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* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
* VM thread support.
#include "jni.h"
#include "interp/InterpState.h"
#include <errno.h>
#include <cutils/sched_policy.h>
#if defined(CHECK_MUTEX) && !defined(__USE_UNIX98)
/* glibc lacks this unless you #define __USE_UNIX98 */
int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);
* Current status; these map to JDWP constants, so don't rearrange them.
* (If you do alter this, update the strings in dvmDumpThread and the
* conversion table in
* Note that "suspended" is orthogonal to these values (so says JDWP).
typedef enum ThreadStatus {
THREAD_UNDEFINED = -1, /* makes enum compatible with int32_t */
/* these match up with JDWP values */
THREAD_RUNNING = 1, /* RUNNABLE or running now */
THREAD_TIMED_WAIT = 2, /* TIMED_WAITING in Object.wait() */
THREAD_MONITOR = 3, /* BLOCKED on a monitor */
THREAD_WAIT = 4, /* WAITING in Object.wait() */
/* non-JDWP states */
THREAD_INITIALIZING = 5, /* allocated, not yet running */
THREAD_STARTING = 6, /* started, not yet on thread list */
THREAD_NATIVE = 7, /* off in a JNI native method */
THREAD_VMWAIT = 8, /* waiting on a VM resource */
THREAD_SUSPENDED = 9, /* suspended, usually by GC or debugger */
} ThreadStatus;
/* thread priorities, from java.lang.Thread */
enum {
/* initialization */
bool dvmThreadStartup(void);
bool dvmThreadObjStartup(void);
void dvmThreadShutdown(void);
void dvmSlayDaemons(void);
#define kJniLocalRefMin 32
#define kJniLocalRefMax 512 /* arbitrary; should be plenty */
#define kInternalRefDefault 32 /* equally arbitrary */
#define kInternalRefMax 4096 /* mainly a sanity check */
#define kMinStackSize (512 + STACK_OVERFLOW_RESERVE)
#define kDefaultStackSize (16*1024) /* four 4K pages */
#define kMaxStackSize (256*1024 + STACK_OVERFLOW_RESERVE)
* Our per-thread data.
* These are allocated on the system heap.
typedef struct Thread {
* Interpreter state which must be preserved across nested
* interpreter invocations (via JNI callbacks). Must be the first
* element in Thread.
InterpSaveState interpSave;
* Begin interpreter state which does not need to be preserved, but should
* be located towards the beginning of the Thread structure for
* efficiency.
JValue retval;
* This is the number of times the thread has been suspended. When the
* count drops to zero, the thread resumes.
* "dbgSuspendCount" is the portion of the suspend count that the
* debugger is responsible for. This has to be tracked separately so
* that we can recover correctly if the debugger abruptly disconnects
* (suspendCount -= dbgSuspendCount). The debugger should not be able
* to resume GC-suspended threads, because we ignore the debugger while
* a GC is in progress.
* Both of these are guarded by gDvm.threadSuspendCountLock.
* (We could store both of these in the same 32-bit, using 16-bit
* halves, to make atomic ops possible. In practice, you only need
* to read suspendCount, and we need to hold a mutex when making
* changes, so there's no need to merge them. Note the non-debug
* component will rarely be other than 1 or 0 -- not sure it's even
* possible with the way mutexes are currently used.)
int suspendCount;
int dbgSuspendCount;
u1* cardTable;
/* current limit of stack; flexes for StackOverflowError */
const u1* interpStackEnd;
/* FP of bottom-most (currently executing) stack frame on interp stack */
void* curFrame;
/* current exception, or NULL if nothing pending */
Object* exception;
/* small unique integer; useful for "thin" locks and debug messages */
u4 threadId;
bool debugIsMethodEntry;
/* interpreter stack size; our stacks are fixed-length */
int interpStackSize;
bool stackOverflowed;
InterpEntry entryPoint; // What to do when we start the interpreter
/* Assembly interpreter handler tables */
void* curHandlerTable; // Either main or alt table
void* mainHandlerTable; // Table of actual instruction handler
void* altHandlerTable; // Table of breakout handlers
void* unused0; // Consume space to keep offsets
void* unused1; // the same between builds with
void* unused2; // and without assembly interpreters
#ifdef WITH_JIT
struct JitToInterpEntries jitToInterpEntries;
* Whether the current top VM frame is in the interpreter or JIT cache:
* NULL : in the interpreter
* non-NULL: entry address of the JIT'ed code (the actual value doesn't
* matter)
void* inJitCodeCache;
unsigned char* pJitProfTable;
unsigned char** ppJitProfTable; // Used to refresh pJitProfTable
int jitThreshold;
const void* jitResumeNPC;
const u2* jitResumeDPC;
JitState jitState;
int icRechainCount;
const void* pProfileCountdown;
/* JNI local reference tracking */
IndirectRefTable jniLocalRefTable;
ReferenceTable jniLocalRefTable;
#if defined(WITH_JIT)
/* Buffer for register state during self verification */
struct ShadowSpace* shadowSpace;
int currTraceRun;
int totalTraceLen; // Number of Dalvik insts in trace
const u2* currTraceHead; // Start of the trace we're building
const u2* currRunHead; // Start of run we're building
int currRunLen; // Length of run in 16-bit words
const u2* lastPC; // Stage the PC for the threaded interpreter
intptr_t threshFilter[JIT_TRACE_THRESH_FILTER_SIZE];
JitTraceRun trace[MAX_JIT_RUN_LEN];
* Thread's current status. Can only be changed by the thread itself
* (i.e. don't mess with this from other threads).
volatile ThreadStatus status;
/* thread handle, as reported by pthread_self() */
pthread_t handle;
/* thread ID, only useful under Linux */
pid_t systemTid;
/* start (high addr) of interp stack (subtract size to get malloc addr) */
u1* interpStackStart;
/* the java/lang/Thread that we are associated with */
Object* threadObj;
/* the JNIEnv pointer associated with this thread */
JNIEnv* jniEnv;
/* internal reference tracking */
ReferenceTable internalLocalRefTable;
/* JNI native monitor reference tracking (initialized on first use) */
ReferenceTable jniMonitorRefTable;
/* hack to make JNI_OnLoad work right */
Object* classLoaderOverride;
/* mutex to guard the interrupted and the waitMonitor members */
pthread_mutex_t waitMutex;
/* pointer to the monitor lock we're currently waiting on */
/* guarded by waitMutex */
/* TODO: consider changing this to Object* for better JDWP interaction */
Monitor* waitMonitor;
/* thread "interrupted" status; stays raised until queried or thrown */
/* guarded by waitMutex */
bool interrupted;
/* links to the next thread in the wait set this thread is part of */
struct Thread* waitNext;
/* object to sleep on while we are waiting for a monitor */
pthread_cond_t waitCond;
* Set to true when the thread is in the process of throwing an
* OutOfMemoryError.
bool throwingOOME;
/* links to rest of thread list; grab global lock before traversing */
struct Thread* prev;
struct Thread* next;
/* used by threadExitCheck when a thread exits without detaching */
int threadExitCheckCount;
/* JDWP invoke-during-breakpoint support */
DebugInvokeReq invokeReq;
/* Interpreter switching */
int nextMode;
/* base time for per-thread CPU timing (used by method profiling) */
bool cpuClockBaseSet;
u8 cpuClockBase;
/* memory allocation profiling state */
AllocProfState allocProf;
u4 stackCrc;
/* PC, saved on every instruction; redundant with StackSaveArea */
const u2* currentPc2;
} Thread;
/* start point for an internal thread; mimics pthread args */
typedef void* (*InternalThreadStart)(void* arg);
/* args for internal thread creation */
typedef struct InternalStartArgs {
/* inputs */
InternalThreadStart func;
void* funcArg;
char* name;
Object* group;
bool isDaemon;
/* result */
volatile Thread** pThread;
volatile int* pCreateStatus;
} InternalStartArgs;
/* finish init */
bool dvmPrepMainForJni(JNIEnv* pEnv);
bool dvmPrepMainThread(void);
/* utility function to get the tid */
pid_t dvmGetSysThreadId(void);
* Get our Thread* from TLS.
* Returns NULL if this isn't a thread that the VM is aware of.
Thread* dvmThreadSelf(void);
/* grab the thread list global lock */
void dvmLockThreadList(Thread* self);
/* try to grab the thread list global lock */
bool dvmTryLockThreadList(void);
/* release the thread list global lock */
void dvmUnlockThreadList(void);
* Thread suspend/resume, used by the GC and debugger.
typedef enum SuspendCause {
#if defined(WITH_JIT)
SUSPEND_FOR_TBL_RESIZE, // jit-table resize
SUSPEND_FOR_IC_PATCH, // polymorphic callsite inline-cache patch
SUSPEND_FOR_CC_RESET, // code-cache reset
SUSPEND_FOR_REFRESH, // Reload data cached in interpState
} SuspendCause;
void dvmSuspendThread(Thread* thread);
void dvmSuspendSelf(bool jdwpActivity);
void dvmResumeThread(Thread* thread);
void dvmSuspendAllThreads(SuspendCause why);
void dvmResumeAllThreads(SuspendCause why);
void dvmUndoDebuggerSuspensions(void);
* Check suspend state. Grab threadListLock before calling.
bool dvmIsSuspended(const Thread* thread);
* Wait until a thread has suspended. (Used by debugger support.)
void dvmWaitForSuspend(Thread* thread);
* Check to see if we should be suspended now. If so, suspend ourselves
* by sleeping on a condition variable.
bool dvmCheckSuspendPending(Thread* self);
* Fast test for use in the interpreter. Returns "true" if our suspend
* count is nonzero.
INLINE bool dvmCheckSuspendQuick(Thread* self) {
return (self->suspendCount != 0);
* Used when changing thread state. Threads may only change their own.
* The "self" argument, which may be NULL, is accepted as an optimization.
* If you're calling this before waiting on a resource (e.g. THREAD_WAIT
* or THREAD_MONITOR), do so in the same function as the wait -- this records
* the current stack depth for the GC.
* If you're changing to THREAD_RUNNING, this will check for suspension.
* Returns the old status.
ThreadStatus dvmChangeStatus(Thread* self, ThreadStatus newStatus);
* Initialize a mutex.
INLINE void dvmInitMutex(pthread_mutex_t* pMutex)
pthread_mutexattr_t attr;
int cc;
cc = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK_NP);
assert(cc == 0);
pthread_mutex_init(pMutex, &attr);
pthread_mutex_init(pMutex, NULL); // default=PTHREAD_MUTEX_FAST_NP
* Grab a plain mutex.
INLINE void dvmLockMutex(pthread_mutex_t* pMutex)
int cc __attribute__ ((__unused__)) = pthread_mutex_lock(pMutex);
assert(cc == 0);
* Try grabbing a plain mutex. Returns 0 if successful.
INLINE int dvmTryLockMutex(pthread_mutex_t* pMutex)
int cc = pthread_mutex_trylock(pMutex);
assert(cc == 0 || cc == EBUSY);
return cc;
* Unlock pthread mutex.
INLINE void dvmUnlockMutex(pthread_mutex_t* pMutex)
int cc __attribute__ ((__unused__)) = pthread_mutex_unlock(pMutex);
assert(cc == 0);
* Destroy a mutex.
INLINE void dvmDestroyMutex(pthread_mutex_t* pMutex)
int cc __attribute__ ((__unused__)) = pthread_mutex_destroy(pMutex);
assert(cc == 0);
INLINE void dvmBroadcastCond(pthread_cond_t* pCond)
int cc __attribute__ ((__unused__)) = pthread_cond_broadcast(pCond);
assert(cc == 0);
INLINE void dvmSignalCond(pthread_cond_t* pCond)
int cc __attribute__ ((__unused__)) = pthread_cond_signal(pCond);
assert(cc == 0);
INLINE void dvmWaitCond(pthread_cond_t* pCond, pthread_mutex_t* pMutex)
int cc __attribute__ ((__unused__)) = pthread_cond_wait(pCond, pMutex);
assert(cc == 0);
* Create a thread as a result of java.lang.Thread.start().
bool dvmCreateInterpThread(Object* threadObj, int reqStackSize);
* Create a thread internal to the VM. It's visible to interpreted code,
* but found in the "system" thread group rather than "main".
bool dvmCreateInternalThread(pthread_t* pHandle, const char* name,
InternalThreadStart func, void* funcArg);
* Attach or detach the current thread from the VM.
bool dvmAttachCurrentThread(const JavaVMAttachArgs* pArgs, bool isDaemon);
void dvmDetachCurrentThread(void);
* Get the "main" or "system" thread group.
Object* dvmGetMainThreadGroup(void);
Object* dvmGetSystemThreadGroup(void);
* Given a java/lang/VMThread object, return our Thread.
Thread* dvmGetThreadFromThreadObject(Object* vmThreadObj);
* Given a pthread handle, return the associated Thread*.
* Caller must hold the thread list lock.
* Returns NULL if the thread was not found.
Thread* dvmGetThreadByHandle(pthread_t handle);
* Given a thread ID, return the associated Thread*.
* Caller must hold the thread list lock.
* Returns NULL if the thread was not found.
Thread* dvmGetThreadByThreadId(u4 threadId);
* Sleep in a thread. Returns when the sleep timer returns or the thread
* is interrupted.
void dvmThreadSleep(u8 msec, u4 nsec);
* Get the name of a thread. (For safety, hold the thread list lock.)
char* dvmGetThreadName(Thread* thread);
* Convert ThreadStatus to a string.
const char* dvmGetThreadStatusStr(ThreadStatus status);
* Return true if a thread is on the internal list. If it is, the
* thread is part of the GC's root set.
bool dvmIsOnThreadList(const Thread* thread);
* Get/set the JNIEnv field.
INLINE JNIEnv* dvmGetThreadJNIEnv(Thread* self) { return self->jniEnv; }
INLINE void dvmSetThreadJNIEnv(Thread* self, JNIEnv* env) { self->jniEnv = env;}
* Update the priority value of the underlying pthread.
void dvmChangeThreadPriority(Thread* thread, int newPriority);
/* "change flags" values for raise/reset thread priority calls */
#define kChangedPriority 0x01
#define kChangedPolicy 0x02
* If necessary, raise the thread's priority to nice=0 cgroup=fg.
* Returns bit flags indicating changes made (zero if nothing was done).
int dvmRaiseThreadPriorityIfNeeded(Thread* thread, int* pSavedThreadPrio,
SchedPolicy* pSavedThreadPolicy);
* Drop the thread priority to what it was before an earlier call to
* dvmRaiseThreadPriorityIfNeeded().
void dvmResetThreadPriority(Thread* thread, int changeFlags,
int savedThreadPrio, SchedPolicy savedThreadPolicy);
* Debug: dump information about a single thread.
void dvmDumpThread(Thread* thread, bool isRunning);
void dvmDumpThreadEx(const DebugOutputTarget* target, Thread* thread,
bool isRunning);
* Debug: dump information about all threads.
void dvmDumpAllThreads(bool grabLock);
void dvmDumpAllThreadsEx(const DebugOutputTarget* target, bool grabLock);
* Debug: kill a thread to get a debuggerd stack trace. Leaves the VM
* in an uncertain state.
void dvmNukeThread(Thread* thread);
#endif /*_DALVIK_THREAD*/