Annotation of OpenXM_contrib2/asir2000/gc/include/gc_cpp.h, Revision 1.4
1.1 noro 1: #ifndef GC_CPP_H
2: #define GC_CPP_H
3: /****************************************************************************
4: Copyright (c) 1994 by Xerox Corporation. All rights reserved.
5:
6: THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
7: OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
8:
9: Permission is hereby granted to use or copy this program for any
10: purpose, provided the above notices are retained on all copies.
11: Permission to modify the code and to distribute modified code is
12: granted, provided the above notices are retained, and a notice that
13: the code was modified is included with the above copyright notice.
14: ****************************************************************************
15:
16: C++ Interface to the Boehm Collector
17:
18: John R. Ellis and Jesse Hull
19:
20: This interface provides access to the Boehm collector. It provides
21: basic facilities similar to those described in "Safe, Efficient
22: Garbage Collection for C++", by John R. Elis and David L. Detlefs
1.2 noro 23: (ftp://ftp.parc.xerox.com/pub/ellis/gc).
1.1 noro 24:
25: All heap-allocated objects are either "collectable" or
26: "uncollectable". Programs must explicitly delete uncollectable
27: objects, whereas the garbage collector will automatically delete
28: collectable objects when it discovers them to be inaccessible.
29: Collectable objects may freely point at uncollectable objects and vice
30: versa.
31:
32: Objects allocated with the built-in "::operator new" are uncollectable.
33:
34: Objects derived from class "gc" are collectable. For example:
35:
36: class A: public gc {...};
37: A* a = new A; // a is collectable.
38:
39: Collectable instances of non-class types can be allocated using the GC
1.2 noro 40: (or UseGC) placement:
1.1 noro 41:
42: typedef int A[ 10 ];
43: A* a = new (GC) A;
44:
45: Uncollectable instances of classes derived from "gc" can be allocated
46: using the NoGC placement:
47:
48: class A: public gc {...};
49: A* a = new (NoGC) A; // a is uncollectable.
50:
51: Both uncollectable and collectable objects can be explicitly deleted
52: with "delete", which invokes an object's destructors and frees its
53: storage immediately.
54:
55: A collectable object may have a clean-up function, which will be
56: invoked when the collector discovers the object to be inaccessible.
57: An object derived from "gc_cleanup" or containing a member derived
58: from "gc_cleanup" has a default clean-up function that invokes the
59: object's destructors. Explicit clean-up functions may be specified as
60: an additional placement argument:
61:
62: A* a = ::new (GC, MyCleanup) A;
63:
64: An object is considered "accessible" by the collector if it can be
65: reached by a path of pointers from static variables, automatic
66: variables of active functions, or from some object with clean-up
67: enabled; pointers from an object to itself are ignored.
68:
69: Thus, if objects A and B both have clean-up functions, and A points at
70: B, B is considered accessible. After A's clean-up is invoked and its
71: storage released, B will then become inaccessible and will have its
72: clean-up invoked. If A points at B and B points to A, forming a
73: cycle, then that's considered a storage leak, and neither will be
74: collectable. See the interface gc.h for low-level facilities for
75: handling such cycles of objects with clean-up.
76:
77: The collector cannot guarrantee that it will find all inaccessible
78: objects. In practice, it finds almost all of them.
79:
80:
81: Cautions:
82:
83: 1. Be sure the collector has been augmented with "make c++".
84:
85: 2. If your compiler supports the new "operator new[]" syntax, then
1.4 ! noro 86: add -DGC_OPERATOR_NEW_ARRAY to the Makefile.
1.1 noro 87:
88: If your compiler doesn't support "operator new[]", beware that an
89: array of type T, where T is derived from "gc", may or may not be
90: allocated as a collectable object (it depends on the compiler). Use
91: the explicit GC placement to make the array collectable. For example:
92:
93: class A: public gc {...};
94: A* a1 = new A[ 10 ]; // collectable or uncollectable?
95: A* a2 = new (GC) A[ 10 ]; // collectable
96:
97: 3. The destructors of collectable arrays of objects derived from
98: "gc_cleanup" will not be invoked properly. For example:
99:
100: class A: public gc_cleanup {...};
101: A* a = new (GC) A[ 10 ]; // destructors not invoked correctly
102:
103: Typically, only the destructor for the first element of the array will
104: be invoked when the array is garbage-collected. To get all the
105: destructors of any array executed, you must supply an explicit
106: clean-up function:
107:
108: A* a = new (GC, MyCleanUp) A[ 10 ];
109:
110: (Implementing clean-up of arrays correctly, portably, and in a way
111: that preserves the correct exception semantics requires a language
112: extension, e.g. the "gc" keyword.)
113:
114: 4. Compiler bugs:
115:
116: * Solaris 2's CC (SC3.0) doesn't implement t->~T() correctly, so the
117: destructors of classes derived from gc_cleanup won't be invoked.
118: You'll have to explicitly register a clean-up function with
119: new-placement syntax.
120:
121: * Evidently cfront 3.0 does not allow destructors to be explicitly
122: invoked using the ANSI-conforming syntax t->~T(). If you're using
123: cfront 3.0, you'll have to comment out the class gc_cleanup, which
124: uses explicit invocation.
125:
1.2 noro 126: 5. GC name conflicts:
127:
128: Many other systems seem to use the identifier "GC" as an abbreviation
129: for "Graphics Context". Since version 5.0, GC placement has been replaced
130: by UseGC. GC is an alias for UseGC, unless GC_NAME_CONFLICT is defined.
131:
1.1 noro 132: ****************************************************************************/
133:
134: #include "gc.h"
135:
136: #ifndef THINK_CPLUS
137: #define _cdecl
138: #endif
139:
1.4 ! noro 140: #if ! defined( GC_NO_OPERATOR_NEW_ARRAY ) \
! 141: && !defined(_ENABLE_ARRAYNEW) /* Digimars */ \
! 142: && (defined(__BORLANDC__) && (__BORLANDC__ < 0x450) \
! 143: || (defined(__GNUC__) && \
! 144: (__GNUC__ < 2 || __GNUC__ == 2 && __GNUC_MINOR__ < 6)) \
! 145: || (defined(__WATCOMC__) && __WATCOMC__ < 1050))
! 146: # define GC_NO_OPERATOR_NEW_ARRAY
! 147: #endif
! 148:
! 149: #if !defined(GC_NO_OPERATOR_NEW_ARRAY) && !defined(GC_OPERATOR_NEW_ARRAY)
! 150: # define GC_OPERATOR_NEW_ARRAY
1.1 noro 151: #endif
152:
1.2 noro 153: enum GCPlacement {UseGC,
154: #ifndef GC_NAME_CONFLICT
155: GC=UseGC,
156: #endif
157: NoGC, PointerFreeGC};
1.1 noro 158:
159: class gc {public:
160: inline void* operator new( size_t size );
161: inline void* operator new( size_t size, GCPlacement gcp );
1.4 ! noro 162: inline void* operator new( size_t size, void *p );
! 163: /* Must be redefined here, since the other overloadings */
! 164: /* hide the global definition. */
1.1 noro 165: inline void operator delete( void* obj );
1.4 ! noro 166: inline void operator delete( void*, void* );
1.1 noro 167:
1.4 ! noro 168: #ifdef GC_OPERATOR_NEW_ARRAY
1.1 noro 169: inline void* operator new[]( size_t size );
170: inline void* operator new[]( size_t size, GCPlacement gcp );
1.4 ! noro 171: inline void* operator new[]( size_t size, void *p );
1.1 noro 172: inline void operator delete[]( void* obj );
1.4 ! noro 173: inline void gc::operator delete[]( void*, void* );
! 174: #endif /* GC_OPERATOR_NEW_ARRAY */
1.1 noro 175: };
176: /*
177: Instances of classes derived from "gc" will be allocated in the
178: collected heap by default, unless an explicit NoGC placement is
179: specified. */
180:
181: class gc_cleanup: virtual public gc {public:
182: inline gc_cleanup();
183: inline virtual ~gc_cleanup();
184: private:
185: inline static void _cdecl cleanup( void* obj, void* clientData );};
186: /*
187: Instances of classes derived from "gc_cleanup" will be allocated
188: in the collected heap by default. When the collector discovers an
189: inaccessible object derived from "gc_cleanup" or containing a
190: member derived from "gc_cleanup", its destructors will be
191: invoked. */
192:
193: extern "C" {typedef void (*GCCleanUpFunc)( void* obj, void* clientData );}
194:
1.2 noro 195: #ifdef _MSC_VER
196: // Disable warning that "no matching operator delete found; memory will
197: // not be freed if initialization throws an exception"
198: # pragma warning(disable:4291)
199: #endif
200:
1.1 noro 201: inline void* operator new(
202: size_t size,
203: GCPlacement gcp,
204: GCCleanUpFunc cleanup = 0,
205: void* clientData = 0 );
206: /*
207: Allocates a collectable or uncollected object, according to the
208: value of "gcp".
209:
210: For collectable objects, if "cleanup" is non-null, then when the
211: allocated object "obj" becomes inaccessible, the collector will
212: invoke the function "cleanup( obj, clientData )" but will not
213: invoke the object's destructors. It is an error to explicitly
214: delete an object allocated with a non-null "cleanup".
215:
216: It is an error to specify a non-null "cleanup" with NoGC or for
217: classes derived from "gc_cleanup" or containing members derived
218: from "gc_cleanup". */
219:
220:
1.2 noro 221: #ifdef _MSC_VER
222: /** This ensures that the system default operator new[] doesn't get
223: * undefined, which is what seems to happen on VC++ 6 for some reason
224: * if we define a multi-argument operator new[].
225: * There seems to be really redirect new in this environment without
226: * including this everywhere.
227: */
1.4 ! noro 228: void *operator new[]( size_t size );
! 229:
! 230: void operator delete[](void* obj);
! 231:
! 232: void* operator new( size_t size);
1.2 noro 233:
1.4 ! noro 234: void operator delete(void* obj);
1.2 noro 235:
1.4 ! noro 236: // This new operator is used by VC++ in case of Debug builds !
! 237: void* operator new( size_t size,
1.2 noro 238: int ,//nBlockUse,
239: const char * szFileName,
1.4 ! noro 240: int nLine );
! 241: #endif /* _MSC_VER */
! 242:
1.2 noro 243:
1.4 ! noro 244: #ifdef GC_OPERATOR_NEW_ARRAY
1.2 noro 245:
1.1 noro 246: inline void* operator new[](
247: size_t size,
248: GCPlacement gcp,
249: GCCleanUpFunc cleanup = 0,
250: void* clientData = 0 );
251: /*
252: The operator new for arrays, identical to the above. */
253:
1.4 ! noro 254: #endif /* GC_OPERATOR_NEW_ARRAY */
1.1 noro 255:
256: /****************************************************************************
257:
258: Inline implementation
259:
260: ****************************************************************************/
261:
262: inline void* gc::operator new( size_t size ) {
263: return GC_MALLOC( size );}
264:
265: inline void* gc::operator new( size_t size, GCPlacement gcp ) {
1.2 noro 266: if (gcp == UseGC)
1.1 noro 267: return GC_MALLOC( size );
268: else if (gcp == PointerFreeGC)
269: return GC_MALLOC_ATOMIC( size );
270: else
271: return GC_MALLOC_UNCOLLECTABLE( size );}
272:
1.4 ! noro 273: inline void* gc::operator new( size_t size, void *p ) {
! 274: return p;}
! 275:
1.1 noro 276: inline void gc::operator delete( void* obj ) {
277: GC_FREE( obj );}
278:
1.4 ! noro 279: inline void gc::operator delete( void*, void* ) {}
1.1 noro 280:
1.4 ! noro 281: #ifdef GC_OPERATOR_NEW_ARRAY
1.1 noro 282:
283: inline void* gc::operator new[]( size_t size ) {
284: return gc::operator new( size );}
285:
286: inline void* gc::operator new[]( size_t size, GCPlacement gcp ) {
287: return gc::operator new( size, gcp );}
288:
1.4 ! noro 289: inline void* gc::operator new[]( size_t size, void *p ) {
! 290: return p;}
! 291:
1.1 noro 292: inline void gc::operator delete[]( void* obj ) {
293: gc::operator delete( obj );}
1.4 ! noro 294:
! 295: inline void gc::operator delete[]( void*, void* ) {}
1.1 noro 296:
1.4 ! noro 297: #endif /* GC_OPERATOR_NEW_ARRAY */
1.1 noro 298:
299:
300: inline gc_cleanup::~gc_cleanup() {
301: GC_REGISTER_FINALIZER_IGNORE_SELF( GC_base(this), 0, 0, 0, 0 );}
302:
303: inline void gc_cleanup::cleanup( void* obj, void* displ ) {
304: ((gc_cleanup*) ((char*) obj + (ptrdiff_t) displ))->~gc_cleanup();}
305:
306: inline gc_cleanup::gc_cleanup() {
307: GC_finalization_proc oldProc;
308: void* oldData;
309: void* base = GC_base( (void *) this );
1.2 noro 310: if (0 != base) {
1.4 ! noro 311: // Don't call the debug version, since this is a real base address.
! 312: GC_register_finalizer_ignore_self(
1.2 noro 313: base, (GC_finalization_proc)cleanup, (void*) ((char*) this - (char*) base),
1.1 noro 314: &oldProc, &oldData );
1.2 noro 315: if (0 != oldProc) {
1.4 ! noro 316: GC_register_finalizer_ignore_self( base, oldProc, oldData, 0, 0 );}}}
1.1 noro 317:
318: inline void* operator new(
319: size_t size,
320: GCPlacement gcp,
321: GCCleanUpFunc cleanup,
322: void* clientData )
323: {
324: void* obj;
325:
1.2 noro 326: if (gcp == UseGC) {
1.1 noro 327: obj = GC_MALLOC( size );
328: if (cleanup != 0)
329: GC_REGISTER_FINALIZER_IGNORE_SELF(
330: obj, cleanup, clientData, 0, 0 );}
331: else if (gcp == PointerFreeGC) {
332: obj = GC_MALLOC_ATOMIC( size );}
333: else {
334: obj = GC_MALLOC_UNCOLLECTABLE( size );};
335: return obj;}
336:
337:
1.4 ! noro 338: #ifdef GC_OPERATOR_NEW_ARRAY
1.1 noro 339:
340: inline void* operator new[](
341: size_t size,
342: GCPlacement gcp,
343: GCCleanUpFunc cleanup,
344: void* clientData )
345: {
346: return ::operator new( size, gcp, cleanup, clientData );}
347:
1.4 ! noro 348: #endif /* GC_OPERATOR_NEW_ARRAY */
1.1 noro 349:
350:
351: #endif /* GC_CPP_H */
352:
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