/*

 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

 * Copyright (c) 2018 SAP SE. 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/classLoaderData.inline.hpp"

#include "classfile/classLoaderHierarchyDCmd.hpp"

#include "memory/allocation.hpp"

#include "memory/resourceArea.hpp"

#include "runtime/safepoint.hpp"

#include "oops/reflectionAccessorImplKlassHelper.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/ostream.hpp"

ClassLoaderHierarchyDCmd::ClassLoaderHierarchyDCmd(outputStream* output, bool heap)

  : DCmdWithParser(output, heap),

   _show_classes("show-classes", "Print loaded classes.", "BOOLEAN", false, "false"),

  _verbose("verbose", "Print detailed information.", "BOOLEAN", false, "false"),

  _fold("fold", "Show loaders of the same name and class as one.", "BOOLEAN", true, "true") {

  _dcmdparser.add_dcmd_option(&_show_classes);

  _dcmdparser.add_dcmd_option(&_verbose);

  _dcmdparser.add_dcmd_option(&_fold);

}

int ClassLoaderHierarchyDCmd::num_arguments() {

  ResourceMark rm;

  ClassLoaderHierarchyDCmd* dcmd = new ClassLoaderHierarchyDCmd(NULL, false);

  if (dcmd != NULL) {

    DCmdMark mark(dcmd);

    return dcmd->_dcmdparser.num_arguments();

  } else {

    return 0;

  }

}

// Helper class for drawing the branches to the left of a node.

class BranchTracker : public StackObj {

  //       "<x>"

  //       " |---<y>"

  //       " |    |

  //       " |   <z>"

  //       " |    |---<z1>

  //       " |    |---<z2>

  //       ^^^^^^^ ^^^

  //        A       B

  // Some terms for the graphics:

  // - branch: vertical connection between a node's ancestor to a later sibling.

  // - branchwork: (A) the string to print as a prefix at the start of each line, contains all branches.

  // - twig (B): Length of the dashed line connecting a node to its branch.

  // - branch spacing: how many spaces between branches are printed.

public:

  enum { max_depth = 64, twig_len = 2, branch_spacing = 5 };

private:

  char _branches[max_depth];

  int _pos;

public:

  BranchTracker()

    : _pos(0) {}

  void push(bool has_branch) {

    if (_pos < max_depth) {

      _branches[_pos] = has_branch ? '|' : ' ';

    }

    _pos ++; // beyond max depth, omit branch drawing but do count on.

  }

  void pop() {

    assert(_pos > 0, "must be");

    _pos --;

  }

  void print(outputStream* st) {

    for (int i = 0; i < _pos; i ++) {

      st->print("%c%.*s", _branches[i], branch_spacing, "          ");

    }

  }

  class Mark {

    BranchTracker& _tr;

  public:

    Mark(BranchTracker& tr, bool has_branch_here)

      : _tr(tr)  { _tr.push(has_branch_here); }

    ~Mark() { _tr.pop(); }

  };

}; // end: BranchTracker

struct LoadedClassInfo : public ResourceObj {

public:

  LoadedClassInfo* _next;

  Klass* const _klass;

  const ClassLoaderData* const _cld;

  LoadedClassInfo(Klass* klass, const ClassLoaderData* cld)

    : _klass(klass), _cld(cld) {}

};

class LoaderTreeNode : public ResourceObj {

  // We walk the CLDG and, for each CLD which is non-unsafe_anonymous, add

  // a tree node.

  // To add a node we need its parent node; if the parent node does not yet

  // exist - because we have not yet encountered the CLD for the parent loader -

  // we add a preliminary empty LoaderTreeNode for it. This preliminary node

  // just contains the loader oop and nothing else. Once we encounter the CLD of

  // this parent loader, we fill in all the other details.

  const oop _loader_oop;

  const ClassLoaderData* _cld;

  LoaderTreeNode* _child;

  LoaderTreeNode* _next;

  LoadedClassInfo* _classes;

  int _num_classes;

  LoadedClassInfo* _anon_classes;

  int _num_anon_classes;

  // In default view, similar tree nodes (same loader class, same name or no name)

  // are folded into each other to make the output more readable.

  // _num_folded contains the number of nodes which have been folded into this

  // one.

  int _num_folded;

  void print_with_childs(outputStream* st, BranchTracker& branchtracker,

      bool print_classes, bool verbose) const {

    ResourceMark rm;

    if (_cld == NULL) {

      // Not sure how this could happen: we added a preliminary node for a parent but then never encountered

      // its CLD?

      return;

    }

    // Retrieve information.

    const Klass* const loader_klass = _cld->class_loader_klass();

    const Symbol* const loader_name = _cld->name();

    branchtracker.print(st);

    // e.g. "+--- jdk.internal.reflect.DelegatingClassLoader"

    st->print("+%.*s", BranchTracker::twig_len, "----------");

    if (_cld->is_the_null_class_loader_data()) {

      st->print(" <bootstrap>");

    } else {

      if (loader_name != NULL) {

        st->print(" \"%s\",", loader_name->as_C_string());

      }

      st->print(" %s", loader_klass != NULL ? loader_klass->external_name() : "??");

      if (_num_folded > 0) {

        st->print(" (+ %d more)", _num_folded);

      }

    }

    st->cr();

    // Output following this node (node details and child nodes) - up to the next sibling node

    // needs to be prefixed with "|" if there is a follow up sibling.

    const bool have_sibling = _next != NULL;

    BranchTracker::Mark trm(branchtracker, have_sibling);

    {

      // optional node details following this node needs to be prefixed with "|"

      // if there are follow up child nodes.

      const bool have_child = _child != NULL;

      BranchTracker::Mark trm(branchtracker, have_child);

      // Empty line

      branchtracker.print(st);

      st->cr();

      const int indentation = 18;

      if (verbose) {

        branchtracker.print(st);

        st->print_cr("%*s " PTR_FORMAT, indentation, "Loader Oop:", p2i(_loader_oop));

        branchtracker.print(st);

        st->print_cr("%*s " PTR_FORMAT, indentation, "Loader Data:", p2i(_cld));

        branchtracker.print(st);

        st->print_cr("%*s " PTR_FORMAT, indentation, "Loader Klass:", p2i(loader_klass));

        // Empty line

        branchtracker.print(st);

        st->cr();

      }

      if (print_classes) {

        if (_classes != NULL) {

          for (LoadedClassInfo* lci = _classes; lci; lci = lci->_next) {

            // Non-unsafe anonymous classes should live in the primary CLD of its loader

            assert(lci->_cld == _cld, "must be");

            branchtracker.print(st);

            if (lci == _classes) { // first iteration

              st->print("%*s ", indentation, "Classes:");

            } else {

              st->print("%*s ", indentation, "");

            }

            st->print("%s", lci->_klass->external_name());

            // Special treatment for generated core reflection accessor classes: print invocation target.

            if (ReflectionAccessorImplKlassHelper::is_generated_accessor(lci->_klass)) {

              st->print(" (invokes: ");

              ReflectionAccessorImplKlassHelper::print_invocation_target(st, lci->_klass);

              st->print(")");

            }

            st->cr();

          }

          branchtracker.print(st);

          st->print("%*s ", indentation, "");

          st->print_cr("(%u class%s)", _num_classes, (_num_classes == 1) ? "" : "es");

          // Empty line

          branchtracker.print(st);

          st->cr();

        }

        if (_anon_classes != NULL) {

          for (LoadedClassInfo* lci = _anon_classes; lci; lci = lci->_next) {

            branchtracker.print(st);

            if (lci == _anon_classes) { // first iteration

              st->print("%*s ", indentation, "Unsafe Anonymous Classes:");

            } else {

              st->print("%*s ", indentation, "");

            }

            st->print("%s", lci->_klass->external_name());

            // For unsafe anonymous classes, also print CLD if verbose. Should be a different one than the primary CLD.

            assert(lci->_cld != _cld, "must be");

            if (verbose) {

              st->print("  (Loader Data: " PTR_FORMAT ")", p2i(lci->_cld));

            }

            st->cr();

          }

          branchtracker.print(st);

          st->print("%*s ", indentation, "");

          st->print_cr("(%u unsafe anonymous class%s)", _num_anon_classes, (_num_anon_classes == 1) ? "" : "es");

          // Empty line

          branchtracker.print(st);

          st->cr();

        }

      } // end: print_classes

    } // Pop branchtracker mark

    // Print children, recursively

    LoaderTreeNode* c = _child;

    while (c != NULL) {

      c->print_with_childs(st, branchtracker, print_classes, verbose);

      c = c->_next;

    }

  }

  // Helper: Attempt to fold this node into the target node. If success, returns true.

  // Folding can be done if both nodes are leaf nodes and they refer to the same loader class

  // and they have the same name or no name (note: leaf check is done by caller).

  bool can_fold_into(LoaderTreeNode* target_node) const {

    assert(is_leaf() && target_node->is_leaf(), "must be leaf");

    return _cld->class_loader_klass() == target_node->_cld->class_loader_klass() &&

           _cld->name() == target_node->_cld->name();

  }

public:

  LoaderTreeNode(const oop loader_oop)

    : _loader_oop(loader_oop), _cld(NULL), _child(NULL), _next(NULL),

      _classes(NULL), _num_classes(0), _anon_classes(NULL), _num_anon_classes(0),

      _num_folded(0)

    {}

  void set_cld(const ClassLoaderData* cld) {

    _cld = cld;

  }

  void add_child(LoaderTreeNode* info) {

    info->_next = _child;

    _child = info;

  }

  void add_sibling(LoaderTreeNode* info) {

    assert(info->_next == NULL, "must be");

    info->_next = _next;

    _next = info;

  }

  void add_classes(LoadedClassInfo* first_class, int num_classes, bool is_unsafe_anonymous) {

    LoadedClassInfo** p_list_to_add_to = is_unsafe_anonymous ? &_anon_classes : &_classes;

    // Search tail.

    while ((*p_list_to_add_to) != NULL) {

      p_list_to_add_to = &(*p_list_to_add_to)->_next;

    }

    *p_list_to_add_to = first_class;

    if (is_unsafe_anonymous) {

      _num_anon_classes += num_classes;

    } else {

      _num_classes += num_classes;

    }

  }

  const ClassLoaderData* cld() const {

    return _cld;

  }

  const oop loader_oop() const {

    return _loader_oop;

  }

  LoaderTreeNode* find(const oop loader_oop) {

    LoaderTreeNode* result = NULL;

    if (_loader_oop == loader_oop) {

      result = this;

    } else {

      LoaderTreeNode* c = _child;

      while (c != NULL && result == NULL) {

        result = c->find(loader_oop);

        c = c->_next;

      }

    }

    return result;

  }

  bool is_leaf() const { return _child == NULL; }

  // Attempt to fold similar nodes among this node's children. We only fold leaf nodes

  // (no child class loaders).

  // For non-leaf nodes (class loaders with child class loaders), do this recursivly.

  void fold_children() {

    LoaderTreeNode* node = _child;

    LoaderTreeNode* prev = NULL;

    while (node != NULL) {

      LoaderTreeNode* matching_node = NULL;

      if (node->is_leaf()) {

        // Look among the preceeding node siblings for a match.

        for (LoaderTreeNode* node2 = _child; node2 != node && matching_node == NULL;

            node2 = node2->_next) {

          if (node2->is_leaf() && node->can_fold_into(node2)) {

            matching_node = node2;

          }

        }

      } else {

        node->fold_children();

      }

      if (matching_node != NULL) {

        // Increase fold count for the matching node and remove folded node from the child list.

        matching_node->_num_folded ++;

        assert(prev != NULL, "Sanity"); // can never happen since we do not fold the first node.

        prev->_next = node->_next;

      } else {

        prev = node;

      }

      node = node->_next;

    }

  }

  void print_with_childs(outputStream* st, bool print_classes, bool print_add_info) const {

    BranchTracker bwt;

    print_with_childs(st, bwt, print_classes, print_add_info);

  }

};

class LoadedClassCollectClosure : public KlassClosure {

public:

  LoadedClassInfo* _list;

  const ClassLoaderData* _cld;

  int _num_classes;

  LoadedClassCollectClosure(const ClassLoaderData* cld)

    : _list(NULL), _cld(cld), _num_classes(0) {}

  void do_klass(Klass* k) {

    LoadedClassInfo* lki = new LoadedClassInfo(k, _cld);

    lki->_next = _list;

    _list = lki;

    _num_classes ++;

  }

};

class LoaderInfoScanClosure : public CLDClosure {

  const bool _print_classes;

  const bool _verbose;

  LoaderTreeNode* _root;

  static void fill_in_classes(LoaderTreeNode* info, const ClassLoaderData* cld) {

    assert(info != NULL && cld != NULL, "must be");

    LoadedClassCollectClosure lccc(cld);

    const_cast<ClassLoaderData*>(cld)->classes_do(&lccc);

    if (lccc._num_classes > 0) {

      info->add_classes(lccc._list, lccc._num_classes, cld->is_unsafe_anonymous());

    }

  }

  LoaderTreeNode* find_node_or_add_empty_node(oop loader_oop) {

    assert(_root != NULL, "root node must exist");

    if (loader_oop == NULL) {

      return _root;

    }

    // Check if a node for this oop already exists.

    LoaderTreeNode* info = _root->find(loader_oop);

    if (info == NULL) {

      // It does not. Create a node.

      info = new LoaderTreeNode(loader_oop);

      // Add it to tree.

      LoaderTreeNode* parent_info = NULL;

      // Recursively add parent nodes if needed.

      const oop parent_oop = java_lang_ClassLoader::parent(loader_oop);

      if (parent_oop == NULL) {

        parent_info = _root;

      } else {

        parent_info = find_node_or_add_empty_node(parent_oop);

      }

      assert(parent_info != NULL, "must be");

      parent_info->add_child(info);

    }

    return info;

  }

public:

  LoaderInfoScanClosure(bool print_classes, bool verbose)

    : _print_classes(print_classes), _verbose(verbose), _root(NULL) {

    _root = new LoaderTreeNode(NULL);

  }

  void print_results(outputStream* st) const {

    _root->print_with_childs(st, _print_classes, _verbose);

  }

  void do_cld (ClassLoaderData* cld) {

    // We do not display unloading loaders, for now.

    if (!cld->is_alive()) {

      return;

    }

    const oop loader_oop = cld->class_loader();

    LoaderTreeNode* info = find_node_or_add_empty_node(loader_oop);

    assert(info != NULL, "must be");

    // Update CLD in node, but only if this is the primary CLD for this loader.

    if (cld->is_unsafe_anonymous() == false) {

      assert(info->cld() == NULL, "there should be only one primary CLD per loader");

      info->set_cld(cld);

    }

    // Add classes.

    fill_in_classes(info, cld);

  }

  void fold() {

    _root->fold_children();

  }

};

class ClassLoaderHierarchyVMOperation : public VM_Operation {

  outputStream* const _out;

  const bool _show_classes;

  const bool _verbose;

  const bool _fold;

public:

  ClassLoaderHierarchyVMOperation(outputStream* out, bool show_classes, bool verbose, bool fold) :

    _out(out), _show_classes(show_classes), _verbose(verbose), _fold(fold)

  {}

  VMOp_Type type() const {

    return VMOp_ClassLoaderHierarchyOperation;

  }

  void doit() {

    assert(SafepointSynchronize::is_at_safepoint(), "must be a safepoint");

    ResourceMark rm;

    LoaderInfoScanClosure cl (_show_classes, _verbose);

    ClassLoaderDataGraph::cld_do(&cl);