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Java example source code file (codeCache.hpp)

This example Java source code file (codeCache.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

allstatic, codeblob, codeblob\*, codeblobs, codeblobtooopclosure, codeheap, depchange, hotswap, null, oopclosure, prints, product_return, share_vm_code_codecache_hpp, vmstructs

The codeCache.hpp Java example source code

/*
 * Copyright (c) 1997, 2013, 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_CODE_CODECACHE_HPP
#define SHARE_VM_CODE_CODECACHE_HPP

#include "code/codeBlob.hpp"
#include "memory/allocation.hpp"
#include "memory/heap.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/oopsHierarchy.hpp"

// The CodeCache implements the code cache for various pieces of generated
// code, e.g., compiled java methods, runtime stubs, transition frames, etc.
// The entries in the CodeCache are all CodeBlob's.

// Implementation:
//   - Each CodeBlob occupies one chunk of memory.
//   - Like the offset table in oldspace the zone has at table for
//     locating a method given a addess of an instruction.

class OopClosure;
class DepChange;

class CodeCache : AllStatic {
  friend class VMStructs;
 private:
  // CodeHeap is malloc()'ed at startup and never deleted during shutdown,
  // so that the generated assembly code is always there when it's needed.
  // This may cause memory leak, but is necessary, for now. See 4423824,
  // 4422213 or 4436291 for details.
  static CodeHeap * _heap;
  static int _number_of_blobs;
  static int _number_of_adapters;
  static int _number_of_nmethods;
  static int _number_of_nmethods_with_dependencies;
  static bool _needs_cache_clean;
  static nmethod* _scavenge_root_nmethods;  // linked via nm->scavenge_root_link()

  static void verify_if_often() PRODUCT_RETURN;

  static void mark_scavenge_root_nmethods() PRODUCT_RETURN;
  static void verify_perm_nmethods(CodeBlobClosure* f_or_null) PRODUCT_RETURN;

  static int _codemem_full_count;

 public:

  // Initialization
  static void initialize();

  static void report_codemem_full();

  // Allocation/administration
  static CodeBlob* allocate(int size, bool is_critical = false); // allocates a new CodeBlob
  static void commit(CodeBlob* cb);                 // called when the allocated CodeBlob has been filled
  static int alignment_unit();                      // guaranteed alignment of all CodeBlobs
  static int alignment_offset();                    // guaranteed offset of first CodeBlob byte within alignment unit (i.e., allocation header)
  static void free(CodeBlob* cb);                   // frees a CodeBlob
  static void flush();                              // flushes all CodeBlobs
  static bool contains(void *p);                    // returns whether p is included
  static void blobs_do(void f(CodeBlob* cb));       // iterates over all CodeBlobs
  static void blobs_do(CodeBlobClosure* f);         // iterates over all CodeBlobs
  static void nmethods_do(void f(nmethod* nm));     // iterates over all nmethods
  static void alive_nmethods_do(void f(nmethod* nm)); // iterates over all alive nmethods

  // Lookup
  static CodeBlob* find_blob(void* start);
  static nmethod*  find_nmethod(void* start);

  // Lookup that does not fail if you lookup a zombie method (if you call this, be sure to know
  // what you are doing)
  static CodeBlob* find_blob_unsafe(void* start) {
    // NMT can walk the stack before code cache is created
    if (_heap == NULL) return NULL;

    CodeBlob* result = (CodeBlob*)_heap->find_start(start);
    // this assert is too strong because the heap code will return the
    // heapblock containing start. That block can often be larger than
    // the codeBlob itself. If you look up an address that is within
    // the heapblock but not in the codeBlob you will assert.
    //
    // Most things will not lookup such bad addresses. However
    // AsyncGetCallTrace can see intermediate frames and get that kind
    // of invalid address and so can a developer using hsfind.
    //
    // The more correct answer is to return NULL if blob_contains() returns
    // false.
    // assert(result == NULL || result->blob_contains((address)start), "found wrong CodeBlob");

    if (result != NULL && !result->blob_contains((address)start)) {
      result = NULL;
    }
    return result;
  }

  // Iteration
  static CodeBlob* first();
  static CodeBlob* next (CodeBlob* cb);
  static CodeBlob* alive(CodeBlob *cb);
  static nmethod* alive_nmethod(CodeBlob *cb);
  static nmethod* first_nmethod();
  static nmethod* next_nmethod (CodeBlob* cb);
  static int       nof_blobs()                 { return _number_of_blobs; }
  static int       nof_adapters()              { return _number_of_adapters; }
  static int       nof_nmethods()              { return _number_of_nmethods; }

  // GC support
  static void gc_epilogue();
  static void gc_prologue();
  static void verify_oops();
  // If "unloading_occurred" is true, then unloads (i.e., breaks root links
  // to) any unmarked codeBlobs in the cache.  Sets "marked_for_unloading"
  // to "true" iff some code got unloaded.
  static void do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred);
  static void oops_do(OopClosure* f) {
    CodeBlobToOopClosure oopc(f, /*do_marking=*/ false);
    blobs_do(&oopc);
  }
  static void asserted_non_scavengable_nmethods_do(CodeBlobClosure* f = NULL) PRODUCT_RETURN;
  static void scavenge_root_nmethods_do(CodeBlobClosure* f);

  static nmethod* scavenge_root_nmethods()          { return _scavenge_root_nmethods; }
  static void set_scavenge_root_nmethods(nmethod* nm) { _scavenge_root_nmethods = nm; }
  static void add_scavenge_root_nmethod(nmethod* nm);
  static void drop_scavenge_root_nmethod(nmethod* nm);
  static void prune_scavenge_root_nmethods();

  // Printing/debugging
  static void print();                           // prints summary
  static void print_internals();
  static void verify();                          // verifies the code cache
  static void print_trace(const char* event, CodeBlob* cb, int size = 0) PRODUCT_RETURN;
  static void print_summary(outputStream* st, bool detailed = true); // Prints a summary of the code cache usage
  static void log_state(outputStream* st);

  // The full limits of the codeCache
  static address  low_bound()                    { return (address) _heap->low_boundary(); }
  static address  high_bound()                   { return (address) _heap->high_boundary(); }
  static address  high()                         { return (address) _heap->high(); }

  // Profiling
  static address first_address();                // first address used for CodeBlobs
  static address last_address();                 // last  address used for CodeBlobs
  static size_t  capacity()                      { return _heap->capacity(); }
  static size_t  max_capacity()                  { return _heap->max_capacity(); }
  static size_t  unallocated_capacity()          { return _heap->unallocated_capacity(); }
  static double  reverse_free_ratio();

  static bool needs_cache_clean()                { return _needs_cache_clean; }
  static void set_needs_cache_clean(bool v)      { _needs_cache_clean = v;    }
  static void clear_inline_caches();             // clear all inline caches

  // Deoptimization
  static int  mark_for_deoptimization(DepChange& changes);
#ifdef HOTSWAP
  static int  mark_for_evol_deoptimization(instanceKlassHandle dependee);
#endif // HOTSWAP

  static void mark_all_nmethods_for_deoptimization();
  static int  mark_for_deoptimization(Method* dependee);
  static void make_marked_nmethods_zombies();
  static void make_marked_nmethods_not_entrant();

    // tells how many nmethods have dependencies
  static int number_of_nmethods_with_dependencies();

  static int get_codemem_full_count() { return _codemem_full_count; }
};

#endif // SHARE_VM_CODE_CODECACHE_HPP

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