/*

 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * This source code is provided to illustrate the usage of a given feature

 * or technique and has been deliberately simplified. Additional steps

 * required for a production-quality application, such as security checks,

 * input validation and proper error handling, might not be present in

 * this sample code.

 */

#include "hprof.h"

/* This file contains the cpu loop for the option cpu=samples */

/* The cpu_loop thread basically waits for gdata->sample_interval millisecs

 *   then wakes up, and for each running thread it gets their stack trace,

 *   and updates the traces with 'hits'.

 *

 * No threads are suspended or resumed, and the thread sampling is in the

 *   file hprof_tls.c, which manages all active threads. The sampling

 *   technique (what is sampled) is also in hprof_tls.c.

 *

 * No adjustments are made to the pause time or sample interval except

 *   by the user via the interval=n option (default is 10ms).

 *

 * This thread can cause havoc when started prematurely or not terminated

 *   properly, see cpu_sample_init() and cpu_term(), and their calls in hprof_init.c.

 *

 * The listener loop (hprof_listener.c) can dynamically turn on or off the

 *  sampling of all or selected threads.

 *

 */

/* Private functions */

static void JNICALL

cpu_loop_function(jvmtiEnv *jvmti, JNIEnv *env, void *p)

{

    int         loop_trip_counter;

    jboolean    cpu_loop_running;

    loop_trip_counter          = 0;

    rawMonitorEnter(gdata->cpu_loop_lock); {

        gdata->cpu_loop_running = JNI_TRUE;

        cpu_loop_running = gdata->cpu_loop_running;

        /* Notify cpu_sample_init() that we have started */

        rawMonitorNotifyAll(gdata->cpu_loop_lock);

    } rawMonitorExit(gdata->cpu_loop_lock);

    rawMonitorEnter(gdata->cpu_sample_lock); /* Only waits inside loop let go */

    while ( cpu_loop_running ) {

        ++loop_trip_counter;

        LOG3("cpu_loop()", "iteration", loop_trip_counter);

        /* If a dump is in progress, we pause sampling. */

        rawMonitorEnter(gdata->dump_lock); {

            if (gdata->dump_in_process) {

                gdata->pause_cpu_sampling = JNI_TRUE;

            }

        } rawMonitorExit(gdata->dump_lock);

        /* Check to see if we need to pause sampling (listener_loop command) */

        if (gdata->pause_cpu_sampling) {

            /*

             * Pause sampling for now. Reset sample controls if

             * sampling is resumed again.

             */

            rawMonitorWait(gdata->cpu_sample_lock, 0);

            rawMonitorEnter(gdata->cpu_loop_lock); {

                cpu_loop_running = gdata->cpu_loop_running;

            } rawMonitorExit(gdata->cpu_loop_lock);

            /* Continue the while loop, which will terminate if done. */

            continue;

        }

        /* This is the normal short timed wait before getting a sample */

        rawMonitorWait(gdata->cpu_sample_lock,  (jlong)gdata->sample_interval);

        /* Make sure we really want to continue */

        rawMonitorEnter(gdata->cpu_loop_lock); {

            cpu_loop_running = gdata->cpu_loop_running;

        } rawMonitorExit(gdata->cpu_loop_lock);

        /* Break out if we are done */

        if ( !cpu_loop_running ) {

            break;

        }

        /*

         * If a dump request came in after we checked at the top of

         * the while loop, then we catch that fact here. We

         * don't want to perturb the data that is being dumped so

         * we just ignore the data from this sampling loop.

         */

        rawMonitorEnter(gdata->dump_lock); {

            if (gdata->dump_in_process) {

                gdata->pause_cpu_sampling = JNI_TRUE;

            }

        } rawMonitorExit(gdata->dump_lock);

        /* Sample all the threads and update trace costs */

        if ( !gdata->pause_cpu_sampling) {

            tls_sample_all_threads(env);

        }

        /* Check to see if we need to finish */

        rawMonitorEnter(gdata->cpu_loop_lock); {

            cpu_loop_running = gdata->cpu_loop_running;

        } rawMonitorExit(gdata->cpu_loop_lock);

    }

    rawMonitorExit(gdata->cpu_sample_lock);

    rawMonitorEnter(gdata->cpu_loop_lock); {

        /* Notify cpu_sample_term() that we are done. */

        rawMonitorNotifyAll(gdata->cpu_loop_lock);

    } rawMonitorExit(gdata->cpu_loop_lock);

    LOG2("cpu_loop()", "clean termination");

}

/* External functions */

void

cpu_sample_init(JNIEnv *env)

{

    gdata->cpu_sampling  = JNI_TRUE;

    /* Create the raw monitors needed */

    gdata->cpu_loop_lock = createRawMonitor("HPROF cpu loop lock");

    gdata->cpu_sample_lock = createRawMonitor("HPROF cpu sample lock");

    rawMonitorEnter(gdata->cpu_loop_lock); {

        createAgentThread(env, "HPROF cpu sampling thread",

                            &cpu_loop_function);

        /* Wait for cpu_loop_function() to notify us it has started. */

        rawMonitorWait(gdata->cpu_loop_lock, 0);

    } rawMonitorExit(gdata->cpu_loop_lock);

}

void

cpu_sample_off(JNIEnv *env, ObjectIndex object_index)

{

    jint count;

    count = 1;

    if (object_index != 0) {

        tls_set_sample_status(object_index, 0);

        count = tls_sum_sample_status();

    }

    if ( count == 0 ) {

        gdata->pause_cpu_sampling = JNI_TRUE;

    } else {

        gdata->pause_cpu_sampling = JNI_FALSE;

    }

}

void

cpu_sample_on(JNIEnv *env, ObjectIndex object_index)

{

    if ( gdata->cpu_loop_lock == NULL ) {

        cpu_sample_init(env);

    }

    if (object_index == 0) {

        gdata->cpu_sampling             = JNI_TRUE;

        gdata->pause_cpu_sampling       = JNI_FALSE;

    } else {

        jint     count;

        tls_set_sample_status(object_index, 1);

        count = tls_sum_sample_status();

        if ( count > 0 ) {

            gdata->pause_cpu_sampling   = JNI_FALSE;

        }

    }

    /* Notify the CPU sampling thread that sampling is on */

    rawMonitorEnter(gdata->cpu_sample_lock); {

        rawMonitorNotifyAll(gdata->cpu_sample_lock);

    } rawMonitorExit(gdata->cpu_sample_lock);

}

void

cpu_sample_term(JNIEnv *env)

{

    gdata->pause_cpu_sampling   = JNI_FALSE;

    rawMonitorEnter(gdata->cpu_sample_lock); {

        /* Notify the CPU sampling thread to get out of any sampling Wait */

        rawMonitorNotifyAll(gdata->cpu_sample_lock);

    } rawMonitorExit(gdata->cpu_sample_lock);

    rawMonitorEnter(gdata->cpu_loop_lock); {

        if ( gdata->cpu_loop_running ) {

            gdata->cpu_loop_running = JNI_FALSE;

            /* Wait for cpu_loop_function() thread to tell us it completed. */

            rawMonitorWait(gdata->cpu_loop_lock, 0);

        }

    } rawMonitorExit(gdata->cpu_loop_lock);

}