jdk8-mips64-public/hotspot: src/share/vm/runtime/jniHandles.hpp@2fdf635bcf28 (annotated)

src/share/vm/runtime/jniHandles.hpp@2fdf635bcf28 (annotated)

src/share/vm/runtime/jniHandles.hpp

Thu, 05 Sep 2019 18:52:27 +0800

author: aoqi
date: Thu, 05 Sep 2019 18:52:27 +0800
changeset 9703: 2fdf635bcf28
parent 7994: 04ff2f6cd0eb
parent 9669: 32bc598624bd
permissions: -rw-r--r--

Merge

 /*
  * Copyright (c) 1998, 2017, 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.
  *
  */
 #ifndef SHARE_VM_RUNTIME_JNIHANDLES_HPP
 #define SHARE_VM_RUNTIME_JNIHANDLES_HPP
 #include "runtime/handles.hpp"
 #include "utilities/top.hpp"
 class JNIHandleBlock;
 // Interface for creating and resolving local/global JNI handles
 class JNIHandles : AllStatic {
   friend class VMStructs;
  private:
   static JNIHandleBlock* _global_handles;             // First global handle block
   static JNIHandleBlock* _weak_global_handles;        // First weak global handle block
   static oop _deleted_handle;                         // Sentinel marking deleted handles
   inline static bool is_jweak(jobject handle);
   inline static oop& jobject_ref(jobject handle); // NOT jweak!
   inline static oop& jweak_ref(jobject handle);
   template<bool external_guard> inline static oop guard_value(oop value);
   template<bool external_guard> inline static oop resolve_impl(jobject handle);
   template<bool external_guard> static oop resolve_jweak(jweak handle);
  public:
   // Low tag bit in jobject used to distinguish a jweak.  jweak is
   // type equivalent to jobject, but there are places where we need to
   // be able to distinguish jweak values from other jobjects, and
   // is_weak_global_handle is unsuitable for performance reasons.  To
   // provide such a test we add weak_tag_value to the (aligned) byte
   // address designated by the jobject to produce the corresponding
   // jweak.  Accessing the value of a jobject must account for it
   // being a possibly offset jweak.
   static const uintptr_t weak_tag_size = 1;
   static const uintptr_t weak_tag_alignment = (1u << weak_tag_size);
   static const uintptr_t weak_tag_mask = weak_tag_alignment - 1;
   static const int weak_tag_value = 1;
   // Resolve handle into oop
   inline static oop resolve(jobject handle);
   // Resolve externally provided handle into oop with some guards
   inline static oop resolve_external_guard(jobject handle);
   // Resolve handle into oop, result guaranteed not to be null
   inline static oop resolve_non_null(jobject handle);
   // Local handles
   static jobject make_local(oop obj);
   static jobject make_local(JNIEnv* env, oop obj);    // Fast version when env is known
   static jobject make_local(Thread* thread, oop obj); // Even faster version when current thread is known
   inline static void destroy_local(jobject handle);
   // Global handles
   static jobject make_global(Handle  obj);
   static void destroy_global(jobject handle);
   // Weak global handles
   static jobject make_weak_global(Handle obj);
   static void destroy_weak_global(jobject handle);
   // Sentinel marking deleted handles in block. Note that we cannot store NULL as
   // the sentinel, since clearing weak global JNI refs are done by storing NULL in
   // the handle. The handle may not be reused before destroy_weak_global is called.
   static oop deleted_handle()   { return _deleted_handle; }
   // Initialization
   static void initialize();
   // Debugging
   static void print_on(outputStream* st);
   static void print()           { print_on(tty); }
   static void verify();
   static bool is_local_handle(Thread* thread, jobject handle);
   static bool is_frame_handle(JavaThread* thr, jobject obj);
   static bool is_global_handle(jobject handle);
   static bool is_weak_global_handle(jobject handle);
   static long global_handle_memory_usage();
   static long weak_global_handle_memory_usage();
   // Garbage collection support(global handles only, local handles are traversed from thread)
   // Traversal of regular global handles
   static void oops_do(OopClosure* f);
   // Traversal of weak global handles. Unreachable oops are cleared.
   static void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f);
   // Traversal of weak global handles.
   static void weak_oops_do(OopClosure* f);
 };
 // JNI handle blocks holding local/global JNI handles
 class JNIHandleBlock : public CHeapObj<mtInternal> {
   friend class VMStructs;
   friend class CppInterpreter;
  private:
   enum SomeConstants {
     block_size_in_oops  = 32                    // Number of handles per handle block
   };
   oop             _handles[block_size_in_oops]; // The handles
   int             _top;                         // Index of next unused handle
   JNIHandleBlock* _next;                        // Link to next block
   // The following instance variables are only used by the first block in a chain.
   // Having two types of blocks complicates the code and the space overhead in negligble.
   JNIHandleBlock* _last;                        // Last block in use
   JNIHandleBlock* _pop_frame_link;              // Block to restore on PopLocalFrame call
   oop*            _free_list;                   // Handle free list
   int             _allocate_before_rebuild;     // Number of blocks to allocate before rebuilding free list
   // Check JNI, "planned capacity" for current frame (or push/ensure)
   size_t          _planned_capacity;
   #ifndef PRODUCT
   JNIHandleBlock* _block_list_link;             // Link for list below
   static JNIHandleBlock* _block_list;           // List of all allocated blocks (for debugging only)
   #endif
   static JNIHandleBlock* _block_free_list;      // Free list of currently unused blocks
   static int      _blocks_allocated;            // For debugging/printing
   // Fill block with bad_handle values
   void zap();
  protected:
   // No more handles in the both the current and following blocks
   void clear() { _top = 0; }
  private:
   // Free list computation
   void rebuild_free_list();
  public:
   // Handle allocation
   jobject allocate_handle(oop obj);
   // Block allocation and block free list management
   static JNIHandleBlock* allocate_block(Thread* thread = NULL);
   static void release_block(JNIHandleBlock* block, Thread* thread = NULL);
   // JNI PushLocalFrame/PopLocalFrame support
   JNIHandleBlock* pop_frame_link() const          { return _pop_frame_link; }
   void set_pop_frame_link(JNIHandleBlock* block)  { _pop_frame_link = block; }
   // Stub generator support
   static int top_offset_in_bytes()                { return offset_of(JNIHandleBlock, _top); }
   // Garbage collection support
   // Traversal of regular handles
   void oops_do(OopClosure* f);
   // Traversal of weak handles. Unreachable oops are cleared.
   void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f);
   // Checked JNI support
   void set_planned_capacity(size_t planned_capacity) { _planned_capacity = planned_capacity; }
   const size_t get_planned_capacity() { return _planned_capacity; }
   const size_t get_number_of_live_handles();
   // Debugging
   bool chain_contains(jobject handle) const;    // Does this block or following blocks contain handle
   bool contains(jobject handle) const;          // Does this block contain handle
   int length() const;                           // Length of chain starting with this block
   long memory_usage() const;
   #ifndef PRODUCT
   static bool any_contains(jobject handle);     // Does any block currently in use contain handle
   static void print_statistics();
   #endif
 };
 inline bool JNIHandles::is_jweak(jobject handle) {
   STATIC_ASSERT(weak_tag_size == 1);
   STATIC_ASSERT(weak_tag_value == 1);
   return (reinterpret_cast<uintptr_t>(handle) & weak_tag_mask) != 0;
 }
 inline oop& JNIHandles::jobject_ref(jobject handle) {
   assert(!is_jweak(handle), "precondition");
   return *reinterpret_cast<oop*>(handle);
 }
 inline oop& JNIHandles::jweak_ref(jobject handle) {
   assert(is_jweak(handle), "precondition");
   char* ptr = reinterpret_cast<char*>(handle) - weak_tag_value;
   return *reinterpret_cast<oop*>(ptr);
 }
 // external_guard is true if called from resolve_external_guard.
 // Treat deleted (and possibly zapped) as NULL for external_guard,
 // else as (asserted) error.
 template<bool external_guard>
 inline oop JNIHandles::guard_value(oop value) {
   if (!external_guard) {
     assert(value != badJNIHandle, "Pointing to zapped jni handle area");
     assert(value != deleted_handle(), "Used a deleted global handle");
   } else if ((value == badJNIHandle) || (value == deleted_handle())) {
     value = NULL;
   }
   return value;
 }
 // external_guard is true if called from resolve_external_guard.
 template<bool external_guard>
 inline oop JNIHandles::resolve_impl(jobject handle) {
   assert(handle != NULL, "precondition");
   oop result;
   if (is_jweak(handle)) {       // Unlikely
     result = resolve_jweak<external_guard>(handle);
   } else {
     result = jobject_ref(handle);
     // Construction of jobjects canonicalize a null value into a null
     // jobject, so for non-jweak the pointee should never be null.
     assert(external_guard || result != NULL,
            "Invalid value read from jni handle");
     result = guard_value<external_guard>(result);
   }
   return result;
 }
 inline oop JNIHandles::resolve(jobject handle) {
   oop result = NULL;
   if (handle != NULL) {
     result = resolve_impl<false /* external_guard */ >(handle);
   }
   return result;
 }
 // Resolve some erroneous cases to NULL, rather than treating them as
 // possibly unchecked errors.  In particular, deleted handles are
 // treated as NULL (though a deleted and later reallocated handle
 // isn't detected).
 inline oop JNIHandles::resolve_external_guard(jobject handle) {
   oop result = NULL;
   if (handle != NULL) {
     result = resolve_impl<true /* external_guard */ >(handle);
   }
   return result;
 }
 inline oop JNIHandles::resolve_non_null(jobject handle) {
   assert(handle != NULL, "JNI handle should not be null");
   oop result = resolve_impl<false /* external_guard */ >(handle);
   assert(result != NULL, "NULL read from jni handle");
   return result;
 }
 inline void JNIHandles::destroy_local(jobject handle) {
   if (handle != NULL) {
     jobject_ref(handle) = deleted_handle();
   }
 }
 #endif // SHARE_VM_RUNTIME_JNIHANDLES_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/runtime/jniHandles.hpp@2fdf635bcf28 (annotated)

src/share/vm/runtime/jniHandles.hpp