/*
* 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>
static void* signalCatcherThreadStart(void* arg);
/*
* Crank up the signal catcher thread.
*
* Returns immediately.
*/
bool dvmSignalCatcherStartup(void)
{
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(void)
{
gDvm.haltSignalCatcher = true;
if (gDvm.signalCatcherHandle == 0) // not started yet
return;
pthread_kill(gDvm.signalCatcherHandle, SIGQUIT);
pthread_join(gDvm.signalCatcherHandle, NULL);
LOGV("signal catcher has shut down\n");
}
/*
* 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 log or to a file. If it's
* to a file we have a little setup to do.
*/
static void logThreadStacks(void)
{
DebugOutputTarget target;
if (gDvm.stackTraceFile == NULL) {
/* just dump to log file */
dvmCreateLogOutputTarget(&target, ANDROID_LOG_INFO, LOG_TAG);
dvmDumpAllThreadsEx(&target, true);
} else {
FILE* fp = NULL;
int cc, fd;
/*
* Open the stack trace output file, creating it if necessary. It
* needs to be world-writable so other processes can write to it.
*/
fd = open(gDvm.stackTraceFile, O_WRONLY | O_APPEND | O_CREAT, 0666);
if (fd < 0) {
LOGE("Unable to open stack trace file '%s': %s\n",
gDvm.stackTraceFile, strerror(errno));
return;
}
/* gain exclusive access to the file */
cc = flock(fd, LOCK_EX | LOCK_UN);
if (cc != 0) {
LOGV("Sleeping on flock(%s)\n", gDvm.stackTraceFile);
cc = flock(fd, LOCK_EX);
}
if (cc != 0) {
LOGE("Unable to lock stack trace file '%s': %s\n",
gDvm.stackTraceFile, strerror(errno));
close(fd);
return;
}
fp = fdopen(fd, "a");
if (fp == NULL) {
LOGE("Unable to fdopen '%s' (%d): %s\n",
gDvm.stackTraceFile, fd, strerror(errno));
flock(fd, LOCK_UN);
close(fd);
return;
}
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");
fflush(fp); /* emit at least the header if we crash during dump */
dvmDumpAllThreadsEx(&target, true);
fprintf(fp, "----- end %d -----\n", pid);
/*
* Unlock and close the file, flushing pending data before we unlock
* it. The fclose() will close the underyling fd.
*/
fflush(fp);
flock(fd, LOCK_UN);
fclose(fp);
LOGI("Wrote stack trace to '%s'\n", gDvm.stackTraceFile);
}
}
/*
* Sleep in sigwait() until a signal arrives.
*/
static void* signalCatcherThreadStart(void* arg)
{
Thread* self = dvmThreadSelf();
sigset_t mask;
int cc;
UNUSED_PARAMETER(arg);
LOGV("Signal catcher thread started (threadid=%d)\n", self->threadId);
/* set up mask with signals we want to handle */
sigemptyset(&mask);
sigaddset(&mask, SIGQUIT);
sigaddset(&mask, SIGUSR1);
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.
*
* We want to suspend all other threads, so that it's safe to
* traverse their stacks.
*
* When running under GDB we occasionally return with EINTR (e.g.
* when other threads exit).
*/
loop:
cc = sigwait(&mask, &rcvd);
if (cc != 0) {
if (cc == EINTR) {
//LOGV("sigwait: EINTR\n");
goto loop;
}
assert(!"bad result from sigwait");
}
if (!gDvm.haltSignalCatcher) {
LOGI("threadid=%d: reacting to signal %d\n",
dvmThreadSelf()->threadId, rcvd);
}
/* set our status to RUNNING, self-suspending if GC in progress */
dvmChangeStatus(self, THREAD_RUNNING);
if (gDvm.haltSignalCatcher)
break;
if (rcvd == SIGQUIT) {
dvmSuspendAllThreads(SUSPEND_FOR_STACK_DUMP);
dvmDumpLoaderStats("sig");
logThreadStacks();
if (false) {
dvmLockMutex(&gDvm.jniGlobalRefLock);
dvmDumpReferenceTable(&gDvm.jniGlobalRefTable, "JNI global");
dvmUnlockMutex(&gDvm.jniGlobalRefLock);
}
//dvmDumpTrackedAllocations(true);
dvmResumeAllThreads(SUSPEND_FOR_STACK_DUMP);
} else if (rcvd == SIGUSR1) {
#if WITH_HPROF
LOGI("SIGUSR1 forcing GC and HPROF dump\n");
hprofDumpHeap(NULL);
#else
LOGI("SIGUSR1 forcing GC (no HPROF)\n");
dvmCollectGarbage(false);
#endif
} else {
LOGE("unexpected signal %d\n", rcvd);
}
}
return NULL;
}