1 /*
2 * Copyright (C) 2019 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 #include "perfetto/tracing/internal/in_process_tracing_backend.h"
18
19 #include "perfetto/base/logging.h"
20 #include "perfetto/base/task_runner.h"
21 #include "perfetto/ext/base/paged_memory.h"
22 #include "perfetto/ext/tracing/core/shared_memory.h"
23 #include "perfetto/ext/tracing/core/tracing_service.h"
24
25 // TODO(primiano): When the in-process backend is used, we should never end up
26 // in a situation where the thread where the TracingService and Producer live
27 // writes a packet and hence can get into the GetNewChunk() stall.
28 // This would happen only if the API client code calls Trace() from one of the
29 // callbacks it receives (e.g. OnStart(), OnStop()). We should either cause a
30 // hard crash or ignore traces from that thread if that happens, because it
31 // will deadlock (the Service will never free up the SMB because won't ever get
32 // to run the task).
33
34 namespace perfetto {
35 namespace internal {
36
37 namespace {
38
39 class InProcessShm : public SharedMemory {
40 public:
41 explicit InProcessShm(size_t size);
42 ~InProcessShm() override;
43 void* start() const override;
44 size_t size() const override;
45
46 private:
47 base::PagedMemory mem_;
48 };
49
50 class InProcessShmFactory : public SharedMemory::Factory {
51 public:
52 ~InProcessShmFactory() override;
53 std::unique_ptr<SharedMemory> CreateSharedMemory(size_t) override;
54 };
55
56 InProcessShm::~InProcessShm() = default;
57
InProcessShm(size_t size)58 InProcessShm::InProcessShm(size_t size)
59 : mem_(base::PagedMemory::Allocate(size)) {}
60
start() const61 void* InProcessShm::start() const {
62 return mem_.Get();
63 }
64
size() const65 size_t InProcessShm::size() const {
66 return mem_.size();
67 }
68
69 InProcessShmFactory::~InProcessShmFactory() = default;
CreateSharedMemory(size_t size)70 std::unique_ptr<SharedMemory> InProcessShmFactory::CreateSharedMemory(
71 size_t size) {
72 return std::unique_ptr<SharedMemory>(new InProcessShm(size));
73 }
74
75 } // namespace
76
77 // static
GetInstance()78 TracingBackend* InProcessTracingBackend::GetInstance() {
79 static auto* instance = new InProcessTracingBackend();
80 return instance;
81 }
82
InProcessTracingBackend()83 InProcessTracingBackend::InProcessTracingBackend() {}
84
ConnectProducer(const ConnectProducerArgs & args)85 std::unique_ptr<ProducerEndpoint> InProcessTracingBackend::ConnectProducer(
86 const ConnectProducerArgs& args) {
87 PERFETTO_DCHECK(args.task_runner->RunsTasksOnCurrentThread());
88
89 // This should never happen as we can have at most one in-process backend.
90 if (service_)
91 PERFETTO_FATAL("InProcessTracingBackend initialized twice");
92
93 return GetOrCreateService(args.task_runner)
94 ->ConnectProducer(args.producer, /*uid=*/0, args.producer_name,
95 args.shmem_size_hint_bytes,
96 /*in_process=*/true,
97 TracingService::ProducerSMBScrapingMode::kEnabled,
98 args.shmem_page_size_hint_bytes);
99 }
100
ConnectConsumer(const ConnectConsumerArgs & args)101 std::unique_ptr<ConsumerEndpoint> InProcessTracingBackend::ConnectConsumer(
102 const ConnectConsumerArgs& args) {
103 return GetOrCreateService(args.task_runner)
104 ->ConnectConsumer(args.consumer, /*uid=*/0);
105 }
106
GetOrCreateService(base::TaskRunner * task_runner)107 TracingService* InProcessTracingBackend::GetOrCreateService(
108 base::TaskRunner* task_runner) {
109 if (!service_) {
110 std::unique_ptr<InProcessShmFactory> shm(new InProcessShmFactory());
111 service_ = TracingService::CreateInstance(std::move(shm), task_runner);
112 service_->SetSMBScrapingEnabled(true);
113 }
114 return service_.get();
115 }
116
117 } // namespace internal
118 } // namespace perfetto
119