/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This is a thread that catches signals and does something useful. For
* example, when a SIGQUIT (Ctrl-\) arrives, suspend the VM and dump the
* status of all threads.
*/
#include "Dalvik.h"
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <pthread.h>
#include <sys/file.h>
#include <sys/time.h>
#include <fcntl.h>
#include <errno.h>
#include <cutils/open_memstream.h>
static void* signalCatcherThreadStart(void* arg);
/*
* Crank up the signal catcher thread.
*
* Returns immediately.
*/
bool dvmSignalCatcherStartup()
{
gDvm.haltSignalCatcher = false;
if (!dvmCreateInternalThread(&gDvm.signalCatcherHandle,
"Signal Catcher", signalCatcherThreadStart, NULL))
return false;
return true;
}
/*
* Shut down the signal catcher thread if it was started.
*
* Since we know the thread is just sitting around waiting for signals
* to arrive, send it one.
*/
void dvmSignalCatcherShutdown()
{
gDvm.haltSignalCatcher = true;
if (gDvm.signalCatcherHandle == 0) // not started yet
return;
pthread_kill(gDvm.signalCatcherHandle, SIGQUIT);
pthread_join(gDvm.signalCatcherHandle, NULL);
ALOGV("signal catcher has shut down");
}
/*
* Print the name of the current process, if we can get it.
*/
static void printProcessName(const DebugOutputTarget* target)
{
int fd = -1;
fd = open("/proc/self/cmdline", O_RDONLY, 0);
if (fd < 0)
goto bail;
char tmpBuf[256];
ssize_t actual;
actual = read(fd, tmpBuf, sizeof(tmpBuf)-1);
if (actual <= 0)
goto bail;
tmpBuf[actual] = '\0';
dvmPrintDebugMessage(target, "Cmd line: %s\n", tmpBuf);
bail:
if (fd >= 0)
close(fd);
}
/*
* Dump the stack traces for all threads to the supplied file, putting
* a timestamp header on it.
*/
static void logThreadStacks(FILE* fp)
{
DebugOutputTarget target;
dvmCreateFileOutputTarget(&target, fp);
pid_t pid = getpid();
time_t now = time(NULL);
struct tm* ptm;
#ifdef HAVE_LOCALTIME_R
struct tm tmbuf;
ptm = localtime_r(&now, &tmbuf);
#else
ptm = localtime(&now);
#endif
dvmPrintDebugMessage(&target,
"\n\n----- pid %d at %04d-%02d-%02d %02d:%02d:%02d -----\n",
pid, ptm->tm_year + 1900, ptm->tm_mon+1, ptm->tm_mday,
ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
printProcessName(&target);
dvmPrintDebugMessage(&target, "\n");
dvmDumpAllThreadsEx(&target, true);
fprintf(fp, "----- end %d -----\n", pid);
}
/*
* Respond to a SIGQUIT by dumping the thread stacks. Optionally dump
* a few other things while we're at it.
*
* Thread stacks can either go to the log or to a file designated for holding
* ANR traces. If we're writing to a file, we want to do it in one shot,
* so we can use a single O_APPEND write instead of contending for exclusive
* access with flock(). There may be an advantage in resuming the VM
* before doing the file write, so we don't stall the VM if disk I/O is
* bottlenecked.
*
* If JIT tuning is compiled in, dump compiler stats as well.
*/
static void handleSigQuit()
{
char* traceBuf = NULL;
size_t traceLen;
dvmSuspendAllThreads(SUSPEND_FOR_STACK_DUMP);
dvmDumpLoaderStats("sig");
if (gDvm.stackTraceFile == NULL) {
/* just dump to log */
DebugOutputTarget target;
dvmCreateLogOutputTarget(&target, ANDROID_LOG_INFO, LOG_TAG);
dvmDumpAllThreadsEx(&target, true);
} else {
/* write to memory buffer */
FILE* memfp = open_memstream(&traceBuf, &traceLen);
if (memfp == NULL) {
ALOGE("Unable to create memstream for stack traces");
traceBuf = NULL; /* make sure it didn't touch this */
/* continue on */
} else {
logThreadStacks(memfp);
fclose(memfp);
}
}
#if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
dvmCompilerDumpStats();
#endif
if (false) dvmDumpTrackedAllocations(true);
dvmResumeAllThreads(SUSPEND_FOR_STACK_DUMP);
if (traceBuf != NULL) {
/*
* We don't know how long it will take to do the disk I/O, so put us
* into VMWAIT for the duration.
*/
ThreadStatus oldStatus = dvmChangeStatus(dvmThreadSelf(), THREAD_VMWAIT);
/*
* Open the stack trace output file, creating it if necessary. It
* needs to be world-writable so other processes can write to it.
*/
int fd = open(gDvm.stackTraceFile, O_WRONLY | O_APPEND | O_CREAT, 0666);
if (fd < 0) {
ALOGE("Unable to open stack trace file '%s': %s",
gDvm.stackTraceFile, strerror(errno));
} else {
ssize_t actual = write(fd, traceBuf, traceLen);
if (actual != (ssize_t) traceLen) {
ALOGE("Failed to write stack traces to %s (%d of %zd): %s",
gDvm.stackTraceFile, (int) actual, traceLen,
strerror(errno));
} else {
ALOGI("Wrote stack traces to '%s'", gDvm.stackTraceFile);
}
close(fd);
}
free(traceBuf);
dvmChangeStatus(dvmThreadSelf(), oldStatus);
}
}
/*
* Respond to a SIGUSR1 by forcing a GC.
*/
static void handleSigUsr1()
{
ALOGI("SIGUSR1 forcing GC (no HPROF)");
dvmCollectGarbage();
}
#if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
/* Sample callback function for dvmJitScanAllClassPointers */
void printAllClass(void *ptr)
{
ClassObject **classPP = (ClassObject **) ptr;
ALOGE("class %s", (*classPP)->descriptor);
}
/*
* Respond to a SIGUSR2 by dumping some JIT stats and possibly resetting
* the code cache.
*/
static void handleSigUsr2()
{
static int codeCacheResetCount = 0;
gDvmJit.receivedSIGUSR2 ^= true;
if ((--codeCacheResetCount & 7) == 0) {
/* Dump all class pointers in the traces */
dvmJitScanAllClassPointers(printAllClass);
gDvmJit.codeCacheFull = true;
} else {
dvmCompilerDumpStats();
/* Stress-test unchain all */
dvmJitUnchainAll();
ALOGD("Send %d more signals to reset the code cache",
codeCacheResetCount & 7);
}
dvmCheckInterpStateConsistency();
}
#endif
/*
* Sleep in sigwait() until a signal arrives.
*/
static void* signalCatcherThreadStart(void* arg)
{
Thread* self = dvmThreadSelf();
sigset_t mask;
int cc;
UNUSED_PARAMETER(arg);
ALOGV("Signal catcher thread started (threadid=%d)", self->threadId);
/* set up mask with signals we want to handle */
sigemptyset(&mask);
sigaddset(&mask, SIGQUIT);
sigaddset(&mask, SIGUSR1);
#if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
sigaddset(&mask, SIGUSR2);
#endif
while (true) {
int rcvd;
dvmChangeStatus(self, THREAD_VMWAIT);
/*
* Signals for sigwait() must be blocked but not ignored. We
* block signals like SIGQUIT for all threads, so the condition
* is met. When the signal hits, we wake up, without any signal
* handlers being invoked.
*
* When running under GDB we occasionally return from sigwait()
* with EINTR (e.g. when other threads exit).
*/
loop:
cc = sigwait(&mask, &rcvd);
if (cc != 0) {
if (cc == EINTR) {
//ALOGV("sigwait: EINTR");
goto loop;
}
assert(!"bad result from sigwait");
}
if (!gDvm.haltSignalCatcher) {
ALOGI("threadid=%d: reacting to signal %d",
dvmThreadSelf()->threadId, rcvd);
}
/* set our status to RUNNING, self-suspending if GC in progress */
dvmChangeStatus(self, THREAD_RUNNING);
if (gDvm.haltSignalCatcher)
break;
switch (rcvd) {
case SIGQUIT:
handleSigQuit();
break;
case SIGUSR1:
handleSigUsr1();
break;
#if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
case SIGUSR2:
handleSigUsr2();
break;
#endif
default:
ALOGE("unexpected signal %d", rcvd);
break;
}
}
return NULL;
}