[pypy-commit] pypy stmgc-c8-gcc: import stmgc with finalizer fixes

[Raemi]

Author: Remi Meier <remi.me...@inf.ethz.ch>
Branch: stmgc-c8-gcc
Changeset: r79242:163412702b2b
Date: 2015-08-27 10:25 +0200
http://bitbucket.org/pypy/pypy/changeset/163412702b2b/

Log:    import stmgc with finalizer fixes

diff --git a/rpython/translator/stm/src_stm/revision 
b/rpython/translator/stm/src_stm/revision
--- a/rpython/translator/stm/src_stm/revision
+++ b/rpython/translator/stm/src_stm/revision
@@ -1,1 +1,1 @@
-a3cb98b78053
+08c773f2b6ef
diff --git a/rpython/translator/stm/src_stm/stm/core.c 
b/rpython/translator/stm/src_stm/stm/core.c
--- a/rpython/translator/stm/src_stm/stm/core.c
+++ b/rpython/translator/stm/src_stm/stm/core.c
@@ -1365,9 +1365,10 @@
         stm_rewind_jmp_forget(STM_SEGMENT->running_thread);
     }
 
+    commit_finalizers();
+
     /* XXX do we still need a s_mutex_lock() section here? */
     s_mutex_lock();
-    commit_finalizers();
 
     /* update 'overflow_number' if needed */
     if (STM_PSEGMENT->overflow_number_has_been_used) {
diff --git a/rpython/translator/stm/src_stm/stm/finalizer.c 
b/rpython/translator/stm/src_stm/stm/finalizer.c
--- a/rpython/translator/stm/src_stm/stm/finalizer.c
+++ b/rpython/translator/stm/src_stm/stm/finalizer.c
@@ -29,6 +29,9 @@
 static void _commit_finalizers(void)
 {
     /* move finalizer lists to g_finalizers for major collections */
+    while (__sync_lock_test_and_set(&g_finalizers.lock, 1) != 0) {
+        spin_loop();
+    }
 
     if (STM_PSEGMENT->finalizers->run_finalizers != NULL) {
         /* copy 'STM_PSEGMENT->finalizers->run_finalizers' into
@@ -60,6 +63,8 @@
 
     free(STM_PSEGMENT->finalizers);
     STM_PSEGMENT->finalizers = NULL;
+
+    __sync_lock_release(&g_finalizers.lock);
 }
 
 static void abort_finalizers(struct stm_priv_segment_info_s *pseg)
@@ -389,7 +394,7 @@
 static void deal_with_objects_with_finalizers(void)
 {
     /* for non-light finalizers */
-
+    assert(_has_mutex());
     /* there is one 'objects_with_finalizers' list per segment.
        Objects that die at a major collection running in the same
        transaction as they were created will be put in the
@@ -481,25 +486,44 @@
     LIST_FREE(f->run_finalizers);
 }
 
+/* XXX: can there be a race between _invoke_general_finalizers
+        and _commit_finalizer on g_finalizers (+other places?)?
+   XXX: what happens in _execute_finalizer if the transaction
+        conflicts (or fails to become inevitable) in a finalizer?
+        (the run_finalizers list is half-way cleared?)
+   XXX: according to translator.backendopt.finalizer, getfield_gc
+        for primitive types is a safe op in light finalizers.
+        I don't think that's correct in general (maybe if
+        getfield on *dying obj*).
+*/
+
 static void _invoke_general_finalizers(stm_thread_local_t *tl)
 {
     /* called between transactions */
-    static int lock = 0;
-
-    if (__sync_lock_test_and_set(&lock, 1) != 0) {
-        /* can't acquire the lock: someone else is likely already
-           running this function, so don't wait. */
-        return;
-    }
-
     rewind_jmp_buf rjbuf;
     stm_rewind_jmp_enterframe(tl, &rjbuf);
     _stm_start_transaction(tl);
+    /* XXX: become inevitable, bc. otherwise, we would need to keep
+       around the original g_finalizers.run_finalizers to restore it
+       in case of an abort. */
+    _stm_become_inevitable("finalizer-Tx");
 
-    _execute_finalizers(&g_finalizers);
+    while (__sync_lock_test_and_set(&g_finalizers.lock, 1) != 0) {
+        /* somebody is adding more finalizers (_commit_finalizer()) */
+        spin_loop();
+    }
+    struct finalizers_s copy = g_finalizers;
+    assert(copy.running_next == NULL);
+    g_finalizers.run_finalizers = NULL;
+    /* others may add to g_finalizers again: */
+    __sync_lock_release(&g_finalizers.lock);
+
+    if (copy.run_finalizers != NULL) {
+        _execute_finalizers(&copy);
+    }
 
     _stm_commit_transaction();
     stm_rewind_jmp_leaveframe(tl, &rjbuf);
 
-    __sync_lock_release(&lock);
+    LIST_FREE(copy.run_finalizers);
 }
diff --git a/rpython/translator/stm/src_stm/stm/finalizer.h 
b/rpython/translator/stm/src_stm/stm/finalizer.h
--- a/rpython/translator/stm/src_stm/stm/finalizer.h
+++ b/rpython/translator/stm/src_stm/stm/finalizer.h
@@ -1,5 +1,7 @@
 /* Imported by rpython/translator/stm/import_stmgc.py */
+/* see deal_with_objects_with_finalizers() for explanation of these fields */
 struct finalizers_s {
+    long lock;
     struct list_s *objects_with_finalizers;
     uintptr_t count_non_young;
     struct list_s *run_finalizers;
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