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| Subject | I am beginning to lose trust in my ability to code straight. | ||||||||||||||||||||||||
| From | downs <default_357-line@yahoo.de> | ||||||||||||||||||||||||
| Date | Wed, 25 Jun 2008 19:17:29 +0200 | ||||||||||||||||||||||||
| Newsgroups | digitalmars.D | ||||||||||||||||||||||||
| Attachment(s) | phobos_gc_constant_time_removeRange.patch | ||||||||||||||||||||||||
Aaaand another one! This time, it's a race condition. When two threads try to removeRange at the same time, the position of a Range might change before the lock is engaged. Fixed by passing the index by reference until inside the sync block. | |||||||||||||||||||||||||
diff -Nur --exclude aaA.d --exclude math.d dgcc/d/phobos/internal/gc/gc.d gcc-4.2.4/gcc/d/phobos/internal/gc/gc.d --- dgcc/d/phobos/internal/gc/gc.d 2008-03-07 16:55:56.000000000 +0100 +++ gcc-4.2.4/gcc/d/phobos/internal/gc/gc.d 2008-06-25 19:10:37.000000000 +0200 @@ -56,8 +56,11 @@ void addRoot(void *p) { _gc.addRoot(p); } void removeRoot(void *p) { _gc.removeRoot(p); } -void addRange(void *pbot, void *ptop) { _gc.addRange(pbot, ptop); } +void addRange(void *pbot, void *ptop, size_t* target = null) { + _gc.addRange(pbot, ptop, target); +} void removeRange(void *pbot) { _gc.removeRange(pbot); } +void removeRange(ref size_t index) { _gc.removeRange(index); } void fullCollect() { _gc.fullCollect(); } void fullCollectNoStack() { _gc.fullCollectNoStack(); } void genCollect() { _gc.genCollect(); } diff -Nur --exclude aaA.d --exclude math.d dgcc/d/phobos/internal/gc/gcx.d gcc-4.2.4/gcc/d/phobos/internal/gc/gcx.d --- dgcc/d/phobos/internal/gc/gcx.d 2008-06-18 19:36:26.000000000 +0200 +++ gcc-4.2.4/gcc/d/phobos/internal/gc/gcx.d 2008-06-25 19:11:14.000000000 +0200 @@ -966,7 +970,7 @@ /** * add range to scan for roots */ - void addRange(void *pbot, void *ptop) + void addRange(void *pbot, void *ptop, size_t* target = null) { if (!pbot || !ptop) { @@ -976,11 +980,11 @@ //debug(PRINTF) printf("+GC.addRange(pbot = x%x, ptop = x%x)\n", pbot, ptop); if (!thread_needLock()) { - gcx.addRange(pbot, ptop); + gcx.addRange(pbot, ptop, target); } else synchronized (gcLock) { - gcx.addRange(pbot, ptop); + gcx.addRange(pbot, ptop, target); } //debug(PRINTF) printf("-GC.addRange()\n"); } @@ -1006,6 +1010,20 @@ } } + /** + * remove range with index + */ + void removeRange(ref size_t index) + { + if (!thread_needLock()) + { + gcx.removeRange(index); + } + else synchronized (gcLock) + { + gcx.removeRange(index); + } + } /** * do full garbage collection @@ -1211,6 +1229,7 @@ struct Range { + size_t* target; void *pbot; void *ptop; } @@ -1417,7 +1436,7 @@ /** * */ - void addRange(void *pbot, void *ptop) + void addRange(void *pbot, void *ptop, size_t* target = null) { debug(THREADINVARIANT) { debug(PRINTF) printf("Thread %x ", pthread_self()); } debug(PRINTF) printf("%x.Gcx::addRange(%x, %x), nranges = %d\n", this, pbot, ptop, nranges); @@ -1438,7 +1457,9 @@ } ranges[nranges].pbot = pbot; ranges[nranges].ptop = ptop; - nranges++; + ranges[nranges].target = target; + if (target) *target = nranges; + nranges ++; } @@ -1453,8 +1474,9 @@ { if (ranges[i].pbot == pbot) { - nranges--; - cstring.memmove(ranges + i, ranges + i + 1, (nranges - i) * ranges[0].sizeof); + /*nranges--; + cstring.memmove(ranges + i, ranges + i + 1, (nranges - i) * ranges[0].sizeof);*/ + removeRange(i); return; } } @@ -1466,6 +1488,18 @@ //assert(zero); } + void removeRange(size_t index) { + debug(PRINTF) printf("%x.Gcx.removeRange(%d), nranges=%d\n", this, index, nranges); + if (index !< nranges) + throw new Exception("removeRange: No such index!"); + if (index < nranges - 1) { + ranges[index] = ranges[nranges - 1]; + if (ranges[index].target) + *ranges[index].target = index; + } + nranges--; + } + /** * Find Pool that pointer is in. diff -Nur --exclude aaA.d --exclude math.d dgcc/d/phobos/std/gc.d gcc-4.2.4/gcc/d/phobos/std/gc.d --- dgcc/d/phobos/std/gc.d 2007-10-16 21:02:09.000000000 +0200 +++ gcc-4.2.4/gcc/d/phobos/std/gc.d 2008-06-25 19:12:01.000000000 +0200 @@ -52,12 +52,13 @@ /** * Add range to scan for roots. */ -void addRange(void *pbot, void *ptop); // add range to scan for roots +void addRange(void *pbot, void *ptop, size_t* target = null); /** * Remove range. */ void removeRange(void *pbot); // remove range +void removeRange(ref size_t index); // remove range by index /** * Mark a gc allocated block of memory as possibly containing pointers. | |||||||||||||||||||||||||
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