diff -r fd16c54261b3 -r 489c9b5090e2 hotspot/src/share/vm/classfile/loaderConstraints.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/classfile/loaderConstraints.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,507 @@
+/*
+ * Copyright 2003-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_loaderConstraints.cpp.incl"
+
+LoaderConstraintTable::LoaderConstraintTable(int nof_buckets)
+  : Hashtable(nof_buckets, sizeof(LoaderConstraintEntry)) {};
+
+
+LoaderConstraintEntry* LoaderConstraintTable::new_entry(
+                                 unsigned int hash, symbolOop name,
+                                 klassOop klass, int num_loaders,
+                                 int max_loaders) {
+  LoaderConstraintEntry* entry;
+  entry = (LoaderConstraintEntry*)Hashtable::new_entry(hash, klass);
+  entry->set_name(name);
+  entry->set_num_loaders(num_loaders);
+  entry->set_max_loaders(max_loaders);
+  return entry;
+}
+
+
+void LoaderConstraintTable::oops_do(OopClosure* f) {
+  for (int index = 0; index < table_size(); index++) {
+    for (LoaderConstraintEntry* probe = bucket(index);
+                                probe != NULL;
+                                probe = probe->next()) {
+      f->do_oop((oop*)(probe->name_addr()));
+      if (probe->klass() != NULL) {
+        f->do_oop((oop*)probe->klass_addr());
+      }
+      for (int n = 0; n < probe->num_loaders(); n++) {
+        if (probe->loader(n) != NULL) {
+          f->do_oop(probe->loader_addr(n));
+        }
+      }
+    }
+  }
+}
+
+// We must keep the symbolOop used in the name alive.  We'll use the
+// loaders to decide if a particular entry can be purged.
+void LoaderConstraintTable::always_strong_classes_do(OopClosure* blk) {
+  // We must keep the symbolOop used in the name alive.
+  for (int cindex = 0; cindex < table_size(); cindex++) {
+    for (LoaderConstraintEntry* lc_probe = bucket(cindex);
+                                lc_probe != NULL;
+                                lc_probe = lc_probe->next()) {
+      assert (lc_probe->name() != NULL,  "corrupted loader constraint table");
+      blk->do_oop((oop*)lc_probe->name_addr());
+    }
+  }
+}
+
+
+// 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(
+                                    symbolHandle name, Handle loader) {
+
+  unsigned int hash = compute_hash(name);
+  int index = hash_to_index(hash);
+  LoaderConstraintEntry** pp = bucket_addr(index);
+  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(i) == loader()) {
+            return pp;
+          }
+        }
+      }
+    }
+    pp = p->next_addr();
+  }
+  return pp;
+}
+
+
+void LoaderConstraintTable::purge_loader_constraints(BoolObjectClosure* is_alive) {
+  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;
+      klassOop klass = probe->klass();
+      // Remove klass that is no longer alive
+      if (klass != NULL && !is_alive->do_object_b(klass)) {
+        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,
+                          SystemDictionary::loader_name(probe->loader(i)));
+          }
+        }
+      }
+      // Remove entries no longer alive from loader array
+      int n = 0;
+      while (n < probe->num_loaders()) {
+        if (probe->loader(n) != NULL) {
+          if (!is_alive->do_object_b(probe->loader(n))) {
+            if (TraceLoaderConstraints) {
+              ResourceMark rm;
+              tty->print_cr("[Purging loader %s from constraint for name %s",
+                            SystemDictionary::loader_name(probe->loader(n)),
+                            probe->name()->as_C_string()
+                            );
+            }
+
+            // Compact array
+            int num = probe->num_loaders() - 1;
+            probe->set_num_loaders(num);
+            probe->set_loader(n, probe->loader(num));
+            probe->set_loader(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,
+                              SystemDictionary::loader_name(probe->loader(i)));
+              }
+            }
+
+            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());
+        free_entry(probe);
+      } else {
+#ifdef ASSERT
+        assert(is_alive->do_object_b(probe->name()), "name should be live");
+        if (probe->klass() != NULL) {
+          assert(is_alive->do_object_b(probe->klass()), "klass should be live");
+        }
+        for (n = 0; n < probe->num_loaders(); n++) {
+          if (probe->loader(n) != NULL) {
+            assert(is_alive->do_object_b(probe->loader(n)), "loader should be live");
+          }
+        }
+#endif
+        // Go to next entry
+        p = probe->next_addr();
+      }
+    }
+  }
+}
+
+bool LoaderConstraintTable::add_entry(symbolHandle class_name,
+                                      klassOop klass1, Handle class_loader1,
+                                      klassOop klass2, Handle class_loader2) {
+  int failure_code = 0; // encode different reasons for failing
+
+  if (klass1 != NULL && klass2 != NULL && klass1 != klass2) {
+    failure_code = 1;
+  } else {
+    klassOop 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(oop, 2));
+        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,
+                                                   symbolHandle 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;
+  }
+}
+
+klassOop LoaderConstraintTable::find_constrained_klass(symbolHandle name,
+                                                       Handle loader) {
+  LoaderConstraintEntry *p = *(find_loader_constraint(name, loader));
+  if (p != NULL && p->klass() != NULL)
+    return p->klass();
+
+  // No constraints, or else no klass loaded yet.
+  return NULL;
+}
+
+
+klassOop LoaderConstraintTable::find_constrained_elem_klass(symbolHandle name,
+                                                            symbolHandle elem_name,
+                                                            Handle loader,
+                                                            TRAPS) {
+  LoaderConstraintEntry *p = *(find_loader_constraint(name, loader));
+  if (p != NULL) {
+    assert(p->klass() == NULL, "Expecting null array klass");
+
+    // The array name has a constraint, but it will not have a class. Check
+    // each loader for an associated elem
+    for (int i = 0; i < p->num_loaders(); i++) {
+      Handle no_protection_domain;
+
+      klassOop k = SystemDictionary::find(elem_name, p->loader(i), no_protection_domain, THREAD);
+      if (k != NULL) {
+        // Return the first elem klass found.
+        return k;
+      }
+    }
+  }
+
+  // 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();
+        oop* new_loaders = NEW_C_HEAP_ARRAY(oop, n);
+        memcpy(new_loaders, p->loaders(), sizeof(oop) * p->num_loaders());
+        p->set_max_loaders(n);
+        FREE_C_HEAP_ARRAY(oop, p->loaders());
+        p->set_loaders(new_loaders);
+    }
+}
+
+
+void LoaderConstraintTable::extend_loader_constraint(LoaderConstraintEntry* p,
+                                                     Handle loader,
+                                                     klassOop 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,
+                                                   klassOop 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(num, p2->loader(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,
+                    SystemDictionary::loader_name(p1->loader(i)));
+    }
+    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());
+  free_entry(p2);
+  return;
+}
+
+
+void LoaderConstraintTable::verify(Dictionary* dictionary) {
+  Thread *thread = Thread::current();
+  for (int cindex = 0; cindex < _loader_constraint_size; cindex++) {
+    for (LoaderConstraintEntry* probe = bucket(cindex);
+                                probe != NULL;
+                                probe = probe->next()) {
+      guarantee(probe->name()->is_symbol(), "should be symbol");
+      if (probe->klass() != NULL) {
+        instanceKlass* ik = instanceKlass::cast(probe->klass());
+        guarantee(ik->name() == probe->name(), "name should match");
+        symbolHandle name (thread, ik->name());
+        Handle loader(thread, ik->class_loader());
+        unsigned int d_hash = dictionary->compute_hash(name, loader);
+        int d_index = dictionary->hash_to_index(d_hash);
+        klassOop k = dictionary->find_class(d_index, d_hash, name, loader);
+        guarantee(k == probe->klass(), "klass should be in dictionary");
+      }
+      for (int n = 0; n< probe->num_loaders(); n++) {
+        guarantee(probe->loader(n)->is_oop_or_null(), "should be oop");
+      }
+    }
+  }
+}
+
+#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(n)->print_value();
+        tty->print(", ");
+      }
+      tty->cr();
+    }
+  }
+}
+#endif