Clean up some minor white space issues in trans-decl.c and trans-expr.c
[official-gcc.git] / boehm-gc / include / private / specific.h
blobd04e19f5a4b5dcd9c60f66a24d7ff7e626402250
1 /*
2 * This is a reimplementation of a subset of the pthread_getspecific/setspecific
3 * interface. This appears to outperform the standard linuxthreads one
4 * by a significant margin.
5 * The major restriction is that each thread may only make a single
6 * pthread_setspecific call on a single key. (The current data structure
7 * doesn't really require that. The restriction should be easily removable.)
8 * We don't currently support the destruction functions, though that
9 * could be done.
10 * We also currently assume that only one pthread_setspecific call
11 * can be executed at a time, though that assumption would be easy to remove
12 * by adding a lock.
15 #include <errno.h>
17 /* Called during key creation or setspecific. */
18 /* For the GC we already hold lock. */
19 /* Currently allocated objects leak on thread exit. */
20 /* That's hard to fix, but OK if we allocate garbage */
21 /* collected memory. */
22 #define MALLOC_CLEAR(n) GC_INTERNAL_MALLOC(n, NORMAL)
23 #define PREFIXED(name) GC_##name
25 #define TS_CACHE_SIZE 1024
26 #define CACHE_HASH(n) (((((long)n) >> 8) ^ (long)n) & (TS_CACHE_SIZE - 1))
27 #define TS_HASH_SIZE 1024
28 #define HASH(n) (((((long)n) >> 8) ^ (long)n) & (TS_HASH_SIZE - 1))
30 /* An entry describing a thread-specific value for a given thread. */
31 /* All such accessible structures preserve the invariant that if either */
32 /* thread is a valid pthread id or qtid is a valid "quick tread id" */
33 /* for a thread, then value holds the corresponding thread specific */
34 /* value. This invariant must be preserved at ALL times, since */
35 /* asynchronous reads are allowed. */
36 typedef struct thread_specific_entry {
37 unsigned long qtid; /* quick thread id, only for cache */
38 void * value;
39 struct thread_specific_entry *next;
40 pthread_t thread;
41 } tse;
44 /* We represent each thread-specific datum as two tables. The first is */
45 /* a cache, indexed by a "quick thread identifier". The "quick" thread */
46 /* identifier is an easy to compute value, which is guaranteed to */
47 /* determine the thread, though a thread may correspond to more than */
48 /* one value. We typically use the address of a page in the stack. */
49 /* The second is a hash table, indexed by pthread_self(). It is used */
50 /* only as a backup. */
52 /* Return the "quick thread id". Default version. Assumes page size, */
53 /* or at least thread stack separation, is at least 4K. */
54 /* Must be defined so that it never returns 0. (Page 0 can't really */
55 /* be part of any stack, since that would make 0 a valid stack pointer.)*/
56 static __inline__ unsigned long quick_thread_id() {
57 int dummy;
58 return (unsigned long)(&dummy) >> 12;
61 #define INVALID_QTID ((unsigned long)0)
62 #define INVALID_THREADID ((pthread_t)0)
64 typedef struct thread_specific_data {
65 tse * volatile cache[TS_CACHE_SIZE];
66 /* A faster index to the hash table */
67 tse * hash[TS_HASH_SIZE];
68 pthread_mutex_t lock;
69 } tsd;
71 typedef tsd * PREFIXED(key_t);
73 extern int PREFIXED(key_create) (tsd ** key_ptr, void (* destructor)(void *));
75 extern int PREFIXED(setspecific) (tsd * key, void * value);
77 extern void PREFIXED(remove_specific) (tsd * key);
79 /* An internal version of getspecific that assumes a cache miss. */
80 void * PREFIXED(slow_getspecific) (tsd * key, unsigned long qtid,
81 tse * volatile * cache_entry);
83 static __inline__ void * PREFIXED(getspecific) (tsd * key) {
84 long qtid = quick_thread_id();
85 unsigned hash_val = CACHE_HASH(qtid);
86 tse * volatile * entry_ptr = key -> cache + hash_val;
87 tse * entry = *entry_ptr; /* Must be loaded only once. */
88 if (EXPECT(entry -> qtid == qtid, 1)) {
89 GC_ASSERT(entry -> thread == pthread_self());
90 return entry -> value;
92 return PREFIXED(slow_getspecific) (key, qtid, entry_ptr);