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unplugged-system/art/runtime/trace.h

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/*
* Copyright (C) 2011 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.
*/
#ifndef ART_RUNTIME_TRACE_H_
#define ART_RUNTIME_TRACE_H_
#include <bitset>
#include <map>
#include <memory>
#include <ostream>
#include <set>
#include <string>
#include <unordered_map>
#include <vector>
#include "base/atomic.h"
#include "base/locks.h"
#include "base/macros.h"
#include "base/mutex.h"
#include "base/os.h"
#include "base/safe_map.h"
#include "instrumentation.h"
#include "runtime_globals.h"
namespace unix_file {
class FdFile;
} // namespace unix_file
namespace art {
class ArtField;
class ArtMethod;
class DexFile;
class ShadowFrame;
class Thread;
using DexIndexBitSet = std::bitset<65536>;
enum TracingMode {
kTracingInactive,
kMethodTracingActive, // Trace activity synchronous with method progress.
kSampleProfilingActive, // Trace activity captured by sampling thread.
};
std::ostream& operator<<(std::ostream& os, TracingMode rhs);
// File format:
// header
// record 0
// record 1
// ...
//
// Header format:
// u4 magic ('SLOW')
// u2 version
// u2 offset to data
// u8 start date/time in usec
// u2 record size in bytes (version >= 2 only)
// ... padding to 32 bytes
//
// Record format v1:
// u1 thread ID
// u4 method ID | method action
// u4 time delta since start, in usec
//
// Record format v2:
// u2 thread ID
// u4 method ID | method action
// u4 time delta since start, in usec
//
// Record format v3:
// u2 thread ID
// u4 method ID | method action
// u4 time delta since start, in usec
// u4 wall time since start, in usec (when clock == "dual" only)
//
// 32 bits of microseconds is 70 minutes.
//
// All values are stored in little-endian order.
enum TraceAction {
kTraceMethodEnter = 0x00, // method entry
kTraceMethodExit = 0x01, // method exit
kTraceUnroll = 0x02, // method exited by exception unrolling
// 0x03 currently unused
kTraceMethodActionMask = 0x03, // two bits
};
// Class for recording event traces. Trace data is either collected
// synchronously during execution (TracingMode::kMethodTracingActive),
// or by a separate sampling thread (TracingMode::kSampleProfilingActive).
class Trace final : public instrumentation::InstrumentationListener {
public:
enum TraceFlag {
kTraceCountAllocs = 0x001,
kTraceClockSourceWallClock = 0x010,
kTraceClockSourceThreadCpu = 0x100,
};
enum class TraceOutputMode {
kFile,
kDDMS,
kStreaming
};
enum class TraceMode {
kMethodTracing,
kSampling
};
static void SetDefaultClockSource(TraceClockSource clock_source);
static void Start(const char* trace_filename,
size_t buffer_size,
int flags,
TraceOutputMode output_mode,
TraceMode trace_mode,
int interval_us)
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_,
!Locks::trace_lock_);
static void Start(int trace_fd,
size_t buffer_size,
int flags,
TraceOutputMode output_mode,
TraceMode trace_mode,
int interval_us)
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_,
!Locks::trace_lock_);
static void Start(std::unique_ptr<unix_file::FdFile>&& file,
size_t buffer_size,
int flags,
TraceOutputMode output_mode,
TraceMode trace_mode,
int interval_us)
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_,
!Locks::trace_lock_);
static void StartDDMS(size_t buffer_size,
int flags,
TraceMode trace_mode,
int interval_us)
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_,
!Locks::trace_lock_);
// Stop tracing. This will finish the trace and write it to file/send it via DDMS.
static void Stop()
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::trace_lock_);
// Abort tracing. This will just stop tracing and *not* write/send the collected data.
static void Abort()
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::trace_lock_);
static void Shutdown()
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::trace_lock_);
static TracingMode GetMethodTracingMode() REQUIRES(!Locks::trace_lock_);
// Flush the per-thread buffer. This is called when the thread is about to detach.
static void FlushThreadBuffer(Thread* thread) REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::trace_lock_) NO_THREAD_SAFETY_ANALYSIS;
bool UseWallClock();
bool UseThreadCpuClock();
void MeasureClockOverhead();
uint32_t GetClockOverheadNanoSeconds();
void CompareAndUpdateStackTrace(Thread* thread, std::vector<ArtMethod*>* stack_trace)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_);
// InstrumentationListener implementation.
void MethodEntered(Thread* thread, ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!tracing_lock_) override;
void MethodExited(Thread* thread,
ArtMethod* method,
instrumentation::OptionalFrame frame,
JValue& return_value)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_)
override;
void MethodUnwind(Thread* thread,
ArtMethod* method,
uint32_t dex_pc)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_)
override;
void DexPcMoved(Thread* thread,
Handle<mirror::Object> this_object,
ArtMethod* method,
uint32_t new_dex_pc)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_)
override;
void FieldRead(Thread* thread,
Handle<mirror::Object> this_object,
ArtMethod* method,
uint32_t dex_pc,
ArtField* field)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_) override;
void FieldWritten(Thread* thread,
Handle<mirror::Object> this_object,
ArtMethod* method,
uint32_t dex_pc,
ArtField* field,
const JValue& field_value)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_) override;
void ExceptionThrown(Thread* thread,
Handle<mirror::Throwable> exception_object)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_) override;
void ExceptionHandled(Thread* thread, Handle<mirror::Throwable> exception_object)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_) override;
void Branch(Thread* thread,
ArtMethod* method,
uint32_t dex_pc,
int32_t dex_pc_offset)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_) override;
void WatchedFramePop(Thread* thread, const ShadowFrame& frame)
REQUIRES_SHARED(Locks::mutator_lock_) override;
// Reuse an old stack trace if it exists, otherwise allocate a new one.
static std::vector<ArtMethod*>* AllocStackTrace();
// Clear and store an old stack trace for later use.
static void FreeStackTrace(std::vector<ArtMethod*>* stack_trace);
// Save id and name of a thread before it exits.
static void StoreExitingThreadInfo(Thread* thread);
static TraceOutputMode GetOutputMode() REQUIRES(!Locks::trace_lock_);
static TraceMode GetMode() REQUIRES(!Locks::trace_lock_);
static size_t GetBufferSize() REQUIRES(!Locks::trace_lock_);
static int GetFlags() REQUIRES(!Locks::trace_lock_);
static int GetIntervalInMillis() REQUIRES(!Locks::trace_lock_);
// Used by class linker to prevent class unloading.
static bool IsTracingEnabled() REQUIRES(!Locks::trace_lock_);
private:
Trace(File* trace_file,
size_t buffer_size,
int flags,
TraceOutputMode output_mode,
TraceMode trace_mode);
// The sampling interval in microseconds is passed as an argument.
static void* RunSamplingThread(void* arg) REQUIRES(!Locks::trace_lock_);
static void StopTracing(bool finish_tracing, bool flush_file)
REQUIRES(!Locks::mutator_lock_, !Locks::thread_list_lock_, !Locks::trace_lock_)
// There is an annoying issue with static functions that create a new object and call into
// that object that causes them to not be able to tell that we don't currently hold the lock.
// This causes the negative annotations to incorrectly have a false positive. TODO: Figure out
// how to annotate this.
NO_THREAD_SAFETY_ANALYSIS;
void FinishTracing()
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_);
void ReadClocks(Thread* thread, uint32_t* thread_clock_diff, uint64_t* timestamp_counter);
void LogMethodTraceEvent(Thread* thread,
ArtMethod* method,
TraceAction action,
uint32_t thread_clock_diff,
uint64_t timestamp_counter) REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!tracing_lock_);
// Methods to output traced methods and threads.
void DumpMethodList(std::ostream& os)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_);
void DumpThreadList(std::ostream& os) REQUIRES(!Locks::thread_list_lock_);
void RecordMethodEvent(Thread* thread,
ArtMethod* method,
TraceAction action,
uint32_t thread_clock_diff,
uint64_t timestamp) REQUIRES(!tracing_lock_);
// Encodes event in non-streaming mode. This assumes that there is enough space reserved to
// encode the entry.
void EncodeEventEntry(uint8_t* ptr,
Thread* thread,
uint32_t method_index,
TraceAction action,
uint32_t thread_clock_diff,
uint32_t wall_clock_diff) REQUIRES(tracing_lock_);
// These methods are used to encode events in streaming mode.
// This records the method event in the per-thread buffer if there is sufficient space for the
// entire record. If the buffer is full then it just flushes the buffer and then records the
// entry.
void RecordStreamingMethodEvent(Thread* thread,
ArtMethod* method,
TraceAction action,
uint32_t thread_clock_diff,
uint64_t timestamp) REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!tracing_lock_);
// This encodes all the events in the per-thread trace buffer and writes it to the trace file.
// This acquires streaming lock to prevent any other threads writing concurrently. It is required
// to serialize these since each method is encoded with a unique id which is assigned when the
// method is seen for the first time in the recoreded events. So we need to serialize these
// flushes across threads.
void FlushStreamingBuffer(Thread* thread) REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!tracing_lock_);
// Ensures there is sufficient space in the buffer to record the requested_size. If there is not
// enough sufficient space the current contents of the buffer are written to the file and
// current_index is reset to 0. This doesn't check if buffer_size is big enough to hold the
// requested size.
void EnsureSpace(uint8_t* buffer,
size_t* current_index,
size_t buffer_size,
size_t required_size);
// Writes header followed by data to the buffer at the current_index. This also updates the
// current_index to point to the next entry.
void WriteToBuf(uint8_t* header,
size_t header_size,
const std::string& data,
size_t* current_index,
uint8_t* buffer,
size_t buffer_size);
uint32_t EncodeTraceMethod(ArtMethod* method) REQUIRES(tracing_lock_);
ArtMethod* DecodeTraceMethod(uint32_t tmid) REQUIRES(tracing_lock_);
std::string GetMethodLine(ArtMethod* method, uint32_t method_id) REQUIRES(tracing_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void DumpBuf(uint8_t* buf, size_t buf_size, TraceClockSource clock_source)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!tracing_lock_);
void UpdateThreadsList(Thread* thread);
// Singleton instance of the Trace or null when no method tracing is active.
static Trace* volatile the_trace_ GUARDED_BY(Locks::trace_lock_);
// The default profiler clock source.
static TraceClockSource default_clock_source_;
// Sampling thread, non-zero when sampling.
static pthread_t sampling_pthread_;
// Used to remember an unused stack trace to avoid re-allocation during sampling.
static std::unique_ptr<std::vector<ArtMethod*>> temp_stack_trace_;
// File to write trace data out to, null if direct to ddms.
std::unique_ptr<File> trace_file_;
// Buffer to store trace data. In streaming mode, this is protected
// by the tracing_lock_. In non-streaming mode, reserved regions
// are atomically allocated (using cur_offset_) for log entries to
// be written.
std::unique_ptr<uint8_t[]> buf_;
// Flags enabling extra tracing of things such as alloc counts.
const int flags_;
// The kind of output for this tracing.
const TraceOutputMode trace_output_mode_;
// The tracing method.
const TraceMode trace_mode_;
const TraceClockSource clock_source_;
// Size of buf_.
const size_t buffer_size_;
// Time trace was created.
const uint64_t start_time_;
// Clock overhead.
const uint32_t clock_overhead_ns_;
// Offset into buf_. The field is atomic to allow multiple writers
// to concurrently reserve space in the buffer. The newly written
// buffer contents are not read without some other form of thread
// synchronization, such as suspending all potential writers or
// acquiring *tracing_lock_. Reading cur_offset_ is thus never
// used to ensure visibility of any other objects, and all accesses
// are memory_order_relaxed.
//
// All accesses to buf_ in streaming mode occur whilst holding the
// streaming lock. In streaming mode, the buffer may be written out
// so cur_offset_ can move forwards and backwards.
//
// When not in streaming mode, the buf_ writes can come from
// multiple threads when the trace mode is kMethodTracing. When
// trace mode is kSampling, writes only come from the sampling
// thread.
//
// Reads to the buffer happen after the event sources writing to the
// buffer have been shutdown and all stores have completed. The
// stores are made visible in StopTracing() when execution leaves
// the ScopedSuspendAll block.
AtomicInteger cur_offset_;
// Did we overflow the buffer recording traces?
bool overflow_;
// Map of thread ids and names. We record the information when the threads are
// exiting and when the tracing has finished.
SafeMap<pid_t, std::string> threads_list_;
// Sampling profiler sampling interval.
int interval_us_;
// A flag to indicate to the sampling thread whether to stop tracing
bool stop_tracing_;
// Streaming mode data.
Mutex tracing_lock_;
// Map from ArtMethod* to index.
std::unordered_map<ArtMethod*, uint32_t> art_method_id_map_ GUARDED_BY(tracing_lock_);
uint32_t current_method_index_ = 0;
DISALLOW_COPY_AND_ASSIGN(Trace);
};
} // namespace art
#endif // ART_RUNTIME_TRACE_H_
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