g1RootProcessor.hpp

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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_ROOTPROCESSOR_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_ROOTPROCESSOR_HPP

#include "memory/allocation.hpp"
#include "memory/sharedHeap.hpp"
#include "runtime/mutex.hpp"

class CLDClosure;
class CodeBlobClosure;
class G1CollectedHeap;
class G1GCPhaseTimes;
class G1ParPushHeapRSClosure;
class G1RootClosures;
class Monitor;
class OopClosure;
class SubTasksDone;

// Scoped object to assist in applying oop, CLD and code blob closures to
// root locations. Handles claiming of different root scanning tasks
// and takes care of global state for root scanning via a StrongRootsScope.
// In the parallel case there is a shared G1RootProcessor object where all
// worker thread call the process_roots methods.
class G1RootProcessor : public StackObj {
  G1CollectedHeap* _g1h;
  SubTasksDone _process_strong_tasks;
  SharedHeap::StrongRootsScope _srs;

  // Used to implement the Thread work barrier.
  Monitor _lock;
  volatile jint _n_workers_discovered_strong_classes;

  enum G1H_process_roots_tasks {
    G1RP_PS_Universe_oops_do,
    G1RP_PS_JNIHandles_oops_do,
    G1RP_PS_ObjectSynchronizer_oops_do,
    G1RP_PS_FlatProfiler_oops_do,
    G1RP_PS_Management_oops_do,
    G1RP_PS_SystemDictionary_oops_do,
    G1RP_PS_ClassLoaderDataGraph_oops_do,
    G1RP_PS_jvmti_oops_do,
    G1RP_PS_CodeCache_oops_do,
    G1RP_PS_filter_satb_buffers,
    G1RP_PS_refProcessor_oops_do,
    // Leave this one last.
    G1RP_PS_NumElements
  };

  void worker_has_discovered_all_strong_classes();
  void wait_until_all_strong_classes_discovered();

  void process_all_roots(OopClosure* oops,
                         CLDClosure* clds,
                         CodeBlobClosure* blobs,
                         bool process_string_table);

  void process_java_roots(OopClosure* scan_non_heap_roots,
                          CLDClosure* thread_stack_clds,
                          CLDClosure* scan_strong_clds,
                          CLDClosure* scan_weak_clds,
                          CodeBlobClosure* scan_strong_code,
                          G1GCPhaseTimes* phase_times,
                          uint worker_i);

  void process_vm_roots(OopClosure* scan_non_heap_roots,
                        OopClosure* scan_non_heap_weak_roots,
                        G1GCPhaseTimes* phase_times,
                        uint worker_i);

  void process_string_table_roots(OopClosure* scan_non_heap_weak_roots,
                                  G1GCPhaseTimes* phase_times,
                                  uint worker_i);

  void process_code_cache_roots(CodeBlobClosure* code_closure,
                                G1GCPhaseTimes* phase_times,
                                uint worker_i);

public:
  G1RootProcessor(G1CollectedHeap* g1h);

  // Apply closures to the strongly and weakly reachable roots in the system
  // in a single pass.
  // Record and report timing measurements for sub phases using the worker_i
  void evacuate_roots(OopClosure* scan_non_heap_roots,
                      OopClosure* scan_non_heap_weak_roots,
                      CLDClosure* scan_strong_clds,
                      CLDClosure* scan_weak_clds,
                      bool trace_metadata,
                      uint worker_i);

  // Apply oops, clds and blobs to all strongly reachable roots in the system
  void process_strong_roots(OopClosure* oops,
                            CLDClosure* clds,
                            CodeBlobClosure* blobs);

  // Apply oops, clds and blobs to strongly and weakly reachable roots in the system
  void process_all_roots(OopClosure* oops,
                         CLDClosure* clds,
                         CodeBlobClosure* blobs);

  // Apply scan_rs to all locations in the union of the remembered sets for all
  // regions in the collection set
  // (having done "set_region" to indicate the region in which the root resides),
  void scan_remembered_sets(G1ParPushHeapRSClosure* scan_rs,
                            OopClosure* scan_non_heap_weak_roots,
                            uint worker_i);

  // Apply oops, clds and blobs to strongly and weakly reachable roots in the system,
  // the only thing different from process_all_roots is that we skip the string table
  // to avoid keeping every string live when doing class unloading.
  void process_all_roots_no_string_table(OopClosure* oops,
                                         CLDClosure* clds,
                                         CodeBlobClosure* blobs);

  // Inform the root processor about the number of worker threads
  void set_num_workers(int active_workers);
};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_ROOTPROCESSOR_HPP