1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133

// Copyright 2018-2020 Cargill Incorporated
//
// Licensed 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.

//! Module containing ResourceTemporarilyUnavailableError implementation.

use std::error;
use std::fmt;
use std::time::Duration;

/// An error which is returned when an underlying resource is unavailable.
///
/// This error can be handled by retrying, usually in a loop with a small delay.
#[derive(Debug)]
pub struct ResourceTemporarilyUnavailableError {
    source: Box<dyn error::Error>,
    retry_duration_hint: Option<Duration>,
}

impl ResourceTemporarilyUnavailableError {
    /// Constructs a new `ResourceTemporarilyUnavailableError` from a specified source error.
    ///
    /// The implementation of `std::fmt::Display` for this error will simply pass through the
    /// display of the source message unmodified.
    ///
    /// # Examples
    ///
    /// ```
    /// use grid_sdk::error::ResourceTemporarilyUnavailableError;
    ///
    /// let io_err = std::io::Error::new(std::io::ErrorKind::Other, "io error");
    /// let rtu_error = ResourceTemporarilyUnavailableError::from_source(Box::new(io_err));
    /// assert_eq!(format!("{}", rtu_error), "io error");
    /// ```
    pub fn from_source(source: Box<dyn error::Error>) -> Self {
        Self {
            source,
            retry_duration_hint: None,
        }
    }

    /// Constructs a new `ResourceTemporarilyUnavailableError` from a specified source error with
    /// a retry duration hint.
    ///
    /// The hint specified here can be used by the caller as the duration between retry attempts.
    /// Callers may ignore this hint and provide their own algorithms, or may use this `Duration`
    /// as provided.
    ///
    /// The implementation of `std::fmt::Display` for this error will simply pass through the
    /// display of the source message unmodified.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::time::Duration;
    ///
    /// use grid_sdk::error::ResourceTemporarilyUnavailableError;
    ///
    /// let io_err = std::io::Error::new(std::io::ErrorKind::Other, "io error");
    /// let rtu_error = ResourceTemporarilyUnavailableError::from_source_with_hint(Box::new(io_err), Duration::new(10, 0));
    /// assert_eq!(format!("{}", rtu_error), "io error");
    /// ```
    pub fn from_source_with_hint(
        source: Box<dyn error::Error>,
        retry_duration_hint: Duration,
    ) -> Self {
        Self {
            source,
            retry_duration_hint: Some(retry_duration_hint),
        }
    }

    /// Returns the duration which the underlying library provides as a suggestion for an
    /// appropriate amount of time between retry attempts.
    pub fn retry_duration_hint(&self) -> Option<Duration> {
        self.retry_duration_hint
    }
}

impl error::Error for ResourceTemporarilyUnavailableError {
    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
        Some(self.source.as_ref())
    }
}

impl fmt::Display for ResourceTemporarilyUnavailableError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.source)
    }
}

#[cfg(test)]
pub mod tests {
    use std::time::Duration;

    use crate::error::InternalError;

    use super::*;

    /// Tests that error constructed with `ResourceTemporarilyUnavailableError::from_source` return
    /// a display string which is the same as the source's display string.
    #[test]
    fn test_display_from_source() {
        let msg = "test message";
        let err = ResourceTemporarilyUnavailableError::from_source(Box::new(
            InternalError::with_message(msg.to_string()),
        ));
        assert_eq!(format!("{}", err), msg);
    }

    /// Tests that error constructed with
    /// `ResourceTemporarilyUnavailableError::from_source_with_hint` return a display string which
    /// is the same as the source's display string.
    #[test]
    fn test_display_from_source_with_hint() {
        let msg = "test message";
        let err = ResourceTemporarilyUnavailableError::from_source_with_hint(
            Box::new(InternalError::with_message(msg.to_string())),
            Duration::new(10, 0),
        );
        assert_eq!(format!("{}", err), msg);
    }
}