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Diffstat (limited to 'src/perfetto/rx_producer.cc')
| -rw-r--r-- | src/perfetto/rx_producer.cc | 939 |
1 files changed, 0 insertions, 939 deletions
diff --git a/src/perfetto/rx_producer.cc b/src/perfetto/rx_producer.cc deleted file mode 100644 index 824600c..0000000 --- a/src/perfetto/rx_producer.cc +++ /dev/null @@ -1,939 +0,0 @@ -// 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 |