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
|
#include <mbgl/storage/request.hpp>
#include <mbgl/storage/response.hpp>
#include <mbgl/util/util.hpp>
#include <mbgl/util/uv_detail.hpp>
#include <cassert>
#include <functional>
#include <memory>
namespace mbgl {
// Note: This requires that loop is running in the current thread (or not yet running).
Request::Request(const Resource &resource_, uv_loop_t *loop, Callback callback_)
: async(std::make_unique<uv::async>(loop, [this] { notifyCallback(); })),
callback(callback_),
resource(resource_) {
}
// Called in the originating thread.
void Request::notifyCallback() {
std::unique_lock<std::mutex> lock(mtx);
if (!canceled) {
// Move the response object out so that we can't accidentally notify twice.
auto res = std::move(response);
assert(!response);
// Unlock before, since callbacks may call cancel, which also locks this mutex.
lock.unlock();
// The user could supply a null pointer or empty std::function as a callback. In this case, we
// still do the file request, but we don't need to deliver a result.
// Similarly, two consecutive updates could trigger two notifyCallbacks, so we need to make
// sure
if (callback && res) {
callback(*res);
}
} else {
// Don't delete right way, because we have to unlock the mutex before deleting.
if (confirmed) {
lock.unlock();
delete this;
}
}
}
Request::~Request() = default;
// Called in the FileSource thread.
void Request::notify(const std::shared_ptr<const Response> &response_) {
std::lock_guard<std::mutex> lock(mtx);
assert(response_);
response = response_;
async->send();
}
// Called in the originating thread.
void Request::cancel() {
std::lock_guard<std::mutex> lock(mtx);
assert(!canceled);
canceled = true;
}
// Called in the FileSource thread.
// Will only ever be invoked after cancel() was called in the original requesting thread.
void Request::destruct() {
std::lock_guard<std::mutex> lock(mtx);
assert(canceled);
confirmed = true;
// We need to extend the lock until after the async has been sent, otherwise the requesting
// thread could destroy the async while this call is still in progress.
async->send();
// After this method returns, the FileSource thread has no knowledge of
// this object anymore.
}
}
|
