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
use crate::{
utils::{err_from_event, str_slice_to_array},
ObjectStore,
};
use std::{
cell::RefCell,
future::Future,
marker::PhantomData,
pin::Pin,
rc::Rc,
task::{Context, Poll},
};
use web_sys::{
wasm_bindgen::{JsCast, JsValue},
IdbDatabase, IdbRequest, IdbTransaction, IdbTransactionMode,
};
mod runner;
pub(crate) mod unsafe_jar;
pub use runner::{RunnableTransaction, TransactionResult};
/// Wrapper for [`IDBTransaction`](https://developer.mozilla.org/en-US/docs/Web/API/IDBTransaction)
#[derive(Debug)]
pub struct Transaction<Err> {
sys: IdbTransaction,
_phantom: PhantomData<Err>,
}
impl<Err> Transaction<Err> {
pub(crate) fn from_sys(sys: IdbTransaction) -> Transaction<Err> {
Transaction {
sys,
_phantom: PhantomData,
}
}
pub(crate) fn as_sys(&self) -> &IdbTransaction {
&self.sys
}
/// Returns an [`ObjectStore`] that can be used to operate on data in this transaction
///
/// Internally, this uses [`IDBTransaction::objectStore`](https://developer.mozilla.org/en-US/docs/Web/API/IDBTransaction/objectStore).
pub fn object_store(&self, name: &str) -> crate::Result<ObjectStore<Err>, Err> {
Ok(ObjectStore::from_sys(self.sys.object_store(name).map_err(
|err| match error_name!(&err) {
Some("NotFoundError") => crate::Error::DoesNotExist,
_ => crate::Error::from_js_value(err),
},
)?))
}
}
/// Helper to build a transaction
pub struct TransactionBuilder {
db: IdbDatabase,
stores: JsValue,
mode: IdbTransactionMode,
// TODO: add support for transaction durability when web-sys gets it
}
impl TransactionBuilder {
pub(crate) fn from_names(db: IdbDatabase, names: &[&str]) -> TransactionBuilder {
TransactionBuilder {
db,
stores: str_slice_to_array(names).into(),
mode: IdbTransactionMode::Readonly,
}
}
/// Allow writes in this transaction
///
/// Without this, the transaction will only be allowed reads, and will error upon trying to
/// write objects.
pub fn rw(mut self) -> Self {
self.mode = IdbTransactionMode::Readwrite;
self
}
/// Actually execute the transaction
///
/// The `transaction` argument defines what will be run in the transaction. Note that due to
/// limitations of the IndexedDb API, the future returned by `transaction` cannot call `.await`
/// on any future except the ones provided by the [`Transaction`] itself. This function will
/// do its best to detect these cases to abort the transaction and panic, but you should avoid
/// doing so anyway. Note also that these errors are not recoverable: even if wasm32 were not
/// having `panic=abort`, once there is such a panic no `indexed-db` functions will work any
/// longer.
///
/// If `transaction` returns an `Ok` value, then the transaction will be committed. If it
/// returns an `Err` value, then it will be aborted.
///
/// Note that you should avoid sending requests that you do not await. If you do, it is hard
/// to say whether the transaction will commit or abort, due to both the IndexedDB and the
/// `wasm-bindgen` semantics.
///
/// Note that transactions cannot be nested.
///
/// Internally, this uses [`IDBDatabase::transaction`](https://developer.mozilla.org/en-US/docs/Web/API/IDBDatabase/transaction).
// For more details of what will happen if one does not await:
// - If the `Closure` from `transaction_request` is not dropped yet, then the error will be
// explicitly ignored, and thus transaction will commit.
// - If the `Closure` from `transaction_request` has already been dropped, then the callback
// will panic. Most likely this will lead to the transaction aborting, but this is an
// untested and unsupported code path.
pub async fn run<Ret, Err>(
self,
transaction: impl AsyncFnOnce(Transaction<Err>) -> crate::Result<Ret, Err>,
) -> crate::Result<Ret, Err> {
let t = self
.db
.transaction_with_str_sequence_and_mode(&self.stores, self.mode)
.map_err(|err| match error_name!(&err) {
Some("InvalidStateError") => crate::Error::DatabaseIsClosed,
Some("NotFoundError") => crate::Error::DoesNotExist,
Some("InvalidAccessError") => crate::Error::InvalidArgument,
_ => crate::Error::from_js_value(err),
})?;
let result = RefCell::new(None);
let result = &result;
let (finished_tx, finished_rx) = futures_channel::oneshot::channel();
unsafe_jar::extend_lifetime_to_scope_and_run(
Box::new(move |()| {
RunnableTransaction::new(
t.clone(),
transaction(Transaction::from_sys(t)),
result,
finished_tx,
)
}),
async move |s| {
s.run(());
let _ = finished_rx.await;
let result = result
.borrow_mut()
.take()
.expect("Transaction finished without setting result");
match result {
TransactionResult::PolledForbiddenThing => {
panic!("{}", crate::POLLED_FORBIDDEN_THING_PANIC)
}
TransactionResult::Done(r) => r,
}
},
)
.await
}
}
struct FakeFuture<'a, T> {
watching: &'a RefCell<Option<T>>,
}
impl<'a, T> FakeFuture<'a, T> {
fn new(watching: &'a RefCell<Option<T>>) -> FakeFuture<'a, T> {
FakeFuture { watching }
}
}
impl<'a, T> Future for FakeFuture<'a, T> {
type Output = T;
fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> {
// Don't do this at home! This only works thanks to our unsafe jar polling regardless of the waker
match self.watching.borrow_mut().take() {
None => Poll::Pending,
Some(r) => Poll::Ready(r),
}
}
}
pub(crate) async fn transaction_request(req: IdbRequest) -> Result<JsValue, JsValue> {
let result = Rc::new(RefCell::new(None));
// Keep the callbacks alive until execution completed
let _callbacks = runner::add_request(req, &result);
match FakeFuture::new(&result).await {
Ok(evt) => {
let result = evt.target()
.expect("Trying to parse indexed_db::Error from an event that has no target")
.dyn_into::<web_sys::IdbRequest>()
.expect("Trying to parse indexed_db::Error from an event that is not from an IDBRequest")
.result()
.expect("Failed retrieving the result of successful IDBRequest");
Ok(result)
}
Err(evt) => Err(err_from_event(evt).into()),
}
}