/*

 * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "classfile/stringTable.hpp"

#include "classfile/systemDictionary.hpp"

#include "code/codeCache.hpp"

#include "gc_interface/collectedHeap.inline.hpp"

#include "memory/sharedHeap.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.inline.hpp"

#include "runtime/fprofiler.hpp"

#include "runtime/java.hpp"

#include "services/management.hpp"

#include "utilities/copy.hpp"

#include "utilities/workgroup.hpp"

PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

SharedHeap* SharedHeap::_sh;

// The set of potentially parallel tasks in root scanning.

enum SH_process_roots_tasks {

  SH_PS_Universe_oops_do,

  SH_PS_JNIHandles_oops_do,

  SH_PS_ObjectSynchronizer_oops_do,

  SH_PS_FlatProfiler_oops_do,

  SH_PS_Management_oops_do,

  SH_PS_SystemDictionary_oops_do,

  SH_PS_ClassLoaderDataGraph_oops_do,

  SH_PS_jvmti_oops_do,

  SH_PS_CodeCache_oops_do,

  // Leave this one last.

  SH_PS_NumElements

};

SharedHeap::SharedHeap(CollectorPolicy* policy_) :

  CollectedHeap(),

  _collector_policy(policy_),

  _rem_set(NULL),

  _strong_roots_scope(NULL),

  _strong_roots_parity(0),

  _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),

  _workers(NULL)

{

  if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {

    vm_exit_during_initialization("Failed necessary allocation.");

  }

  _sh = this;  // ch is static, should be set only once.

  if (UseConcMarkSweepGC || UseG1GC) {

    _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,

                            /* are_GC_task_threads */true,

                            /* are_ConcurrentGC_threads */false);

    if (_workers == NULL) {

      vm_exit_during_initialization("Failed necessary allocation.");

    } else {

      _workers->initialize_workers();

    }

  }

}

int SharedHeap::n_termination() {

  return _process_strong_tasks->n_threads();

}

void SharedHeap::set_n_termination(int t) {

  _process_strong_tasks->set_n_threads(t);

}

bool SharedHeap::heap_lock_held_for_gc() {

  Thread* t = Thread::current();

  return    Heap_lock->owned_by_self()

         || (   (t->is_GC_task_thread() ||  t->is_VM_thread())

             && _thread_holds_heap_lock_for_gc);

}

void SharedHeap::set_par_threads(uint t) {

  assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");

  _n_par_threads = t;

  _process_strong_tasks->set_n_threads(t);

}

#ifdef ASSERT

class AssertNonScavengableClosure: public OopClosure {

public:

  virtual void do_oop(oop* p) {

    assert(!Universe::heap()->is_in_partial_collection(*p),

      "Referent should not be scavengable.");  }

  virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }

};

static AssertNonScavengableClosure assert_is_non_scavengable_closure;

#endif

SharedHeap::StrongRootsScope* SharedHeap::active_strong_roots_scope() const {

  return _strong_roots_scope;

}

void SharedHeap::register_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {

  assert(_strong_roots_scope == NULL, "Should only have one StrongRootsScope active");

  assert(scope != NULL, "Illegal argument");

  _strong_roots_scope = scope;

}

void SharedHeap::unregister_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {

  assert(_strong_roots_scope == scope, "Wrong scope unregistered");

  _strong_roots_scope = NULL;

}

void SharedHeap::change_strong_roots_parity() {

  // Also set the new collection parity.

  assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,

         "Not in range.");

  _strong_roots_parity++;

  if (_strong_roots_parity == 3) _strong_roots_parity = 1;

  assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,

         "Not in range.");

}

SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* heap, bool activate)

  : MarkScope(activate), _sh(heap), _n_workers_done_with_threads(0)

{

  if (_active) {

    _sh->register_strong_roots_scope(this);

    _sh->change_strong_roots_parity();

    // Zero the claimed high water mark in the StringTable

    StringTable::clear_parallel_claimed_index();

  }

}

SharedHeap::StrongRootsScope::~StrongRootsScope() {

  if (_active) {

    _sh->unregister_strong_roots_scope(this);

  }

}

void SharedHeap::StrongRootsScope::mark_worker_done_with_threads(uint n_workers) {

  // The Thread work barrier is only needed by G1 Class Unloading.

  // No need to use the barrier if this is single-threaded code.

  if (UseG1GC && ClassUnloadingWithConcurrentMark && n_workers > 0) {

    uint new_value = (uint)Atomic::add(1, &_n_workers_done_with_threads);

    if (new_value == n_workers) {

      // This thread is last. Notify the others.

      MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);

      _lock->notify_all();

    }

  }

}

void SharedHeap::StrongRootsScope::wait_until_all_workers_done_with_threads(uint n_workers) {

  assert(UseG1GC,                          "Currently only used by G1");

  assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");

  // No need to use the barrier if this is single-threaded code.

  if (n_workers > 0 && (uint)_n_workers_done_with_threads != n_workers) {

    MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);

    while ((uint)_n_workers_done_with_threads != n_workers) {

      _lock->wait(Mutex::_no_safepoint_check_flag, 0, false);

    }

  }

}

void SharedHeap::process_roots(bool activate_scope,

                               ScanningOption so,

                               OopClosure* strong_roots,

                               OopClosure* weak_roots,

                               CLDClosure* strong_cld_closure,

                               CLDClosure* weak_cld_closure,

                               CodeBlobClosure* code_roots) {

  StrongRootsScope srs(this, activate_scope);

  // General roots.

  assert(_strong_roots_parity != 0, "must have called prologue code");

  assert(code_roots != NULL, "code root closure should always be set");

  // _n_termination for _process_strong_tasks should be set up stream

  // in a method not running in a GC worker.  Otherwise the GC worker

  // could be trying to change the termination condition while the task

  // is executing in another GC worker.

  // Iterating over the CLDG and the Threads are done early to allow G1 to

  // first process the strong CLDs and nmethods and then, after a barrier,

  // let the thread process the weak CLDs and nmethods.

  if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {

    ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);

  }

  // Some CLDs contained in the thread frames should be considered strong.

  // Don't process them if they will be processed during the ClassLoaderDataGraph phase.

  CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;

  // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway

  CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;

  Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);

  // This is the point where this worker thread will not find more strong CLDs/nmethods.

  // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.

  active_strong_roots_scope()->mark_worker_done_with_threads(n_par_threads());

  if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {

    Universe::oops_do(strong_roots);

  }

  // Global (strong) JNI handles

  if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))

    JNIHandles::oops_do(strong_roots);

  if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))

    ObjectSynchronizer::oops_do(strong_roots);

  if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))

    FlatProfiler::oops_do(strong_roots);

  if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))

    Management::oops_do(strong_roots);

  if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))

    JvmtiExport::oops_do(strong_roots);

  if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {

    SystemDictionary::roots_oops_do(strong_roots, weak_roots);

  }

  // All threads execute the following. A specific chunk of buckets

  // from the StringTable are the individual tasks.

  if (weak_roots != NULL) {

    if (CollectedHeap::use_parallel_gc_threads()) {

      StringTable::possibly_parallel_oops_do(weak_roots);

    } else {

      StringTable::oops_do(weak_roots);

    }

  }

  if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {

    if (so & SO_ScavengeCodeCache) {

      assert(code_roots != NULL, "must supply closure for code cache");

      // We only visit parts of the CodeCache when scavenging.

      CodeCache::scavenge_root_nmethods_do(code_roots);

    }

    if (so & SO_AllCodeCache) {

      assert(code_roots != NULL, "must supply closure for code cache");

      // CMSCollector uses this to do intermediate-strength collections.

      // We scan the entire code cache, since CodeCache::do_unloading is not called.

      CodeCache::blobs_do(code_roots);

    }

    // Verify that the code cache contents are not subject to

    // movement by a scavenging collection.

    DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));

    DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));

  }

  _process_strong_tasks->all_tasks_completed();

}

void SharedHeap::process_all_roots(bool activate_scope,

                                   ScanningOption so,

                                   OopClosure* roots,

                                   CLDClosure* cld_closure,

                                   CodeBlobClosure* code_closure) {

  process_roots(activate_scope, so,

                roots, roots,

                cld_closure, cld_closure,

                code_closure);

}

void SharedHeap::process_strong_roots(bool activate_scope,

                                      ScanningOption so,

                                      OopClosure* roots,

                                      CLDClosure* cld_closure,

                                      CodeBlobClosure* code_closure) {

  process_roots(activate_scope, so,

                roots, NULL,

                cld_closure, NULL,

                code_closure);

}

class AlwaysTrueClosure: public BoolObjectClosure {

public:

  bool do_object_b(oop p) { return true; }

};

static AlwaysTrueClosure always_true;

void SharedHeap::process_weak_roots(OopClosure* root_closure) {

  // Global (weak) JNI handles

  JNIHandles::weak_oops_do(&always_true, root_closure);

}

void SharedHeap::set_barrier_set(BarrierSet* bs) {

  _barrier_set = bs;

  // Cached barrier set for fast access in oops

  oopDesc::set_bs(bs);

}

void SharedHeap::post_initialize() {

  CollectedHeap::post_initialize();

  ref_processing_init();

}

void SharedHeap::ref_processing_init() {}

// Some utilities.

void SharedHeap::print_size_transition(outputStream* out,

                                       size_t bytes_before,

                                       size_t bytes_after,

                                       size_t capacity) {

  out->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",

             byte_size_in_proper_unit(bytes_before),

             proper_unit_for_byte_size(bytes_before),

             byte_size_in_proper_unit(bytes_after),

             proper_unit_for_byte_size(bytes_after),

             byte_size_in_proper_unit(capacity),

             proper_unit_for_byte_size(capacity));

}