text: /*
   * 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");
      dvmDumpJniStats(&target);
      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);
          dvmDumpJniStats(&target);
          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 = TEMP_FAILURE_RETRY(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;
  }
  