diff options
Diffstat (limited to 'libjava/java/lang')
| -rw-r--r-- | libjava/java/lang/Class.h | 1 | ||||
| -rw-r--r-- | libjava/java/lang/Object.h | 12 | ||||
| -rw-r--r-- | libjava/java/lang/natObject.cc | 952 | ||||
| -rw-r--r-- | libjava/java/lang/natString.cc | 20 |
4 files changed, 963 insertions, 22 deletions
diff --git a/libjava/java/lang/Class.h b/libjava/java/lang/Class.h index 8cce30f3f6e..4986dbf391b 100644 --- a/libjava/java/lang/Class.h +++ b/libjava/java/lang/Class.h @@ -267,6 +267,7 @@ private: friend jobject _Jv_AllocObject (jclass, jint); friend void *_Jv_AllocObj (jint, jclass); + friend void *_Jv_AllocPtrFreeObj (jint, jclass); friend void *_Jv_AllocArray (jint, jclass); friend jobject _Jv_JNI_ToReflectedField (_Jv_JNIEnv *, jclass, jfieldID, diff --git a/libjava/java/lang/Object.h b/libjava/java/lang/Object.h index 352d48b501d..93e207fc467 100644 --- a/libjava/java/lang/Object.h +++ b/libjava/java/lang/Object.h @@ -42,8 +42,8 @@ public: void wait (void); void wait (jlong timeout); - friend jint _Jv_MonitorEnter (jobject obj); - friend jint _Jv_MonitorExit (jobject obj); + friend void _Jv_MonitorEnter (jobject obj); + friend void _Jv_MonitorExit (jobject obj); friend void _Jv_InitializeSyncMutex (void); friend void _Jv_FinalizeObject (jobject obj); @@ -63,10 +63,12 @@ private: // This does not actually refer to a Java object. Instead it is a // placeholder for a piece of internal data (the synchronization // information). - jobject sync_info; +# ifndef JV_HASH_SYNCHRONIZATION + jobject sync_info; +# endif - // Initialize the sync_info field. - void sync_init (void); + // Initialize the sync_info field. Not called with JV_HASH_SYNCHRONIZATION. + void sync_init (void); }; #endif /* __JAVA_LANG_OBJECT_H__ */ diff --git a/libjava/java/lang/natObject.cc b/libjava/java/lang/natObject.cc index 3ea073ba057..fb2c6d45355 100644 --- a/libjava/java/lang/natObject.cc +++ b/libjava/java/lang/natObject.cc @@ -28,6 +28,10 @@ details. */ #include <java/lang/Cloneable.h> #include <java/lang/Thread.h> +#ifdef LOCK_DEBUG +# include <stdio.h> +#endif + // This is used to represent synchronization information. @@ -100,11 +104,26 @@ java::lang::Object::clone (void) return r; } +void +_Jv_FinalizeObject (jobject obj) +{ + // Ignore exceptions. From section 12.6 of the Java Language Spec. + try + { + obj->finalize (); + } + catch (java::lang::Throwable *t) + { + // Ignore. + } +} + // // Synchronization code. // +#ifndef JV_HASH_SYNCHRONIZATION // This global is used to make sure that only one thread sets an // object's `sync_info' field. static _Jv_Mutex_t sync_mutex; @@ -153,7 +172,7 @@ java::lang::Object::sync_init (void) // been finalized. So if we just reinitialize the old one, // we'll never be able to (re-)destroy the mutex and/or // condition variable. - si = (_Jv_SyncInfo *) _Jv_AllocBytesChecked (sizeof (_Jv_SyncInfo)); + si = (_Jv_SyncInfo *) _Jv_AllocBytes (sizeof (_Jv_SyncInfo)); _Jv_MutexInit (&si->mutex); _Jv_CondInit (&si->condition); #if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) @@ -219,7 +238,7 @@ _Jv_InitializeSyncMutex (void) _Jv_MutexInit (&sync_mutex); } -jint +void _Jv_MonitorEnter (jobject obj) { #ifndef HANDLE_SEGV @@ -229,10 +248,12 @@ _Jv_MonitorEnter (jobject obj) if (__builtin_expect (INIT_NEEDED (obj), false)) obj->sync_init (); _Jv_SyncInfo *si = (_Jv_SyncInfo *) obj->sync_info; - return _Jv_MutexLock (&si->mutex); + _Jv_MutexLock (&si->mutex); + // FIXME: In the Windows case, this can return a nonzero error code. + // We should turn that into some exception ... } -jint +void _Jv_MonitorExit (jobject obj) { JvAssert (obj); @@ -240,19 +261,928 @@ _Jv_MonitorExit (jobject obj) _Jv_SyncInfo *si = (_Jv_SyncInfo *) obj->sync_info; if (__builtin_expect (_Jv_MutexUnlock (&si->mutex), false)) throw new java::lang::IllegalMonitorStateException; - return 0; } +#else /* JV_HASH_SYNCHRONIZATION */ + +// FIXME: We shouldn't be calling GC_register_finalizer directly. +#ifndef HAVE_BOEHM_GC +# error Hash synchronization currently requires boehm-gc +// That's actually a bit of a lie: It should also work with the null GC, +// probably even better than the alternative. +// To really support alternate GCs here, we would need to widen the +// interface to finalization, since we sometimes have to register a +// second finalizer for an object that already has one. +// We might also want to move the GC interface to a .h file, since +// the number of procedure call levels involved in some of these +// operations is already ridiculous, and would become worse if we +// went through the proper intermediaries. +#else +# include "gc.h" +#endif + +// What follows currenly assumes a Linux-like platform. +// Some of it specifically assumes X86 or IA64 Linux, though that +// should be easily fixable. + +// A Java monitor implemention based on a table of locks. +// Each entry in the table describes +// locks held for objects that hash to that location. +// This started out as a reimplementation of the technique used in SGIs JVM, +// for which we obtained permission from SGI. +// But in fact, this ended up quite different, though some ideas are +// still shared with the original. +// It was also influenced by some of the published IBM work, +// though it also differs in many ways from that. +// We could speed this up if we had a way to atomically update +// an entire cache entry, i.e. 2 contiguous words of memory. +// That would usually be the case with a 32 bit ABI on a 64 bit processor. +// But we don't currently go out of our way to target those. +// I don't know how to do much better with a N bit ABI on a processor +// that can atomically update only N bits at a time. +// Author: Hans-J. Boehm (Hans_Boehm@hp.com, boehm@acm.org) + +#include <assert.h> +#include <limits.h> +#include <unistd.h> // for usleep, sysconf. +#include <sched.h> // for sched_yield. +#include <gcj/javaprims.h> + +typedef size_t obj_addr_t; /* Integer type big enough for object */ + /* address. */ + +// The following should move to some standard place. Linux-threads +// already defines roughly these, as do more recent versions of boehm-gc. +// The problem is that neither exports them. + +#if defined(__GNUC__) && defined(__i386__) + // Atomically replace *addr by new_val if it was initially equal to old. + // Return true if the comparison succeeded. + // Assumed to have acquire semantics, i.e. later memory operations + // cannot execute before the compare_and_swap finishes. + inline static bool + compare_and_swap(volatile obj_addr_t *addr, + obj_addr_t old, + obj_addr_t new_val) + { + char result; + __asm__ __volatile__("lock; cmpxchgl %2, %0; setz %1" + : "=m"(*(addr)), "=q"(result) + : "r" (new_val), "0"(*(addr)), "a"(old) : "memory"); + return (bool) result; + } + + // Set *addr to new_val with release semantics, i.e. making sure + // that prior loads and stores complete before this + // assignment. + // On X86, the hardware shouldn't reorder reads and writes, + // so we just have to convince gcc not to do it either. + inline static void + release_set(volatile obj_addr_t *addr, obj_addr_t new_val) + { + __asm__ __volatile__(" " : : : "memory"); + *(addr) = new_val; + } + + // Compare_and_swap with release semantics instead of acquire semantics. + // On many architecture, the operation makes both guarantees, so the + // implementation can be the same. + inline static bool + compare_and_swap_release(volatile obj_addr_t *addr, + obj_addr_t old, + obj_addr_t new_val) + { + return compare_and_swap(addr, old, new_val); + } +#endif + +#if defined(__GNUC__) && defined(__ia64__) && SIZEOF_VOID_P == 8 + inline static bool + compare_and_swap(volatile obj_addr_t *addr, + obj_addr_t old, + obj_addr_t new_val) + { + unsigned long oldval; + __asm__ __volatile__("mov ar.ccv=%4 ;; cmpxchg8.acq %0=%1,%2,ar.ccv" + : "=r"(oldval), "=m"(*addr) + : "r"(new_val), "1"(*addr), "r"(old) : "memory"); + return (oldval == old); + } + + // The fact that *addr is volatile should cause the compiler to + // automatically generate an st8.rel. + inline static void + release_set(volatile obj_addr_t *addr, obj_addr_t new_val) + { + __asm__ __volatile__(" " : : : "memory"); + *(addr) = new_val; + } + + inline static bool + compare_and_swap_release(volatile obj_addr_t *addr, + obj_addr_t old, + obj_addr_t new_val) + { + unsigned long oldval; + __asm__ __volatile__("mov ar.ccv=%4 ;; cmpxchg8.rel %0=%1,%2,ar.ccv" + : "=r"(oldval), "=m"(*addr) + : "r"(new_val), "1"(*addr), "r"(old) : "memory"); + return (oldval == old); + } +#endif + +// Try to determine whether we are on a multiprocessor, i.e. whether +// spinning may be profitable. +// This should really use a suitable autoconf macro. +// False is the conservative answer, though the right one is much better. +static bool +is_mp() +{ + long nprocs = sysconf(_SC_NPROCESSORS_ONLN); + return (nprocs > 1); +} + +// A call to keep_live(p) forces p to be accessible to the GC +// at this point. +inline static void +keep_live(obj_addr_t p) +{ + __asm__ __volatile__("" : : "rm"(p) : "memory"); +} + + +// Each hash table entry holds a single preallocated "lightweight" lock. +// In addition, it holds a chain of "heavyweight" locks. Lightweight +// locks do not support Object.wait(), and are converted to heavyweight +// status in response to contention. Unlike the SGI scheme, both +// ligtweight and heavyweight locks in one hash entry can be simultaneously +// in use. (The SGI scheme requires that we be able to acquire a heavyweight +// lock on behalf of another thread, and can thus convert a lock we don't +// hold to heavyweight status. Here we don't insist on that, and thus +// let the original holder of the lighweight lock keep it.) + +struct heavy_lock { + void * reserved_for_gc; + struct heavy_lock *next; // Hash chain link. + // The only field traced by GC. + obj_addr_t address; // Object to which this lock corresponds. + // Should not be traced by GC. + _Jv_SyncInfo si; + // The remaining fields save prior finalization info for + // the object, which we needed to replace in order to arrange + // for cleanup of the lock structure. + GC_finalization_proc old_finalization_proc; + void * old_client_data; +}; + +#ifdef LOCK_DEBUG void -_Jv_FinalizeObject (jobject obj) +print_hl_list(heavy_lock *hl) { - // Ignore exceptions. From section 12.6 of the Java Language Spec. - try + heavy_lock *p = hl; + for (; 0 != p; p = p->next) + fprintf (stderr, "(hl = %p, addr = %p)", p, (void *)(p -> address)); +} +#endif /* LOCK_DEBUG */ + +#if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) +// If we have to run a destructor for a sync_info member, then this +// function is registered as a finalizer for the sync_info. +static void +heavy_lock_finalization_proc (jobject obj) +{ + heavy_lock *hl = (heavy_lock *) obj; +#if defined (_Jv_HaveCondDestroy) + _Jv_CondDestroy (&hl->si.condition); +#endif +#if defined (_Jv_HaveMutexDestroy) + _Jv_MutexDestroy (&hl->si.mutex); +#endif + hl->si.init = false; +} +#endif /* defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) */ + +// We convert the lock back to lightweight status when +// we exit, so that a single contention episode doesn't doom the lock +// forever. But we also need to make sure that lock structures for dead +// objects are eventually reclaimed. We do that in a an additional +// finalizer on the underlying object. +// Note that if the corresponding object is dead, it is safe to drop +// the heavy_lock structure from its list. It is not necessarily +// safe to deallocate it, since the unlock code could still be running. + +struct hash_entry { + volatile obj_addr_t address; // Address of object for which lightweight + // k is held. + // We assume the 3 low order bits are zero. + // With the Boehm collector and bitmap + // allocation, objects of size 4 bytes are + // broken anyway. Thus this is primarily + // a constraint on statically allocated + // objects used for synchronization. + // This allows us to use the low order + // bits as follows: +# define LOCKED 1 // This hash entry is locked, and its + // state may be invalid. + // The lock protects both the hash_entry + // itself (except for the light_count + // and light_thr_id fields, which + // are protected by the lightweight + // lock itself), and any heavy_monitor + // structures attached to it. +# define HEAVY 2 // There may be heavyweight locks + // associated with this cache entry. + // The lightweight entry is still valid, + // if the leading bits of the address + // field are nonzero. + // Set if heavy_count is > 0 . + // Stored redundantly so a single + // compare-and-swap works in the easy case. +# define REQUEST_CONVERSION 4 // The lightweight lock is held. But + // one or more other threads have tried + // to acquire the lock, and hence request + // conversion to heavyweight status. +# define FLAGS (LOCKED | HEAVY | REQUEST_CONVERSION) + volatile _Jv_ThreadId_t light_thr_id; + // Thr_id of holder of lightweight lock. + // Only updated by lightweight lock holder. + // Must be recognizably invalid if the + // lightweight lock is not held. +# define INVALID_THREAD_ID 0 // Works for Linux? + // If zero doesn't work, we have to + // initialize lock table. + volatile unsigned short light_count; + // Number of times the lightweight lock + // is held minus one. Zero if lightweight + // lock is not held. + unsigned short heavy_count; // Total number of times heavyweight locks + // associated with this hash entry are held + // or waiting to be acquired. + // Threads in wait() are included eventhough + // they have temporarily released the lock. + struct heavy_lock * heavy_locks; + // Chain of heavy locks. Protected + // by lockbit for he. Locks may + // remain allocated here even if HEAVY + // is not set and heavy_count is 0. + // If a lightweight and hevyweight lock + // correspond to the same address, the + // lightweight lock is the right one. +}; + +#ifndef JV_SYNC_TABLE_SZ +# define JV_SYNC_TABLE_SZ 1024 +#endif + +hash_entry light_locks[JV_SYNC_TABLE_SZ]; + +#define JV_SYNC_HASH(p) (((long)p ^ ((long)p >> 10)) % JV_SYNC_TABLE_SZ) + +#ifdef LOCK_DEBUG + void print_he(hash_entry *he) + { + fprintf(stderr, "lock hash entry = %p, index = %d, address = 0x%lx\n" + "\tlight_thr_id = 0x%lx, light_count = %d, " + "heavy_count = %d\n\theavy_locks:", he, + he - light_locks, he -> address, he -> light_thr_id, + he -> light_count, he -> heavy_count); + print_hl_list(he -> heavy_locks); + fprintf(stderr, "\n"); + } +#endif /* LOCK_DEBUG */ + +// Wait for roughly 2^n units, touching as little memory as possible. +static void +spin(unsigned n) +{ + const unsigned MP_SPINS = 10; + const unsigned YIELDS = 4; + const unsigned SPINS_PER_UNIT = 30; + const unsigned MIN_SLEEP_USECS = 2001; // Shorter times spin under Linux. + const unsigned MAX_SLEEP_USECS = 200000; + static unsigned spin_limit = 0; + static unsigned yield_limit = YIELDS; + static bool mp = false; + static bool spin_initialized = false; + + if (!spin_initialized) { - obj->finalize (); + mp = is_mp(); + if (mp) + { + spin_limit = MP_SPINS; + yield_limit = MP_SPINS + YIELDS; + } + spin_initialized = true; } - catch (java::lang::Throwable *t) + if (n < spin_limit) { - // Ignore. + unsigned i = SPINS_PER_UNIT << n; + for (; i > 0; --i) + __asm__ __volatile__(""); + } + else if (n < yield_limit) + { + sched_yield(); + } + else + { + unsigned duration = MIN_SLEEP_USECS << (n - yield_limit); + if (n >= 15 + yield_limit || duration > MAX_SLEEP_USECS) + duration = MAX_SLEEP_USECS; + usleep(duration); + } +} + +// Wait for a hash entry to become unlocked. +static void +wait_unlocked (hash_entry *he) +{ + unsigned i = 0; + while (he -> address & LOCKED) + spin (i++); +} + +// Return the heavy lock for addr if it was already allocated. +// The client passes in the appropriate hash_entry. +// We hold the lock for he. +static inline heavy_lock * +find_heavy (obj_addr_t addr, hash_entry *he) +{ + heavy_lock *hl = he -> heavy_locks; + while (hl != 0 && hl -> address != addr) hl = hl -> next; + return hl; +} + +// Unlink the heavy lock for the given address from its hash table chain. +// Dies miserably and conspicuously if it's not there, since that should +// be impossible. +static inline void +unlink_heavy (obj_addr_t addr, hash_entry *he) +{ + heavy_lock **currentp = &(he -> heavy_locks); + while ((*currentp) -> address != addr) + currentp = &((*currentp) -> next); + *currentp = (*currentp) -> next; +} + +// Finalization procedure for objects that have associated heavy-weight +// locks. This may replace the real finalization procedure. +static void +heavy_lock_obj_finalization_proc (void *obj, void *cd) +{ + heavy_lock *hl = (heavy_lock *)cd; + obj_addr_t addr = (obj_addr_t)obj; + GC_finalization_proc old_finalization_proc = hl -> old_finalization_proc; + void * old_client_data = hl -> old_client_data; + + if (old_finalization_proc != 0) + { + // We still need to run a real finalizer. In an idealized + // world, in which people write thread-safe finalizers, that is + // likely to require synchronization. Thus we reregister + // ourselves as the only finalizer, and simply run the real one. + // Thus we don't clean up the lock yet, but we're likely to do so + // on the next GC cycle. + hl -> old_finalization_proc = 0; + hl -> old_client_data = 0; +# ifdef HAVE_BOEHM_GC + GC_REGISTER_FINALIZER_NO_ORDER(obj, heavy_lock_obj_finalization_proc, cd, 0, 0); +# endif + old_finalization_proc(obj, old_client_data); + } + else + { + // The object is really dead, although it's conceivable that + // some thread may still be in the process of releasing the + // heavy lock. Unlink it and, if necessary, register a finalizer + // to distroy sync_info. + hash_entry *he = light_locks + JV_SYNC_HASH(addr); + obj_addr_t address = (he -> address & ~LOCKED); + while (!compare_and_swap(&(he -> address), address, address | LOCKED )) + { + // Hash table entry is currently locked. We can't safely touch + // touch the list of heavy locks. + wait_unlocked(he); + address = (he -> address & ~LOCKED); + } + unlink_heavy(addr, light_locks + JV_SYNC_HASH(addr)); + release_set(&(he -> address), address); +# if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) + // Register a finalizer, yet again. + hl->si.init = true; + _Jv_RegisterFinalizer (hl, heavy_lock_finalization_proc); +# endif + } +} + +// Allocate a new heavy lock for addr, returning its address. +// Assumes we already have the hash_entry locked, and there +// is currently no lightweight or allocated lock for addr. +// We register a finalizer for addr, which is responsible for +// removing the heavy lock when addr goes away, in addition +// to the responsibilities of any prior finalizer. +static heavy_lock * +alloc_heavy(obj_addr_t addr, hash_entry *he) +{ + heavy_lock * hl = (heavy_lock *) _Jv_AllocTraceOne(sizeof (heavy_lock)); + + hl -> address = addr; + _Jv_MutexInit (&(hl -> si.mutex)); + _Jv_CondInit (&(hl -> si.condition)); +# if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) + si->init = true; // needed ? +# endif + hl -> next = he -> heavy_locks; + he -> heavy_locks = hl; + // FIXME: The only call that cheats and goes directly to the GC interface. +# ifdef HAVE_BOEHM_GC + GC_REGISTER_FINALIZER_NO_ORDER( + (void *)addr, heavy_lock_obj_finalization_proc, + hl, &hl->old_finalization_proc, + &hl->old_client_data); +# endif /* HAVE_BOEHM_GC */ + return hl; +} + +// Return the heavy lock for addr, allocating if necessary. +// Assumes we have the cache entry locked, and there is no lightweight +// lock for addr. +static heavy_lock * +get_heavy(obj_addr_t addr, hash_entry *he) +{ + heavy_lock *hl = find_heavy(addr, he); + if (0 == hl) + hl = alloc_heavy(addr, he); + return hl; +} + +void +_Jv_MonitorEnter (jobject obj) +{ + obj_addr_t addr = (obj_addr_t)obj; + obj_addr_t address; + unsigned hash = JV_SYNC_HASH(addr); + hash_entry * he = light_locks + hash; + _Jv_ThreadId_t self = _Jv_ThreadSelf(); + unsigned count; + const unsigned N_SPINS = 18; + + assert(!(addr & FLAGS)); +retry: + if (__builtin_expect(compare_and_swap(&(he -> address), + 0, addr),true)) + { + assert(he -> light_thr_id == INVALID_THREAD_ID); + assert(he -> light_count == 0); + he -> light_thr_id = self; + // Count fields are set correctly. Heavy_count was also zero, + // but can change asynchronously. + // This path is hopefully both fast and the most common. + return; + } + address = he -> address; + if ((address & ~(HEAVY | REQUEST_CONVERSION)) == addr) + { + if (he -> light_thr_id == self) + { + // We hold the lightweight lock, and it's for the right + // address. + count = he -> light_count; + if (count == USHRT_MAX) + { + // I think most JVMs don't check for this. + // But I'm not convinced I couldn't turn this into a security + // hole, even with a 32 bit counter. + throw new java::lang::IllegalMonitorStateException( + JvNewStringLatin1("maximum monitor nesting level exceeded")); + } + he -> light_count = count + 1; + return; + } + else + { + // Lightweight lock is held, but by somone else. + // Spin a few times. This avoids turning this into a heavyweight + // lock if the current holder is about to release it. + for (unsigned int i = 0; i < N_SPINS; ++i) + { + if ((he -> address & ~LOCKED) != (address & ~LOCKED)) goto retry; + spin(i); + } + address &= ~LOCKED; + if (!compare_and_swap(&(he -> address), address, address | LOCKED )) + { + wait_unlocked(he); + goto retry; + } + heavy_lock *hl = get_heavy(addr, he); + ++ (he -> heavy_count); + // The hl lock acquisition can't block for long, since it can + // only be held by other threads waiting for conversion, and + // they, like us, drop it quickly without blocking. + _Jv_MutexLock(&(hl->si.mutex)); + assert(he -> address == address | LOCKED ); + release_set(&(he -> address), (address | REQUEST_CONVERSION | HEAVY)); + // release lock on he + while ((he -> address & ~FLAGS) == (address & ~FLAGS)) + { + // Once converted, the lock has to retain heavyweight + // status, since heavy_count > 0 . + _Jv_CondWait (&(hl->si.condition), &(hl->si.mutex), 0, 0); + } + keep_live(addr); + // Guarantee that hl doesn't get unlinked by finalizer. + // This is only an issue if the client fails to release + // the lock, which is unlikely. + assert(he -> address & HEAVY); + // Lock has been converted, we hold the heavyweight lock, + // heavy_count has been incremented. + return; + } + } + obj_addr_t was_heavy = (address & HEAVY); + address &= ~LOCKED; + if (!compare_and_swap(&(he -> address), address, (address | LOCKED ))) + { + wait_unlocked(he); + goto retry; + } + if ((address & ~(HEAVY | REQUEST_CONVERSION)) == 0) + { + // Either was_heavy is true, or something changed out from under us, + // since the initial test for 0 failed. + assert(!(address & REQUEST_CONVERSION)); + // Can't convert a nonexistent lightweight lock. + heavy_lock *hl; + hl = (was_heavy? find_heavy(addr, he) : 0); + if (0 == hl) + { + // It is OK to use the lighweight lock, since either the + // heavyweight lock does not exist, or none of the + // heavyweight locks currently exist. Future threads + // trying to acquire the lock will see the lightweight + // one first and use that. + he -> light_thr_id = self; // OK, since nobody else can hold + // light lock or do this at the same time. + assert(he -> light_count == 0); + assert(was_heavy == (he -> address & HEAVY)); + release_set(&(he -> address), (addr | was_heavy)); + } + else + { + // Must use heavy lock. + ++ (he -> heavy_count); + assert(0 == (address & ~HEAVY)); + release_set(&(he -> address), HEAVY); + _Jv_MutexLock(&(hl->si.mutex)); + keep_live(addr); + } + return; + } + // Lightweight lock is held, but does not correspond to this object. + // We hold the lock on the hash entry, and he -> address can't + // change from under us. Neither can the chain of heavy locks. + { + assert(0 == he -> heavy_count || (address & HEAVY)); + heavy_lock *hl = get_heavy(addr, he); + ++ (he -> heavy_count); + release_set(&(he -> address), address | HEAVY); + _Jv_MutexLock(&(hl->si.mutex)); + keep_live(addr); } } + + +void +_Jv_MonitorExit (jobject obj) +{ + obj_addr_t addr = (obj_addr_t)obj; + _Jv_ThreadId_t self = _Jv_ThreadSelf(); + unsigned hash = JV_SYNC_HASH(addr); + hash_entry * he = light_locks + hash; + _Jv_ThreadId_t light_thr_id; + unsigned count; + obj_addr_t address; + +retry: + light_thr_id = he -> light_thr_id; + // Unfortunately, it turns out we always need to read the address + // first. Even if we are going to update it with compare_and_swap, + // we need to reset light_thr_id, and that's not safe unless we know + // know that we hold the lock. + address = he -> address; + // First the (relatively) fast cases: + if (__builtin_expect(light_thr_id == self, true)) + { + count = he -> light_count; + if (__builtin_expect((address & ~HEAVY) == addr, true)) + { + if (count != 0) + { + // We held the lightweight lock all along. Thus the values + // we saw for light_thr_id and light_count must have been valid. + he -> light_count = count - 1; + return; + } + else + { + // We hold the lightweight lock once. + he -> light_thr_id = INVALID_THREAD_ID; + if (compare_and_swap_release(&(he -> address), address, + address & HEAVY)) + return; + else + { + he -> light_thr_id = light_thr_id; // Undo prior damage. + goto retry; + } + } + } + // else lock is not for this address, conversion is requested, + // or the lock bit in the address field is set. + } + else + { + if ((address & ~(HEAVY | REQUEST_CONVERSION)) == addr) + { +# ifdef LOCK_DEBUG + fprintf(stderr, "Lightweight lock held by other thread\n\t" + "light_thr_id = 0x%lx, self = 0x%lx, " + "address = 0x%lx, pid = %d\n", + light_thr_id, self, address, getpid()); + print_he(he); + for(;;) {} +# endif + // Someone holds the lightweight lock for this object, and + // it can't be us. + throw new java::lang::IllegalMonitorStateException( + JvNewStringLatin1("current thread not owner")); + } + else + count = he -> light_count; + } + if (address & LOCKED) + { + wait_unlocked(he); + goto retry; + } + // Now the unlikely cases. + // We do know that: + // - Address is set, and doesn't contain the LOCKED bit. + // - If address refers to the same object as addr, then he -> light_thr_id + // refers to this thread, and count is valid. + // - The case in which we held the lightweight lock has been + // completely handled, except for the REQUEST_CONVERSION case. + // + if ((address & ~FLAGS) == addr) + { + // The lightweight lock is assigned to this object. + // Thus we must be in the REQUEST_CONVERSION case. + if (0 != count) + { + // Defer conversion until we exit completely. + he -> light_count = count - 1; + return; + } + assert(he -> light_thr_id == self); + assert(address & REQUEST_CONVERSION); + // Conversion requested + // Convert now. + if (!compare_and_swap(&(he -> address), address, address | LOCKED)) + goto retry; + heavy_lock *hl = find_heavy(addr, he); + assert (0 != hl); + // Requestor created it. + he -> light_count = 0; + assert(he -> heavy_count > 0); + // was incremented by requestor. + _Jv_MutexLock(&(hl->si.mutex)); + // Release the he lock after acquiring the mutex. + // Otherwise we can accidentally + // notify a thread that has already seen a heavyweight + // lock. + he -> light_thr_id = INVALID_THREAD_ID; + release_set(&(he -> address), HEAVY); + // lightweight lock now unused. + _Jv_CondNotifyAll(&(hl->si.condition), &(hl->si.mutex)); + _Jv_MutexUnlock(&(hl->si.mutex)); + // heavy_count was already incremented by original requestor. + keep_live(addr); + return; + } + // lightweight lock not for this object. + assert(!(address & LOCKED)); + assert((address & ~FLAGS) != addr); + if (!compare_and_swap(&(he -> address), address, address | LOCKED)) + goto retry; + heavy_lock *hl = find_heavy(addr, he); + if (NULL == hl) + { +# ifdef LOCK_DEBUG + fprintf(stderr, "Failed to find heavyweight lock for addr 0x%lx" + " pid = %d\n", addr, getpid()); + print_he(he); + for(;;) {} +# endif + throw new java::lang::IllegalMonitorStateException( + JvNewStringLatin1("current thread not owner")); + } + assert(address & HEAVY); + count = he -> heavy_count; + assert(count > 0); + --count; + if (0 == count) address &= ~HEAVY; + he -> heavy_count = count; + release_set(&(he -> address), address); + // release lock bit, preserving + // REQUEST_CONVERSION + // and object address. + _Jv_MutexUnlock(&(hl->si.mutex)); + // Unlock after releasing the lock bit, so that + // we don't switch to another thread prematurely. + keep_live(addr); +} + +// The rest of these are moderately thin veneers on _Jv_Cond ops. +// The current version of Notify might be able to make the pthread +// call AFTER releasing the lock, thus saving some context switches?? + +void +java::lang::Object::wait (jlong timeout, jint nanos) +{ + obj_addr_t addr = (obj_addr_t)this; + _Jv_ThreadId_t self = _Jv_ThreadSelf(); + unsigned hash = JV_SYNC_HASH(addr); + hash_entry * he = light_locks + hash; + unsigned count; + obj_addr_t address; + heavy_lock *hl; + + if (__builtin_expect (timeout < 0 || nanos < 0 || nanos > 999999, false)) + throw new IllegalArgumentException; +retry: + address = he -> address; + address &= ~LOCKED; + if (!compare_and_swap(&(he -> address), address, address | LOCKED)) + { + wait_unlocked(he); + goto retry; + } + // address does not have the lock bit set. We hold the lock on he. + if ((address & ~FLAGS) == addr) + { + // Convert to heavyweight. + if (he -> light_thr_id != self) + { +# ifdef LOCK_DEBUG + fprintf(stderr, "Found wrong lightweight lock owner in wait " + "address = 0x%lx pid = %d\n", address, getpid()); + print_he(he); + for(;;) {} +# endif + release_set(&(he -> address), address); + throw new IllegalMonitorStateException (JvNewStringLatin1 + ("current thread not owner")); + } + count = he -> light_count; + hl = get_heavy(addr, he); + he -> light_count = 0; + he -> heavy_count += count + 1; + for (unsigned i = 0; i <= count; ++i) + _Jv_MutexLock(&(hl->si.mutex)); + // Again release the he lock after acquiring the mutex. + he -> light_thr_id = INVALID_THREAD_ID; + release_set(&(he -> address), HEAVY); // lightweight lock now unused. + if (address & REQUEST_CONVERSION) + _Jv_CondNotify (&(hl->si.condition), &(hl->si.mutex)); + } + else /* We should hold the heavyweight lock. */ + { + hl = find_heavy(addr, he); + release_set(&(he -> address), address); + if (0 == hl) + { +# ifdef LOCK_DEBUG + fprintf(stderr, "Couldn't find heavy lock in wait " + "addr = 0x%lx pid = %d\n", addr, getpid()); + print_he(he); + for(;;) {} +# endif + throw new IllegalMonitorStateException (JvNewStringLatin1 + ("current thread not owner")); + } + assert(address & HEAVY); + } + switch (_Jv_CondWait (&(hl->si.condition), &(hl->si.mutex), timeout, nanos)) + { + case _JV_NOT_OWNER: + throw new IllegalMonitorStateException (JvNewStringLatin1 + ("current thread not owner")); + case _JV_INTERRUPTED: + if (Thread::interrupted ()) + throw new InterruptedException; + } +} + +void +java::lang::Object::notify (void) +{ + obj_addr_t addr = (obj_addr_t)this; + _Jv_ThreadId_t self = _Jv_ThreadSelf(); + unsigned hash = JV_SYNC_HASH(addr); + hash_entry * he = light_locks + hash; + heavy_lock *hl; + obj_addr_t address; + int result; + +retry: + address = ((he -> address) & ~LOCKED); + if (!compare_and_swap(&(he -> address), address, address | LOCKED)) + { + wait_unlocked(he); + goto retry; + } + if ((address & ~FLAGS) == addr && he -> light_thr_id == self) + { + // We hold lightweight lock. Since it has not + // been inflated, there are no waiters. + release_set(&(he -> address), address); // unlock + return; + } + hl = find_heavy(addr, he); + // Hl can't disappear since we point to the underlying object. + // It's important that we release the lock bit before the notify, since + // otherwise we will try to wake up thee target while we still hold the + // bit. This results in lock bit contention, which we don't handle + // terribly well. + release_set(&(he -> address), address); // unlock + if (0 == hl) + { + throw new IllegalMonitorStateException(JvNewStringLatin1 + ("current thread not owner")); + return; + } + result = _Jv_CondNotify(&(hl->si.condition), &(hl->si.mutex)); + keep_live(addr); + if (__builtin_expect (result, 0)) + throw new IllegalMonitorStateException(JvNewStringLatin1 + ("current thread not owner")); +} + +void +java::lang::Object::notifyAll (void) +{ + obj_addr_t addr = (obj_addr_t)this; + _Jv_ThreadId_t self = _Jv_ThreadSelf(); + unsigned hash = JV_SYNC_HASH(addr); + hash_entry * he = light_locks + hash; + heavy_lock *hl; + obj_addr_t address; + int result; + +retry: + address = (he -> address) & ~LOCKED; + if (!compare_and_swap(&(he -> address), address, address | LOCKED)) + { + wait_unlocked(he); + goto retry; + } + hl = find_heavy(addr, he); + if ((address & ~FLAGS) == addr && he -> light_thr_id == self) + { + // We hold lightweight lock. Since it has not + // been inflated, there are no waiters. + release_set(&(he -> address), address); // unlock + return; + } + release_set(&(he -> address), address); // unlock + if (0 == hl) + { + throw new IllegalMonitorStateException(JvNewStringLatin1 + ("current thread not owner")); + } + result = _Jv_CondNotifyAll(&(hl->si.condition), &(hl->si.mutex)); + if (__builtin_expect (result, 0)) + throw new IllegalMonitorStateException(JvNewStringLatin1 + ("current thread not owner")); +} + +// This is declared in Java code and in Object.h. +// It should never be called with JV_HASH_SYNCHRONIZATION +void +java::lang::Object::sync_init (void) +{ + throw new IllegalMonitorStateException(JvNewStringLatin1 + ("internal error: sync_init")); +} + +// This is called on startup and declared in Object.h. +// For now we just make it a no-op. +void +_Jv_InitializeSyncMutex (void) +{ +} + +#endif /* JV_HASH_SYNCHRONIZATION */ + diff --git a/libjava/java/lang/natString.cc b/libjava/java/lang/natString.cc index 659810f31e7..520188274f6 100644 --- a/libjava/java/lang/natString.cc +++ b/libjava/java/lang/natString.cc @@ -121,8 +121,7 @@ java::lang::String::rehash() if (strhash == NULL) { strhash_size = 1024; - strhash = (jstring *) _Jv_AllocBytesChecked (strhash_size - * sizeof (jstring)); + strhash = (jstring *) _Jv_AllocBytes (strhash_size * sizeof (jstring)); memset (strhash, 0, strhash_size * sizeof (jstring)); } else @@ -130,8 +129,7 @@ java::lang::String::rehash() int i = strhash_size; jstring* ptr = strhash + i; int nsize = strhash_size * 2; - jstring *next = (jstring *) _Jv_AllocBytesChecked (nsize - * sizeof (jstring)); + jstring *next = (jstring *) _Jv_AllocBytes (nsize * sizeof (jstring)); memset (next, 0, nsize * sizeof (jstring)); while (--i >= 0) @@ -392,8 +390,18 @@ _Jv_AllocString(jsize len) { jsize sz = sizeof(java::lang::String) + len * sizeof(jchar); - jstring obj = (jstring) JvAllocObject(&StringClass, sz); - + // We assert that for strings allocated this way, the data field + // will always point to the object itself. Thus there is no reason + // for the garbage collector to scan any of it. + // Furthermore, we're about to overwrite the string data, so + // initialization of the object is not an issue. +#ifdef ENABLE_JVMPI + jstring obj = (jstring) _Jv_AllocPtrFreeObject(&StringClass, sz); +#else + // Class needs no initialization, and there is no finalizer, so + // we can go directly to the collector's allocator interface. + jstring obj = (jstring) _Jv_AllocPtrFreeObj(&StringClass, sz); +#endif obj->data = obj; obj->boffset = sizeof(java::lang::String); obj->count = len; |