1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/message_loop/message_pump_android.h"
6
7 #include <jni.h>
8
9 #include "base/android/jni_android.h"
10 #include "base/android/scoped_java_ref.h"
11 #include "base/lazy_instance.h"
12 #include "base/logging.h"
13 #include "base/run_loop.h"
14 #include "base/time/time.h"
15 #include "jni/SystemMessageHandler_jni.h"
16
17 using base::android::ScopedJavaLocalRef;
18
19 // ----------------------------------------------------------------------------
20 // Native JNI methods called by Java.
21 // ----------------------------------------------------------------------------
22 // This method can not move to anonymous namespace as it has been declared as
23 // 'static' in system_message_handler_jni.h.
DoRunLoopOnce(JNIEnv * env,jobject obj,jlong native_delegate,jlong delayed_scheduled_time_ticks)24 static void DoRunLoopOnce(JNIEnv* env, jobject obj, jlong native_delegate,
25 jlong delayed_scheduled_time_ticks) {
26 base::MessagePump::Delegate* delegate =
27 reinterpret_cast<base::MessagePump::Delegate*>(native_delegate);
28 DCHECK(delegate);
29 // This is based on MessagePumpForUI::DoRunLoop() from desktop.
30 // Note however that our system queue is handled in the java side.
31 // In desktop we inspect and process a single system message and then
32 // we call DoWork() / DoDelayedWork().
33 // On Android, the java message queue may contain messages for other handlers
34 // that will be processed before calling here again.
35 bool did_work = delegate->DoWork();
36
37 // In the java side, |SystemMessageHandler| keeps a single "delayed" message.
38 // It's an expensive operation to |removeMessage| there, so this is optimized
39 // to avoid those calls.
40 //
41 // At this stage, |next_delayed_work_time| can be:
42 // 1) The same as previously scheduled: nothing to be done, move along. This
43 // is the typical case, since this method is called for every single message.
44 //
45 // 2) Not previously scheduled: just post a new message in java.
46 //
47 // 3) Shorter than previously scheduled: far less common. In this case,
48 // |removeMessage| and post a new one.
49 //
50 // 4) Longer than previously scheduled (or null): nothing to be done, move
51 // along.
52 //
53 // Side note: base::TimeTicks is a C++ representation and can't be
54 // compared in java. When calling |scheduleDelayedWork|, pass the
55 // |InternalValue()| to java and then back to C++ so the comparisons can be
56 // done here.
57 // This roundtrip allows comparing TimeTicks directly (cheap) and
58 // avoid comparisons with TimeDelta / Now() (expensive).
59 base::TimeTicks next_delayed_work_time;
60 did_work |= delegate->DoDelayedWork(&next_delayed_work_time);
61
62 if (!next_delayed_work_time.is_null()) {
63 // Schedule a new message if there's nothing already scheduled or there's a
64 // shorter delay than previously scheduled (see (2) and (3) above).
65 if (delayed_scheduled_time_ticks == 0 ||
66 next_delayed_work_time < base::TimeTicks::FromInternalValue(
67 delayed_scheduled_time_ticks)) {
68 Java_SystemMessageHandler_scheduleDelayedWork(env, obj,
69 next_delayed_work_time.ToInternalValue(),
70 (next_delayed_work_time -
71 base::TimeTicks::Now()).InMillisecondsRoundedUp());
72 }
73 }
74
75 // This is a major difference between android and other platforms: since we
76 // can't inspect it and process just one single message, instead we'll yeld
77 // the callstack.
78 if (did_work)
79 return;
80
81 delegate->DoIdleWork();
82 }
83
84 namespace base {
85
MessagePumpForUI()86 MessagePumpForUI::MessagePumpForUI()
87 : run_loop_(NULL) {
88 }
89
~MessagePumpForUI()90 MessagePumpForUI::~MessagePumpForUI() {
91 }
92
Run(Delegate * delegate)93 void MessagePumpForUI::Run(Delegate* delegate) {
94 NOTREACHED() << "UnitTests should rely on MessagePumpForUIStub in"
95 " test_stub_android.h";
96 }
97
Start(Delegate * delegate)98 void MessagePumpForUI::Start(Delegate* delegate) {
99 run_loop_ = new RunLoop();
100 // Since the RunLoop was just created above, BeforeRun should be guaranteed to
101 // return true (it only returns false if the RunLoop has been Quit already).
102 if (!run_loop_->BeforeRun())
103 NOTREACHED();
104
105 DCHECK(system_message_handler_obj_.is_null());
106
107 JNIEnv* env = base::android::AttachCurrentThread();
108 DCHECK(env);
109
110 system_message_handler_obj_.Reset(
111 Java_SystemMessageHandler_create(
112 env, reinterpret_cast<intptr_t>(delegate)));
113 }
114
Quit()115 void MessagePumpForUI::Quit() {
116 if (!system_message_handler_obj_.is_null()) {
117 JNIEnv* env = base::android::AttachCurrentThread();
118 DCHECK(env);
119
120 Java_SystemMessageHandler_removeAllPendingMessages(env,
121 system_message_handler_obj_.obj());
122 system_message_handler_obj_.Reset();
123 }
124
125 if (run_loop_) {
126 run_loop_->AfterRun();
127 delete run_loop_;
128 run_loop_ = NULL;
129 }
130 }
131
ScheduleWork()132 void MessagePumpForUI::ScheduleWork() {
133 DCHECK(!system_message_handler_obj_.is_null());
134
135 JNIEnv* env = base::android::AttachCurrentThread();
136 DCHECK(env);
137
138 Java_SystemMessageHandler_scheduleWork(env,
139 system_message_handler_obj_.obj());
140 }
141
ScheduleDelayedWork(const TimeTicks & delayed_work_time)142 void MessagePumpForUI::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
143 DCHECK(!system_message_handler_obj_.is_null());
144
145 JNIEnv* env = base::android::AttachCurrentThread();
146 DCHECK(env);
147
148 jlong millis =
149 (delayed_work_time - TimeTicks::Now()).InMillisecondsRoundedUp();
150 // Note that we're truncating to milliseconds as required by the java side,
151 // even though delayed_work_time is microseconds resolution.
152 Java_SystemMessageHandler_scheduleDelayedWork(env,
153 system_message_handler_obj_.obj(),
154 delayed_work_time.ToInternalValue(), millis);
155 }
156
157 // static
RegisterBindings(JNIEnv * env)158 bool MessagePumpForUI::RegisterBindings(JNIEnv* env) {
159 return RegisterNativesImpl(env);
160 }
161
162 } // namespace base
163