/*

 * 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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * Copyright 2003 Wily Technology, Inc.

 */

#include    <jni.h>

#include    <jvmti.h>

#include    "JPLISAssert.h"

#include    "Reentrancy.h"

#include    "JPLISAgent.h"

/*

 *  This module provides some utility functions to support the "same thread" re-entrancy management.

 *  Uses JVMTI TLS to store a single bit per thread.

 *  Non-zero means the thread is already inside; zero means the thread is not inside.

 */

/*

 *  Local prototypes

 */

/* Wrapper around set that does the set then re-fetches to make sure it worked.

 * Degenerates to a simple set when assertions are disabled.

 * This routine is only here because of a bug in the JVMTI where set to 0 fails.

 */

jvmtiError

confirmingTLSSet(   jvmtiEnv *      jvmtienv,

                    jthread         thread,

                    const void *    newValue);

/* Confirmation routine only; used to assure that the TLS slot holds the value we expect it to. */

void

assertTLSValue( jvmtiEnv *      jvmtienv,

                jthread         thread,

                const void *    expected);

#define JPLIS_CURRENTLY_INSIDE_TOKEN                ((void *) 0x7EFFC0BB)

#define JPLIS_CURRENTLY_OUTSIDE_TOKEN               ((void *) 0)

jvmtiError

confirmingTLSSet(   jvmtiEnv *      jvmtienv,

                    jthread         thread,

                    const void *    newValue) {

    jvmtiError  error;

    error = (*jvmtienv)->SetThreadLocalStorage(

                                    jvmtienv,

                                    thread,

                                    newValue);

    check_phase_ret_blob(error, error);

#if JPLISASSERT_ENABLEASSERTIONS

    assertTLSValue( jvmtienv,

                    thread,

                    newValue);

#endif

    return error;

}

void

assertTLSValue( jvmtiEnv *      jvmtienv,

                jthread         thread,

                const void *    expected) {

    jvmtiError  error;

    void *      test = (void *) 0x99999999;

    /* now check if we do a fetch we get what we wrote */

    error = (*jvmtienv)->GetThreadLocalStorage(

                                jvmtienv,

                                thread,

                                &test);

    check_phase_ret(error);

    jplis_assert(error == JVMTI_ERROR_NONE);

    jplis_assert(test == expected);

}

jboolean

tryToAcquireReentrancyToken(    jvmtiEnv *  jvmtienv,

                                jthread     thread) {

    jboolean    result      = JNI_FALSE;

    jvmtiError  error       = JVMTI_ERROR_NONE;

    void *      storedValue = NULL;

    error = (*jvmtienv)->GetThreadLocalStorage(

                                jvmtienv,

                                thread,

                                &storedValue);

    check_phase_ret_false(error);

    jplis_assert(error == JVMTI_ERROR_NONE);

    if ( error == JVMTI_ERROR_NONE ) {

        /* if this thread is already inside, just return false and short-circuit */

        if ( storedValue == JPLIS_CURRENTLY_INSIDE_TOKEN ) {

            result = JNI_FALSE;

        }

        else {

            /* stuff in the sentinel and return true */

#if JPLISASSERT_ENABLEASSERTIONS

            assertTLSValue( jvmtienv,

                            thread,

                            JPLIS_CURRENTLY_OUTSIDE_TOKEN);

#endif

            error = confirmingTLSSet (  jvmtienv,

                                        thread,

                                        JPLIS_CURRENTLY_INSIDE_TOKEN);

            jplis_assert(error == JVMTI_ERROR_NONE);

            if ( error != JVMTI_ERROR_NONE ) {

                result = JNI_FALSE;

            }

            else {

                result = JNI_TRUE;

            }

        }

    }

    return result;

}

void

releaseReentrancyToken(         jvmtiEnv *  jvmtienv,

                                jthread     thread)  {

    jvmtiError  error       = JVMTI_ERROR_NONE;

/* assert we hold the token */

#if JPLISASSERT_ENABLEASSERTIONS

    assertTLSValue( jvmtienv,

                    thread,

                    JPLIS_CURRENTLY_INSIDE_TOKEN);

#endif

    error = confirmingTLSSet(   jvmtienv,

                                thread,

                                JPLIS_CURRENTLY_OUTSIDE_TOKEN);

    jplis_assert(error == JVMTI_ERROR_NONE);

}