/*

 * Copyright (c) 2014, 2019, 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.

 *

 */

#ifndef SHARE_SERVICES_MALLOCSITETABLE_HPP

#define SHARE_SERVICES_MALLOCSITETABLE_HPP

#if INCLUDE_NMT

#include "memory/allocation.hpp"

#include "runtime/atomic.hpp"

#include "services/allocationSite.hpp"

#include "services/mallocTracker.hpp"

#include "services/nmtCommon.hpp"

#include "utilities/nativeCallStack.hpp"

// MallocSite represents a code path that eventually calls

// os::malloc() to allocate memory

class MallocSite : public AllocationSite<MemoryCounter> {

 public:

  MallocSite() :

    AllocationSite<MemoryCounter>(NativeCallStack::empty_stack(), mtNone) {}

  MallocSite(const NativeCallStack& stack, MEMFLAGS flags) :

    AllocationSite<MemoryCounter>(stack, flags) {}

  void allocate(size_t size)      { data()->allocate(size);   }

  void deallocate(size_t size)    { data()->deallocate(size); }

  // Memory allocated from this code path

  size_t size()  const { return peek()->size(); }

  // The number of calls were made

  size_t count() const { return peek()->count(); }

};

// Malloc site hashtable entry

class MallocSiteHashtableEntry : public CHeapObj<mtNMT> {

 private:

  MallocSite                         _malloc_site;

  MallocSiteHashtableEntry* volatile _next;

 public:

  MallocSiteHashtableEntry() : _next(NULL) { }

  MallocSiteHashtableEntry(NativeCallStack stack, MEMFLAGS flags):

    _malloc_site(stack, flags), _next(NULL) {

    assert(flags != mtNone, "Expect a real memory type");

  }

  inline const MallocSiteHashtableEntry* next() const {

    return _next;

  }

  // Insert an entry atomically.

  // Return true if the entry is inserted successfully.

  // The operation can be failed due to contention from other thread.

  bool atomic_insert(MallocSiteHashtableEntry* entry);

  void set_callsite(const MallocSite& site) {

    _malloc_site = site;

  }

  inline const MallocSite* peek() const { return &_malloc_site; }

  inline MallocSite* data()             { return &_malloc_site; }

  inline long hash() const { return _malloc_site.hash(); }

  inline bool equals(const NativeCallStack& stack) const {

    return _malloc_site.equals(stack);

  }

  // Allocation/deallocation on this allocation site

  inline void allocate(size_t size)   { _malloc_site.allocate(size);   }

  inline void deallocate(size_t size) { _malloc_site.deallocate(size); }

  // Memory counters

  inline size_t size() const  { return _malloc_site.size();  }

  inline size_t count() const { return _malloc_site.count(); }

};

// The walker walks every entry on MallocSiteTable

class MallocSiteWalker : public StackObj {

 public:

   virtual bool do_malloc_site(const MallocSite* e) { return false; }

};

/*

 * Native memory tracking call site table.

 * The table is only needed when detail tracking is enabled.

 */

class MallocSiteTable : AllStatic {

 private:

  // The number of hash bucket in this hashtable. The number should

  // be tuned if malloc activities changed significantly.

  // The statistics data can be obtained via Jcmd

  // jcmd <pid> VM.native_memory statistics.

  // Currently, (number of buckets / number of entires) ratio is

  // about 1 / 6

  enum {

    table_base_size = 128,   // The base size is calculated from statistics to give

                             // table ratio around 1:6

    table_size = (table_base_size * NMT_TrackingStackDepth - 1)

  };

  // This is a very special lock, that allows multiple shared accesses (sharedLock), but

  // once exclusive access (exclusiveLock) is requested, all shared accesses are

  // rejected forever.

  class AccessLock : public StackObj {

    enum LockState {

      NoLock,

      SharedLock,

      ExclusiveLock

    };

   private:

    // A very large negative number. The only possibility to "overflow"

    // this number is when there are more than -min_jint threads in

    // this process, which is not going to happen in foreseeable future.

    const static int _MAGIC_ = min_jint;

    LockState      _lock_state;

    volatile int*  _lock;

   public:

    AccessLock(volatile int* lock) :

      _lock_state(NoLock), _lock(lock) {

    }

    ~AccessLock() {

      if (_lock_state == SharedLock) {

        Atomic::dec(_lock);

      }

    }

    // Acquire shared lock.

    // Return true if shared access is granted.

    inline bool sharedLock() {

      jint res = Atomic::add(_lock, 1);

      if (res < 0) {

        Atomic::dec(_lock);

        return false;

      }

      _lock_state = SharedLock;

      return true;

    }

    // Acquire exclusive lock

    void exclusiveLock();

 };

 public:

  static bool initialize();

  static void shutdown();

  NOT_PRODUCT(static int access_peak_count() { return _peak_count; })

  // Number of hash buckets

  static inline int hash_buckets()      { return (int)table_size; }

  // Access and copy a call stack from this table. Shared lock should be

  // acquired before access the entry.

  static inline bool access_stack(NativeCallStack& stack, size_t bucket_idx,

    size_t pos_idx) {

    AccessLock locker(&_access_count);

    if (locker.sharedLock()) {

      NOT_PRODUCT(_peak_count = MAX2(_peak_count, _access_count);)

      MallocSite* site = malloc_site(bucket_idx, pos_idx);

      if (site != NULL) {

        stack = *site->call_stack();

        return true;

      }

    }

    return false;

  }

  // Record a new allocation from specified call path.

  // Return true if the allocation is recorded successfully, bucket_idx

  // and pos_idx are also updated to indicate the entry where the allocation

  // information was recorded.

  // Return false only occurs under rare scenarios:

  //  1. out of memory

  //  2. overflow hash bucket

  static inline bool allocation_at(const NativeCallStack& stack, size_t size,

    size_t* bucket_idx, size_t* pos_idx, MEMFLAGS flags) {

    AccessLock locker(&_access_count);

    if (locker.sharedLock()) {

      NOT_PRODUCT(_peak_count = MAX2(_peak_count, _access_count);)

      MallocSite* site = lookup_or_add(stack, bucket_idx, pos_idx, flags);

      if (site != NULL) site->allocate(size);

      return site != NULL;

    }

    return false;

  }

  // Record memory deallocation. bucket_idx and pos_idx indicate where the allocation

  // information was recorded.

  static inline bool deallocation_at(size_t size, size_t bucket_idx, size_t pos_idx) {

    AccessLock locker(&_access_count);

    if (locker.sharedLock()) {

      NOT_PRODUCT(_peak_count = MAX2(_peak_count, _access_count);)

      MallocSite* site = malloc_site(bucket_idx, pos_idx);

      if (site != NULL) {

        site->deallocate(size);

        return true;

      }

    }

    return false;

  }

  // Walk this table.

  static bool walk_malloc_site(MallocSiteWalker* walker);

 private:

  static MallocSiteHashtableEntry* new_entry(const NativeCallStack& key, MEMFLAGS flags);

  static void reset();

  // Delete a bucket linked list

  static void delete_linked_list(MallocSiteHashtableEntry* head);

  static MallocSite* lookup_or_add(const NativeCallStack& key, size_t* bucket_idx, size_t* pos_idx, MEMFLAGS flags);

  static MallocSite* malloc_site(size_t bucket_idx, size_t pos_idx);

  static bool walk(MallocSiteWalker* walker);

  static inline unsigned int hash_to_index(unsigned int hash) {

    return (hash % table_size);

  }

  static inline const NativeCallStack* hash_entry_allocation_stack() {

    assert(_hash_entry_allocation_stack != NULL, "Must be set");

    return _hash_entry_allocation_stack;

  }

  static inline const MallocSiteHashtableEntry* hash_entry_allocation_site() {

    assert(_hash_entry_allocation_site != NULL, "Must be set");

    return _hash_entry_allocation_site;

  }

 private:

  // Counter for counting concurrent access

  static volatile int                _access_count;

  // The callsite hashtable. It has to be a static table,

  // since malloc call can come from C runtime linker.

  static MallocSiteHashtableEntry*        _table[table_size];

  static const NativeCallStack*           _hash_entry_allocation_stack;

  static const MallocSiteHashtableEntry*  _hash_entry_allocation_site;

  NOT_PRODUCT(static int     _peak_count;)

};

#endif // INCLUDE_NMT

#endif // SHARE_SERVICES_MALLOCSITETABLE_HPP