JDK14/Java14源码在线阅读

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 * version 2 for more details (a copy is included in the LICENSE file that
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#ifndef SHARE_JFR_RECORDER_STORAGE_JFRVIRTUALMEMORY_HPP
#define SHARE_JFR_RECORDER_STORAGE_JFRVIRTUALMEMORY_HPP

#include "jfr/utilities/jfrAllocation.hpp"

class JfrVirtualMemoryManager;

class JfrVirtualMemory : public JfrCHeapObj {
 private:
  JfrVirtualMemoryManager* _vmm;
  const u1* _reserved_low; // lowest address of reservation
  const u1* _reserved_high; // highest address of reservation
  u1* _top; // current allocation address
  const u1* _commit_point; // synch points for committing new memory
  size_t _physical_commit_size_request_words; // aligned to os::vm_allocation_granularity()
  size_t _aligned_datum_size_bytes; // datum alignment

  bool commit_memory_block();
  void* commit(size_t block_size_request_words);
  void* index_ptr(size_t index); // index to address map

 public:
  JfrVirtualMemory();
  ~JfrVirtualMemory();

  // initialization will do the reservation and return it
  void* initialize(size_t reservation_size_request_bytes, size_t block_size_request_bytes, size_t datum_size_bytes = 1);

  void* new_datum(); // datum oriented allocation
  void* get(size_t index); // direct access retrieval
  size_t aligned_datum_size_bytes() const;

  bool is_full() const; // limit of reservation committed and in use

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