/* * Copyright (c) 1996-1997 * Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Silicon Graphics makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. */ #ifndef __ALLOC_H #define __ALLOC_H #include #ifdef __SUNPRO_CC # define __PRIVATE public // Extra access restrictions prevent us from really making some things // private. #else # define __PRIVATE private #endif #ifdef __STL_STATIC_TEMPLATE_MEMBER_BUG # define __USE_MALLOC #endif // This implements some standard node allocators. These are // NOT the same as the allocators in the C++ draft standard or in // in the original STL. They do not encapsulate different pointer // types; indeed we assume that there is only one pointer type. // The allocation primitives are intended to allocate individual objects, // not larger arenas as with the original STL allocators. #if 0 # include # define __THROW_BAD_ALLOC throw bad_alloc #elif !defined(__THROW_BAD_ALLOC) # include # define __THROW_BAD_ALLOC cerr << "out of memory" << endl; exit(1) #endif #ifndef __ALLOC # define __ALLOC alloc #endif #ifdef __STL_WIN32THREADS # include // This must precede stl_config.h #endif #include #include #include #include #ifndef __RESTRICT # define __RESTRICT #endif #if !defined(_PTHREADS) && !defined(_NOTHREADS) \ && !defined(__STL_SGI_THREADS) && !defined(__STL_WIN32THREADS) # define _NOTHREADS #endif # ifdef _PTHREADS // POSIX Threads // This is dubious, since this is likely to be a high contention // lock. Performance may not be adequate. # include # define __NODE_ALLOCATOR_LOCK \ if (threads) pthread_mutex_lock(&__node_allocator_lock) # define __NODE_ALLOCATOR_UNLOCK \ if (threads) pthread_mutex_unlock(&__node_allocator_lock) # define __NODE_ALLOCATOR_THREADS true # define __VOLATILE volatile // Needed at -O3 on SGI # endif # ifdef __STL_WIN32THREADS // The lock needs to be initialized by constructing an allocator // objects of the right type. We do that here explicitly for alloc. # define __NODE_ALLOCATOR_LOCK \ EnterCriticalSection(&__node_allocator_lock) # define __NODE_ALLOCATOR_UNLOCK \ LeaveCriticalSection(&__node_allocator_lock) # define __NODE_ALLOCATOR_THREADS true # define __VOLATILE volatile // may not be needed # endif /* WIN32THREADS */ # ifdef __STL_SGI_THREADS // This should work without threads, with sproc threads, or with // pthreads. It is suboptimal in all cases. // It is unlikely to even compile on nonSGI machines. # include # define __NODE_ALLOCATOR_LOCK if (threads && __us_rsthread_malloc) \ { __lock(&__node_allocator_lock); } # define __NODE_ALLOCATOR_UNLOCK if (threads && __us_rsthread_malloc) \ { __unlock(&__node_allocator_lock); } # define __NODE_ALLOCATOR_THREADS true # define __VOLATILE volatile // Needed at -O3 on SGI # endif # ifdef _NOTHREADS // Thread-unsafe # define __NODE_ALLOCATOR_LOCK # define __NODE_ALLOCATOR_UNLOCK # define __NODE_ALLOCATOR_THREADS false # define __VOLATILE # endif #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32) #pragma set woff 1174 #endif // Malloc-based allocator. Typically slower than default alloc below. // Typically thread-safe and more storage efficient. #ifdef __STL_STATIC_TEMPLATE_MEMBER_BUG # ifdef __DECLARE_GLOBALS_HERE void (* __malloc_alloc_oom_handler)() = 0; // g++ 2.7.2 does not handle static template data members. # else extern void (* __malloc_alloc_oom_handler)(); # endif #endif template class __malloc_alloc_template { private: static void *oom_malloc(size_t); static void *oom_realloc(void *, size_t); #ifndef __STL_STATIC_TEMPLATE_MEMBER_BUG static void (* __malloc_alloc_oom_handler)(); #endif public: static void * allocate(size_t n) { void *result = malloc(n); if (0 == result) result = oom_malloc(n); return result; } static void deallocate(void *p, size_t /* n */) { free(p); } static void * reallocate(void *p, size_t /* old_sz */, size_t new_sz) { void * result = realloc(p, new_sz); if (0 == result) result = oom_realloc(p, new_sz); return result; } static void (* set_malloc_handler(void (*f)()))() { void (* old)() = __malloc_alloc_oom_handler; __malloc_alloc_oom_handler = f; return(old); } }; // malloc_alloc out-of-memory handling #ifndef __STL_STATIC_TEMPLATE_MEMBER_BUG template void (* __malloc_alloc_template::__malloc_alloc_oom_handler)() = 0; #endif template void * __malloc_alloc_template::oom_malloc(size_t n) { void (* my_malloc_handler)(); void *result; for (;;) { my_malloc_handler = __malloc_alloc_oom_handler; if (0 == my_malloc_handler) { __THROW_BAD_ALLOC; } (*my_malloc_handler)(); result = malloc(n); if (result) return(result); } } template void * __malloc_alloc_template::oom_realloc(void *p, size_t n) { void (* my_malloc_handler)(); void *result; for (;;) { my_malloc_handler = __malloc_alloc_oom_handler; if (0 == my_malloc_handler) { __THROW_BAD_ALLOC; } (*my_malloc_handler)(); result = realloc(p, n); if (result) return(result); } } typedef __malloc_alloc_template<0> malloc_alloc; template class simple_alloc { public: static T *allocate(size_t n) { return 0 == n? 0 : (T*) Alloc::allocate(n * sizeof (T)); } static T *allocate(void) { return (T*) Alloc::allocate(sizeof (T)); } static void deallocate(T *p, size_t n) { if (0 != n) Alloc::deallocate(p, n * sizeof (T)); } static void deallocate(T *p) { Alloc::deallocate(p, sizeof (T)); } }; // Allocator adaptor to check size arguments for debugging. // Reports errors using assert. Checking can be disabled with // NDEBUG, but it's far better to just use the underlying allocator // instead when no checking is desired. // There is some evidence that this can confuse Purify. template class debug_alloc { private: enum {extra = 8}; // Size of space used to store size. Note // that this must be large enough to preserve // alignment. public: static void * allocate(size_t n) { char *result = (char *)Alloc::allocate(n + extra); *(size_t *)result = n; return result + extra; } static void deallocate(void *p, size_t n) { char * real_p = (char *)p - extra; assert(*(size_t *)real_p == n); Alloc::deallocate(real_p, n + extra); } static void * reallocate(void *p, size_t old_sz, size_t new_sz) { char * real_p = (char *)p - extra; assert(*(size_t *)real_p == old_sz); char * result = (char *) Alloc::reallocate(real_p, old_sz + extra, new_sz + extra); *(size_t *)result = new_sz; return result + extra; } }; # ifdef __USE_MALLOC typedef malloc_alloc alloc; typedef malloc_alloc single_client_alloc; # else // Default node allocator. // With a reasonable compiler, this should be roughly as fast as the // original STL class-specific allocators, but with less fragmentation. // Default_alloc_template parameters are experimental and MAY // DISAPPEAR in the future. Clients should just use alloc for now. // // Important implementation properties: // 1. If the client request an object of size > __MAX_BYTES, the resulting // object will be obtained directly from malloc. // 2. In all other cases, we allocate an object of size exactly // ROUND_UP(requested_size). Thus the client has enough size // information that we can return the object to the proper free list // without permanently losing part of the object. // // The first template parameter specifies whether more than one thread // may use this allocator. It is safe to allocate an object from // one instance of a default_alloc and deallocate it with another // one. This effectively transfers its ownership to the second one. // This may have undesirable effects on reference locality. // The second parameter is unreferenced and serves only to allow the // creation of multiple default_alloc instances. // Node that containers built on different allocator instances have // different types, limiting the utility of this approach. #ifdef __SUNPRO_CC // breaks if we make these template class members: enum {__ALIGN = 8}; enum {__MAX_BYTES = 128}; enum {__NFREELISTS = __MAX_BYTES/__ALIGN}; #endif template class __default_alloc_template { private: // Really we should use static const int x = N // instead of enum { x = N }, but few compilers accept the former. # ifndef __SUNPRO_CC enum {__ALIGN = 8}; enum {__MAX_BYTES = 128}; enum {__NFREELISTS = __MAX_BYTES/__ALIGN}; # endif static size_t ROUND_UP(size_t bytes) { return (((bytes) + __ALIGN-1) & ~(__ALIGN - 1)); } __PRIVATE: union obj { union obj * free_list_link; char client_data[1]; /* The client sees this. */ }; private: # ifdef __SUNPRO_CC static obj * __VOLATILE free_list[]; // Specifying a size results in duplicate def for 4.1 # else static obj * __VOLATILE free_list[__NFREELISTS]; # endif static size_t FREELIST_INDEX(size_t bytes) { return (((bytes) + __ALIGN-1)/__ALIGN - 1); } // Returns an object of size n, and optionally adds to size n free list. static void *refill(size_t n); // Allocates a chunk for nobjs of size size. nobjs may be reduced // if it is inconvenient to allocate the requested number. static char *chunk_alloc(size_t size, int &nobjs); // Chunk allocation state. static char *start_free; static char *end_free; static size_t heap_size; # ifdef __STL_SGI_THREADS static volatile unsigned long __node_allocator_lock; static void __lock(volatile unsigned long *); static inline void __unlock(volatile unsigned long *); # endif # ifdef _PTHREADS static pthread_mutex_t __node_allocator_lock; # endif # ifdef __STL_WIN32THREADS static CRITICAL_SECTION __node_allocator_lock; static bool __node_allocator_lock_initialized; public: __default_alloc_template() { // This assumes the first constructor is called before threads // are started. if (!__node_allocator_lock_initialized) { InitializeCriticalSection(&__node_allocator_lock); __node_allocator_lock_initialized = true; } } private: # endif class lock { public: lock() { __NODE_ALLOCATOR_LOCK; } ~lock() { __NODE_ALLOCATOR_UNLOCK; } }; friend class lock; public: /* n must be > 0 */ static void * allocate(size_t n) { obj * __VOLATILE * my_free_list; obj * __RESTRICT result; if (n > __MAX_BYTES) { return(malloc_alloc::allocate(n)); } my_free_list = free_list + FREELIST_INDEX(n); // Acquire the lock here with a constructor call. // This ensures that it is released in exit or during stack // unwinding. /*REFERENCED*/ lock lock_instance; result = *my_free_list; if (result == 0) { void *r = refill(ROUND_UP(n)); return r; } *my_free_list = result -> free_list_link; return (result); }; /* p may not be 0 */ static void deallocate(void *p, size_t n) { obj *q = (obj *)p; obj * __VOLATILE * my_free_list; if (n > __MAX_BYTES) { malloc_alloc::deallocate(p, n); return; } my_free_list = free_list + FREELIST_INDEX(n); // acquire lock /*REFERENCED*/ lock lock_instance; q -> free_list_link = *my_free_list; *my_free_list = q; // lock is released here } static void * reallocate(void *p, size_t old_sz, size_t new_sz); } ; typedef __default_alloc_template<__NODE_ALLOCATOR_THREADS, 0> alloc; typedef __default_alloc_template single_client_alloc; /* We allocate memory in large chunks in order to avoid fragmenting */ /* the malloc heap too much. */ /* We assume that size is properly aligned. */ /* We hold the allocation lock. */ template char* __default_alloc_template::chunk_alloc(size_t size, int& nobjs) { char * result; size_t total_bytes = size * nobjs; size_t bytes_left = end_free - start_free; if (bytes_left >= total_bytes) { result = start_free; start_free += total_bytes; return(result); } else if (bytes_left >= size) { nobjs = bytes_left/size; total_bytes = size * nobjs; result = start_free; start_free += total_bytes; return(result); } else { size_t bytes_to_get = 2 * total_bytes + ROUND_UP(heap_size >> 4); // Try to make use of the left-over piece. if (bytes_left > 0) { obj * __VOLATILE * my_free_list = free_list + FREELIST_INDEX(bytes_left); ((obj *)start_free) -> free_list_link = *my_free_list; *my_free_list = (obj *)start_free; } start_free = (char *)malloc(bytes_to_get); if (0 == start_free) { int i; obj * __VOLATILE * my_free_list, *p; // Try to make do with what we have. That can't // hurt. We do not try smaller requests, since that tends // to result in disaster on multi-process machines. for (i = size; i <= __MAX_BYTES; i += __ALIGN) { my_free_list = free_list + FREELIST_INDEX(i); p = *my_free_list; if (0 != p) { *my_free_list = p -> free_list_link; start_free = (char *)p; end_free = start_free + i; return(chunk_alloc(size, nobjs)); // Any leftover piece will eventually make it to the // right free list. } } start_free = (char *)malloc_alloc::allocate(bytes_to_get); // This should either throw an // exception or remedy the situation. Thus we assume it // succeeded. } heap_size += bytes_to_get; end_free = start_free + bytes_to_get; return(chunk_alloc(size, nobjs)); } } /* Returns an object of size n, and optionally adds to size n free list.*/ /* We assume that n is properly aligned. */ /* We hold the allocation lock. */ template void* __default_alloc_template::refill(size_t n) { int nobjs = 20; char * chunk = chunk_alloc(n, nobjs); obj * __VOLATILE * my_free_list; obj * result; obj * current_obj, * next_obj; int i; if (1 == nobjs) return(chunk); my_free_list = free_list + FREELIST_INDEX(n); /* Build free list in chunk */ result = (obj *)chunk; *my_free_list = next_obj = (obj *)(chunk + n); for (i = 1; ; i++) { current_obj = next_obj; next_obj = (obj *)((char *)next_obj + n); if (nobjs - 1 == i) { current_obj -> free_list_link = 0; break; } else { current_obj -> free_list_link = next_obj; } } return(result); } template void* __default_alloc_template::reallocate(void *p, size_t old_sz, size_t new_sz) { void * result; size_t copy_sz; if (old_sz > __MAX_BYTES && new_sz > __MAX_BYTES) { return(realloc(p, new_sz)); } if (ROUND_UP(old_sz) == ROUND_UP(new_sz)) return(p); result = allocate(new_sz); copy_sz = new_sz > old_sz? old_sz : new_sz; memcpy(result, p, copy_sz); deallocate(p, old_sz); return(result); } #ifdef _PTHREADS template pthread_mutex_t __default_alloc_template::__node_allocator_lock = PTHREAD_MUTEX_INITIALIZER; #endif #ifdef __STL_WIN32THREADS template CRITICAL_SECTION __default_alloc_template::__node_allocator_lock; template bool __default_alloc_template::__node_allocator_lock_initialized = false; #endif #ifdef __STL_SGI_THREADS #include #include // Somewhat generic lock implementations. We need only test-and-set // and some way to sleep. These should work with both SGI pthreads // and sproc threads. They may be useful on other systems. template volatile unsigned long __default_alloc_template::__node_allocator_lock = 0; #if __mips < 3 || !(defined (_ABIN32) || defined(_ABI64)) || defined(__GNUC__) # define __test_and_set(l,v) test_and_set(l,v) #endif template void __default_alloc_template::__lock(volatile unsigned long *lock) { const unsigned low_spin_max = 30; // spin cycles if we suspect uniprocessor const unsigned high_spin_max = 1000; // spin cycles for multiprocessor static unsigned spin_max = low_spin_max; unsigned my_spin_max; static unsigned last_spins = 0; unsigned my_last_spins; static struct timespec ts = {0, 1000}; unsigned junk; # define __ALLOC_PAUSE junk *= junk; junk *= junk; junk *= junk; junk *= junk int i; if (!__test_and_set((unsigned long *)lock, 1)) { return; } my_spin_max = spin_max; my_last_spins = last_spins; for (i = 0; i < my_spin_max; i++) { if (i < my_last_spins/2 || *lock) { __ALLOC_PAUSE; continue; } if (!__test_and_set((unsigned long *)lock, 1)) { // got it! // Spinning worked. Thus we're probably not being scheduled // against the other process with which we were contending. // Thus it makes sense to spin longer the next time. last_spins = i; spin_max = high_spin_max; return; } } // We are probably being scheduled against the other process. Sleep. spin_max = low_spin_max; for (;;) { if (!__test_and_set((unsigned long *)lock, 1)) { return; } nanosleep(&ts, 0); } } template inline void __default_alloc_template::__unlock(volatile unsigned long *lock) { # if defined(__GNUC__) && __mips >= 3 asm("sync"); *lock = 0; # elif __mips >= 3 && (defined (_ABIN32) || defined(_ABI64)) __lock_release(lock); # else *lock = 0; // This is not sufficient on many multiprocessors, since // writes to protected variables and the lock may be reordered. # endif } #endif template char *__default_alloc_template::start_free = 0; template char *__default_alloc_template::end_free = 0; template size_t __default_alloc_template::heap_size = 0; template __default_alloc_template::obj * __VOLATILE __default_alloc_template ::free_list[ # ifdef __SUNPRO_CC __NFREELISTS # else __default_alloc_template::__NFREELISTS # endif ] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }; // The 16 zeros are necessary to make version 4.1 of the SunPro // compiler happy. Otherwise it appears to allocate too little // space for the array. # ifdef __STL_WIN32THREADS // Create one to get critical section initialized. // We do this onece per file, but only the first constructor // does anything. static alloc __node_allocator_dummy_instance; # endif #endif /* ! __USE_MALLOC */ #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32) #pragma reset woff 1174 #endif #endif /* __NODE_ALLOC_H */