| // Copyright (C) 2019 The Android Open Source Project |
| // |
| // 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. |
| |
| #include "common/debug.h" |
| #include "common/expected.h" |
| #include "perfetto/rx_producer.h" |
| |
| #include <android-base/file.h> |
| #include <android-base/properties.h> |
| #include <android-base/unique_fd.h> |
| |
| #include <iostream> |
| |
| #include <sched.h> |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <syscall.h> |
| #include <fcntl.h> |
| #include <unistd.h> |
| |
| // TODO: move to perfetto code |
| namespace perfetto { |
| namespace consumer { |
| |
| std::ostream& operator<<(std::ostream& os, State state) { |
| switch (state) { |
| case State::kTraceFailed: |
| os << "kTraceFailed"; |
| break; |
| case State::kConnectionError: |
| os << "kConnectionError"; |
| break; |
| case State::kSessionNotFound: |
| os << "kSessionNotFound"; |
| break; |
| case State::kIdle: |
| os << "kIdle"; |
| break; |
| case State::kConnecting: |
| os << "kConnecting"; |
| break; |
| case State::kConfigured: |
| os << "kConfigured"; |
| break; |
| case State::kTracing: |
| os << "kTracing"; |
| break; |
| case State::kTraceEnded: |
| os << "kTraceEnded"; |
| break; |
| default: |
| os << "(unknown)"; // did someone forget to update this code? |
| break; |
| } |
| return os; |
| } |
| |
| } // namespace consumer |
| } // namespace perfetto |
| |
| namespace iorap::perfetto { |
| |
| PerfettoDependencies::Component PerfettoDependencies::CreateComponent() { |
| // TODO: read from config. |
| static const uint32_t kTraceDurationMs = |
| ::android::base::GetUintProperty("iorapd.perfetto.trace_duration_ms", /*default*/5000U); |
| |
| static const uint32_t kBufferSize = |
| ::android::base::GetUintProperty("iorapd.perfetto.buffer_size", /*default*/4096U); |
| |
| return fruit::createComponent() |
| .bind<PerfettoConsumer, PerfettoConsumerImpl>() |
| .registerProvider([]() /* -> TraceConfig */ { |
| return CreateConfig(kTraceDurationMs, |
| /*deferred_start*/false, |
| kBufferSize); |
| }); |
| } |
| |
| ::perfetto::protos::TraceConfig PerfettoDependencies::CreateConfig(uint32_t duration_ms, |
| bool deferred_start, |
| uint32_t buffer_size) { |
| ::perfetto::protos::TraceConfig trace_config; |
| |
| trace_config.set_duration_ms(duration_ms); |
| trace_config.add_buffers()->set_size_kb(buffer_size); |
| trace_config.set_deferred_start(deferred_start); |
| |
| auto* ds_config = trace_config.add_data_sources()->mutable_config(); |
| ds_config->set_name("linux.ftrace"); |
| ds_config->mutable_ftrace_config()->add_ftrace_events( |
| "mm_filemap_add_to_page_cache"); |
| ds_config->mutable_ftrace_config()->add_ftrace_events( |
| "mm_filemap_delete_from_page_cache"); |
| ds_config->set_target_buffer(0); |
| |
| return trace_config; |
| } |
| |
| // RAII-style wrapper around a perfetto handle that calls Destroy |
| // in a thread-safe manner. |
| struct PerfettoConsumerHandle { |
| private: |
| std::shared_ptr<PerfettoConsumer> consumer_; |
| PerfettoConsumer::Handle handle_; |
| |
| public: |
| // Takes over ownership of the 'handle'. |
| // |
| // Consumer must not be null. |
| PerfettoConsumerHandle(std::shared_ptr<PerfettoConsumer> consumer, |
| PerfettoConsumer::Handle handle) |
| : consumer_{std::move(consumer)}, |
| handle_{std::move(handle)} { |
| DCHECK(consumer_ != nullptr); |
| } |
| |
| std::shared_ptr<PerfettoConsumer> GetConsumer() const { |
| return consumer_; |
| } |
| |
| PerfettoConsumer::Handle GetHandle() const { |
| return handle_; |
| } |
| |
| ~PerfettoConsumerHandle() { |
| LOG(VERBOSE) << "PerfettoConsumerHandle::Destroy(" << handle_ << ")"; |
| consumer_->Destroy(handle_); |
| } |
| |
| bool operator==(const PerfettoConsumerHandle& other) const { |
| return handle_ == other.handle_ && consumer_ == other.consumer_; |
| } |
| |
| bool operator!=(const PerfettoConsumerHandle& other) const { |
| return !(*this == other); |
| } |
| }; |
| |
| |
| // Snapshot of a single perfetto OnStateChanged callback. |
| // |
| // Operate on the PerfettoConsumer to further change the state. |
| // |
| // The Handle is kept 'valid' until all references to the PerfettoConsumerHandle |
| // are dropped to 0. This ensures the Handle is not destroyed too early. All |
| // direct usages of 'Handle' must be scoped by the PerfettoConsumerHandle. |
| struct PerfettoStateChange { |
| public: |
| using State = ::perfetto::consumer::State; |
| using Handle = ::perfetto::consumer::Handle; |
| |
| State state; // Never invalid. |
| std::shared_ptr<PerfettoConsumerHandle> perfetto_consumer_and_handle; // Never null. |
| |
| // Safety: Use only within scope of the PerfettoStateChange. |
| Handle GetHandle() const { |
| // TODO: it would be even safer to wrap all the calls to the handle inside a class, |
| // instead of exposing this raw Handle. |
| return perfetto_consumer_and_handle->GetHandle(); |
| } |
| |
| std::shared_ptr<PerfettoConsumer> GetConsumer() const { |
| return perfetto_consumer_and_handle->GetConsumer(); |
| } |
| }; |
| |
| std::ostream& operator<<(std::ostream& os, const PerfettoStateChange& state_change) { |
| os << "PerfettoStateChange{" << state_change.state << "," |
| << state_change.GetHandle() << "," |
| << state_change.GetConsumer().get() << "}"; |
| return os; |
| } |
| |
| // Once created, this acts as a hot observable, emitting 'PerfettoStateChange' transition items. |
| // Only the 'state' will vary, the handle and perfetto_consumer are always the same value. |
| // |
| // Clients only need to handle the success states in #on_next, all failure states will go to |
| // #on_error. |
| // |
| // Upon reaching the appropriate terminal states, either #on_completed or #on_error is called. |
| // No future callbacks will then occur, so this object should be subsequently deleted. |
| // |
| // The Handle is destroyed automatically after the last item is emitted, so it must only be |
| // manipulated from the #on_next callbacks. Do not save the Handle and use it at other times. |
| class StateChangedSubject { |
| public: |
| using State = ::perfetto::consumer::State; |
| using Handle = ::perfetto::consumer::Handle; |
| |
| // Static members to solve use-after-free bug. |
| // The object is accessed from not only perfetto thread, but also iorap |
| // thread. Use this global map to manage it. |
| static std::mutex state_subject_mutex_; |
| static std::unordered_map<Handle, StateChangedSubject*> state_subject_map_; |
| |
| StateChangedSubject(const ::perfetto::protos::TraceConfig& trace_config, |
| rxcpp::subscriber<PerfettoStateChange> destination, |
| std::shared_ptr<PerfettoConsumer> perfetto_consumer) |
| : deferred_start(trace_config.deferred_start()), |
| dest(std::move(destination)), |
| perfetto_consumer_(std::move(perfetto_consumer)) { |
| DCHECK(perfetto_consumer_ != nullptr); |
| } |
| |
| private: |
| struct StateChangedError : public std::runtime_error { |
| explicit StateChangedError(const std::string& what_arg) : std::runtime_error(what_arg) {} |
| }; |
| |
| std::shared_ptr<PerfettoConsumerHandle> handle_; // non-null after bound_ == true. |
| std::atomic<bool> bound_{false}; // synchronize-with for BindHandle -> OnStateChanged. |
| |
| State last_state{State::kIdle}; |
| bool deferred_start{false}; |
| |
| rxcpp::subscriber<PerfettoStateChange> dest; |
| std::shared_ptr<PerfettoConsumer> perfetto_consumer_; // This is never null. |
| |
| void DcheckBadStateTransition(State state, bool fail_unless = false) const { |
| DCHECK(fail_unless) << "Invalid state transition to " << state << " from " << last_state; |
| } |
| |
| void DcheckValidStateTransition(State state) { |
| // State must not be out of range. |
| DCHECK_GE(state, State::kTraceFailed); |
| DCHECK_LE(state, State::kTraceEnded); |
| |
| // Internal state that should never leak out into public perfetto API: |
| DCHECK_NE(state, State::kIdle); |
| // These can only be returned by PollState: |
| DCHECK_NE(state, State::kSessionNotFound); |
| |
| // Validate state transitions as per the perfetto API contract. |
| // See the 'state diagram' in consumer_api.h |
| switch (last_state) { |
| case State::kTraceFailed: // Final and unrecoverable. |
| // b/122548195: this can transition to 'kConnectionError' if selinux is disabled. |
| if (state == State::kConnectionError) { |
| LOG(WARNING) << "b/122548195: kTraceFailed is non-terminal, ignoring."; |
| // This is a bit awkward: rxcpp will drop the #on_error calls if its more than once. |
| break; |
| } |
| DcheckBadStateTransition(state); |
| break; |
| case State::kConnectionError: // Final and unrecoverable. |
| DcheckBadStateTransition(state); |
| break; |
| case State::kSessionNotFound: |
| DcheckBadStateTransition(state); |
| break; |
| case State::kIdle: |
| // OK: we initialized our own state to idle prior to the first callback. |
| break; |
| case State::kConnecting: |
| switch (state) { |
| case State::kConfigured: |
| // kConfigured, if |deferred_start| == true in the trace config. |
| DcheckBadStateTransition(state, deferred_start); |
| break; |
| case State::kTracing: |
| // kTracing, if |deferred_start| == false. |
| DcheckBadStateTransition(state, !deferred_start); |
| break; |
| case State::kConnectionError: |
| // An error state, e.g. if cannot reach the traced daemon. |
| break; |
| default: |
| // Unconditionally invalid state transitions from kConnecting to anything else. |
| DcheckBadStateTransition(state); |
| } |
| break; |
| case State::kConfigured: |
| DCHECK(deferred_start); |
| if (state != State::kTracing // OK: this is documented. |
| && state != State::kTraceFailed) { // Undocumented selinux failure. |
| // Undocumented, but it appears to go directly from Configured->TraceEnded |
| // it can also go to kTraceFailed if e.g. there's an selinux violation |
| // however this appears to be underdocumented. |
| // b/122607276 #2 |
| |
| if (state != State::kTraceEnded) { // b/122607276 #1 |
| DcheckBadStateTransition(state); |
| } |
| } |
| break; |
| case State::kTracing: |
| switch (state) { |
| case State::kTraceEnded: |
| break; |
| case State::kTraceFailed: |
| break; |
| default: |
| DcheckBadStateTransition(state); |
| } |
| break; |
| case State::kTraceEnded: |
| // Cannot transition from terminal state to another state. |
| DcheckBadStateTransition(state); |
| break; |
| |
| // default: This list is exhaustive |
| } |
| } |
| |
| constexpr bool IsTerminalState() const { |
| switch (last_state) { |
| case State::kTraceFailed: |
| case State::kConnectionError: |
| case State::kTraceEnded: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| // Returns true for non-terminal states (i.e. this callback will be invoked again). |
| // Returns false otherwise. |
| bool OnStateChanged(Handle handle, State state) { |
| using namespace ::perfetto::consumer; |
| |
| // Block until 'BoundHandle' is called by the other thread. |
| while (!bound_.load()) {} // seq_cst acquire. |
| |
| std::shared_ptr<PerfettoConsumerHandle> handle_ptr = handle_; |
| DCHECK(handle_ptr != nullptr); |
| |
| DCHECK_EQ(handle_ptr->GetHandle(), handle); |
| DcheckValidStateTransition(state); |
| |
| switch (state) { |
| // Error states (terminal). |
| case State::kTraceFailed: |
| EmitError("kTraceFailed"); |
| break; |
| case State::kConnectionError: |
| EmitError("kConnectionError"); |
| break; |
| |
| // Regular transitions (non-terminal). |
| case State::kConnecting: |
| case State::kConfigured: |
| case State::kTracing: |
| EmitNext(state); |
| break; |
| // Regular transitions (terminal). |
| case State::kTraceEnded: // XX: do we even need to emit the 'TraceEnded' state? |
| EmitNext(state); |
| dest.on_completed(); |
| break; |
| default: |
| DcheckBadStateTransition(state); |
| } |
| |
| bool force_non_terminal = false; |
| |
| if (last_state == State::kConfigured && state == State::kConnectionError) { |
| // b/122548195: this can transition to 'kConnectionError' if selinux is disabled. |
| force_non_terminal = true; |
| // This function must 'return true' in this buggy case, otherwise we will |
| // call the destructor too early and subsequent callbacks will crash. |
| } |
| |
| // Remember the state to validate prior state transitions. |
| last_state = state; |
| |
| // The owner of this class should avoid leaking memory once we reach a terminal state. |
| return !IsTerminalState() || force_non_terminal; |
| } |
| |
| public: |
| // Thread safety: Called by main thread, terminates the rx stream. |
| // When this function is invoked, no calls to this class from other threads can occur. |
| void OnCreateFailed() { |
| // returned when an invalid handle is passed to PollState(). |
| last_state = State::kSessionNotFound; |
| EmitError("Create returned kInvalidHandle"); |
| } |
| |
| // Thread safety: Called by main thread, this could be concurrent to |
| // 'CallbackOnStateChanged'. |
| void BindHandle(const std::shared_ptr<PerfettoConsumerHandle>& handle) { |
| handle_ = handle; |
| |
| // Unblock OnStateChanged. |
| bound_.store(true); // seq_cst release. |
| } |
| |
| |
| // Called by libperfetto background thread (same one every time) and iorap |
| // thread. |
| static void CallbackOnStateChanged(Handle handle, State state, void* callback_arg) { |
| LOG(VERBOSE) << "CallbackOnStateChanged(handle=" << handle << ",state=" << state |
| << ",callback_arg=" << callback_arg << ")"; |
| |
| // Validate OnStateChanged callback invariants, guaranteed by libperfetto. |
| DCHECK_NE(handle, ::perfetto::consumer::kInvalidHandle); |
| |
| // TODO: the memory ordering guarantees should be explicitly specified in consumer_api.h: |
| // This isn't specific enough: |
| // "The callback will be invoked on an internal thread and must not block." |
| // However looking at the implementation it posts onto a single-thread task runner, |
| // so this must be the case. |
| |
| // This current thread owns 'StateChangedSubject', no other threads must access it. |
| // Explicit synchronization is not necessary. |
| |
| { |
| std::lock_guard<std::mutex> guard(StateChangedSubject::state_subject_mutex_); |
| auto it = StateChangedSubject::state_subject_map_.find(handle); |
| // If the object is already deleted, do nothing. |
| if (it == StateChangedSubject::state_subject_map_.end()) { |
| return; |
| } |
| |
| StateChangedSubject* state_subject = it->second; |
| if (!state_subject->OnStateChanged(handle, state)) { |
| // Clean up the state tracker when we reach a terminal state. |
| // This means that no future callbacks will occur anymore. |
| StateChangedSubject::state_subject_map_.erase(it); |
| delete state_subject; |
| } |
| } |
| } |
| |
| private: |
| void EmitError(const std::string& msg) { |
| // Sidenote: Exact error class does not matter, rxcpp only lets us access the error |
| // as a string (rxcpp::util::what). |
| // |
| // Either way, the recovery strategy is identical (log then try and restart). |
| dest.on_error(rxcpp::util::make_error_ptr(StateChangedError{msg})); |
| } |
| |
| void EmitNext(State state) { |
| if (WOULD_LOG(VERBOSE) && !dest.is_subscribed()) { |
| // This is purely for logging: #on_next already filters out items after unsubscription. |
| LOG(VERBOSE) << "StateChangedSubject#EmitNext(" << state << ") - drop due to unsubscribe"; |
| } |
| |
| auto handle_ptr = handle_; |
| DCHECK(handle_ptr != nullptr); |
| |
| // Non-null guarantee for the items emitted into this stream. |
| PerfettoStateChange state_change{state, handle_ptr}; |
| dest.on_next(std::move(state_change)); |
| } |
| |
| // TODO: inherit from rx subject and handle #unsubscribe explicitly, instead |
| // of just being subject-like? |
| }; |
| |
| std::mutex StateChangedSubject::state_subject_mutex_; |
| std::unordered_map<::perfetto::consumer::Handle, |
| StateChangedSubject*> StateChangedSubject::state_subject_map_; |
| |
| // Note: The states will be emitted on a separate thread, so e.g. #as_blocking() |
| // needs to be used to avoid dropping everything on the floor. |
| // |
| // Important: The #on_error case must be handled explicitly by the observable, |
| // because the default behavior is to 'throw' which will cause an std::terminate with -fno-except. |
| static auto /*[observable<State>, shared_ptr<PerfettoConsumerHandle>]*/ |
| CreatePerfettoStateStream(::perfetto::protos::TraceConfig perfetto_config, |
| std::shared_ptr<PerfettoConsumer> perfetto_consumer) { |
| auto obs = rxcpp::observable<>::create<PerfettoStateChange>( |
| [perfetto_config = std::move(perfetto_config), perfetto_consumer = std::move(perfetto_consumer)] |
| (rxcpp::subscriber<PerfettoStateChange> subscriber) { |
| std::unique_ptr<StateChangedSubject> state_subject{ |
| new StateChangedSubject{perfetto_config, subscriber, perfetto_consumer}}; |
| |
| // Perfetto API requires a pointer to a serialized protobuf, it doesn't accept |
| // the code-generated object. |
| std::string perfetto_config_str = perfetto_config.SerializeAsString(); |
| |
| ::perfetto::consumer::Handle handle = |
| perfetto_consumer->Create(perfetto_config_str.data(), |
| perfetto_config_str.size(), |
| // executes on the same background thread repeatedly. |
| &StateChangedSubject::CallbackOnStateChanged, |
| // inter-thread-move |
| reinterpret_cast<void*>(state_subject.get())); |
| // perfetto::consumer::Create synchronizes-with OnStateChanged callback, this means |
| // we don't need to explicitly synchronize state_subject here so long as we don't access |
| // it on this thread again. |
| LOG(DEBUG) << "Create Perfetto handle " << handle; |
| |
| if (handle == ::perfetto::consumer::kInvalidHandle) { |
| LOG(ERROR) << "Failed to create Perfetto handle"; |
| // No callbacks will occur, so our thread still owns the state subject. |
| state_subject->OnCreateFailed(); |
| return; |
| } |
| |
| { |
| std::lock_guard<std::mutex> guard(StateChangedSubject::state_subject_mutex_); |
| StateChangedSubject::state_subject_map_[handle] = state_subject.get(); |
| } |
| |
| std::shared_ptr<PerfettoConsumerHandle> safe_handle{ |
| new PerfettoConsumerHandle{perfetto_consumer, handle}}; |
| |
| // Share ownership of the Handle with the StateSubject. |
| // This way we defer calling 'Destroy' until the callback reaches a terminal state |
| // *and* all users of the stream are done with the handle. |
| state_subject->BindHandle(safe_handle); |
| |
| // state_subject ownership is taken over by OnStateChanged. |
| // It will also be touched in a separate thread, so we must never access it here again. |
| state_subject.release(); |
| |
| // 'subscriber#add' is actually a call to register an on_unsubscribe listener. |
| subscriber.add([safe_handle]() { |
| LOG(VERBOSE) << "PerfettoStateChange#unsubscribe"; |
| |
| // Release our ref-count to the handle. |
| // safe_handle.reset(); // This happens implicitly. |
| |
| // TODO: I think this won't handle the case where we need to shut down early. |
| // Need to use the explicit kShutdown for that? |
| }); |
| |
| // TODO: this would be an excellent place to shuffle the perfetto config protobuf |
| // into a global debug state for dumpsys. |
| }); |
| |
| return obs; |
| } |
| |
| template <typename T> |
| bool BinaryWireProtobuf<T>::WriteFullyToFile(const std::string& path, |
| bool follow_symlinks) const { |
| // TODO: it would be great if android::base had a string_view overload to avoid copying |
| // data into an std::string. |
| |
| // u g o |
| // rw-rw---- |
| // |
| // Protobufs can be read/written but not executed. |
| static constexpr const mode_t kMode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP; |
| |
| int flags = |
| O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_BINARY | (follow_symlinks ? 0 : O_NOFOLLOW); |
| android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), flags, kMode))); |
| |
| if (fd == -1) { |
| PLOG(ERROR) << "BinaryWireProtobuf::WriteFullyToFile open failed"; |
| return false; |
| } |
| |
| if (!::android::base::WriteFully(fd, data_.data(), size())) { |
| PLOG(ERROR) << "BinaryWireProtobuf::WriteFullyToFile write failed"; |
| return CleanUpAfterFailedWrite(path); |
| } |
| |
| return true; |
| } |
| |
| template <typename T> |
| bool BinaryWireProtobuf<T>::CleanUpAfterFailedWrite(const std::string& path) { |
| // Something went wrong. Let's not leave a corrupt file lying around. |
| int saved_errno = errno; |
| unlink(path.c_str()); |
| errno = saved_errno; |
| return false; |
| } |
| |
| template <typename T> |
| bool BinaryWireProtobuf<T>::WriteStringToFd(int fd) const { |
| const char* p = reinterpret_cast<const char*>(data_.data()); |
| size_t left = size(); |
| while (left > 0) { |
| ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, left)); |
| if (n == -1) { |
| return false; |
| } |
| p += n; |
| left -= n; |
| } |
| return true; |
| } |
| |
| template <typename T> |
| std::optional<BinaryWireProtobuf<T>> BinaryWireProtobuf<T>::ReadFullyFromFile( |
| const std::string& path, |
| bool follow_symlinks) { |
| std::vector<std::byte> data; |
| |
| int flags = O_RDONLY | O_CLOEXEC | O_BINARY | (follow_symlinks ? 0 : O_NOFOLLOW); |
| android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), flags))); |
| if (fd == -1) { |
| return std::nullopt; |
| } |
| |
| if (ReadFdToString(fd.get(), /*out*/&data)) { |
| return BinaryWireProtobuf<T>{std::move(data)}; |
| } else { |
| return std::nullopt; |
| } |
| } |
| |
| template <typename T> |
| bool BinaryWireProtobuf<T>::operator==(const BinaryWireProtobuf<T>& other) const { |
| if (data_.size() != other.data_.size()) { |
| return false; |
| } |
| return std::equal(data_.begin(), data_.end(), other.data_.begin()); |
| } |
| |
| template <typename T> |
| bool BinaryWireProtobuf<T>::ReadFdToString(int fd, /*out*/std::vector<std::byte>* content) { |
| DCHECK(content != nullptr); |
| |
| content->clear(); |
| |
| struct stat sb; |
| if (fstat(fd, /*out*/&sb) != -1 && sb.st_size > 0) { |
| content->reserve(sb.st_size); |
| } |
| |
| char buf[BUFSIZ]; |
| auto it = content->begin(); |
| ssize_t n; |
| while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) { |
| content->insert(it, |
| reinterpret_cast<std::byte*>(&buf[0]), |
| reinterpret_cast<std::byte*>(&buf[n])); |
| |
| std::advance(/*inout*/it, static_cast<size_t>(n)); |
| |
| static_assert(sizeof(char) == sizeof(std::byte), "sanity check for reinterpret cast"); |
| } |
| return (n == 0) ? true : false; |
| } |
| |
| // explicit template instantiation. |
| template struct BinaryWireProtobuf<::google::protobuf::MessageLite>; |
| // TODO: refactor this not to need the template instantiation. |
| |
| // Copy of the 2.6.18 kernel header (linux/ioprio.h) |
| |
| #define IOPRIO_WHO_PROCESS (1) |
| #define IOPRIO_CLASS_IDLE (3) |
| |
| #define IOPRIO_BITS (16) |
| #define IOPRIO_CLASS_SHIFT (13) |
| #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) |
| |
| #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT) |
| #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK) |
| #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) |
| |
| static int ioprio_get(int which, int who) { |
| return syscall(SYS_ioprio_get, which, who); |
| } |
| |
| static int ioprio_set(int which, int who, int ioprio) { |
| return syscall(SYS_ioprio_set, which, who, ioprio); |
| } |
| |
| // An rx Coordination, which will cause a new thread to spawn for each new Worker. |
| // |
| // Idle-class priority is set for the CPU and IO priorities on the new thread. |
| rxcpp::observe_on_one_worker ObserveOnNewIoThread() { |
| // IO thread factory for idle-priority threads. |
| // Both the CPU scheduler and the IO scheduler are set to idle. |
| // |
| // Use this when needing to schedule disk access from a normal-priority thread onto a |
| // very low priority thread, but not so low that we need to use a BackgroundJobScheduler. |
| struct io_thread_factory { |
| std::thread operator()(std::function<void()> start) const { |
| return std::thread{ |
| [start=std::move(start)]() { |
| // Set IO priority to idle. |
| do { |
| int value = ioprio_get(IOPRIO_WHO_PROCESS, /*pid*/0); |
| if (value == -1) { |
| PLOG(ERROR) << "io_thread_factory failed ioprio_get"; |
| break; // Can't set the ioprio, we don't know what data to use. |
| } |
| |
| int data = IOPRIO_PRIO_DATA(value); // priority level |
| // This appears to be '4' in practice. We may want to raise to |
| // be the highest-priority within the idle class. |
| |
| // idle scheduling class. only access disk when nobody else needs disk. |
| int res = ioprio_set(IOPRIO_WHO_PROCESS, |
| /*pid*/0, |
| IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, data)); |
| if (res < 0) { |
| PLOG(ERROR) << "io_thread_factory failed ioprio_set"; |
| break; |
| } |
| |
| // Changing the IO priority only has any effect with cfq scheduler: |
| // $> cat /sys/block/sda/queue/scheduler |
| LOG(VERBOSE) << "ioprio_set(WHO_PROCESS, class=IDLE, data=" << data << ")"; |
| } while (false); |
| |
| // Set CPU priority to idle. |
| do { |
| struct sched_param param{}; |
| param.sched_priority = 0; // Required to be statically 0 when used with SCHED_IDLE. |
| |
| if (sched_setscheduler(/*pid*/0, // current thread, |
| SCHED_IDLE, |
| /*in*/¶m) != 0) { |
| PLOG(ERROR) << "io_thread_factory failed sched_setscheduler"; |
| break; |
| } |
| |
| LOG(VERBOSE) << "sched_setscheduler(self, IDLE)"; |
| } while (false); |
| |
| // XX: if changing the scheduling is too aggressive (i.e. it causes starvation), |
| // we may want to stick with the default class and change the nice (priority) levels |
| // to the minimum. |
| |
| // TODO: future work, maybe use cgroups configuration file instead? |
| |
| // Call the rxcpp-supplied code. |
| start(); |
| } |
| }; |
| } |
| }; |
| |
| static rxcpp::schedulers::scheduler thread_scheduler = |
| rxcpp::schedulers::make_new_thread(io_thread_factory{}); |
| |
| static rxcpp::observe_on_one_worker observe_on_io_thread{thread_scheduler}; |
| |
| return observe_on_io_thread; |
| } |
| |
| static auto/*observable<PerfettoTraceProto>*/ |
| CreatePerfettoStream(rxcpp::observable<PerfettoStreamCommand> input, |
| std::shared_ptr<PerfettoConsumer> perfetto_consumer, |
| const ::perfetto::protos::TraceConfig& trace_config) { |
| // XX: should I also take a scheduler for input here??? |
| |
| auto /*observable<PerfettoStateChange>*/ perfetto_states = |
| CreatePerfettoStateStream(trace_config, perfetto_consumer); |
| |
| using State = ::perfetto::consumer::State; |
| |
| auto/*coordinator*/ serialize_coordinator = rxcpp::observe_on_new_thread(); |
| // Rx note: |
| // The optimal thing to do would be to have a lock/unlock for an entire subset of a chain. |
| // This would avoid creating new threads, and could also be used to intentionally block |
| // the regular C-callback perfetto thread. |
| // |
| // It seems possible to create a coordinator to lock a single operator in a chain, but this |
| // appears to be unsound. In particular, it doesn't even make life any simpler below because |
| // it would only apply the synchronization to 'zip' but not 'flat_map' which is unsound. |
| // |
| // There is also the built-in 'serialize_new_thread' which seems to create a new thread but |
| // then never actually uses it, that seems unfortunate and wasteful. |
| // |
| // Instead, do the simple thing which is create a new thread and always queue on there. |
| // Execution an action on that worker is itself unsynchronized, but this doesn't matter since |
| // the worker is only backed by 1 thread (no 2 schedulables can be executed concurrently |
| // on the 'observe_new_thread' worker). |
| return input |
| .tap([](PerfettoStreamCommand command) { |
| LOG(VERBOSE) << "CreatePerfettoStreamCommand#tap(command=" << command << ")"; |
| }) |
| // Input A, thread tA. Input B, thread tB. Continue execution with (A,B) on thread tC. |
| .zip(serialize_coordinator, // rest of chain is also executed on the same thread. |
| perfetto_states) |
| // Note: zip terminates when either of the streams complete. |
| .flat_map( |
| [](std::tuple<PerfettoStreamCommand, PerfettoStateChange> p) { |
| auto& [command, state_change] = p; |
| LOG(VERBOSE) << "CreatePerfettoStream#combine(" |
| << command << "," << state_change << ")"; |
| if (command == PerfettoStreamCommand::kShutdown) { |
| // Perfetto: Always safe to call ::perfetto::consumer::Destroy |
| // at any time. |
| // |
| // XX: How do we clean up the StateChangedSubject without racing |
| // against the callback? It strikes me that we may need a 'kDestroyed' |
| // state that perfetto can transition to from kConfigured. |
| LOG(VERBOSE) << "Call Perfetto_Consumer->Destroy"; |
| state_change.GetConsumer()->Destroy(state_change.GetHandle()); |
| |
| // XX: Do we even have any guarantees about not getting more callbacks? |
| // We could just say 'there can still be spurious output after Shutdown' |
| // and just ignore it (e.g. Shutdown and immediately unsubscribe). |
| } else if (command == PerfettoStreamCommand::kStartTracing |
| && state_change.state == State::kConfigured) { |
| LOG(VERBOSE) << "Call Perfetto_Consumer->StartTracing"; |
| state_change.GetConsumer()->StartTracing(state_change.GetHandle()); |
| } else if (command == PerfettoStreamCommand::kStopTracing && |
| state_change.state == State::kTraceEnded) { |
| // TODO: if perfetto actually had a 'StopTracing' we could call that here. |
| // right now we just pretend it exists, but rely on the config timer instead. |
| ::perfetto::consumer::TraceBuffer trace_buffer = |
| state_change.GetConsumer()->ReadTrace(state_change.GetHandle()); |
| |
| LOG(VERBOSE) << "Perfetto Trace ended" |
| << ", addr=" << reinterpret_cast<void*>(trace_buffer.begin) |
| << ",size= " << trace_buffer.size; |
| |
| PerfettoTraceProto wire_proto{trace_buffer.begin, trace_buffer.size}; |
| return rxcpp::observable<>::just(std::move(wire_proto)).as_dynamic(); |
| } |
| return rxcpp::observable<>::empty<PerfettoTraceProto>().as_dynamic(); |
| } |
| ); |
| } |
| |
| std::ostream& operator<<(std::ostream& os, PerfettoStreamCommand c) { |
| switch (c) { |
| case PerfettoStreamCommand::kStartTracing: |
| os << "kStartTracing"; |
| break; |
| case PerfettoStreamCommand::kStopTracing: |
| os << "kStopTracing"; |
| break; |
| case PerfettoStreamCommand::kShutdown: |
| os << "kShutdown"; |
| break; |
| default: |
| os << "(unknown)"; |
| break; |
| } |
| return os; |
| } |
| |
| RxProducerFactory::RxProducerFactory(PerfettoDependencies::Injector& injector) |
| : injector_(injector) { |
| } |
| |
| // TODO: (fruit) maybe this could be streamlined further by avoiding this boilerplate? |
| rxcpp::observable<PerfettoTraceProto> RxProducerFactory::CreateTraceStream( |
| rxcpp::observable<PerfettoStreamCommand> commands) { |
| std::shared_ptr<PerfettoConsumer> perfetto_consumer = |
| injector_.get<std::shared_ptr<PerfettoConsumer>>(); |
| const ::perfetto::protos::TraceConfig& trace_config = |
| injector_.get<::perfetto::protos::TraceConfig>(); |
| |
| DCHECK(perfetto_consumer != nullptr); |
| DCHECK(reinterpret_cast<volatile const void*>(&trace_config) != nullptr); |
| |
| return CreatePerfettoStream(commands, |
| perfetto_consumer, |
| trace_config); |
| } |
| |
| // For testing/debugging only. |
| // |
| // Saves protobuf results in file name specified by 'arg_output_proto'. |
| void CollectPerfettoTraceBufferImmediately( |
| RxProducerFactory& producer_factory, |
| const std::string& arg_output_proto) { |
| LOG(VERBOSE) << "CollectPerfettoTraceBufferImmediately"; |
| |
| std::shared_ptr<PerfettoConsumer> perfetto_consumer = |
| producer_factory.injector_.get<std::shared_ptr<PerfettoConsumer>>(); |
| const ::perfetto::protos::TraceConfig& trace_config = |
| producer_factory.injector_.get<const ::perfetto::protos::TraceConfig&>(); |
| |
| auto /*observable<PerfettoStateChange>*/ perfetto_states = |
| CreatePerfettoStateStream(trace_config, perfetto_consumer); |
| |
| perfetto_states |
| .as_blocking() // Wait for observable to terminate with on_completed or on_error. |
| .subscribe(/*on_next*/[&](auto state_change) { |
| LOG(VERBOSE) << "Perfetto post-processed State change: " << state_change; |
| |
| using State = ::perfetto::consumer::State; |
| switch (state_change.state) { |
| case State::kConnecting: |
| LOG(VERBOSE) << "Perfetto Tracing is Connecting"; |
| // Transitional state. No-op. |
| break; |
| case State::kConfigured: |
| state_change.GetConsumer()->StartTracing(state_change.GetHandle()); |
| break; |
| case State::kTracing: |
| LOG(VERBOSE) << "Perfetto Tracing started"; |
| // Transitional state. No-op. |
| break; |
| case State::kTraceEnded: { |
| ::perfetto::consumer::TraceBuffer trace_buffer = |
| state_change.GetConsumer()->ReadTrace(state_change.GetHandle()); |
| |
| LOG(VERBOSE) << "Perfetto Trace ended" |
| << ", addr=" << reinterpret_cast<void*>(trace_buffer.begin) |
| << ",size= " << trace_buffer.size; |
| |
| if (!arg_output_proto.empty()) { |
| std::string trace_buffer_str; |
| trace_buffer_str.resize(trace_buffer.size); |
| std::copy(trace_buffer.begin, |
| trace_buffer.begin + trace_buffer.size, |
| trace_buffer_str.data()); |
| if (!android::base::WriteStringToFile(trace_buffer_str, arg_output_proto)) { |
| LOG(ERROR) << "Failed to save TraceBuffer to " << arg_output_proto; |
| } else { |
| LOG(INFO) << "TraceBuffer saved to file: " << arg_output_proto; |
| LOG(INFO); |
| LOG(INFO) << "To print this in a human readable form, execute these commands:"; |
| LOG(INFO) << "$> adb pull '" << arg_output_proto << "'"; |
| LOG(INFO) << "$> trace_to_text systrace <filename.pb>"; |
| } |
| } |
| |
| // TODO: something more useful with this TraceBuffer, such as saving it to a file |
| // and printing the output. |
| break; |
| } |
| default: |
| // No other states are possible, because they go to #on_error or cause a dcheck. |
| DCHECK(false) << "Invalid state: " << state_change; |
| } |
| |
| //INTENTIONAL_COMPILER_ERROR_HERE // lets make sure this code actually does a trace. |
| |
| }, /*on_error*/[](rxcpp::util::error_ptr err) { |
| LOG(ERROR) << "Perfetto post-processed state change failed: " << rxcpp::util::what(err); |
| }, /*on_completed*/[]() { |
| LOG(VERBOSE) << "Perfetto post-processed State #on_completed"; |
| }); |
| } |
| |
| |
| } // namespace iorap::perfetto |
