src/hotspot/share/runtime/vmOperation.hpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 *
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef SHARE_RUNTIME_VMOPERATION_HPP
#define SHARE_RUNTIME_VMOPERATION_HPP

#include "memory/allocation.hpp"

// The following classes are used for operations
// initiated by a Java thread but that must
// take place in the VMThread.

#define VM_OP_ENUM(type)   VMOp_##type,

// Note: When new VM_XXX comes up, add 'XXX' to the template table.
#define VM_OPS_DO(template)                       \
  template(Halt)                                  \
  template(SafepointALot)                         \
  template(ThreadDump)                            \
  template(PrintThreads)                          \
  template(FindDeadlocks)                         \
  template(ClearICs)                              \
  template(ForceSafepoint)                        \
  template(DeoptimizeFrame)                       \
  template(DeoptimizeAll)                         \
  template(ZombieAll)                             \
  template(Verify)                                \
  template(HeapDumper)                            \
  template(CollectForMetadataAllocation)          \
  template(CollectForCodeCacheAllocation)         \
  template(GC_HeapInspection)                     \
  template(SerialCollectForAllocation)            \
  template(SerialGCCollect)                       \
  template(ParallelCollectForAllocation)          \
  template(ParallelGCCollect)                     \
  template(G1CollectForAllocation)                \
  template(G1CollectFull)                         \
  template(G1PauseRemark)                         \
  template(G1PauseCleanup)                        \
  template(G1TryInitiateConcMark)                 \
  template(ZMarkEndOld)                           \
  template(ZMarkEndYoung)                         \
  template(ZMarkFlushOperation)                   \
  template(ZMarkStartYoung)                       \
  template(ZMarkStartYoungAndOld)                 \
  template(ZRelocateStartOld)                     \
  template(ZRelocateStartYoung)                   \
  template(ZRendezvousGCThreads)                  \
  template(ZVerifyOld)                            \
  template(XMarkStart)                            \
  template(XMarkEnd)                              \
  template(XRelocateStart)                        \
  template(XVerify)                               \
  template(HandshakeAllThreads)                   \
  template(PopulateDumpSharedSpace)               \
  template(JNIFunctionTableCopier)                \
  template(RedefineClasses)                       \
  template(GetObjectMonitorUsage)                 \
  template(GetAllStackTraces)                     \
  template(GetThreadListStackTraces)              \
  template(ChangeBreakpoints)                     \
  template(GetOrSetLocal)                         \
  template(VirtualThreadGetOrSetLocal)            \
  template(ChangeSingleStep)                      \
  template(SetNotifyJvmtiEventsMode)              \
  template(HeapWalkOperation)                     \
  template(HeapIterateOperation)                  \
  template(ReportJavaOutOfMemory)                 \
  template(JFRSafepointClear)                     \
  template(JFRSafepointWrite)                     \
  template(ShenandoahFullGC)                      \
  template(ShenandoahInitMark)                    \
  template(ShenandoahFinalMarkStartEvac)          \
  template(ShenandoahInitUpdateRefs)              \
  template(ShenandoahFinalUpdateRefs)             \
  template(ShenandoahFinalRoots)                  \
  template(ShenandoahDegeneratedGC)               \
  template(Exit)                                  \
  template(LinuxDllLoad)                          \
  template(WhiteBoxOperation)                     \
  template(JVMCIResizeCounters)                   \
  template(ClassLoaderStatsOperation)             \
  template(ClassLoaderHierarchyOperation)         \
  template(DumpHashtable)                         \
  template(CleanClassLoaderDataMetaspaces)        \
  template(RehashStringTable)                     \
  template(RehashSymbolTable)                     \
  template(PrintCompileQueue)                     \
  template(PrintClassHierarchy)                   \
  template(PrintClasses)                          \
  template(PrintMetadata)                         \
  template(GTestExecuteAtSafepoint)               \
  template(GTestStopSafepoint)                    \
  template(JFROldObject)                          \
  template(JvmtiPostObjectFree)                   \
  template(RendezvousGCThreads)                   \
  template(JFRInitializeCPUTimeSampler)       \
  template(JFRTerminateCPUTimeSampler)        \
  template(ReinitializeMDO)

class Thread;
class outputStream;

class VM_Operation : public StackObj {
 public:
  enum VMOp_Type {
    VM_OPS_DO(VM_OP_ENUM)
    VMOp_Terminating
  };

 private:
  Thread*         _calling_thread;

  // The VM operation name array
  static const char* _names[];

 public:
  VM_Operation() : _calling_thread(nullptr) {}

  // VM operation support (used by VM thread)
  Thread* calling_thread() const                 { return _calling_thread; }
  void set_calling_thread(Thread* thread);

  // Called by VM thread - does in turn invoke doit(). Do not override this
  void evaluate();

  // evaluate() is called by the VMThread and in turn calls doit().
  // If the thread invoking VMThread::execute((VM_Operation*) is a JavaThread,
  // doit_prologue() is called in that thread before transferring control to
  // the VMThread.
  // If doit_prologue() returns true the VM operation will proceed, and
  // doit_epilogue() will be called by the JavaThread once the VM operation
  // completes. If doit_prologue() returns false the VM operation is cancelled.
  virtual void doit()                            = 0;
  virtual bool doit_prologue()                   { return true; };
  virtual void doit_epilogue()                   {};

  // Configuration. Override these appropriately in subclasses.
  virtual VMOp_Type type() const = 0;
  virtual bool allow_nested_vm_operations() const { return false; }

  // You may override skip_thread_oop_barriers to return true if the operation
  // does not access thread-private oops (including frames).
  virtual bool skip_thread_oop_barriers() const { return false; }

  // An operation can either be done inside a safepoint
  // or concurrently with Java threads running.
  virtual bool evaluate_at_safepoint() const { return true; }

  // Debugging
  virtual void print_on_error(outputStream* st) const;
  virtual const char* name() const  { return _names[type()]; }
  static const char* name(int type) {
    assert(type >= 0 && type < VMOp_Terminating, "invalid VM operation type");
    return _names[type];
  }
  // Extra information about what triggered this operation.
  virtual const char* cause() const { return nullptr; }
#ifndef PRODUCT
  void print_on(outputStream* st) const { print_on_error(st); }
#endif
};

#endif // SHARE_RUNTIME_VMOPERATION_HPP