Thread.h revision 375fb116bcb817b37509ab579dbd55cdbb765cbf 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * VM thread support.
19 */
20#ifndef DALVIK_THREAD_H_
21#define DALVIK_THREAD_H_
22
23#include "jni.h"
24#include "interp/InterpState.h"
25
26#include <errno.h>
27#include <cutils/sched_policy.h>
28
29#if defined(CHECK_MUTEX) && !defined(__USE_UNIX98)
30/* glibc lacks this unless you #define __USE_UNIX98 */
31int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);
32enum { PTHREAD_MUTEX_ERRORCHECK = PTHREAD_MUTEX_ERRORCHECK_NP };
33#endif
34
35/*
36 * Current status; these map to JDWP constants, so don't rearrange them.
37 * (If you do alter this, update the strings in dvmDumpThread and the
38 * conversion table in VMThread.java.)
39 *
40 * Note that "suspended" is orthogonal to these values (so says JDWP).
41 */
42enum ThreadStatus {
43    THREAD_UNDEFINED    = -1,       /* makes enum compatible with int32_t */
44
45    /* these match up with JDWP values */
46    THREAD_ZOMBIE       = 0,        /* TERMINATED */
47    THREAD_RUNNING      = 1,        /* RUNNABLE or running now */
48    THREAD_TIMED_WAIT   = 2,        /* TIMED_WAITING in Object.wait() */
49    THREAD_MONITOR      = 3,        /* BLOCKED on a monitor */
50    THREAD_WAIT         = 4,        /* WAITING in Object.wait() */
51    /* non-JDWP states */
52    THREAD_INITIALIZING = 5,        /* allocated, not yet running */
53    THREAD_STARTING     = 6,        /* started, not yet on thread list */
54    THREAD_NATIVE       = 7,        /* off in a JNI native method */
55    THREAD_VMWAIT       = 8,        /* waiting on a VM resource */
56    THREAD_SUSPENDED    = 9,        /* suspended, usually by GC or debugger */
57};
58
59/* thread priorities, from java.lang.Thread */
60enum {
61    THREAD_MIN_PRIORITY     = 1,
62    THREAD_NORM_PRIORITY    = 5,
63    THREAD_MAX_PRIORITY     = 10,
64};
65
66
67/* initialization */
68bool dvmThreadStartup(void);
69void dvmThreadShutdown(void);
70void dvmSlayDaemons(void);
71
72
73#define kJniLocalRefMin         64
74#define kJniLocalRefMax         512     /* arbitrary; should be plenty */
75#define kInternalRefDefault     32      /* equally arbitrary */
76#define kInternalRefMax         4096    /* mainly a sanity check */
77
78#define kMinStackSize       (512 + STACK_OVERFLOW_RESERVE)
79#define kDefaultStackSize   (16*1024)   /* four 4K pages */
80#define kMaxStackSize       (256*1024 + STACK_OVERFLOW_RESERVE)
81
82/*
83 * Interpreter control struction.  Packed into a long long to enable
84 * atomic updates.
85 */
86union InterpBreak {
87    volatile int64_t   all;
88    struct {
89        uint16_t   subMode;
90        uint8_t    breakFlags;
91        int8_t     unused;   /* for future expansion */
92#ifndef DVM_NO_ASM_INTERP
93        void* curHandlerTable;
94#else
95        void* unused;
96#endif
97    } ctl;
98};
99
100/*
101 * Our per-thread data.
102 *
103 * These are allocated on the system heap.
104 */
105struct Thread {
106    /*
107     * Interpreter state which must be preserved across nested
108     * interpreter invocations (via JNI callbacks).  Must be the first
109     * element in Thread.
110     */
111    InterpSaveState interpSave;
112
113    /* small unique integer; useful for "thin" locks and debug messages */
114    u4          threadId;
115
116    /*
117     * Begin interpreter state which does not need to be preserved, but should
118     * be located towards the beginning of the Thread structure for
119     * efficiency.
120     */
121
122    /*
123     * interpBreak contains info about the interpreter mode, as well as
124     * a count of the number of times the thread has been suspended.  When
125     * the count drops to zero, the thread resumes.
126     */
127    InterpBreak interpBreak;
128
129    /*
130     * "dbgSuspendCount" is the portion of the suspend count that the
131     * debugger is responsible for.  This has to be tracked separately so
132     * that we can recover correctly if the debugger abruptly disconnects
133     * (suspendCount -= dbgSuspendCount).  The debugger should not be able
134     * to resume GC-suspended threads, because we ignore the debugger while
135     * a GC is in progress.
136     *
137     * Both of these are guarded by gDvm.threadSuspendCountLock.
138     *
139     * Note the non-debug component will rarely be other than 1 or 0 -- (not
140     * sure it's even possible with the way mutexes are currently used.)
141     */
142
143    int suspendCount;
144    int dbgSuspendCount;
145
146    u1*         cardTable;
147
148    /* current limit of stack; flexes for StackOverflowError */
149    const u1*   interpStackEnd;
150
151    /* FP of bottom-most (currently executing) stack frame on interp stack */
152    void*       XcurFrame;
153    /* current exception, or NULL if nothing pending */
154    Object*     exception;
155
156    bool        debugIsMethodEntry;
157    /* interpreter stack size; our stacks are fixed-length */
158    int         interpStackSize;
159    bool        stackOverflowed;
160
161    /* thread handle, as reported by pthread_self() */
162    pthread_t   handle;
163
164    /* Assembly interpreter handler tables */
165#ifndef DVM_NO_ASM_INTERP
166    void*       mainHandlerTable;   // Table of actual instruction handler
167    void*       altHandlerTable;    // Table of breakout handlers
168#else
169    void*       unused0;            // Consume space to keep offsets
170    void*       unused1;            //   the same between builds with
171#endif
172
173    /*
174     * singleStepCount is a countdown timer used with the breakFlag
175     * kInterpSingleStep.  If kInterpSingleStep is set in breakFlags,
176     * singleStepCount will decremented each instruction execution.
177     * Once it reaches zero, the kInterpSingleStep flag in breakFlags
178     * will be cleared.  This can be used to temporarily prevent
179     * execution from re-entering JIT'd code or force inter-instruction
180     * checks by delaying the reset of curHandlerTable to mainHandlerTable.
181     */
182    int         singleStepCount;
183
184#ifdef WITH_JIT
185    struct JitToInterpEntries jitToInterpEntries;
186    /*
187     * Whether the current top VM frame is in the interpreter or JIT cache:
188     *   NULL    : in the interpreter
189     *   non-NULL: entry address of the JIT'ed code (the actual value doesn't
190     *             matter)
191     */
192    void*             inJitCodeCache;
193    unsigned char*    pJitProfTable;
194    int               jitThreshold;
195    const void*       jitResumeNPC;     // Translation return point
196    const u4*         jitResumeNSP;     // Native SP at return point
197    const u2*         jitResumeDPC;     // Dalvik inst following single-step
198    JitState    jitState;
199    int         icRechainCount;
200    const void* pProfileCountdown;
201    const ClassObject* callsiteClass;
202    const Method*     methodToCall;
203#endif
204
205    /* JNI local reference tracking */
206    IndirectRefTable jniLocalRefTable;
207
208#if defined(WITH_JIT)
209#if defined(WITH_SELF_VERIFICATION)
210    /* Buffer for register state during self verification */
211    struct ShadowSpace* shadowSpace;
212#endif
213    int         currTraceRun;
214    int         totalTraceLen;  // Number of Dalvik insts in trace
215    const u2*   currTraceHead;  // Start of the trace we're building
216    const u2*   currRunHead;    // Start of run we're building
217    int         currRunLen;     // Length of run in 16-bit words
218    const u2*   lastPC;         // Stage the PC for the threaded interpreter
219    const Method*  traceMethod; // Starting method of current trace
220    intptr_t    threshFilter[JIT_TRACE_THRESH_FILTER_SIZE];
221    JitTraceRun trace[MAX_JIT_RUN_LEN];
222#endif
223
224    /*
225     * Thread's current status.  Can only be changed by the thread itself
226     * (i.e. don't mess with this from other threads).
227     */
228    volatile ThreadStatus status;
229
230    /* thread ID, only useful under Linux */
231    pid_t       systemTid;
232
233    /* start (high addr) of interp stack (subtract size to get malloc addr) */
234    u1*         interpStackStart;
235
236    /* the java/lang/Thread that we are associated with */
237    Object*     threadObj;
238
239    /* the JNIEnv pointer associated with this thread */
240    JNIEnv*     jniEnv;
241
242    /* internal reference tracking */
243    ReferenceTable  internalLocalRefTable;
244
245
246    /* JNI native monitor reference tracking (initialized on first use) */
247    ReferenceTable  jniMonitorRefTable;
248
249    /* hack to make JNI_OnLoad work right */
250    Object*     classLoaderOverride;
251
252    /* mutex to guard the interrupted and the waitMonitor members */
253    pthread_mutex_t    waitMutex;
254
255    /* pointer to the monitor lock we're currently waiting on */
256    /* guarded by waitMutex */
257    /* TODO: consider changing this to Object* for better JDWP interaction */
258    Monitor*    waitMonitor;
259
260    /* thread "interrupted" status; stays raised until queried or thrown */
261    /* guarded by waitMutex */
262    bool        interrupted;
263
264    /* links to the next thread in the wait set this thread is part of */
265    struct Thread*     waitNext;
266
267    /* object to sleep on while we are waiting for a monitor */
268    pthread_cond_t     waitCond;
269
270    /*
271     * Set to true when the thread is in the process of throwing an
272     * OutOfMemoryError.
273     */
274    bool        throwingOOME;
275
276    /* links to rest of thread list; grab global lock before traversing */
277    struct Thread* prev;
278    struct Thread* next;
279
280    /* used by threadExitCheck when a thread exits without detaching */
281    int         threadExitCheckCount;
282
283    /* JDWP invoke-during-breakpoint support */
284    DebugInvokeReq  invokeReq;
285
286    /* base time for per-thread CPU timing (used by method profiling) */
287    bool        cpuClockBaseSet;
288    u8          cpuClockBase;
289
290    /* memory allocation profiling state */
291    AllocProfState allocProf;
292
293#ifdef WITH_JNI_STACK_CHECK
294    u4          stackCrc;
295#endif
296
297#if WITH_EXTRA_GC_CHECKS > 1
298    /* PC, saved on every instruction; redundant with StackSaveArea */
299    const u2*   currentPc2;
300#endif
301
302    /* Safepoint callback state */
303    pthread_mutex_t   callbackMutex;
304    SafePointCallback callback;
305    void*             callbackArg;
306};
307
308/* start point for an internal thread; mimics pthread args */
309typedef void* (*InternalThreadStart)(void* arg);
310
311/* args for internal thread creation */
312struct InternalStartArgs {
313    /* inputs */
314    InternalThreadStart func;
315    void*       funcArg;
316    char*       name;
317    Object*     group;
318    bool        isDaemon;
319    /* result */
320    volatile Thread** pThread;
321    volatile int*     pCreateStatus;
322};
323
324/* finish init */
325bool dvmPrepMainForJni(JNIEnv* pEnv);
326bool dvmPrepMainThread(void);
327
328/* utility function to get the tid */
329pid_t dvmGetSysThreadId(void);
330
331/*
332 * Get our Thread* from TLS.
333 *
334 * Returns NULL if this isn't a thread that the VM is aware of.
335 */
336Thread* dvmThreadSelf(void);
337
338/* grab the thread list global lock */
339void dvmLockThreadList(Thread* self);
340/* try to grab the thread list global lock */
341bool dvmTryLockThreadList(void);
342/* release the thread list global lock */
343void dvmUnlockThreadList(void);
344
345/*
346 * Thread suspend/resume, used by the GC and debugger.
347 */
348enum SuspendCause {
349    SUSPEND_NOT = 0,
350    SUSPEND_FOR_GC,
351    SUSPEND_FOR_DEBUG,
352    SUSPEND_FOR_DEBUG_EVENT,
353    SUSPEND_FOR_STACK_DUMP,
354    SUSPEND_FOR_DEX_OPT,
355    SUSPEND_FOR_VERIFY,
356    SUSPEND_FOR_HPROF,
357#if defined(WITH_JIT)
358    SUSPEND_FOR_TBL_RESIZE,  // jit-table resize
359    SUSPEND_FOR_IC_PATCH,    // polymorphic callsite inline-cache patch
360    SUSPEND_FOR_CC_RESET,    // code-cache reset
361    SUSPEND_FOR_REFRESH,     // Reload data cached in interpState
362#endif
363};
364void dvmSuspendThread(Thread* thread);
365void dvmSuspendSelf(bool jdwpActivity);
366void dvmResumeThread(Thread* thread);
367void dvmSuspendAllThreads(SuspendCause why);
368void dvmResumeAllThreads(SuspendCause why);
369void dvmUndoDebuggerSuspensions(void);
370
371/*
372 * Check suspend state.  Grab threadListLock before calling.
373 */
374bool dvmIsSuspended(const Thread* thread);
375
376/*
377 * Wait until a thread has suspended.  (Used by debugger support.)
378 */
379void dvmWaitForSuspend(Thread* thread);
380
381/*
382 * Check to see if we should be suspended now.  If so, suspend ourselves
383 * by sleeping on a condition variable.
384 */
385extern "C" bool dvmCheckSuspendPending(Thread* self);
386
387/*
388 * Fast test for use in the interpreter.  Returns "true" if our suspend
389 * count is nonzero.
390 */
391INLINE bool dvmCheckSuspendQuick(Thread* self) {
392    return (self->interpBreak.ctl.subMode & kSubModeSuspendPending);
393}
394
395/*
396 * Used when changing thread state.  Threads may only change their own.
397 * The "self" argument, which may be NULL, is accepted as an optimization.
398 *
399 * If you're calling this before waiting on a resource (e.g. THREAD_WAIT
400 * or THREAD_MONITOR), do so in the same function as the wait -- this records
401 * the current stack depth for the GC.
402 *
403 * If you're changing to THREAD_RUNNING, this will check for suspension.
404 *
405 * Returns the old status.
406 */
407ThreadStatus dvmChangeStatus(Thread* self, ThreadStatus newStatus);
408
409/*
410 * Initialize a mutex.
411 */
412INLINE void dvmInitMutex(pthread_mutex_t* pMutex)
413{
414#ifdef CHECK_MUTEX
415    pthread_mutexattr_t attr;
416    int cc;
417
418    pthread_mutexattr_init(&attr);
419    cc = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK_NP);
420    assert(cc == 0);
421    pthread_mutex_init(pMutex, &attr);
422    pthread_mutexattr_destroy(&attr);
423#else
424    pthread_mutex_init(pMutex, NULL);       // default=PTHREAD_MUTEX_FAST_NP
425#endif
426}
427
428/*
429 * Grab a plain mutex.
430 */
431INLINE void dvmLockMutex(pthread_mutex_t* pMutex)
432{
433    int cc __attribute__ ((__unused__)) = pthread_mutex_lock(pMutex);
434    assert(cc == 0);
435}
436
437/*
438 * Try grabbing a plain mutex.  Returns 0 if successful.
439 */
440INLINE int dvmTryLockMutex(pthread_mutex_t* pMutex)
441{
442    int cc = pthread_mutex_trylock(pMutex);
443    assert(cc == 0 || cc == EBUSY);
444    return cc;
445}
446
447/*
448 * Unlock pthread mutex.
449 */
450INLINE void dvmUnlockMutex(pthread_mutex_t* pMutex)
451{
452    int cc __attribute__ ((__unused__)) = pthread_mutex_unlock(pMutex);
453    assert(cc == 0);
454}
455
456/*
457 * Destroy a mutex.
458 */
459INLINE void dvmDestroyMutex(pthread_mutex_t* pMutex)
460{
461    int cc __attribute__ ((__unused__)) = pthread_mutex_destroy(pMutex);
462    assert(cc == 0);
463}
464
465INLINE void dvmBroadcastCond(pthread_cond_t* pCond)
466{
467    int cc __attribute__ ((__unused__)) = pthread_cond_broadcast(pCond);
468    assert(cc == 0);
469}
470
471INLINE void dvmSignalCond(pthread_cond_t* pCond)
472{
473    int cc __attribute__ ((__unused__)) = pthread_cond_signal(pCond);
474    assert(cc == 0);
475}
476
477INLINE void dvmWaitCond(pthread_cond_t* pCond, pthread_mutex_t* pMutex)
478{
479    int cc __attribute__ ((__unused__)) = pthread_cond_wait(pCond, pMutex);
480    assert(cc == 0);
481}
482
483/*
484 * Create a thread as a result of java.lang.Thread.start().
485 */
486bool dvmCreateInterpThread(Object* threadObj, int reqStackSize);
487
488/*
489 * Create a thread internal to the VM.  It's visible to interpreted code,
490 * but found in the "system" thread group rather than "main".
491 */
492bool dvmCreateInternalThread(pthread_t* pHandle, const char* name,
493    InternalThreadStart func, void* funcArg);
494
495/*
496 * Attach or detach the current thread from the VM.
497 */
498bool dvmAttachCurrentThread(const JavaVMAttachArgs* pArgs, bool isDaemon);
499void dvmDetachCurrentThread(void);
500
501/*
502 * Get the "main" or "system" thread group.
503 */
504Object* dvmGetMainThreadGroup(void);
505Object* dvmGetSystemThreadGroup(void);
506
507/*
508 * Given a java/lang/VMThread object, return our Thread.
509 */
510Thread* dvmGetThreadFromThreadObject(Object* vmThreadObj);
511
512/*
513 * Given a pthread handle, return the associated Thread*.
514 * Caller must hold the thread list lock.
515 *
516 * Returns NULL if the thread was not found.
517 */
518Thread* dvmGetThreadByHandle(pthread_t handle);
519
520/*
521 * Given a thread ID, return the associated Thread*.
522 * Caller must hold the thread list lock.
523 *
524 * Returns NULL if the thread was not found.
525 */
526Thread* dvmGetThreadByThreadId(u4 threadId);
527
528/*
529 * Sleep in a thread.  Returns when the sleep timer returns or the thread
530 * is interrupted.
531 */
532void dvmThreadSleep(u8 msec, u4 nsec);
533
534/*
535 * Get the name of a thread.
536 *
537 * For correctness, the caller should hold the thread list lock to ensure
538 * that the thread doesn't go away mid-call.
539 */
540std::string dvmGetThreadName(Thread* thread);
541
542/*
543 * Convert ThreadStatus to a string.
544 */
545const char* dvmGetThreadStatusStr(ThreadStatus status);
546
547/*
548 * Return true if a thread is on the internal list.  If it is, the
549 * thread is part of the GC's root set.
550 */
551bool dvmIsOnThreadList(const Thread* thread);
552
553/*
554 * Get/set the JNIEnv field.
555 */
556INLINE JNIEnv* dvmGetThreadJNIEnv(Thread* self) { return self->jniEnv; }
557INLINE void dvmSetThreadJNIEnv(Thread* self, JNIEnv* env) { self->jniEnv = env;}
558
559/*
560 * Update the priority value of the underlying pthread.
561 */
562void dvmChangeThreadPriority(Thread* thread, int newPriority);
563
564/* "change flags" values for raise/reset thread priority calls */
565#define kChangedPriority    0x01
566#define kChangedPolicy      0x02
567
568/*
569 * If necessary, raise the thread's priority to nice=0 cgroup=fg.
570 *
571 * Returns bit flags indicating changes made (zero if nothing was done).
572 */
573int dvmRaiseThreadPriorityIfNeeded(Thread* thread, int* pSavedThreadPrio,
574    SchedPolicy* pSavedThreadPolicy);
575
576/*
577 * Drop the thread priority to what it was before an earlier call to
578 * dvmRaiseThreadPriorityIfNeeded().
579 */
580void dvmResetThreadPriority(Thread* thread, int changeFlags,
581    int savedThreadPrio, SchedPolicy savedThreadPolicy);
582
583/*
584 * Debug: dump information about a single thread.
585 */
586void dvmDumpThread(Thread* thread, bool isRunning);
587void dvmDumpThreadEx(const DebugOutputTarget* target, Thread* thread,
588    bool isRunning);
589
590/*
591 * Debug: dump information about all threads.
592 */
593void dvmDumpAllThreads(bool grabLock);
594void dvmDumpAllThreadsEx(const DebugOutputTarget* target, bool grabLock);
595
596/*
597 * Debug: kill a thread to get a debuggerd stack trace.  Leaves the VM
598 * in an uncertain state.
599 */
600void dvmNukeThread(Thread* thread);
601
602#endif  // DALVIK_THREAD_H_
603