/*

 * Copyright (c) 2012, 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.

 *

 */

#include "precompiled.hpp"

#include "jvm.h"

#include "runtime/orderAccess.hpp"

#include "runtime/vmThread.hpp"

#include "runtime/vmOperations.hpp"

#include "services/memBaseline.hpp"

#include "services/memReporter.hpp"

#include "services/mallocTracker.inline.hpp"

#include "services/memTracker.hpp"

#include "services/threadStackTracker.hpp"

#include "utilities/debug.hpp"

#include "utilities/defaultStream.hpp"

#include "utilities/vmError.hpp"

#ifdef _WINDOWS

#include <windows.h>

#endif

#ifdef SOLARIS

  volatile bool NMT_stack_walkable = false;

#else

  volatile bool NMT_stack_walkable = true;

#endif

volatile NMT_TrackingLevel MemTracker::_tracking_level = NMT_unknown;

NMT_TrackingLevel MemTracker::_cmdline_tracking_level = NMT_unknown;

MemBaseline MemTracker::_baseline;

bool MemTracker::_is_nmt_env_valid = true;

static const size_t buffer_size = 64;

NMT_TrackingLevel MemTracker::init_tracking_level() {

  // Memory type is encoded into tracking header as a byte field,

  // make sure that we don't overflow it.

  STATIC_ASSERT(mt_number_of_types <= max_jubyte);

  char nmt_env_variable[buffer_size];

  jio_snprintf(nmt_env_variable, sizeof(nmt_env_variable), "NMT_LEVEL_%d", os::current_process_id());

  const char* nmt_env_value;

#ifdef _WINDOWS

  // Read the NMT environment variable from the PEB instead of the CRT

  char value[buffer_size];

  nmt_env_value = GetEnvironmentVariable(nmt_env_variable, value, (DWORD)sizeof(value)) != 0 ? value : NULL;

#else

  nmt_env_value = ::getenv(nmt_env_variable);

#endif

  NMT_TrackingLevel level = NMT_off;

  if (nmt_env_value != NULL) {

    if (strcmp(nmt_env_value, "summary") == 0) {

      level = NMT_summary;

    } else if (strcmp(nmt_env_value, "detail") == 0) {

      level = NMT_detail;

    } else if (strcmp(nmt_env_value, "off") != 0) {

      // The value of the environment variable is invalid

      _is_nmt_env_valid = false;

    }

    // Remove the environment variable to avoid leaking to child processes

    os::unsetenv(nmt_env_variable);

  }

  if (!MallocTracker::initialize(level) ||

      !VirtualMemoryTracker::initialize(level)) {

    level = NMT_off;

  }

  return level;

}

void MemTracker::init() {

  NMT_TrackingLevel level = tracking_level();

  if (level >= NMT_summary) {

    if (!VirtualMemoryTracker::late_initialize(level) ||

        !ThreadStackTracker::late_initialize(level)) {

      shutdown();

      return;

    }

  }

}

bool MemTracker::check_launcher_nmt_support(const char* value) {

  if (strcmp(value, "=detail") == 0) {

    if (MemTracker::tracking_level() != NMT_detail) {

      return false;

    }

  } else if (strcmp(value, "=summary") == 0) {

    if (MemTracker::tracking_level() != NMT_summary) {

      return false;

    }

  } else if (strcmp(value, "=off") == 0) {

    if (MemTracker::tracking_level() != NMT_off) {

      return false;

    }

  } else {

    _is_nmt_env_valid = false;

  }

  return true;

}

bool MemTracker::verify_nmt_option() {

  return _is_nmt_env_valid;

}

void* MemTracker::malloc_base(void* memblock) {

  return MallocTracker::get_base(memblock);

}

void Tracker::record(address addr, size_t size) {

  if (MemTracker::tracking_level() < NMT_summary) return;

  switch(_type) {

    case uncommit:

      VirtualMemoryTracker::remove_uncommitted_region(addr, size);

      break;

    case release:

      VirtualMemoryTracker::remove_released_region(addr, size);

        break;

    default:

      ShouldNotReachHere();

  }

}

// Shutdown can only be issued via JCmd, and NMT JCmd is serialized by lock

void MemTracker::shutdown() {

  // We can only shutdown NMT to minimal tracking level if it is ever on.

  if (tracking_level() > NMT_minimal) {

    transition_to(NMT_minimal);

  }

}

bool MemTracker::transition_to(NMT_TrackingLevel level) {

  NMT_TrackingLevel current_level = tracking_level();

  assert(level != NMT_off || current_level == NMT_off, "Cannot transition NMT to off");

  if (current_level == level) {

    return true;

  } else if (current_level > level) {

    // Downgrade tracking level, we want to lower the tracking level first

    _tracking_level = level;

    // Make _tracking_level visible immediately.

    OrderAccess::fence();

    VirtualMemoryTracker::transition(current_level, level);

    MallocTracker::transition(current_level, level);

    ThreadStackTracker::transition(current_level, level);

  } else {

    // Upgrading tracking level is not supported and has never been supported.

    // Allocating and deallocating malloc tracking structures is not thread safe and

    // leads to inconsistencies unless a lot coarser locks are added.

  }

  return true;

}

static volatile bool g_final_report_did_run = false;

void MemTracker::final_report(outputStream* output) {

  // This function is called during both error reporting and normal VM exit.

  // However, it should only ever run once.  E.g. if the VM crashes after

  // printing the final report during normal VM exit, it should not print

  // the final report again. In addition, it should be guarded from

  // recursive calls in case NMT reporting itself crashes.

  if (Atomic::cmpxchg(&g_final_report_did_run, false, true) == false) {

    NMT_TrackingLevel level = tracking_level();

    if (level >= NMT_summary) {

      report(level == NMT_summary, output);

    }

  }

}

void MemTracker::report(bool summary_only, outputStream* output) {

 assert(output != NULL, "No output stream");

  MemBaseline baseline;

  if (baseline.baseline(summary_only)) {

    if (summary_only) {

      MemSummaryReporter rpt(baseline, output);

      rpt.report();

    } else {

      MemDetailReporter rpt(baseline, output);

      rpt.report();

      output->print("Metaspace:");

      // The basic metaspace report avoids any locking and should be safe to

      // be called at any time.

      MetaspaceUtils::print_basic_report(output, K);

    }

  }

}

// This is a walker to gather malloc site hashtable statistics,

// the result is used for tuning.

class StatisticsWalker : public MallocSiteWalker {

 private:

  enum Threshold {

    // aggregates statistics over this threshold into one

    // line item.

    report_threshold = 20

  };

 private:

  // Number of allocation sites that have all memory freed

  int   _empty_entries;

  // Total number of allocation sites, include empty sites

  int   _total_entries;

  // Number of captured call stack distribution

  int   _stack_depth_distribution[NMT_TrackingStackDepth];

  // Hash distribution

  int   _hash_distribution[report_threshold];

  // Number of hash buckets that have entries over the threshold

  int   _bucket_over_threshold;

  // The hash bucket that walker is currently walking

  int   _current_hash_bucket;

  // The length of current hash bucket

  int   _current_bucket_length;

  // Number of hash buckets that are not empty

  int   _used_buckets;

  // Longest hash bucket length

  int   _longest_bucket_length;

 public:

  StatisticsWalker() : _empty_entries(0), _total_entries(0) {

    int index = 0;

    for (index = 0; index < NMT_TrackingStackDepth; index ++) {

      _stack_depth_distribution[index] = 0;

    }

    for (index = 0; index < report_threshold; index ++) {

      _hash_distribution[index] = 0;

    }

    _bucket_over_threshold = 0;

    _longest_bucket_length = 0;

    _current_hash_bucket = -1;

    _current_bucket_length = 0;

    _used_buckets = 0;

  }

  virtual bool do_malloc_site(const MallocSite* e) {

    if (e->size() == 0) _empty_entries ++;

    _total_entries ++;

    // stack depth distrubution

    int frames = e->call_stack()->frames();

    _stack_depth_distribution[frames - 1] ++;

    // hash distribution

    int hash_bucket = e->hash() % MallocSiteTable::hash_buckets();

    if (_current_hash_bucket == -1) {

      _current_hash_bucket = hash_bucket;

      _current_bucket_length = 1;

    } else if (_current_hash_bucket == hash_bucket) {

      _current_bucket_length ++;

    } else {

      record_bucket_length(_current_bucket_length);

      _current_hash_bucket = hash_bucket;

      _current_bucket_length = 1;

    }

    return true;

  }

  // walk completed

  void completed() {

    record_bucket_length(_current_bucket_length);

  }

  void report_statistics(outputStream* out) {

    int index;

    out->print_cr("Malloc allocation site table:");

    out->print_cr("\tTotal entries: %d", _total_entries);

    out->print_cr("\tEmpty entries: %d (%2.2f%%)", _empty_entries, ((float)_empty_entries * 100) / _total_entries);

    out->print_cr(" ");

    out->print_cr("Hash distribution:");

    if (_used_buckets < MallocSiteTable::hash_buckets()) {

      out->print_cr("empty bucket: %d", (MallocSiteTable::hash_buckets() - _used_buckets));

    }

    for (index = 0; index < report_threshold; index ++) {

      if (_hash_distribution[index] != 0) {

        if (index == 0) {

          out->print_cr("  %d    entry: %d", 1, _hash_distribution[0]);

        } else if (index < 9) { // single digit

          out->print_cr("  %d  entries: %d", (index + 1), _hash_distribution[index]);

        } else {

          out->print_cr(" %d entries: %d", (index + 1), _hash_distribution[index]);

        }

      }

    }

    if (_bucket_over_threshold > 0) {

      out->print_cr(" >%d entries: %d", report_threshold,  _bucket_over_threshold);

    }

    out->print_cr("most entries: %d", _longest_bucket_length);

    out->print_cr(" ");

    out->print_cr("Call stack depth distribution:");

    for (index = 0; index < NMT_TrackingStackDepth; index ++) {

      if (_stack_depth_distribution[index] > 0) {

        out->print_cr("\t%d: %d", index + 1, _stack_depth_distribution[index]);

      }

    }

  }

 private:

  void record_bucket_length(int length) {

    _used_buckets ++;

    if (length <= report_threshold) {

      _hash_distribution[length - 1] ++;

    } else {

      _bucket_over_threshold ++;

    }

    _longest_bucket_length = MAX2(_longest_bucket_length, length);

  }

};

void MemTracker::tuning_statistics(outputStream* out) {

  // NMT statistics

  StatisticsWalker walker;

  MallocSiteTable::walk_malloc_site(&walker);

  walker.completed();

  out->print_cr("Native Memory Tracking Statistics:");

  out->print_cr("Malloc allocation site table size: %d", MallocSiteTable::hash_buckets());

  out->print_cr("             Tracking stack depth: %d", NMT_TrackingStackDepth);

  NOT_PRODUCT(out->print_cr("Peak concurrent access: %d", MallocSiteTable::access_peak_count());)

  out->print_cr(" ");

  walker.report_statistics(out);

}