8270333: -XX:+VerifyStringTableAtExit should not do linear search

Reviewed-by: dholmes, minqi

Author: iklam

src/hotspot/share/classfile/javaClasses.cpp

@@ -502,7 +502,7 @@ jchar* java_lang_String::as_unicode_string_or_null(oop java_string, int& length)
   return result;
 }
 
-unsigned int java_lang_String::hash_code(oop java_string) {
+inline unsigned int java_lang_String::hash_code_impl(oop java_string, bool update) {
   // The hash and hashIsZero fields are subject to a benign data race,
   // making it crucial to ensure that any observable result of the
   // calculation in this method stays correct under any possible read of
@@ -529,14 +529,25 @@ unsigned int java_lang_String::hash_code(oop java_string) {
     }
   }
 
-  if (hash != 0) {
-    java_string->int_field_put(_hash_offset, hash);
-  } else {
-    java_string->bool_field_put(_hashIsZero_offset, true);
+  if (update) {
+    if (hash != 0) {
+      java_string->int_field_put(_hash_offset, hash);
+    } else {
+      java_string->bool_field_put(_hashIsZero_offset, true);
+    }
   }
   return hash;
 }
 
+unsigned int java_lang_String::hash_code(oop java_string) {
+  return hash_code_impl(java_string, /*update=*/true);
+}
+
+unsigned int java_lang_String::hash_code_noupdate(oop java_string) {
+  return hash_code_impl(java_string, /*update=*/false);
+}
+
+
 char* java_lang_String::as_quoted_ascii(oop java_string) {
   typeArrayOop value  = java_lang_String::value(java_string);
   int          length = java_lang_String::length(java_string, value);

src/hotspot/share/classfile/javaClasses.hpp

@@ -127,6 +127,8 @@ class java_lang_String : AllStatic {
   // returning true if the bit was already set.
   static bool test_and_set_flag(oop java_string, uint8_t flag_mask);
 
+  static inline unsigned int hash_code_impl(oop java_string, bool update);
+
  public:
 
   // Coders
@@ -222,6 +224,7 @@ class java_lang_String : AllStatic {
   }
 
   static unsigned int hash_code(oop java_string);
+  static unsigned int hash_code_noupdate(oop java_string);
 
   static bool equals(oop java_string, const jchar* chars, int len);
   static bool equals(oop str1, oop str2);

src/hotspot/share/classfile/stringTable.cpp

@@ -53,6 +53,7 @@
 #include "utilities/concurrentHashTable.inline.hpp"
 #include "utilities/concurrentHashTableTasks.inline.hpp"
 #include "utilities/macros.hpp"
+#include "utilities/resizeableResourceHash.hpp"
 #include "utilities/utf8.hpp"
 
 // We prefer short chains of avg 2
@@ -597,39 +598,40 @@ void StringTable::verify() {
 
 // Verification and comp
 class VerifyCompStrings : StackObj {
-  GrowableArray<oop>* _oops;
+  static unsigned string_hash(oop const& str) {
+    return java_lang_String::hash_code_noupdate(str);
+  }
+  static bool string_equals(oop const& a, oop const& b) {
+    return java_lang_String::equals(a, b);
+  }
+
+  ResizeableResourceHashtable<oop, bool,
+                              ResourceObj::C_HEAP, mtInternal,
+                              string_hash, string_equals> _table;
  public:
   size_t _errors;
-  VerifyCompStrings(GrowableArray<oop>* oops) : _oops(oops), _errors(0) {}
+  VerifyCompStrings() : _table(unsigned(_items_count / 8) + 1), _errors(0) {}
   bool operator()(WeakHandle* val) {
     oop s = val->resolve();
     if (s == NULL) {
       return true;
     }
-    int len = _oops->length();
-    for (int i = 0; i < len; i++) {
-      bool eq = java_lang_String::equals(s, _oops->at(i));
-      assert(!eq, "Duplicate strings");
-      if (eq) {
-        _errors++;
-      }
+    bool created;
+    _table.put_if_absent(s, true, &created);
+    assert(created, "Duplicate strings");
+    if (!created) {
+      _errors++;
     }
-    _oops->push(s);
     return true;
   };
 };
 
 size_t StringTable::verify_and_compare_entries() {
   Thread* thr = Thread::current();
-  GrowableArray<oop>* oops =
-    new (ResourceObj::C_HEAP, mtInternal)
-      GrowableArray<oop>((int)_current_size, mtInternal);
-
-  VerifyCompStrings vcs(oops);
+  VerifyCompStrings vcs;
   if (!_local_table->try_scan(thr, vcs)) {
     log_info(stringtable)("verify unavailable at this moment");
   }
-  delete oops;
   return vcs._errors;
 }