/* Block until the queue length is 0, or there is a pending suspend request */
void dvmCompilerDrainQueue(void)
{
Thread *self = dvmThreadSelf();
dvmLockMutex(&gDvmJit.compilerLock);
while (workQueueLength() != 0 && !gDvmJit.haltCompilerThread &&
self->suspendCount == 0) {
/*
* Use timed wait here - more than one mutator threads may be blocked
* but the compiler thread will only signal once when the queue is
* emptied. Furthermore, the compiler thread may have been shutdown
* so the blocked thread may never get the wakeup signal.
*/
dvmRelativeCondWait(&gDvmJit.compilerQueueEmpty, &gDvmJit.compilerLock, 1000, 0);
}
dvmUnlockMutex(&gDvmJit.compilerLock);
}
/**
* @brief 丢弃编译队列
*/
void dvmCompilerDrainQueue(void)
{
Thread *self = dvmThreadSelf();
dvmLockMutex(&gDvmJit.compilerLock);
/* 遍历整个队列，并不停的检测编译线程是否终止，并且自身线程没有被挂起 */
while (workQueueLength() != 0 && !gDvmJit.haltCompilerThread &&
self->suspendCount == 0) {
/*
* Use timed wait here - more than one mutator threads may be blocked
* but the compiler thread will only signal once when the queue is
* emptied. Furthermore, the compiler thread may have been shutdown
* so the blocked thread may never get the wakeup signal.
*/
/* 使用等待时间 - 超过一个mutator线程被阻塞但是编译器线程将
* 仅有一条一次当队列被提交，编译器线程不关闭，阻塞线程将永远不会唤醒*/
dvmRelativeCondWait(&gDvmJit.compilerQueueEmpty, &gDvmJit.compilerLock, 1000, 0);
}
dvmUnlockMutex(&gDvmJit.compilerLock);
}
static void *compilerThreadStart(void *arg)
{
dvmChangeStatus(NULL, THREAD_VMWAIT);
/*
* If we're not running stand-alone, wait a little before
* recieving translation requests on the assumption that process start
* up code isn't worth compiling. We'll resume when the framework
* signals us that the first screen draw has happened, or the timer
* below expires (to catch daemons).
*
* There is a theoretical race between the callback to
* VMRuntime.startJitCompiation and when the compiler thread reaches this
* point. In case the callback happens earlier, in order not to permanently
* hold the system_server (which is not using the timed wait) in
* interpreter-only mode we bypass the delay here.
*/
if (gDvmJit.runningInAndroidFramework &&
!gDvmJit.alreadyEnabledViaFramework) {
/*
* If the current VM instance is the system server (detected by having
* 0 in gDvm.systemServerPid), we will use the indefinite wait on the
* conditional variable to determine whether to start the JIT or not.
* If the system server detects that the whole system is booted in
* safe mode, the conditional variable will never be signaled and the
* system server will remain in the interpreter-only mode. All
* subsequent apps will be started with the --enable-safemode flag
* explicitly appended.
*/
if (gDvm.systemServerPid == 0) {
dvmLockMutex(&gDvmJit.compilerLock);
pthread_cond_wait(&gDvmJit.compilerQueueActivity,
&gDvmJit.compilerLock);
dvmUnlockMutex(&gDvmJit.compilerLock);
ALOGD("JIT started for system_server");
} else {
dvmLockMutex(&gDvmJit.compilerLock);
/*
* TUNING: experiment with the delay & perhaps make it
* target-specific
*/
dvmRelativeCondWait(&gDvmJit.compilerQueueActivity,
&gDvmJit.compilerLock, 3000, 0);
dvmUnlockMutex(&gDvmJit.compilerLock);
}
if (gDvmJit.haltCompilerThread) {
return NULL;
}
}
compilerThreadStartup();
dvmLockMutex(&gDvmJit.compilerLock);
/*
* Since the compiler thread will not touch any objects on the heap once
* being created, we just fake its state as VMWAIT so that it can be a
* bit late when there is suspend request pending.
*/
while (!gDvmJit.haltCompilerThread) {
if (workQueueLength() == 0) {
int cc;
cc = pthread_cond_signal(&gDvmJit.compilerQueueEmpty);
assert(cc == 0);
pthread_cond_wait(&gDvmJit.compilerQueueActivity,
&gDvmJit.compilerLock);
continue;
} else {
do {
CompilerWorkOrder work = workDequeue();
dvmUnlockMutex(&gDvmJit.compilerLock);
#if defined(WITH_JIT_TUNING)
/*
* This is live across setjmp(). Mark it volatile to suppress
* a gcc warning. We should not need this since it is assigned
* only once but gcc is not smart enough.
*/
volatile u8 startTime = dvmGetRelativeTimeUsec();
#endif
/*
* Check whether there is a suspend request on me. This
* is necessary to allow a clean shutdown.
*
* However, in the blocking stress testing mode, let the
* compiler thread continue doing compilations to unblock
* other requesting threads. This may occasionally cause
* shutdown from proceeding cleanly in the standalone invocation
* of the vm but this should be acceptable.
*/
if (!gDvmJit.blockingMode)
dvmCheckSuspendPending(dvmThreadSelf());
/* Is JitTable filling up? */
if (gDvmJit.jitTableEntriesUsed >
(gDvmJit.jitTableSize - gDvmJit.jitTableSize/4)) {
bool resizeFail =
dvmJitResizeJitTable(gDvmJit.jitTableSize * 2);
/*
* If the jit table is full, consider it's time to reset
* the code cache too.
*/
gDvmJit.codeCacheFull |= resizeFail;
}
if (gDvmJit.haltCompilerThread) {
ALOGD("Compiler shutdown in progress - discarding request");
} else if (!gDvmJit.codeCacheFull) {
jmp_buf jmpBuf;
work.bailPtr = &jmpBuf;
bool aborted = setjmp(jmpBuf);
if (!aborted) {
bool codeCompiled = dvmCompilerDoWork(&work);
/*
* Make sure we are still operating with the
* same translation cache version. See
* Issue 4271784 for details.
*/
dvmLockMutex(&gDvmJit.compilerLock);
if ((work.result.cacheVersion ==
gDvmJit.cacheVersion) &&
codeCompiled &&
!work.result.discardResult &&
work.result.codeAddress) {
dvmJitSetCodeAddr(work.pc, work.result.codeAddress,
work.result.instructionSet,
false, /* not method entry */
work.result.profileCodeSize);
}
dvmUnlockMutex(&gDvmJit.compilerLock);
}
dvmCompilerArenaReset();
}
free(work.info);
#if defined(WITH_JIT_TUNING)
gDvmJit.jitTime += dvmGetRelativeTimeUsec() - startTime;
#endif
dvmLockMutex(&gDvmJit.compilerLock);
} while (workQueueLength() != 0);
}
}
pthread_cond_signal(&gDvmJit.compilerQueueEmpty);
dvmUnlockMutex(&gDvmJit.compilerLock);
/*
* As part of detaching the thread we need to call into Java code to update
* the ThreadGroup, and we should not be in VMWAIT state while executing
* interpreted code.
*/
dvmChangeStatus(NULL, THREAD_RUNNING);
if (gDvm.verboseShutdown)
ALOGD("Compiler thread shutting down");
return NULL;
}
static void resetCodeCache(void)
{
Thread* thread;
u8 startTime = dvmGetRelativeTimeUsec();
int inJit = 0;
int byteUsed = gDvmJit.codeCacheByteUsed;
/* If any thread is found stuck in the JIT state, don't reset the cache */
dvmLockThreadList(NULL);
for (thread = gDvm.threadList; thread != NULL; thread = thread->next) {
/*
* Crawl the stack to wipe out the returnAddr field so that
* 1) the soon-to-be-deleted code in the JIT cache won't be used
* 2) or the thread stuck in the JIT land will soon return
* to the interpreter land
*/
crawlDalvikStack(thread, false);
if (thread->inJitCodeCache) {
inJit++;
}
/* Cancel any ongoing trace selection */
dvmDisableSubMode(thread, kSubModeJitTraceBuild);
}
dvmUnlockThreadList();
if (inJit) {
ALOGD("JIT code cache reset delayed (%d bytes %d/%d)",
gDvmJit.codeCacheByteUsed, gDvmJit.numCodeCacheReset,
++gDvmJit.numCodeCacheResetDelayed);
return;
}
/* Lock the mutex to clean up the work queue */
dvmLockMutex(&gDvmJit.compilerLock);
/* Update the translation cache version */
gDvmJit.cacheVersion++;
/* Drain the work queue to free the work orders */
while (workQueueLength()) {
CompilerWorkOrder work = workDequeue();
free(work.info);
}
/* Reset the JitEntry table contents to the initial unpopulated state */
dvmJitResetTable();
UNPROTECT_CODE_CACHE(gDvmJit.codeCache, gDvmJit.codeCacheByteUsed);
/*
* Wipe out the code cache content to force immediate crashes if
* stale JIT'ed code is invoked.
*/
dvmCompilerCacheClear((char *) gDvmJit.codeCache + gDvmJit.templateSize,
gDvmJit.codeCacheByteUsed - gDvmJit.templateSize);
dvmCompilerCacheFlush((intptr_t) gDvmJit.codeCache,
(intptr_t) gDvmJit.codeCache + gDvmJit.codeCacheByteUsed);
PROTECT_CODE_CACHE(gDvmJit.codeCache, gDvmJit.codeCacheByteUsed);
/* Reset the current mark of used bytes to the end of template code */
gDvmJit.codeCacheByteUsed = gDvmJit.templateSize;
gDvmJit.numCompilations = 0;
/* Reset the work queue */
memset(gDvmJit.compilerWorkQueue, 0,
sizeof(CompilerWorkOrder) * COMPILER_WORK_QUEUE_SIZE);
gDvmJit.compilerWorkEnqueueIndex = gDvmJit.compilerWorkDequeueIndex = 0;
gDvmJit.compilerQueueLength = 0;
/* Reset the IC patch work queue */
dvmLockMutex(&gDvmJit.compilerICPatchLock);
gDvmJit.compilerICPatchIndex = 0;
dvmUnlockMutex(&gDvmJit.compilerICPatchLock);
/*
* Reset the inflight compilation address (can only be done in safe points
* or by the compiler thread when its thread state is RUNNING).
*/
gDvmJit.inflightBaseAddr = NULL;
/* All clear now */
gDvmJit.codeCacheFull = false;
dvmUnlockMutex(&gDvmJit.compilerLock);
ALOGD("JIT code cache reset in %lld ms (%d bytes %d/%d)",
(dvmGetRelativeTimeUsec() - startTime) / 1000,
byteUsed, ++gDvmJit.numCodeCacheReset,
gDvmJit.numCodeCacheResetDelayed);
}
