eventhandler.c

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/* @(#)eventHandler.c	1.96 06/10/25
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program 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 program 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 at /legal/license.txt). 
 * 
 * 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 or visit www.sun.com if you need additional
 * information or have any questions. 
 */
/*
 * eventHandler
 *
 * This module handles events as they come in directly from JVMTI
 * and also maps them to JDI events.  JDI events are those requested
 * at the JDI or JDWP level and seen on those levels.  Mapping is
 * one-to-many, a JVMTI event may map to several JDI events, or
 * to none.  Part of that mapping process is filteration, which 
 * eventFilter sub-module handles.  A JDI EventRequest corresponds
 * to a HandlerNode and a JDI filter to the hidden HandlerNode data
 * used by eventFilter.  For example, if at the JDI level the user
 * executed:
 *   
 *   EventRequestManager erm = vm.eventRequestManager();
 *   BreakpointRequest bp = erm.createBreakpointRequest();
 *   bp.enable();
 *   ClassPrepareRequest req = erm.createClassPrepareRequest();
 *   req.enable();
 *   req = erm.createClassPrepareRequest();
 *   req.addClassFilter("Foo*");
 *   req.enable();
 *
 * Three handlers would be created, the first with a LocationOnly
 * filter and the last with a ClassMatch  filter. 
 * When a JVMTI class prepare event for "Foobar"
 * comes in, the second handler will create one JDI event, the
 * third handler will compare the class signature, and since
 * it matchs create a second event.  There may also be internal
 * events as there are in this case, one created by the front-end
 * and one by the back-end.
 *
 * Each event kind has a handler chain, which is a doublely linked
 * list of handlers for that kind of event.
 */
#include "util.h"
#include "eventHandler.h"
#include "eventHandlerRestricted.h"
#include "eventFilter.h"
#include "eventFilterRestricted.h"
#include "standardHandlers.h"
#include "threadControl.h"
#include "eventHelper.h"
#include "classTrack.h"
#include "commonRef.h"
#include "debugLoop.h"

static HandlerID requestIdCounter;
static jbyte currentSessionID;

/* Counter of active callbacks and flag for vm_death */
static int      active_callbacks   = 0;
static jboolean vm_death_callback_active = JNI_FALSE;
static jrawMonitorID callbackLock;
static jrawMonitorID callbackBlock;

/* Macros to surround callback code (non-VM_DEATH callbacks).
 *   Note that this just keeps a count of the non-VM_DEATH callbacks that 
 *   are currently active, it does not prevent these callbacks from
 *   operating in parallel. It's the VM_DEATH callback that will wait
 *   for all these callbacks to finish up, so that it can report the
 *   VM_DEATH in a clean state.
 *   If the VM_DEATH callback is active in the BEGIN macro then this
 *   callback just blocks until released by the VM_DEATH callback.
 *   If the VM_DEATH callback is active in the END macro, then this
 *   callback will notify the VM_DEATH callback if it's the last one,
 *   and then block until released by the VM_DEATH callback.
 *   Why block? These threads are often the threads of the Java program,
 *   not blocking might mean that a return would continue execution of
 *   some java thread in the middle of VM_DEATH, this seems troubled.
 *
 *   WARNING: No not 'return' or 'goto' out of the BEGIN_CALLBACK/END_CALLBACK
 *            block, this will mess up the count.
 */

#define BEGIN_CALLBACK()                                                \
{ /* BEGIN OF CALLBACK */                                               \
    jboolean bypass = JNI_TRUE;                                         \
    debugMonitorEnter(callbackLock); {                                  \
        if (vm_death_callback_active) {                                 \
            /* allow VM_DEATH callback to finish */                     \
            debugMonitorExit(callbackLock);                             \
            /* Now block because VM is about to die */                  \
            debugMonitorEnter(callbackBlock);                           \
            debugMonitorExit(callbackBlock);                            \
        } else {                                                        \
            active_callbacks++;                                         \
            bypass = JNI_FALSE;                                         \
            debugMonitorExit(callbackLock);                             \
        }                                                               \
    }                                                                   \
    if ( !bypass ) {                                                    \
        /* BODY OF CALLBACK CODE */

#define END_CALLBACK() /* Part of bypass if body */                     \
        debugMonitorEnter(callbackLock); {                              \
            active_callbacks--;                                         \
            if (active_callbacks < 0) {                                 \
                EXIT_ERROR(0, "Problems tracking active callbacks");    \
            }                                                           \
            if (vm_death_callback_active) {                             \
                if (active_callbacks == 0) {                            \
                    debugMonitorNotifyAll(callbackLock);                \
                }                                                       \
                /* allow VM_DEATH callback to finish */                 \
                debugMonitorExit(callbackLock);                         \
                /* Now block because VM is about to die */              \
                debugMonitorEnter(callbackBlock);                       \
                debugMonitorExit(callbackBlock);                        \
            } else {                                                    \
                debugMonitorExit(callbackLock);                         \
            }                                                           \
        }                                                               \
    }                                                                   \
} /* END OF CALLBACK */

/*
 * We are starting with a very simple locking scheme
 * for event handling.  All readers and writers of data in
 * the handlers[] chain must own this lock for the duration
 * of its use. If contention becomes a problem, we can:
 * 
 * 1) create a lock per event type. 
 * 2) move to a readers/writers approach where multiple threads 
 * can access the chains simultaneously while reading (the
 * normal activity of an event callback). 
 */
static jrawMonitorID handlerLock;

typedef struct HandlerChain_ {
    HandlerNode *first;
    /* add lock here */
} HandlerChain;

/*
 * This array maps event kinds to handler chains.
 * Protected by handlerLock.
 */

static HandlerChain __handlers[EI_max-EI_min+1];

/* Given a HandlerNode, these access our private data.
 */
#define PRIVATE_DATA(node) \
       (&(((EventHandlerRestricted_HandlerNode*)(void*)(node))->private_ehpd))

#define NEXT(node) (PRIVATE_DATA(node)->private_next)
#define PREV(node) (PRIVATE_DATA(node)->private_prev)
#define CHAIN(node) (PRIVATE_DATA(node)->private_chain)
#define HANDLER_FUNCTION(node) (PRIVATE_DATA(node)->private_handlerFunction)

static jclass getMethodClass(jvmtiEnv *jvmti_env, jmethodID method);
static jvmtiError freeHandler(HandlerNode *node);

static jvmtiError freeHandlerChain(HandlerChain *chain);

static HandlerChain *
getHandlerChain(EventIndex i)
{
    if ( i < EI_min || i > EI_max ) {
        EXIT_ERROR(AGENT_ERROR_INVALID_EVENT_TYPE,"bad index for handler");
    }
    return &(__handlers[i-EI_min]);
}

static void
insert(HandlerChain *chain, HandlerNode *node)
{
    HandlerNode *oldHead = chain->first;
    NEXT(node) = oldHead;
    PREV(node) = NULL;
    CHAIN(node) = chain;
    if (oldHead != NULL) {
        PREV(oldHead) = node;
    }
    chain->first = node;
}

static HandlerNode *
findInChain(HandlerChain *chain, HandlerID handlerID)
{
    HandlerNode *node = chain->first;
    while (node != NULL) {
        if (node->handlerID == handlerID) {
            return node;
        }
        node = NEXT(node);
    }
    return NULL;
}

static HandlerNode *
find(EventIndex ei, HandlerID handlerID)
{
    return findInChain(getHandlerChain(ei), handlerID);
}

/**
 * Deinsert.  Safe for non-inserted nodes.
 */
static void
deinsert(HandlerNode *node)
{
    HandlerChain *chain = CHAIN(node);

    if (chain == NULL) {
        return;
    }
    if (chain->first == node) {
        chain->first = NEXT(node);
    }
    if (NEXT(node) != NULL) {
        PREV(NEXT(node)) = PREV(node);
    }
    if (PREV(node) != NULL) {
        NEXT(PREV(node)) = NEXT(node);
    }
    CHAIN(node) = NULL;
}

jboolean 
eventHandlerRestricted_iterator(EventIndex ei,
                              IteratorFunction func, void *arg)
{
    HandlerChain *chain;
    HandlerNode *node;
    JNIEnv *env;
    
    chain = getHandlerChain(ei);
    node = chain->first;
    env = getEnv();

    if ( func == NULL ) {
        EXIT_ERROR(AGENT_ERROR_INTERNAL,"iterator function NULL");
    }
    
    while (node != NULL) {
        if (((func)(env, node, arg))) {
            return JNI_TRUE;
        }
        node = NEXT(node);
    }
    return JNI_FALSE;
}

/* BREAKPOINT, METHOD_ENTRY and SINGLE_STEP events are covered by
 * the co-location of events policy. Of these three co-located
 * events, METHOD_ENTRY is  always reported first and BREAKPOINT
 * is always reported last. Here are the possible combinations and
 * their order:
 *
 * (p1) METHOD_ENTRY, BREAKPOINT (existing)
 * (p2) METHOD_ENTRY, BREAKPOINT (new)
 * (p1) METHOD_ENTRY, SINGLE_STEP
 * (p1) METHOD_ENTRY, SINGLE_STEP, BREAKPOINT (existing)
 * (p1/p2) METHOD_ENTRY, SINGLE_STEP, BREAKPOINT (new)
 * (p1) SINGLE_STEP, BREAKPOINT (existing)
 * (p2) SINGLE_STEP, BREAKPOINT (new)
 *
 * BREAKPOINT (existing) indicates a BREAKPOINT that is set before
 * the other co-located event is posted. BREAKPOINT (new) indicates
 * a BREAKPOINT that is set after the other co-located event is
 * posted and before the thread has resumed execution.
 *
 * Co-location of events policy used to be implemented via
 * temporary BREAKPOINTs along with deferring the reporting of
 * non-BREAKPOINT co-located events, but the temporary BREAKPOINTs
 * caused performance problems on VMs where setting or clearing
 * BREAKPOINTs is expensive, e.g., HotSpot.
 *
 * The policy is now implemented in two phases. Phase 1: when a
 * METHOD_ENTRY or SINGLE_STEP event is received, if there is an
 * existing co-located BREAKPOINT, then the current event is
 * deferred. When the BREAKPOINT event is processed, the event
 * bag will contain the deferred METHOD_ENTRY and/or SINGLE_STEP
 * events along with the BREAKPOINT event. For a METHOD_ENTRY
 * event where there is not an existing co-located BREAKPOINT,
 * if SINGLE_STEP events are also enabled for the thread, then
 * the METHOD_ENTRY event is deferred. When the SINGLE_STEP event
 * is processed, the event bag will also contain the deferred
 * METHOD_ENTRY event. This covers each of the combinations
 * marked with 'p1' above.
 *
 * Phase 2: if there is no existing co-located BREAKPOINT, then the
 * location information for the METHOD_ENTRY or SINGLE_STEP event
 * is recorded in the ThreadNode. If the next event for the thread
 * is a co-located BREAKPOINT, then the first BREAKPOINT event will
 * be skipped since it cannot be delivered in the same event set.
 * This covers each of the combinations marked with 'p2' above.
 *
 * For the combination marked p1/p2, part of the case is handled
 * during phase 1 and the rest is handled during phase 2.
 *
 * The recording of information in the ThreadNode is handled in
 * this routine. The special handling of the next event for the
 * thread is handled in skipEventReport().
 */

static jboolean
deferEventReport(JNIEnv *env, jthread thread, 
            EventIndex ei, jclass clazz, jmethodID method, jlocation location)
{
    jboolean deferring = JNI_FALSE;

    switch (ei) {
        case EI_METHOD_ENTRY:
            if (!isMethodNative(method)) {
                jvmtiError error;
                jlocation start;
                jlocation end;
                error = methodLocation(method, &start, &end);
                if (error == JVMTI_ERROR_NONE) {
                    deferring = isBreakpointSet(clazz, method, start) ||
                                threadControl_getInstructionStepMode(thread)
                                    == JVMTI_ENABLE;
                    if (!deferring) {
                        threadControl_saveCLEInfo(env, thread, ei,
                                                  clazz, method, start);
                    }
                }
            }
            break;
        case EI_SINGLE_STEP:
            deferring = isBreakpointSet(clazz, method, location);
            if (!deferring) {
                threadControl_saveCLEInfo(env, thread, ei,
                                          clazz, method, location);
            }
            break;
        default:
            break;
    }
    /* TO DO: Once JVMTI supports a way to know if we're
     * at the end of a method, we should check here for
     * break and step events which precede a method exit
     * event.  
     */
    return deferring;
}

/* Handle phase 2 of the co-located events policy. See detailed
 * comments in deferEventReport() above.
 */
static jboolean
skipEventReport(JNIEnv *env, jthread thread, EventIndex ei,
                        jclass clazz, jmethodID method, jlocation location)
{ 
    jboolean skipping = JNI_FALSE;

    if (ei == EI_BREAKPOINT) {
        if (threadControl_cmpCLEInfo(env, thread, clazz, method, location)) {
            LOG_MISC(("Co-located breakpoint event found: "
                "%s,thread=%p,clazz=%p,method=%p,location=%d",
                eventText(ei), thread, clazz, method, location));
            skipping = JNI_TRUE;
        }
    }

    threadControl_clearCLEInfo(env, thread);

    return skipping;
}

static void 
reportEvents(JNIEnv *env, jbyte sessionID, jthread thread, EventIndex ei,
             jclass clazz, jmethodID method, jlocation location,
             struct bag *eventBag)
{
    jbyte suspendPolicy;
    jboolean invoking;

    if (bagSize(eventBag) < 1) {
        return;
    }

    /*
     * Never report events before initialization completes
     */
    if (!debugInit_isInitComplete()) {
        return;
    }

    /*
     * Check to see if we should skip reporting this event due to
     * co-location of events policy.
     */
    if (thread != NULL && 
           skipEventReport(env, thread, ei, clazz, method, location)) {
        LOG_MISC(("event report being skipped: "
            "ei=%s,thread=%p,clazz=%p,method=%p,location=%d",
            eventText(ei), thread, clazz, method, location));
        bagDeleteAll(eventBag);
        return;
    }

    /* We delay the reporting of some events so that they can be