Sampling profiler

runtime/vm/profiler.h

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef VM_PROFILER_H_
+#define VM_PROFILER_H_
+
+#include "platform/hashmap.h"
+#include "platform/thread.h"
+#include "vm/allocation.h"
+#include "vm/code_observers.h"
+#include "vm/globals.h"
+
+namespace dart {
+
+// Forward declarations.
+class JSONStream;
+
+// Profiler manager.
+class ProfilerManager : public AllStatic {
+ public:
+  static void InitOnce();
+  static void Shutdown();
+
+  static void SetupIsolateForProfiling(Isolate* isolate);
+  static void ShutdownIsolateForProfiling(Isolate* isolate);
+  static void ScheduleIsolate(Isolate* isolate);
+  static void DescheduleIsolate(Isolate* isolate);
+
+  static void PrintToJSONStream(Isolate* isolate, JSONStream* stream);
+
+  static void WriteTracing(Isolate* isolate, const char* name, Dart_Port port);
+
+ private:
+  static const intptr_t kMaxProfiledIsolates = 4096;
+  static bool initialized_;
+  static bool shutdown_;
+  static Monitor* monitor_;
+
+  static Isolate** isolates_;
+  static intptr_t isolates_capacity_;
+  static intptr_t isolates_size_;
+
+  static void ResizeIsolates(intptr_t new_capacity);
+  static void AddIsolate(Isolate* isolate);
+  static intptr_t FindIsolate(Isolate* isolate);
+  static void RemoveIsolate(intptr_t i);
+
+  // Returns the microseconds until the next live timer fires.
+  static int64_t SampleAndRescheduleIsolates(int64_t current_time);
+  static void FreeIsolateProfilingData(Isolate* isolate);
+  static void ThreadMain(uword parameters);
+};
+
+
+class IsolateProfilerData {
+ public:
+  static const int64_t kDescheduledCpuUsage = -1;
+  static const int64_t kNoExpirationTime = -2;
+
+  IsolateProfilerData(Isolate* isolate, SampleBuffer* sample_buffer);
+  ~IsolateProfilerData();
+
+  int64_t sample_interval_micros() const { return sample_interval_micros_; }
+
+  void set_sample_interval_micros(int64_t sample_interval) {
+    sample_interval_micros_ = sample_interval;
+  }
+
+  bool CanExpire() const {
+    return timer_expiration_micros_ != kNoExpirationTime;
+  }
+
+  bool ShouldSample(int64_t current_time) const {
+    return CanExpire() && TimeUntilExpiration(current_time) <= 0;
+  }
+
+  int64_t TimeUntilExpiration(int64_t current_time_micros) const {
+    ASSERT(CanExpire());
+    return timer_expiration_micros_ - current_time_micros;
+  }
+
+  void set_cpu_usage(int64_t cpu_usage) {
+    cpu_usage_ = cpu_usage;
+  }
+
+  void SampledAt(int64_t current_time);
+
+  void Scheduled(int64_t current_time, ThreadId thread);
+
+  void Descheduled();
+
+  int64_t cpu_usage() const { return cpu_usage_; }
+
+  int64_t ComputeDeltaAndSetCpuUsage(int64_t cpu_usage) {
+    int64_t delta = 0;
+    if (cpu_usage_ != kDescheduledCpuUsage) {
+      // Only compute the real delta if we are being sampled regularly.
+      delta = cpu_usage - cpu_usage_;
+    }
+    set_cpu_usage(cpu_usage);
+    return delta;
+  }
+
+  ThreadId thread_id() const { return thread_id_; }
+
+  Isolate* isolate() const { return isolate_; }
+
+  SampleBuffer* sample_buffer() const { return sample_buffer_; }
+
+ private:
+  int64_t last_sampled_micros_;
+  int64_t timer_expiration_micros_;
+  int64_t sample_interval_micros_;
+  int64_t cpu_usage_;
+  ThreadId thread_id_;
+  Isolate* isolate_;
+  SampleBuffer* sample_buffer_;
+  DISALLOW_COPY_AND_ASSIGN(IsolateProfilerData);
+};
+
+
+// Profile sample.
+struct Sample {
+  static const char* kLookupSymbol;
+  static const char* kNoSymbol;
+  static const intptr_t kNumStackFrames = 4;
+  enum SampleState {
+    kIdle = 0,
+    kExecuting = 1,
+    kNumSampleStates
+  };
+  int64_t timestamp;
+  int64_t cpu_usage;
+  uintptr_t pcs[kNumStackFrames];
+  uint16_t vm_tags;
+  uint16_t runtime_tags;
+  Sample();
+};
+
+
+// Ring buffer of samples. One per isolate.
+class SampleBuffer {
+ public:
+  static const intptr_t kDefaultBufferCapacity = 1000000;
+
+  explicit SampleBuffer(intptr_t capacity = kDefaultBufferCapacity);
+  ~SampleBuffer();
+
+  intptr_t capacity() const { return capacity_; }
+
+  Sample* ReserveSample();
+
+  Sample* FirstSample() const;
+  Sample* NextSample(Sample* sample) const;
+  Sample* LastSample() const;
+ private:
+  Sample* samples_;
+  intptr_t capacity_;
+  intptr_t start_;
+  intptr_t end_;
+
+  intptr_t WrapIncrement(intptr_t i) const;
+  DISALLOW_COPY_AND_ASSIGN(SampleBuffer);
+};
+
+
+class ProfilerSampleStackWalker : public ValueObject {
+ public:
+  ProfilerSampleStackWalker(Sample* sample,
+                            uintptr_t stack_lower,
+                            uintptr_t stack_upper,
+                            uintptr_t pc,
+                            uintptr_t fp,
+                            uintptr_t sp);
+
+  int walk();
+
+ private:
+  uword* CallerPC(uword* fp);
+  uword* CallerFP(uword* fp);
+
+  bool ValidInstructionPointer(uword* pc);
+
+  bool ValidFramePointer(uword* fp);
+
+  Sample* sample_;
+  const uintptr_t stack_lower_;
+  const uintptr_t stack_upper_;
+  const uintptr_t original_pc_;
+  const uintptr_t original_fp_;
+  const uintptr_t original_sp_;
+};
+
+
+}  // namespace dart
+
+#endif  // VM_PROFILER_H_