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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
//! Resting place for [ResolvedResult]
/// Contains all possibilities for finished retryable operations -- conversible to `Result<>` --
/// and some nice facilities for instrumentation (like building a succinct report of the retry errors)
pub enum ResolvedResult<ReportedInput,
OriginalInput,
Output,
ErrorType> {
Ok {
reported_input: ReportedInput,
output: Output,
},
Fatal {
input: OriginalInput,
error: ErrorType,
},
Recovered {
reported_input: ReportedInput,
output: Output,
retry_errors: Vec<ErrorType>,
},
GivenUp {
input: OriginalInput,
retry_errors: Vec<ErrorType>,
fatal_error: ErrorType,
},
Unrecoverable {
input: OriginalInput,
retry_errors: Vec<ErrorType>,
fatal_error: ErrorType,
},
}
impl<ReportedInput,
OriginalInput,
Output,
ErrorType>
ResolvedResult<ReportedInput,
OriginalInput,
Output,
ErrorType> {
pub fn from_ok_result(reported_input: ReportedInput, output: Output) -> Self {
ResolvedResult::Ok { reported_input, output }
}
pub fn from_err_result(original_input: OriginalInput, error: ErrorType) -> Self {
ResolvedResult::Fatal { input: original_input, error }
}
pub fn inspect_ok<IgnoredReturn,
F: FnOnce(&ReportedInput, &Output) -> IgnoredReturn>
(self, f: F) -> Self {
if let Self::Ok { ref reported_input, ref output } = self {
f(reported_input, output);
}
self
}
pub fn inspect_fatal<IgnoredReturn,
F: FnOnce(&OriginalInput, &ErrorType) -> IgnoredReturn>
(self, f: F) -> Self {
if let Self::Fatal { ref input, ref error } = self {
f(input, error);
}
self
}
/// Spots on the data of an already resolved (and unsuccessful) operation that required some retry attempts to succeed.
/// - `f(&reported_input, &output, &retry_errors_list)`
/// - if the error type implements `Debug`, you can do `let loggable_retry_errors = keen_retry::loggable_retry_errors(&retry_errors_list)`
pub fn inspect_recovered<IgnoredReturn,
F: FnOnce(&ReportedInput, &Output, &Vec<ErrorType>) -> IgnoredReturn>
(self, f: F) -> Self {
if let Self::Recovered { ref reported_input, ref output, ref retry_errors } = self {
f(reported_input, output, retry_errors);
}
self
}
/// Spots on the data of an already resolved (but unsuccessful) operation that got retried as much as it could.
/// - `f(&original_input, &retry_errors_list, &fatal_error)`
/// - if the error type implements `Debug`, you can do `let loggable_retry_errors = keen_retry::loggable_retry_errors(&retry_errors_list)`
pub fn inspect_given_up<IgnoredReturn,
F: FnOnce(&OriginalInput, &Vec<ErrorType>, /*fatal_error: */&ErrorType) -> IgnoredReturn>
(self, f: F) -> Self {
if let Self::GivenUp { ref input, ref retry_errors, ref fatal_error } = self {
f(input, retry_errors, fatal_error);
}
self
}
/// Spots on the data of an already resolved (but unsuccessful) operation that failed fatably in one of its retry attempts.
/// - `f(&original_input, &retry_errors_list, &fatal_error)`
/// - if the error type implements `Debug`, you can do `let loggable_retry_errors = keen_retry::loggable_retry_errors(&retry_errors_list)`
pub fn inspect_unrecoverable<IgnoredReturn,
F: FnOnce(&OriginalInput, &Vec<ErrorType>, /*fatal_error: */&ErrorType) -> IgnoredReturn>
(self, f: F) -> Self {
if let Self::Unrecoverable { ref input, ref retry_errors, ref fatal_error } = self {
f(input, retry_errors, fatal_error);
}
self
}
/// Changes the original input data of an already resolved (but unsuccessful) operation.
/// - `f(original_input) -> new_original_input`.
///
/// A possible usage would be to downgrade a laden payload to its initial form, so it may be returned back to the caller:
/// ```nocompile
/// // downgrades the laden payload that was useful when logging the retry attempts & outcomes
/// .map_unrecoverable_input(|(loggable_payload, original_payload, retry_start)| original_payload)
pub fn map_unrecoverable_input<NewOriginalInput,
F: FnOnce(OriginalInput) -> NewOriginalInput>
(self, f: F) -> ResolvedResult<ReportedInput, NewOriginalInput, Output, ErrorType> {
match self {
ResolvedResult::Ok { reported_input, output } => ResolvedResult::Ok { reported_input, output },
ResolvedResult::Fatal { input, error } => ResolvedResult::Fatal { input: f(input), error },
ResolvedResult::Recovered { reported_input, output, retry_errors } => ResolvedResult::Recovered { reported_input, output, retry_errors },
ResolvedResult::GivenUp { input, retry_errors, fatal_error } => ResolvedResult::GivenUp { input: f(input), retry_errors, fatal_error },
ResolvedResult::Unrecoverable { input, retry_errors, fatal_error } => ResolvedResult::Unrecoverable { input: f(input), retry_errors, fatal_error },
}
}
/// Allows changing the reported input data of an already resolved (and unsuccessful) operation.\
/// A successful operation is likely to consume the input and the `reported_input` is expected, if desirable,
/// to be a lightweight representation of it -- lets say, for instrumentation purposes.\
/// This method allows a laden `reported_input` to be downgraded to its original form, where:
/// - `f(reported_input) -> new_reported_input`.
///
/// Example:
/// ```nocompile
/// // downgrades the laden `reported_input` that was useful during logging & retrying
/// .map_reported_input(|(loggable_payload, duration)| loggable_payload)
pub fn map_reported_input<NewReportedInput,
F: FnOnce(ReportedInput) -> NewReportedInput>
(self, f: F) -> ResolvedResult<NewReportedInput, OriginalInput, Output, ErrorType> {
match self {
ResolvedResult::Ok { reported_input, output } => ResolvedResult::Ok { reported_input: f(reported_input), output },
ResolvedResult::Fatal { input, error} => ResolvedResult::Fatal { input, error },
ResolvedResult::Recovered { reported_input, output, retry_errors } => ResolvedResult::Recovered { reported_input: f(reported_input), output, retry_errors },
ResolvedResult::GivenUp { input, retry_errors, fatal_error } => ResolvedResult::GivenUp { input, retry_errors, fatal_error },
ResolvedResult::Unrecoverable { input, retry_errors, fatal_error } => ResolvedResult::Unrecoverable { input, retry_errors, fatal_error },
}
}
/// Allows changing the `reported_input` and `output` of an already resolved (and successful) operation.\
/// - `f(reported_input, output) -> (new_reported_input, new_output)`
///
/// A possible usage would be to swap the `output` and `reported_input`, so the `reported_input` may end up in
/// a `Result<>` (instead of the usual output):
/// ```nocompile
/// .map_reported_input_and_output(|reported_input, output| (output, reported_input) )
pub fn map_reported_input_and_output<NewReportedInput,
NewOutput,
F: FnOnce(ReportedInput, Output) -> (NewReportedInput, NewOutput)>
(self, f: F) -> ResolvedResult<NewReportedInput, OriginalInput, NewOutput, ErrorType> {
match self {
ResolvedResult::Fatal { input, error} => ResolvedResult::Fatal { input, error },
ResolvedResult::GivenUp { input, retry_errors, fatal_error } => ResolvedResult::GivenUp { input, retry_errors, fatal_error },
ResolvedResult::Unrecoverable { input, retry_errors, fatal_error } => ResolvedResult::Unrecoverable { input, retry_errors, fatal_error },
ResolvedResult::Recovered { reported_input, output, retry_errors } => {
let (reported_input, output) = f(reported_input, output);
ResolvedResult::Recovered { reported_input, output, retry_errors }
},
ResolvedResult::Ok { reported_input, output } => {
let (reported_input, output) = f(reported_input, output);
ResolvedResult::Ok { reported_input, output }
},
}
}
/// Allows changing the `input` and `errors` of already resolved & unsuccessful operations:
/// - fatal_map_fn(input, fatal_error) -> (new_input, new_fatal_error)
/// - retry_errors_map_fn(retry_error) -> new_retry_error
///
/// Covers the case where it is needed to move the `input` into the fatal `error`, so it may contain the
/// failed payload when converted to `Result<>`.
///
/// See also [RetryResult::map_inputs_and_errors()] for similar semantics when you wish to skip retrying.
pub fn map_inputs_and_errors<NewOriginalInput,
NewErrorType,
FatalMapFn: FnOnce(OriginalInput, ErrorType) -> (NewOriginalInput, NewErrorType),
RetryErrorsMapFn: FnMut(ErrorType) -> NewErrorType>
(self,
fatal_map_fn: FatalMapFn,
retry_errors_map_fn: RetryErrorsMapFn)
-> ResolvedResult<ReportedInput, NewOriginalInput, Output, NewErrorType> {
match self {
ResolvedResult::Ok { reported_input, output } => ResolvedResult::Ok { reported_input, output },
ResolvedResult::Recovered { reported_input, output, retry_errors } => ResolvedResult::Recovered { reported_input, output, retry_errors: retry_errors.into_iter().map(retry_errors_map_fn).collect() },
ResolvedResult::Unrecoverable { input, retry_errors, fatal_error } => {
let (new_input, new_fatal_error) = fatal_map_fn(input, fatal_error);
ResolvedResult::Unrecoverable { input: new_input, retry_errors: retry_errors.into_iter().map(retry_errors_map_fn).collect(), fatal_error: new_fatal_error }
},
ResolvedResult::GivenUp { input, retry_errors, fatal_error } => {
let (new_input, new_fatal_error) = fatal_map_fn(input, fatal_error);
ResolvedResult::GivenUp { input: new_input, retry_errors: retry_errors.into_iter().map(retry_errors_map_fn).collect(), fatal_error: new_fatal_error }
},
ResolvedResult::Fatal { input, error } => {
let (new_input, new_error) = fatal_map_fn(input, error);
ResolvedResult::Fatal { input: new_input, error: new_error }
},
}
}
}
impl<ReportedInput,
OriginalInput,
Output,
ErrorType>
From<ResolvedResult<ReportedInput,
OriginalInput,
Output,
ErrorType>> for
Result<Output, ErrorType> {
/// Lossy operation that will convert this already resolved operation (after some possible retries) into a `Result<>`
fn from(resolved_result: ResolvedResult<ReportedInput, OriginalInput, Output, ErrorType>) -> Result<Output, ErrorType> {
match resolved_result {
ResolvedResult::Ok { reported_input: _, output } => Ok(output),
ResolvedResult::Fatal { input: _, error } => Err(error),
ResolvedResult::Recovered { reported_input: _, output, retry_errors: _ } => Ok(output),
ResolvedResult::GivenUp { input: _, retry_errors: _, fatal_error } => Err(fatal_error),
ResolvedResult::Unrecoverable { input: _, retry_errors: _, fatal_error } => Err(fatal_error),
}
}
}
use std::{
fmt::Debug,
collections::BTreeMap,
};
/// builds an as-short-as-possible list of `retry_errors` occurrences (out of order),
/// provided `ErrorType` implements the `Debug` trait.
pub fn loggable_retry_errors<ErrorType: Debug>(retry_errors: &Vec<ErrorType>) -> String {
let mut counts = BTreeMap::<String, u32>::new();
for error in retry_errors {
let error_string = format!("{:?}", error);
*counts.entry(error_string).or_insert(0) += 1;
}
counts.into_iter()
.map(|(error, count)| format!("{count}x: '{error}'"))
.collect::<Vec<_>>()
.join(", ")
}