implemented Setup.hs to build boehm cpp libs and install them;

[hs-boehmgc.git] / gc-7.2 / include / private / specific.h

diff --git a/gc-7.2/include/private/specific.h b/gc-7.2/include/private/specific.h
new file mode 100644 (file)
index 0000000..8b5cf84
--- /dev/null
+++ b/gc-7.2/include/private/specific.h
@@ -0,0 +1,90 @@
+/*
+ * This is a reimplementation of a subset of the pthread_getspecific/setspecific
+ * interface. This appears to outperform the standard linuxthreads one
+ * by a significant margin.
+ * The major restriction is that each thread may only make a single
+ * pthread_setspecific call on a single key.  (The current data structure
+ * doesn't really require that.  The restriction should be easily removable.)
+ * We don't currently support the destruction functions, though that
+ * could be done.
+ * We also currently assume that only one pthread_setspecific call
+ * can be executed at a time, though that assumption would be easy to remove
+ * by adding a lock.
+ */
+
+#include <errno.h>
+#include "atomic_ops.h"
+
+/* Called during key creation or setspecific.           */
+/* For the GC we already hold lock.                     */
+/* Currently allocated objects leak on thread exit.     */
+/* That's hard to fix, but OK if we allocate garbage    */
+/* collected memory.                                    */
+#define MALLOC_CLEAR(n) GC_INTERNAL_MALLOC(n, NORMAL)
+#define PREFIXED(name) GC_##name
+
+#define TS_CACHE_SIZE 1024
+#define CACHE_HASH(n) (((((long)n) >> 8) ^ (long)n) & (TS_CACHE_SIZE - 1))
+#define TS_HASH_SIZE 1024
+#define HASH(n) (((((long)n) >> 8) ^ (long)n) & (TS_HASH_SIZE - 1))
+
+/* An entry describing a thread-specific value for a given thread.      */
+/* All such accessible structures preserve the invariant that if either */
+/* thread is a valid pthread id or qtid is a valid "quick tread id"     */
+/* for a thread, then value holds the corresponding thread specific     */
+/* value.  This invariant must be preserved at ALL times, since         */
+/* asynchronous reads are allowed.                                      */
+typedef struct thread_specific_entry {
+        volatile AO_t qtid;     /* quick thread id, only for cache */
+        void * value;
+        struct thread_specific_entry *next;
+        pthread_t thread;
+} tse;
+
+/* We represent each thread-specific datum as two tables.  The first is */
+/* a cache, indexed by a "quick thread identifier".  The "quick" thread */
+/* identifier is an easy to compute value, which is guaranteed to       */
+/* determine the thread, though a thread may correspond to more than    */
+/* one value.  We typically use the address of a page in the stack.     */
+/* The second is a hash table, indexed by pthread_self().  It is used   */
+/* only as a backup.                                                    */
+
+/* Return the "quick thread id".  Default version.  Assumes page size,  */
+/* or at least thread stack separation, is at least 4K.                 */
+/* Must be defined so that it never returns 0.  (Page 0 can't really be */
+/* part of any stack, since that would make 0 a valid stack pointer.)   */
+#define quick_thread_id() (((unsigned long)GC_approx_sp()) >> 12)
+
+#define INVALID_QTID ((unsigned long)0)
+#define INVALID_THREADID ((pthread_t)0)
+
+typedef struct thread_specific_data {
+    tse * volatile cache[TS_CACHE_SIZE];
+                        /* A faster index to the hash table */
+    tse * hash[TS_HASH_SIZE];
+    pthread_mutex_t lock;
+} tsd;
+
+typedef tsd * PREFIXED(key_t);
+
+int PREFIXED(key_create) (tsd ** key_ptr, void (* destructor)(void *));
+int PREFIXED(setspecific) (tsd * key, void * value);
+void PREFIXED(remove_specific) (tsd * key);
+
+/* An internal version of getspecific that assumes a cache miss.        */
+void * PREFIXED(slow_getspecific) (tsd * key, unsigned long qtid,
+                                   tse * volatile * cache_entry);
+
+/* GC_INLINE is defined in gc_priv.h. */
+GC_INLINE void * PREFIXED(getspecific) (tsd * key)
+{
+    unsigned long qtid = quick_thread_id();
+    unsigned hash_val = CACHE_HASH(qtid);
+    tse * volatile * entry_ptr = key -> cache + hash_val;
+    tse * entry = *entry_ptr;   /* Must be loaded only once.    */
+    if (EXPECT(entry -> qtid == qtid, TRUE)) {
+      GC_ASSERT(entry -> thread == pthread_self());
+      return entry -> value;
+    }
+    return PREFIXED(slow_getspecific) (key, qtid, entry_ptr);
+}