diff options
| -rw-r--r-- | runtime/trace.cc | 11 | ||||
| -rw-r--r-- | runtime/trace.h | 23 |
2 files changed, 7 insertions, 27 deletions
diff --git a/runtime/trace.cc b/runtime/trace.cc index 3a0d7048d4..9ab268351d 100644 --- a/runtime/trace.cc +++ b/runtime/trace.cc @@ -757,7 +757,7 @@ Trace::Trace(File* trace_file, } static_assert(18 <= kMinBufSize, "Minimum buffer size not large enough for trace header"); - cur_offset_.store(kTraceHeaderLength, std::memory_order_relaxed); + cur_offset_ = kTraceHeaderLength; if (output_mode == TraceOutputMode::kStreaming) { // Flush the header information to the file. We use a per thread buffer, so @@ -765,7 +765,7 @@ Trace::Trace(File* trace_file, if (!trace_file_->WriteFully(buf_.get(), kTraceHeaderLength)) { PLOG(WARNING) << "Failed streaming a tracing event."; } - cur_offset_.store(0, std::memory_order_relaxed); + cur_offset_ = 0; } // Thread index of 0 is a special identifier used to distinguish between trace @@ -776,7 +776,8 @@ Trace::Trace(File* trace_file, void Trace::FinishTracing() { size_t final_offset = 0; if (trace_output_mode_ != TraceOutputMode::kStreaming) { - final_offset = cur_offset_.load(std::memory_order_relaxed); + MutexLock mu(Thread::Current(), tracing_lock_); + final_offset = cur_offset_; } // Compute elapsed time. @@ -1069,7 +1070,7 @@ void Trace::FlushBuffer(Thread* thread) { } else { buffer_size = buffer_size_; buffer_ptr = buf_.get(); - current_index = cur_offset_.load(std::memory_order_relaxed); + current_index = cur_offset_; } size_t num_entries = *(thread->GetMethodTraceIndexPtr()); @@ -1119,7 +1120,7 @@ void Trace::FlushBuffer(Thread* thread) { } else { // In non-streaming mode, we keep the data in the buffer and write to the // file when tracing has stopped. Just updated the offset of the buffer. - cur_offset_.store(current_index, std::memory_order_relaxed); + cur_offset_ = current_index; } } diff --git a/runtime/trace.h b/runtime/trace.h index 6eee9f9f78..7e62af4871 100644 --- a/runtime/trace.h +++ b/runtime/trace.h @@ -364,28 +364,7 @@ class Trace final : public instrumentation::InstrumentationListener { // 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_; + size_t cur_offset_ GUARDED_BY(tracing_lock_); // Did we overflow the buffer recording traces? bool overflow_; |