diff -r 000000000000 -r f90c822e73f8 src/share/vm/classfile/loaderConstraints.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/classfile/loaderConstraints.cpp	Wed Apr 27 01:25:04 2016 +0800
@@ -0,0 +1,494 @@
+/*
+ * Copyright (c) 2003, 2012, 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/classLoaderData.inline.hpp"
+#include "classfile/loaderConstraints.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/handles.inline.hpp"
+#include "runtime/safepoint.hpp"
+#include "utilities/hashtable.inline.hpp"
+
+void LoaderConstraintEntry::set_loader(int i, oop p) {
+  set_loader_data(i, ClassLoaderData::class_loader_data(p));
+}
+
+LoaderConstraintTable::LoaderConstraintTable(int nof_buckets)
+  : Hashtable<Klass*, mtClass>(nof_buckets, sizeof(LoaderConstraintEntry)) {};
+
+
+LoaderConstraintEntry* LoaderConstraintTable::new_entry(
+                                 unsigned int hash, Symbol* name,
+                                 Klass* klass, int num_loaders,
+                                 int max_loaders) {
+  LoaderConstraintEntry* entry;
+  entry = (LoaderConstraintEntry*)Hashtable<Klass*, mtClass>::new_entry(hash, klass);
+  entry->set_name(name);
+  entry->set_num_loaders(num_loaders);
+  entry->set_max_loaders(max_loaders);
+  return entry;
+}
+
+void LoaderConstraintTable::free_entry(LoaderConstraintEntry *entry) {
+  // decrement name refcount before freeing
+  entry->name()->decrement_refcount();
+  Hashtable<Klass*, mtClass>::free_entry(entry);
+}
+
+// Enhanced Class Redefinition support
+void LoaderConstraintTable::classes_do(KlassClosure* f) {
+  for (int index = 0; index < table_size(); index++) {
+    for (LoaderConstraintEntry* probe = bucket(index);
+                                probe != NULL;
+                                probe = probe->next()) {
+      if (probe->klass() != NULL) {
+        f->do_klass(probe->klass());
+      }
+        }
+      }
+    }
+
+// The loaderConstraintTable must always be accessed with the
+// SystemDictionary lock held. This is true even for readers as
+// entries in the table could be being dynamically resized.
+
+LoaderConstraintEntry** LoaderConstraintTable::find_loader_constraint(
+                                    Symbol* name, Handle loader) {
+
+  unsigned int hash = compute_hash(name);
+  int index = hash_to_index(hash);
+  LoaderConstraintEntry** pp = bucket_addr(index);
+  ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(loader());
+
+  while (*pp) {
+    LoaderConstraintEntry* p = *pp;
+    if (p->hash() == hash) {
+      if (p->name() == name) {
+        for (int i = p->num_loaders() - 1; i >= 0; i--) {
+          if (p->loader_data(i) == loader_data) {
+            return pp;
+          }
+        }
+      }
+    }
+    pp = p->next_addr();
+  }
+  return pp;
+}
+
+
+void LoaderConstraintTable::purge_loader_constraints() {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+  // Remove unloaded entries from constraint table
+  for (int index = 0; index < table_size(); index++) {
+    LoaderConstraintEntry** p = bucket_addr(index);
+    while(*p) {
+      LoaderConstraintEntry* probe = *p;
+      Klass* klass = probe->klass();
+      // Remove klass that is no longer alive
+      if (klass != NULL &&
+          klass->class_loader_data()->is_unloading()) {
+        probe->set_klass(NULL);
+        if (TraceLoaderConstraints) {
+          ResourceMark rm;
+          tty->print_cr("[Purging class object from constraint for name %s,"
+                     " loader list:",
+                     probe->name()->as_C_string());
+          for (int i = 0; i < probe->num_loaders(); i++) {
+            tty->print_cr("[   [%d]: %s", i,
+                          probe->loader_data(i)->loader_name());
+          }
+        }
+      }
+      // Remove entries no longer alive from loader array
+      int n = 0;
+      while (n < probe->num_loaders()) {
+        if (probe->loader_data(n)->is_unloading()) {
+            if (TraceLoaderConstraints) {
+              ResourceMark rm;
+              tty->print_cr("[Purging loader %s from constraint for name %s",
+                            probe->loader_data(n)->loader_name(),
+                            probe->name()->as_C_string()
+                            );
+            }
+
+            // Compact array
+            int num = probe->num_loaders() - 1;
+            probe->set_num_loaders(num);
+          probe->set_loader_data(n, probe->loader_data(num));
+          probe->set_loader_data(num, NULL);
+
+            if (TraceLoaderConstraints) {
+              ResourceMark rm;
+              tty->print_cr("[New loader list:");
+              for (int i = 0; i < probe->num_loaders(); i++) {
+                tty->print_cr("[   [%d]: %s", i,
+                              probe->loader_data(i)->loader_name());
+              }
+            }
+
+            continue;  // current element replaced, so restart without
+                       // incrementing n
+          }
+        n++;
+      }
+      // Check whether entry should be purged
+      if (probe->num_loaders() < 2) {
+            if (TraceLoaderConstraints) {
+              ResourceMark rm;
+              tty->print("[Purging complete constraint for name %s\n",
+                         probe->name()->as_C_string());
+            }
+
+        // Purge entry
+        *p = probe->next();
+        FREE_C_HEAP_ARRAY(oop, probe->loaders(), mtClass);
+        free_entry(probe);
+      } else {
+#ifdef ASSERT
+        if (probe->klass() != NULL) {
+          ClassLoaderData* loader_data =
+            probe->klass()->class_loader_data();
+          assert(!loader_data->is_unloading(), "klass should be live");
+        }
+#endif
+        // Go to next entry
+        p = probe->next_addr();
+      }
+    }
+  }
+}
+
+bool LoaderConstraintTable::add_entry(Symbol* class_name,
+                                      Klass* klass1, Handle class_loader1,
+                                      Klass* klass2, Handle class_loader2) {
+  int failure_code = 0; // encode different reasons for failing
+
+  if (klass1 != NULL && klass2 != NULL && klass1 != klass2) {
+    failure_code = 1;
+  } else {
+    Klass* klass = klass1 != NULL ? klass1 : klass2;
+
+    LoaderConstraintEntry** pp1 = find_loader_constraint(class_name,
+                                                         class_loader1);
+    if (*pp1 != NULL && (*pp1)->klass() != NULL) {
+      if (klass != NULL) {
+        if (klass != (*pp1)->klass()) {
+          failure_code = 2;
+        }
+      } else {
+        klass = (*pp1)->klass();
+      }
+    }
+
+    LoaderConstraintEntry** pp2 = find_loader_constraint(class_name,
+                                                         class_loader2);
+    if (*pp2 != NULL && (*pp2)->klass() != NULL) {
+      if (klass != NULL) {
+        if (klass != (*pp2)->klass()) {
+          failure_code = 3;
+        }
+      } else {
+        klass = (*pp2)->klass();
+      }
+    }
+
+    if (failure_code == 0) {
+      if (*pp1 == NULL && *pp2 == NULL) {
+        unsigned int hash = compute_hash(class_name);
+        int index = hash_to_index(hash);
+        LoaderConstraintEntry* p;
+        p = new_entry(hash, class_name, klass, 2, 2);
+        p->set_loaders(NEW_C_HEAP_ARRAY(ClassLoaderData*, 2, mtClass));
+        p->set_loader(0, class_loader1());
+        p->set_loader(1, class_loader2());
+        p->set_klass(klass);
+        p->set_next(bucket(index));
+        set_entry(index, p);
+        if (TraceLoaderConstraints) {
+          ResourceMark rm;
+          tty->print("[Adding new constraint for name: %s, loader[0]: %s,"
+                     " loader[1]: %s ]\n",
+                     class_name->as_C_string(),
+                     SystemDictionary::loader_name(class_loader1()),
+                     SystemDictionary::loader_name(class_loader2())
+                     );
+        }
+      } else if (*pp1 == *pp2) {
+        /* constraint already imposed */
+        if ((*pp1)->klass() == NULL) {
+          (*pp1)->set_klass(klass);
+          if (TraceLoaderConstraints) {
+            ResourceMark rm;
+            tty->print("[Setting class object in existing constraint for"
+                       " name: %s and loader %s ]\n",
+                       class_name->as_C_string(),
+                       SystemDictionary::loader_name(class_loader1())
+                       );
+          }
+        } else {
+          assert((*pp1)->klass() == klass, "loader constraints corrupted");
+        }
+      } else if (*pp1 == NULL) {
+        extend_loader_constraint(*pp2, class_loader1, klass);
+      } else if (*pp2 == NULL) {
+        extend_loader_constraint(*pp1, class_loader2, klass);
+      } else {
+        merge_loader_constraints(pp1, pp2, klass);
+      }
+    }
+  }
+
+  if (failure_code != 0 && TraceLoaderConstraints) {
+    ResourceMark rm;
+    const char* reason = "";
+    switch(failure_code) {
+    case 1: reason = "the class objects presented by loader[0] and loader[1]"
+              " are different"; break;
+    case 2: reason = "the class object presented by loader[0] does not match"
+              " the stored class object in the constraint"; break;
+    case 3: reason = "the class object presented by loader[1] does not match"
+              " the stored class object in the constraint"; break;
+    default: reason = "unknown reason code";
+    }
+    tty->print("[Failed to add constraint for name: %s, loader[0]: %s,"
+               " loader[1]: %s, Reason: %s ]\n",
+               class_name->as_C_string(),
+               SystemDictionary::loader_name(class_loader1()),
+               SystemDictionary::loader_name(class_loader2()),
+               reason
+               );
+  }
+
+  return failure_code == 0;
+}
+
+
+// return true if the constraint was updated, false if the constraint is
+// violated
+bool LoaderConstraintTable::check_or_update(instanceKlassHandle k,
+                                                   Handle loader,
+                                                   Symbol* name) {
+  LoaderConstraintEntry* p = *(find_loader_constraint(name, loader));
+  if (p && p->klass() != NULL && p->klass() != k()) {
+    if (TraceLoaderConstraints) {
+      ResourceMark rm;
+      tty->print("[Constraint check failed for name %s, loader %s: "
+                 "the presented class object differs from that stored ]\n",
+                 name->as_C_string(),
+                 SystemDictionary::loader_name(loader()));
+    }
+    return false;
+  } else {
+    if (p && p->klass() == NULL) {
+      p->set_klass(k());
+      if (TraceLoaderConstraints) {
+        ResourceMark rm;
+        tty->print("[Updating constraint for name %s, loader %s, "
+                   "by setting class object ]\n",
+                   name->as_C_string(),
+                   SystemDictionary::loader_name(loader()));
+      }
+    }
+    return true;
+  }
+}
+
+Klass* LoaderConstraintTable::find_constrained_klass(Symbol* name,
+                                                       Handle loader) {
+  LoaderConstraintEntry *p = *(find_loader_constraint(name, loader));
+  if (p != NULL && p->klass() != NULL) {
+    if (p->klass()->oop_is_instance() && !InstanceKlass::cast(p->klass())->is_loaded()) {
+      // Only return fully loaded classes.  Classes found through the
+      // constraints might still be in the process of loading.
+      return NULL;
+    }
+    return p->klass();
+  }
+
+  // No constraints, or else no klass loaded yet.
+  return NULL;
+}
+
+void LoaderConstraintTable::ensure_loader_constraint_capacity(
+                                                     LoaderConstraintEntry *p,
+                                                    int nfree) {
+    if (p->max_loaders() - p->num_loaders() < nfree) {
+        int n = nfree + p->num_loaders();
+        ClassLoaderData** new_loaders = NEW_C_HEAP_ARRAY(ClassLoaderData*, n, mtClass);
+        memcpy(new_loaders, p->loaders(), sizeof(ClassLoaderData*) * p->num_loaders());
+        p->set_max_loaders(n);
+        FREE_C_HEAP_ARRAY(ClassLoaderData*, p->loaders(), mtClass);
+        p->set_loaders(new_loaders);
+    }
+}
+
+
+void LoaderConstraintTable::extend_loader_constraint(LoaderConstraintEntry* p,
+                                                     Handle loader,
+                                                     Klass* klass) {
+  ensure_loader_constraint_capacity(p, 1);
+  int num = p->num_loaders();
+  p->set_loader(num, loader());
+  p->set_num_loaders(num + 1);
+  if (TraceLoaderConstraints) {
+    ResourceMark rm;
+    tty->print("[Extending constraint for name %s by adding loader[%d]: %s %s",
+               p->name()->as_C_string(),
+               num,
+               SystemDictionary::loader_name(loader()),
+               (p->klass() == NULL ? " and setting class object ]\n" : " ]\n")
+               );
+  }
+  if (p->klass() == NULL) {
+    p->set_klass(klass);
+  } else {
+    assert(klass == NULL || p->klass() == klass, "constraints corrupted");
+  }
+}
+
+
+void LoaderConstraintTable::merge_loader_constraints(
+                                                   LoaderConstraintEntry** pp1,
+                                                   LoaderConstraintEntry** pp2,
+                                                   Klass* klass) {
+  // make sure *pp1 has higher capacity
+  if ((*pp1)->max_loaders() < (*pp2)->max_loaders()) {
+    LoaderConstraintEntry** tmp = pp2;
+    pp2 = pp1;
+    pp1 = tmp;
+  }
+
+  LoaderConstraintEntry* p1 = *pp1;
+  LoaderConstraintEntry* p2 = *pp2;
+
+  ensure_loader_constraint_capacity(p1, p2->num_loaders());
+
+  for (int i = 0; i < p2->num_loaders(); i++) {
+    int num = p1->num_loaders();
+    p1->set_loader_data(num, p2->loader_data(i));
+    p1->set_num_loaders(num + 1);
+  }
+
+  if (TraceLoaderConstraints) {
+    ResourceMark rm;
+    tty->print_cr("[Merged constraints for name %s, new loader list:",
+                  p1->name()->as_C_string()
+                  );
+
+    for (int i = 0; i < p1->num_loaders(); i++) {
+      tty->print_cr("[   [%d]: %s", i,
+                    p1->loader_data(i)->loader_name());
+    }
+    if (p1->klass() == NULL) {
+      tty->print_cr("[... and setting class object]");
+    }
+  }
+
+  // p1->klass() will hold NULL if klass, p2->klass(), and old
+  // p1->klass() are all NULL.  In addition, all three must have
+  // matching non-NULL values, otherwise either the constraints would
+  // have been violated, or the constraints had been corrupted (and an
+  // assertion would fail).
+  if (p2->klass() != NULL) {
+    assert(p2->klass() == klass, "constraints corrupted");
+  }
+  if (p1->klass() == NULL) {
+    p1->set_klass(klass);
+  } else {
+    assert(p1->klass() == klass, "constraints corrupted");
+  }
+
+  *pp2 = p2->next();
+  FREE_C_HEAP_ARRAY(oop, p2->loaders(), mtClass);
+  free_entry(p2);
+  return;
+}
+
+
+void LoaderConstraintTable::verify(Dictionary* dictionary,
+                                   PlaceholderTable* placeholders) {
+  Thread *thread = Thread::current();
+  for (int cindex = 0; cindex < _loader_constraint_size; cindex++) {
+    for (LoaderConstraintEntry* probe = bucket(cindex);
+                                probe != NULL;
+                                probe = probe->next()) {
+      if (probe->klass() != NULL) {
+        InstanceKlass* ik = InstanceKlass::cast(probe->klass());
+        guarantee(ik->name() == probe->name(), "name should match");
+        Symbol* name = ik->name();
+        ClassLoaderData* loader_data = ik->class_loader_data();
+        unsigned int d_hash = dictionary->compute_hash(name, loader_data);
+        int d_index = dictionary->hash_to_index(d_hash);
+        Klass* k = dictionary->find_class(d_index, d_hash, name, loader_data);
+        if (k != NULL) {
+          // We found the class in the system dictionary, so we should
+          // make sure that the Klass* matches what we already have.
+          guarantee(k == probe->klass(), "klass should be in dictionary");
+        } else {
+          // If we don't find the class in the system dictionary, it
+          // has to be in the placeholders table.
+          unsigned int p_hash = placeholders->compute_hash(name, loader_data);
+          int p_index = placeholders->hash_to_index(p_hash);
+          PlaceholderEntry* entry = placeholders->get_entry(p_index, p_hash,
+                                                            name, loader_data);
+
+          // The InstanceKlass might not be on the entry, so the only
+          // thing we can check here is whether we were successful in
+          // finding the class in the placeholders table.
+          guarantee(entry != NULL, "klass should be in the placeholders");
+        }
+      }
+      for (int n = 0; n< probe->num_loaders(); n++) {
+        assert(ClassLoaderDataGraph::contains_loader_data(probe->loader_data(n)), "The loader is missing");
+      }
+    }
+  }
+}
+
+#ifndef PRODUCT
+
+// Called with the system dictionary lock held
+void LoaderConstraintTable::print() {
+  ResourceMark rm;
+
+  assert_locked_or_safepoint(SystemDictionary_lock);
+  tty->print_cr("Java loader constraints (entries=%d)", _loader_constraint_size);
+  for (int cindex = 0; cindex < _loader_constraint_size; cindex++) {
+    for (LoaderConstraintEntry* probe = bucket(cindex);
+                                probe != NULL;
+                                probe = probe->next()) {
+      tty->print("%4d: ", cindex);
+      probe->name()->print();
+      tty->print(" , loaders:");
+      for (int n = 0; n < probe->num_loaders(); n++) {
+        probe->loader_data(n)->print_value();
+        tty->print(", ");
+      }
+      tty->cr();
+    }
+  }
+}
+#endif