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
|
//
// Copyright 2015 Google, Inc.
//
// 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.
//
#pragma once
#include <functional>
#include <mutex>
#include <unordered_map>
#include <base/logging.h>
#include <binder/IBinder.h>
#include <binder/IInterface.h>
namespace ipc {
namespace binder {
// Takes care of the grunt work of maintaining a list of remote interfaces,
// typically for the use of performing registered callbacks from a remote
// service. This is a native equivalent of the the android.os.RemoteCallbackList
// Java class. The type "T" must inherit from android::IInterface.
//
// TODO(armansito): We need to unit test this class. Right now it's defined as a
// simple template interface over the native libbinder types directly and we
// can't compile libbinder for host unless the Binder kernel module is enabled
// on the system. Figure out whether to:
// 1) write the Binder test-code in a new target-only executable;
// 2) conditionally compile into the host-native test suite if the Binder
// module is built;
// 3) provide a test-only static library that re-defines the libbinder
// classes as mocks.
// (See http://b/23386387)
//
// TODO(armansito): We should make this class non-final and the template
// interface abstract, so that code that depends on this can be unit tested
// against a mock version of this class.
//
// TODO(armansito): Consider submitting this class to frameworks/native/binder.
template <typename T>
class RemoteCallbackList final {
public:
RemoteCallbackList() = default;
RemoteCallbackList(const RemoteCallbackList&) = delete;
RemoteCallbackList& operator=(const RemoteCallbackList&) = delete;
~RemoteCallbackList();
// Register and unregister a callback interface. Registering will
// automatically start tracking for death notifications in case the remote
// process hosting the Binder dies. In such a case, the Binder is
// automatically removed from the list.
bool Register(const android::sp<T>& callback);
bool Unregister(const android::sp<T>& callback);
// Calls the given function on each of the contained callbacks. The internal
// mutex is locked for the duration of the iteration.
void ForEach(const std::function<void(T*)>& callback);
private:
class CallbackDeathRecipient : public android::IBinder::DeathRecipient {
public:
CallbackDeathRecipient(const android::sp<T>& callback,
RemoteCallbackList* owner);
android::sp<T> get_callback() const { return callback_; }
// android::IBinder::DeathRecipient override:
void binderDied(const android::wp<android::IBinder>& who) override;
private:
android::sp<T> callback_;
RemoteCallbackList<T>* owner_; // weak
};
// Typedef for internal map container. This keeps track of a given Binder and
// a death receiver associated with it.
using CallbackMap = std::unordered_map<android::IBinder*,
android::sp<CallbackDeathRecipient>>;
bool UnregisterInternal(typename CallbackMap::iterator iter);
std::mutex map_lock_;
CallbackMap callbacks_;
};
// Template Implementation details below
using android::IBinder;
using android::IInterface;
using android::sp;
using android::wp;
template <typename T>
RemoteCallbackList<T>::~RemoteCallbackList() {
std::lock_guard<std::mutex> lock(map_lock_);
for (auto iter = callbacks_.begin(); iter != callbacks_.end(); ++iter)
UnregisterInternal(iter);
}
template <typename T>
bool RemoteCallbackList<T>::Register(const sp<T>& callback) {
std::lock_guard<std::mutex> lock(map_lock_);
sp<IBinder> binder = IInterface::asBinder(callback.get());
if (callbacks_.find(binder.get()) != callbacks_.end()) {
VLOG(1) << "Callback list already contains given callback";
return false;
}
sp<CallbackDeathRecipient> dr(new CallbackDeathRecipient(callback, this));
if (binder->linkToDeath(dr) != android::NO_ERROR) {
LOG(ERROR) << "Failed to link death recipient to binder";
return false;
}
callbacks_[binder.get()] = dr;
VLOG(2) << "Callback successfully registered with list";
return true;
}
template <typename T>
bool RemoteCallbackList<T>::Unregister(const sp<T>& callback) {
std::lock_guard<std::mutex> lock(map_lock_);
sp<IBinder> binder = IInterface::asBinder(callback.get());
auto iter = callbacks_.find(binder.get());
if (iter == callbacks_.end()) {
VLOG(2) << "Given callback not registered with this list";
return false;
}
return UnregisterInternal(iter);
}
template <typename T>
void RemoteCallbackList<T>::ForEach(const std::function<void(T*)>& callback) {
std::lock_guard<std::mutex> lock(map_lock_);
for (const auto& iter : callbacks_)
callback(iter.second->get_callback().get());
}
template <typename T>
bool RemoteCallbackList<T>::UnregisterInternal(
typename CallbackMap::iterator iter) {
sp<CallbackDeathRecipient> dr = iter->second;
callbacks_.erase(iter);
if (IInterface::asBinder(dr->get_callback().get())->unlinkToDeath(dr) !=
android::NO_ERROR) {
LOG(ERROR) << "Failed to unlink death recipient from binder";
// We removed the entry from |map_| but unlinkToDeath failed. There isn't
// really much we can do here other than deleting the binder and returning
// an error.
return false;
}
VLOG(2) << "Callback successfully removed from list";
return true;
}
template <typename T>
RemoteCallbackList<T>::CallbackDeathRecipient::CallbackDeathRecipient(
const sp<T>& callback, RemoteCallbackList<T>* owner)
: callback_(callback), owner_(owner) {
CHECK(callback_.get());
CHECK(owner_);
}
template <typename T>
void RemoteCallbackList<T>::CallbackDeathRecipient::binderDied(
const wp<IBinder>& who) {
VLOG(1) << "Received binderDied";
sp<IBinder> binder = IInterface::asBinder(callback_.get());
CHECK(who.unsafe_get() == binder.get());
// Remove the callback but no need to call unlinkToDeath.
std::lock_guard<std::mutex> lock(owner_->map_lock_);
auto iter = owner_->callbacks_.find(binder.get());
CHECK(iter != owner_->callbacks_.end());
owner_->callbacks_.erase(iter);
VLOG(1) << "Callback from dead process unregistered";
}
} // namespace binder
} // namespace ipc
|
