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6988353: refactor contended sync subsystem

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Reduce complexity by factoring synchronizer.cpp

Reviewed-by: dholmes, never, coleenp
This commit is contained in:
Karen Kinnear 2010-10-22 15:59:34 -04:00
parent daa052114f
commit 22929fb78f
29 changed files with 4556 additions and 4792 deletions
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76
hotspot/src/share/vm/runtime/basicLock.cpp Normal file
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@ -0,0 +1,76 @@
/*
* Copyright (c) 1997, 2010, 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.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_basicLock.cpp.incl"
void BasicLock::print_on(outputStream* st) const {
st->print("monitor");
}
void BasicLock::move_to(oop obj, BasicLock* dest) {
// Check to see if we need to inflate the lock. This is only needed
// if an object is locked using "this" lightweight monitor. In that
// case, the displaced_header() is unlocked, because the
// displaced_header() contains the header for the originally unlocked
// object. However the object could have already been inflated. But it
// does not matter, the inflation will just a no-op. For other cases,
// the displaced header will be either 0x0 or 0x3, which are location
// independent, therefore the BasicLock is free to move.
//
// During OSR we may need to relocate a BasicLock (which contains a
// displaced word) from a location in an interpreter frame to a
// new location in a compiled frame. "this" refers to the source
// basiclock in the interpreter frame. "dest" refers to the destination
// basiclock in the new compiled frame. We *always* inflate in move_to().
// The always-Inflate policy works properly, but in 1.5.0 it can sometimes
// cause performance problems in code that makes heavy use of a small # of
// uncontended locks. (We'd inflate during OSR, and then sync performance
// would subsequently plummet because the thread would be forced thru the slow-path).
// This problem has been made largely moot on IA32 by inlining the inflated fast-path
// operations in Fast_Lock and Fast_Unlock in i486.ad.
//
// Note that there is a way to safely swing the object's markword from
// one stack location to another. This avoids inflation. Obviously,
// we need to ensure that both locations refer to the current thread's stack.
// There are some subtle concurrency issues, however, and since the benefit is
// is small (given the support for inflated fast-path locking in the fast_lock, etc)
// we'll leave that optimization for another time.
if (displaced_header()->is_neutral()) {
ObjectSynchronizer::inflate_helper(obj);
// WARNING: We can not put check here, because the inflation
// will not update the displaced header. Once BasicLock is inflated,
// no one should ever look at its content.
} else {
// Typically the displaced header will be 0 (recursive stack lock) or
// unused_mark. Naively we'd like to assert that the displaced mark
// value is either 0, neutral, or 3. But with the advent of the
// store-before-CAS avoidance in fast_lock/compiler_lock_object
// we can find any flavor mark in the displaced mark.
}
// [RGV] The next line appears to do nothing!
intptr_t dh = (intptr_t) displaced_header();
dest->set_displaced_header(displaced_header());
}