+#ifdef NACL
+extern volatile int nacl_thread_parked[MAX_NACL_GC_THREADS];
+extern volatile int nacl_thread_used[MAX_NACL_GC_THREADS];
+extern volatile int nacl_thread_parking_inited;
+extern volatile int nacl_num_gc_threads;
+extern pthread_mutex_t nacl_thread_alloc_lock;
+extern __thread int nacl_thread_idx;
+extern __thread GC_thread nacl_gc_thread_self;
+
+extern void nacl_pre_syscall_hook();
+extern void nacl_post_syscall_hook();
+extern void nacl_register_gc_hooks(void (*pre)(), void (*post)());
+
+#include <stdio.h>
+
+struct nacl_irt_blockhook {
+ int (*register_block_hooks)(void (*pre)(void), void (*post)(void));
+};
+
+extern size_t nacl_interface_query(const char *interface_ident,
+ void *table, size_t tablesize);
+
+void nacl_initialize_gc_thread()
+{
+ int i;
+ static struct nacl_irt_blockhook gc_hook;
+
+ pthread_mutex_lock(&nacl_thread_alloc_lock);
+ if (!nacl_thread_parking_inited)
+ {
+ for (i = 0; i < MAX_NACL_GC_THREADS; i++) {
+ nacl_thread_used[i] = 0;
+ nacl_thread_parked[i] = 0;
+ }
+ // TODO: replace with public 'register hook' function when
+ // available from glibc
+ nacl_interface_query("nacl-irt-blockhook-0.1", &gc_hook, sizeof(gc_hook));
+ gc_hook.register_block_hooks(nacl_pre_syscall_hook, nacl_post_syscall_hook);
+ nacl_thread_parking_inited = 1;
+ }
+ GC_ASSERT(nacl_num_gc_threads <= MAX_NACL_GC_THREADS);
+ for (i = 0; i < MAX_NACL_GC_THREADS; i++) {
+ if (nacl_thread_used[i] == 0) {
+ nacl_thread_used[i] = 1;
+ nacl_thread_idx = i;
+ nacl_num_gc_threads++;
+ break;
+ }
+ }
+ pthread_mutex_unlock(&nacl_thread_alloc_lock);
+}
+
+void nacl_shutdown_gc_thread()
+{
+ pthread_mutex_lock(&nacl_thread_alloc_lock);
+ GC_ASSERT(nacl_thread_idx >= 0 && nacl_thread_idx < MAX_NACL_GC_THREADS);
+ GC_ASSERT(nacl_thread_used[nacl_thread_idx] != 0);
+ nacl_thread_used[nacl_thread_idx] = 0;
+ nacl_thread_idx = -1;
+ nacl_num_gc_threads--;
+ pthread_mutex_unlock(&nacl_thread_alloc_lock);
+}
+
+#endif /* NACL */
+