log.h

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// Copyright (c) 2015, 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 RUNTIME_VM_LOG_H_
#define RUNTIME_VM_LOG_H_
 
#include "vm/allocation.h"
#include "vm/growable_array.h"
#include "vm/os.h"
 
namespace dart {
 
class IsolateGroup;
class LogBlock;
 
#if defined(_MSC_VER)
#define THR_Print(format, ...) Log::Current()->Print(format, __VA_ARGS__)
#else
#define THR_Print(format, ...) Log::Current()->Print(format, ##__VA_ARGS__)
#endif
 
#define THR_VPrint(format, args) Log::Current()->VPrint(format, args)
 
typedef void (*LogPrinter)(const char* data);
 
class Log {
 public:
  explicit Log(LogPrinter printer = nullptr);
  ~Log();
 
  static Log* Current();
 
  // Append a formatted string to the log.
  void Print(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
 
  void VPrint(const char* format, va_list args);
 
  // Flush and truncate the log. The log is flushed starting at cursor
  // and truncated to cursor afterwards.
  void Flush(const intptr_t cursor = 0);
 
  // Clears the log.
  void Clear();
 
  // Current cursor.
  intptr_t cursor() const;
 
  // A logger that does nothing.
  static Log* NoOpLog();
 
 private:
  void TerminateString();
  void EnableManualFlush();
  void DisableManualFlush(const intptr_t cursor);
 
  // Returns true when flush is required.
  bool ShouldFlush() const;
 
  // Returns false if we should drop log messages related to 'isolate'.
  static bool ShouldLogForIsolateGroup(const IsolateGroup* isolate);
 
  static Log noop_log_;
  LogPrinter printer_;
  intptr_t manual_flush_;
  MallocGrowableArray<char> buffer_;
 
  friend class LogBlock;
  friend class LogTestHelper;
  DISALLOW_COPY_AND_ASSIGN(Log);
};
 
// Causes all log messages to be buffered until destructor is called.
// Can be nested.
class LogBlock : public StackResource {
 public:
  LogBlock(ThreadState* thread, Log* log)
      : StackResource(thread), log_(log), cursor_(log->cursor()) {
    Initialize();
  }
 
  LogBlock()
      : StackResource(ThreadState::Current()),
        log_(Log::Current()),
        cursor_(Log::Current()->cursor()) {
    Initialize();
  }
 
  ~LogBlock();
 
 private:
  void Initialize();
 
  Log* const log_;
  const intptr_t cursor_;
};
 
}  // namespace dart
 
#endif  // RUNTIME_VM_LOG_H_