1 /*
2 * Copyright (C) 2023 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define LOG_TAG "OomConnection"
18
19 #include <core_jni_helpers.h>
20 #include <jni.h>
21 #include <memevents/memevents.h>
22
23 namespace android {
24
25 using namespace ::android::bpf::memevents;
26
27 // Used to cache the results of the JNI name lookup
28 static struct {
29 jclass clazz;
30 jmethodID ctor;
31 } sOomKillRecordInfo;
32
33 static MemEventListener memevent_listener(MemEventClient::AMS);
34
35 /**
36 * Initialize listening and waiting for new out-of-memory (OOM) events to occur.
37 * Once a OOM event is detected, we then fetch the list of OOM kills, and return
38 * a corresponding java array with the information gathered.
39 *
40 * In the case that we encounter an error, we make sure to close the epfd, and
41 * the OOM file descriptor, by calling `deregisterAllEvents()`.
42 *
43 * @return list of `android.os.OomKillRecord`
44 * @throws java.lang.RuntimeException
45 */
android_server_am_OomConnection_waitOom(JNIEnv * env,jobject)46 static jobjectArray android_server_am_OomConnection_waitOom(JNIEnv* env, jobject) {
47 if (!memevent_listener.ok()) {
48 memevent_listener.deregisterAllEvents();
49 jniThrowRuntimeException(env, "Failed to initialize memevents listener");
50 return nullptr;
51 }
52
53 if (!memevent_listener.registerEvent(MEM_EVENT_OOM_KILL)) {
54 memevent_listener.deregisterAllEvents();
55 jniThrowRuntimeException(env, "listener failed to register to OOM events");
56 return nullptr;
57 }
58
59 if (!memevent_listener.listen()) {
60 memevent_listener.deregisterAllEvents();
61 jniThrowRuntimeException(env, "listener failed waiting for OOM event");
62 return nullptr;
63 }
64
65 std::vector<mem_event_t> oom_events;
66 if (!memevent_listener.getMemEvents(oom_events)) {
67 memevent_listener.deregisterAllEvents();
68 jniThrowRuntimeException(env, "Failed to get OOM events");
69 return nullptr;
70 }
71
72 jobjectArray java_oom_array =
73 env->NewObjectArray(oom_events.size(), sOomKillRecordInfo.clazz, nullptr);
74 if (java_oom_array == NULL) {
75 memevent_listener.deregisterAllEvents();
76 jniThrowRuntimeException(env, "Failed to create OomKillRecord array");
77 return nullptr;
78 }
79
80 for (int i = 0; i < oom_events.size(); i++) {
81 const mem_event_t mem_event = oom_events[i];
82 if (mem_event.type != MEM_EVENT_OOM_KILL) {
83 memevent_listener.deregisterAllEvents();
84 jniThrowRuntimeException(env, "Received invalid memory event");
85 return java_oom_array;
86 }
87
88 const auto oom_kill = mem_event.event_data.oom_kill;
89
90 jstring process_name = env->NewStringUTF(oom_kill.process_name);
91 if (process_name == NULL) {
92 memevent_listener.deregisterAllEvents();
93 jniThrowRuntimeException(env, "Failed creating java string for process name");
94 }
95 jobject java_oom_kill =
96 env->NewObject(sOomKillRecordInfo.clazz, sOomKillRecordInfo.ctor,
97 oom_kill.timestamp_ms, oom_kill.pid, oom_kill.uid, process_name,
98 oom_kill.oom_score_adj, oom_kill.total_vm_kb, oom_kill.anon_rss_kb,
99 oom_kill.file_rss_kb, oom_kill.shmem_rss_kb, oom_kill.pgtables_kb);
100 if (java_oom_kill == NULL) {
101 memevent_listener.deregisterAllEvents();
102 jniThrowRuntimeException(env, "Failed to create OomKillRecord object");
103 return java_oom_array;
104 }
105 env->SetObjectArrayElement(java_oom_array, i, java_oom_kill);
106 }
107 return java_oom_array;
108 }
109
110 static const JNINativeMethod sOomConnectionMethods[] = {
111 /* name, signature, funcPtr */
112 {"waitOom", "()[Landroid/os/OomKillRecord;",
113 (void*)android_server_am_OomConnection_waitOom},
114 };
115
register_android_server_am_OomConnection(JNIEnv * env)116 int register_android_server_am_OomConnection(JNIEnv* env) {
117 sOomKillRecordInfo.clazz = FindClassOrDie(env, "android/os/OomKillRecord");
118 sOomKillRecordInfo.clazz = MakeGlobalRefOrDie(env, sOomKillRecordInfo.clazz);
119
120 sOomKillRecordInfo.ctor = GetMethodIDOrDie(env, sOomKillRecordInfo.clazz, "<init>",
121 "(JIILjava/lang/String;SJJJJJ)V");
122
123 return RegisterMethodsOrDie(env, "com/android/server/am/OomConnection", sOomConnectionMethods,
124 NELEM(sOomConnectionMethods));
125 }
126 } // namespace android