aoqi@0: /*
poonam@7627:  * Copyright (c) 1998, 2015, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_RUNTIME_JNIHANDLES_HPP
aoqi@0: #define SHARE_VM_RUNTIME_JNIHANDLES_HPP
aoqi@0: 
aoqi@0: #include "runtime/handles.hpp"
aoqi@0: #include "utilities/top.hpp"
aoqi@0: 
aoqi@0: class JNIHandleBlock;
aoqi@0: 
aoqi@0: 
aoqi@0: // Interface for creating and resolving local/global JNI handles
aoqi@0: 
aoqi@0: class JNIHandles : AllStatic {
aoqi@0:   friend class VMStructs;
aoqi@0:  private:
aoqi@0:   static JNIHandleBlock* _global_handles;             // First global handle block
aoqi@0:   static JNIHandleBlock* _weak_global_handles;        // First weak global handle block
aoqi@0:   static oop _deleted_handle;                         // Sentinel marking deleted handles
aoqi@0: 
aoqi@0:  public:
aoqi@0:   // Resolve handle into oop
aoqi@0:   inline static oop resolve(jobject handle);
aoqi@0:   // Resolve externally provided handle into oop with some guards
aoqi@0:   inline static oop resolve_external_guard(jobject handle);
aoqi@0:   // Resolve handle into oop, result guaranteed not to be null
aoqi@0:   inline static oop resolve_non_null(jobject handle);
aoqi@0: 
aoqi@0:   // Local handles
aoqi@0:   static jobject make_local(oop obj);
aoqi@0:   static jobject make_local(JNIEnv* env, oop obj);    // Fast version when env is known
aoqi@0:   static jobject make_local(Thread* thread, oop obj); // Even faster version when current thread is known
aoqi@0:   inline static void destroy_local(jobject handle);
aoqi@0: 
aoqi@0:   // Global handles
aoqi@0:   static jobject make_global(Handle  obj);
aoqi@0:   static void destroy_global(jobject handle);
aoqi@0: 
aoqi@0:   // Weak global handles
aoqi@0:   static jobject make_weak_global(Handle obj);
aoqi@0:   static void destroy_weak_global(jobject handle);
aoqi@0: 
aoqi@0:   // Sentinel marking deleted handles in block. Note that we cannot store NULL as
aoqi@0:   // the sentinel, since clearing weak global JNI refs are done by storing NULL in
aoqi@0:   // the handle. The handle may not be reused before destroy_weak_global is called.
aoqi@0:   static oop deleted_handle()   { return _deleted_handle; }
aoqi@0: 
aoqi@0:   // Initialization
aoqi@0:   static void initialize();
aoqi@0: 
aoqi@0:   // Debugging
aoqi@0:   static void print_on(outputStream* st);
aoqi@0:   static void print()           { print_on(tty); }
aoqi@0:   static void verify();
aoqi@0:   static bool is_local_handle(Thread* thread, jobject handle);
aoqi@0:   static bool is_frame_handle(JavaThread* thr, jobject obj);
aoqi@0:   static bool is_global_handle(jobject handle);
aoqi@0:   static bool is_weak_global_handle(jobject handle);
aoqi@0:   static long global_handle_memory_usage();
aoqi@0:   static long weak_global_handle_memory_usage();
aoqi@0: 
aoqi@0:   // Garbage collection support(global handles only, local handles are traversed from thread)
aoqi@0:   // Traversal of regular global handles
aoqi@0:   static void oops_do(OopClosure* f);
aoqi@0:   // Traversal of weak global handles. Unreachable oops are cleared.
aoqi@0:   static void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f);
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: 
aoqi@0: // JNI handle blocks holding local/global JNI handles
aoqi@0: 
aoqi@0: class JNIHandleBlock : public CHeapObj<mtInternal> {
aoqi@0:   friend class VMStructs;
aoqi@0:   friend class CppInterpreter;
aoqi@0: 
aoqi@0:  private:
aoqi@0:   enum SomeConstants {
aoqi@0:     block_size_in_oops  = 32                    // Number of handles per handle block
aoqi@0:   };
aoqi@0: 
aoqi@0:   oop             _handles[block_size_in_oops]; // The handles
aoqi@0:   int             _top;                         // Index of next unused handle
aoqi@0:   JNIHandleBlock* _next;                        // Link to next block
aoqi@0: 
aoqi@0:   // The following instance variables are only used by the first block in a chain.
aoqi@0:   // Having two types of blocks complicates the code and the space overhead in negligble.
aoqi@0:   JNIHandleBlock* _last;                        // Last block in use
aoqi@0:   JNIHandleBlock* _pop_frame_link;              // Block to restore on PopLocalFrame call
aoqi@0:   oop*            _free_list;                   // Handle free list
aoqi@0:   int             _allocate_before_rebuild;     // Number of blocks to allocate before rebuilding free list
aoqi@0: 
poonam@7627:   // Check JNI, "planned capacity" for current frame (or push/ensure)
poonam@7627:   size_t          _planned_capacity;
poonam@7627: 
aoqi@0:   #ifndef PRODUCT
aoqi@0:   JNIHandleBlock* _block_list_link;             // Link for list below
aoqi@0:   static JNIHandleBlock* _block_list;           // List of all allocated blocks (for debugging only)
aoqi@0:   #endif
aoqi@0: 
aoqi@0:   static JNIHandleBlock* _block_free_list;      // Free list of currently unused blocks
aoqi@0:   static int      _blocks_allocated;            // For debugging/printing
aoqi@0: 
aoqi@0:   // Fill block with bad_handle values
aoqi@0:   void zap();
aoqi@0: 
aoqi@0:  protected:
aoqi@0:   // No more handles in the both the current and following blocks
aoqi@0:   void clear() { _top = 0; }
aoqi@0: 
aoqi@0:  private:
aoqi@0:   // Free list computation
aoqi@0:   void rebuild_free_list();
aoqi@0: 
aoqi@0:  public:
aoqi@0:   // Handle allocation
aoqi@0:   jobject allocate_handle(oop obj);
aoqi@0: 
aoqi@0:   // Block allocation and block free list management
aoqi@0:   static JNIHandleBlock* allocate_block(Thread* thread = NULL);
aoqi@0:   static void release_block(JNIHandleBlock* block, Thread* thread = NULL);
aoqi@0: 
aoqi@0:   // JNI PushLocalFrame/PopLocalFrame support
aoqi@0:   JNIHandleBlock* pop_frame_link() const          { return _pop_frame_link; }
aoqi@0:   void set_pop_frame_link(JNIHandleBlock* block)  { _pop_frame_link = block; }
aoqi@0: 
aoqi@0:   // Stub generator support
aoqi@0:   static int top_offset_in_bytes()                { return offset_of(JNIHandleBlock, _top); }
aoqi@0: 
aoqi@0:   // Garbage collection support
aoqi@0:   // Traversal of regular handles
aoqi@0:   void oops_do(OopClosure* f);
aoqi@0:   // Traversal of weak handles. Unreachable oops are cleared.
aoqi@0:   void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f);
aoqi@0: 
poonam@7627:   // Checked JNI support
poonam@7627:   void set_planned_capacity(size_t planned_capacity) { _planned_capacity = planned_capacity; }
poonam@7627:   const size_t get_planned_capacity() { return _planned_capacity; }
poonam@7627:   const size_t get_number_of_live_handles();
poonam@7627: 
aoqi@0:   // Debugging
aoqi@0:   bool chain_contains(jobject handle) const;    // Does this block or following blocks contain handle
aoqi@0:   bool contains(jobject handle) const;          // Does this block contain handle
aoqi@0:   int length() const;                           // Length of chain starting with this block
aoqi@0:   long memory_usage() const;
aoqi@0:   #ifndef PRODUCT
aoqi@0:   static bool any_contains(jobject handle);     // Does any block currently in use contain handle
aoqi@0:   static void print_statistics();
aoqi@0:   #endif
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: inline oop JNIHandles::resolve(jobject handle) {
aoqi@0:   oop result = (handle == NULL ? (oop)NULL : *(oop*)handle);
aoqi@0:   assert(result != NULL || (handle == NULL || !CheckJNICalls || is_weak_global_handle(handle)), "Invalid value read from jni handle");
aoqi@0:   assert(result != badJNIHandle, "Pointing to zapped jni handle area");
aoqi@0:   return result;
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: inline oop JNIHandles::resolve_external_guard(jobject handle) {
aoqi@0:   if (handle == NULL) return NULL;
aoqi@0:   oop result = *(oop*)handle;
aoqi@0:   if (result == NULL || result == badJNIHandle) return NULL;
aoqi@0:   return result;
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: inline oop JNIHandles::resolve_non_null(jobject handle) {
aoqi@0:   assert(handle != NULL, "JNI handle should not be null");
aoqi@0:   oop result = *(oop*)handle;
aoqi@0:   assert(result != NULL, "Invalid value read from jni handle");
aoqi@0:   assert(result != badJNIHandle, "Pointing to zapped jni handle area");
aoqi@0:   // Don't let that private _deleted_handle object escape into the wild.
aoqi@0:   assert(result != deleted_handle(), "Used a deleted global handle.");
aoqi@0:   return result;
aoqi@0: };
aoqi@0: 
aoqi@0: inline void JNIHandles::destroy_local(jobject handle) {
aoqi@0:   if (handle != NULL) {
aoqi@0:     *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: #endif // SHARE_VM_RUNTIME_JNIHANDLES_HPP