/*

 * Copyright (c) 1998, 2005, 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.

 *

 */

public:

  // Java Thread  - force inlining

  static inline Thread* thread() ;

private:

  static Thread* _get_thread_cache[];  // index by [(raw_id>>9)^(raw_id>>20) % _pd_cache_size]

  static Thread* get_thread_via_cache_slowly(uintptr_t raw_id, int index);

  NOT_PRODUCT(static int _tcacheHit;)

  NOT_PRODUCT(static int _tcacheMiss;)

public:

  // Print cache hit/miss statistics

  static void print_statistics() PRODUCT_RETURN;

  enum Constants {

    _pd_cache_size         =  256*2  // projected typical # of threads * 2

  };

  static void set_thread_in_slot (Thread *) ;

  static uintptr_t pd_raw_thread_id() {

    return _raw_thread_id();

  }

  static int pd_cache_index(uintptr_t raw_id) {

    // Hash function: From email from Dave:

    // The hash function deserves an explanation.  %g7 points to libthread's

    // "thread" structure.  On T1 the thread structure is allocated on the

    // user's stack (yes, really!) so the ">>20" handles T1 where the JVM's

    // stack size is usually >= 1Mb.  The ">>9" is for T2 where Roger allocates

    // globs of thread blocks contiguously.  The "9" has to do with the

    // expected size of the T2 thread structure.  If these constants are wrong

    // the worst thing that'll happen is that the hit rate for heavily threaded

    // apps won't be as good as it could be.  If you want to burn another

    // shift+xor you could mix together _all of the %g7 bits to form the hash,

    // but I think that's excessive.  Making the change above changed the

    // T$ miss rate on SpecJBB (on a 16X system) from about 3% to imperceptible.

    uintptr_t ix = (int) (((raw_id >> 9) ^ (raw_id >> 20)) % _pd_cache_size);

    return ix;

  }