
            // .layer(TimeoutLayer::new().with_io_timeout(Duration::from_nanos(1)))
            .layer(LoggingLayer::default())
            .finish();

        let mut w = op.writer("test_write").await.unwrap();
        w.write("aaa").await.unwrap();
        w.write("bbb").await.unwrap();
        match w.close().await {
            Ok(_) => (),
            Err(_) => {
                w.abort().await.unwrap();
            }
        };
    }

    #[tokio::test]
    async fn test_retry_list() {
        let _ = tracing_subscriber::fmt().with_test_writer().try_init();

        let builder = MockBuilder::default();
        let op = Operator::new(builder.clone())
            .unwrap()
            .layer(RetryLayer::new())
            .finish();

        let expected = vec!["hello", "world", "2023/", "0208/"];

        let mut lister = op
            .lister("retryable_error/")
            .await
            .expect("service must support list");
        let mut actual = Vec::new();
        while let Some(obj) = lister.try_next().await.expect("must success") {
            actual.push(obj.name().to_owned());
        }

        assert_eq!(actual, expected);
    }

    #[tokio::test]
    async fn test_retry_batch() {
        let _ = tracing_subscriber::fmt().with_test_writer().try_init();

        let builder = MockBuilder::default();
        // set to a lower delay to make it run faster
        let op = Operator::new(builder.clone())
            .unwrap()
            .layer(
                RetryLayer::new()
                    .with_min_delay(Duration::from_secs_f32(0.1))
                    .with_max_times(5),
            )
            .finish();

        let paths = vec!["hello", "world", "test", "batch"];
        op.delete_stream(stream::iter(paths)).await.unwrap();
        assert_eq!(*builder.attempt.lock().unwrap(), 5);
    }
}