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
use serde::de::DeserializeOwned;
use serde::ser::Serialize;
use std::collections::{HashMap, HashSet};
use std::sync::{Arc, Mutex};
use error::Error;
use storage::{CommittedCheckpoint, Storage, UncommittedCheckpoint};
type SharedCountMap = Arc<Mutex<HashMap<String, usize>>>;
type SharedSet = Arc<Mutex<HashSet<String>>>;
#[derive(Debug)]
pub struct GuardWrapper<T> {
inner: T,
committed_cps_in_use: SharedCountMap,
uncommitted_cps: SharedSet,
}
impl<T: Storage> GuardWrapper<T> {
pub fn wrap(mut inner: T) -> Result<Self, Error> {
let committed_cps_in_use = SharedCountMap::default();
{
let mut counts = committed_cps_in_use.lock().unwrap();
let identifiers = inner.checkpoint_identifiers().map_err(|_| {
Error::initialization(
"Could not retrieve existing checkpoint identifiers".to_string(),
)
})?;
for identifier in identifiers {
counts.insert(identifier, 0);
}
}
Ok(Self {
inner,
committed_cps_in_use,
uncommitted_cps: SharedSet::default(),
})
}
}
impl<T: Storage> Storage for GuardWrapper<T> {
type Committed = Committed<T::Committed>;
type Uncommitted = Uncommitted<T::Uncommitted>;
fn create_checkpoint(&mut self, identifier: &str) -> Result<Self::Uncommitted, Error> {
let committed_cps = self.committed_cps_in_use.lock().unwrap();
let mut uncommitted_cps = self.uncommitted_cps.lock().unwrap();
if committed_cps.contains_key(identifier) || uncommitted_cps.contains(identifier) {
Err(Error::cp_already_exists(format!(
"Checkpoint {} already exists",
identifier
)))?;
}
let inner = self.inner.create_checkpoint(identifier)?;
uncommitted_cps.insert(identifier.to_string());
Ok(Self::Uncommitted {
inner: Some(inner),
identifier: identifier.to_string(),
uncommitted_cp_set: self.uncommitted_cps.clone(),
})
}
fn commit_checkpoint(
&mut self,
mut uncommitted: Self::Uncommitted,
) -> Result<Self::Committed, Error> {
let identifier = uncommitted.identifier()?.to_string();
let mut committed_cps = self.committed_cps_in_use.lock().unwrap();
if committed_cps.contains_key(&identifier) {
Err(Error::cp_already_exists(format!(
"Checkpoint {} has already been committed",
&identifier
)))?;
}
let inner = self.inner.commit_checkpoint(uncommitted.take_inner()?)?;
committed_cps.insert(identifier.clone(), 1);
Ok(Self::Committed {
committed_cp_counts: self.committed_cps_in_use.clone(),
inner,
identifier,
})
}
fn load_checkpoint(&mut self, identifier: &str) -> Result<Self::Committed, Error> {
let mut committed_cps = self.committed_cps_in_use.lock().unwrap();
if !committed_cps.contains_key(identifier) {
Err(Error::cp_doesnt_exist(format!(
"Checkpoint {} does not exist",
identifier
)))?;
}
let inner = self.inner.load_checkpoint(identifier)?;
*committed_cps.entry(identifier.to_string()).or_insert(0) += 1;
Ok(Self::Committed {
committed_cp_counts: self.committed_cps_in_use.clone(),
inner,
identifier: identifier.to_string(),
})
}
fn remove_checkpoint(&mut self, identifier: &str) -> Result<(), Error> {
let mut counts = self.committed_cps_in_use.lock().unwrap();
if let Some(count) = counts.get(identifier) {
if *count > 0 {
Err(Error::cp_in_use(format!(
"Checkpoint {} already in use",
identifier
)))?;
}
} else {
Err(Error::cp_doesnt_exist(format!(
"Checkpoint {} doesn't exist",
identifier
)))?;
}
self.inner.remove_checkpoint(identifier)?;
counts.remove(identifier);
Ok(())
}
fn checkpoint_identifiers(&mut self) -> Result<Vec<String>, Error> {
self.inner.checkpoint_identifiers()
}
}
#[derive(Debug)]
pub struct Committed<C: CommittedCheckpoint> {
committed_cp_counts: SharedCountMap,
inner: C,
identifier: String,
}
impl<C: CommittedCheckpoint> CommittedCheckpoint for Committed<C> {
fn get<T: DeserializeOwned + Serialize>(&mut self, key: &str) -> Result<T, Error> {
self.inner.get(key)
}
fn keys(&mut self) -> Result<Vec<String>, Error> {
self.inner.keys()
}
fn identifier(&mut self) -> Result<&str, Error> {
Ok(&self.identifier)
}
}
impl<C: CommittedCheckpoint> Drop for Committed<C> {
fn drop(&mut self) {
let identifiers = self.identifier().unwrap().to_string();
let mut committed_cp_counts = self.committed_cp_counts.lock().unwrap();
if let Some(count) = committed_cp_counts.get_mut(&identifiers) {
if *count > 0 {
*count -= 1;
}
}
}
}
#[derive(Debug)]
pub struct Uncommitted<U: UncommittedCheckpoint> {
inner: Option<U>,
identifier: String,
uncommitted_cp_set: SharedSet,
}
impl<U: UncommittedCheckpoint> Uncommitted<U> {
fn inner(&mut self) -> Result<&mut U, Error> {
Ok(self.inner.as_mut().ok_or_else(|| {
Error::other(
"Checkpoint with type Checkpoint::wrappers::guard_wrapper::Uncommitted has \
no inner storage"
.to_string(),
)
})?)
}
fn take_inner(&mut self) -> Result<U, Error> {
match self.inner.take() {
Some(i) => Ok(i),
None => Err(Error::other(
"Checkpoint with type Checkpoint::wrappers::guard_wrapper::Uncommitted has \
no inner storage"
.to_string(),
))?,
}
}
}
impl<U: UncommittedCheckpoint> UncommittedCheckpoint for Uncommitted<U> {
fn get<T: DeserializeOwned + Serialize>(&mut self, key: &str) -> Result<T, Error> {
self.inner()?.get(key)
}
fn keys(&mut self) -> Result<Vec<String>, Error> {
self.inner()?.keys()
}
fn identifier(&mut self) -> Result<&str, Error> {
Ok(&self.identifier)
}
fn put<T: DeserializeOwned + Serialize>(&mut self, key: &str, value: &T) -> Result<(), Error> {
self.inner()?.put(key, value)
}
fn remove(&mut self, key: &str) -> Result<(), Error> {
self.inner()?.remove(key)
}
}
impl<U: UncommittedCheckpoint> Drop for Uncommitted<U> {
fn drop(&mut self) {
let identifier = self.identifier().unwrap().to_string();
let mut uncommitted_cps = self.uncommitted_cp_set.lock().unwrap();
uncommitted_cps.remove(&identifier);
}
}