handletable.cpp@ 10768

Last change on this file since 10768 was 10768, checked in by vboxsync, 16 years ago
Some early commit of the handle table code (home -> work).
Property svn:eol-style set to `native` Property svn:keywords set to `Author Date Id Revision`
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1	/* $Id: handletable.cpp 10768 2008-07-21 02:16:19Z vboxsync $ */
2	/** @file
3	* IPRT - Handle Tables.
4	*/
5
6	/*
7	* Copyright (C) 2008 Sun Microsystems, Inc.
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*
17	* The contents of this file may alternatively be used under the terms
18	* of the Common Development and Distribution License Version 1.0
19	* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20	* VirtualBox OSE distribution, in which case the provisions of the
21	* CDDL are applicable instead of those of the GPL.
22	*
23	* You may elect to license modified versions of this file under the
24	* terms and conditions of either the GPL or the CDDL or both.
25	*
26	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
27	* Clara, CA 95054 USA or visit http://www.sun.com if you need
28	* additional information or have any questions.
29	*/
30
31	/*******************************************************************************
32	* Header Files *
33	*******************************************************************************/
34	#include <iprt/handletable.h>
35	#include <iprt/mem.h>
36	#include <iprt/spinlock.h>
37	#include <iprt/err.h>
38	#include <iprt/assert.h>
39	#include <iprt/param.h>
40	#include <iprt/string.h>
41	#include "internal/magics.h"
42
43
44	/*******************************************************************************
45	* Defined Constants And Macros *
46	*******************************************************************************/
47	/** The number of entries in the 2nd level lookup table. */
48	#define RTHT_LEVEL2_ENTRIES 2048
49
50	/** The number of (max) 1st level entries requiring dynamic allocation of the
51	* 1st level table. If the max number is below this threshold, the 1st level
52	* table will be allocated as part of the handle table structure. */
53	#define RTHT_LEVEL1_DYN_ALLOC_THRESHOLD 256
54
55	/** Checks whether a object pointer is really a free entry or not. */
56	#define RTHT_IS_FREE(pvObj) ( ((uintptr_t)(pvObj) & 3) == 3 )
57
58	/** Sets RTHTENTRYFREE::iNext. */
59	#define RTHT_SET_FREE_IDX(pFree, idx) \
60	do { \
61	(pFree)->iNext = ((uintptr_t)(idx) << 2) \| 3; \
62	} while (0)
63
64	/** Gets the index part of RTHTENTRYFREE::iNext. */
65	#define RTHT_GET_FREE_IDX(pFree) ( (uint32_t)((pFree)->iNext >> 2) )
66
67	/** @def NIL_RTHT_INDEX
68	* The NIL handle index for use in the free list. (The difference between
69	* 32-bit and 64-bit hosts here comes down to the shifting performed for
70	* RTHTENTRYFREE::iNext.) */
71	#if ARCH_BITS == 32
72	# define NIL_RTHT_INDEX ( UINT32_C(0x3fffffff) )
73	#elif ARCH_BITS >= 34
74	# define NIL_RTHT_INDEX ( UINT32_C(0xffffffff) )
75	#else
76	# error "Missing or unsupported ARCH_BITS."
77	#endif
78
79
80	/*******************************************************************************
81	* Structures and Typedefs *
82	*******************************************************************************/
83
84	/**
85	* Handle table entry, simple variant.
86	*/
87	typedef struct RTHTENTRY
88	{
89	/** The object. */
90	void *pvObj;
91	} RTHTENTRY;
92	/** Pointer to a handle table entry, simple variant. */
93	typedef RTHTENTRY *PRTHTENTRY;
94
95
96	/**
97	* Handle table entry, context variant.
98	*/
99	typedef struct RTHTENTRYCTX
100	{
101	/** The context. */
102	void *pvCtx;
103	/** The object. */
104	void *pvObj;
105	} RTHTENTRYCTX;
106	/** Pointer to a handle table entry, context variant. */
107	typedef RTHTENTRYCTX *PRTHTENTRYCTX;
108
109
110	/**
111	* Free handle table entry, shared by all variants.
112	*/
113	typedef struct RTHTENTRYFREE
114	{
115	/** The index of the next handle, special format.
116	* In order to distinguish free and used handle table entries we exploit
117	* the heap alignment and use the lower two bits to do this. Used entries
118	* will have these bits set to 0, while free entries will have tem set
119	* to 3. Use the RTHT_GET_FREE_IDX and RTHT_SET_FREE_IDX macros to access
120	* this field. */
121	uintptr_t iNext;
122	} RTHTENTRYFREE;
123	/** Pointer to a free handle table entry. */
124	typedef RTHTENTRYFREE *PRTHTENTRYFREE;
125
126	AssertCompile(sizeof(RTHTENTRYFREE) <= sizeof(RTHTENTRY));
127	AssertCompile(sizeof(RTHTENTRYFREE) <= sizeof(RTHTENTRYCTX));
128
129
130	/**
131	* Internal handle table structure.
132	*/
133	typedef struct RTHANDLETABLEINT
134	{
135	/** Magic value (RTHANDLETABLE_MAGIC). */
136	uint32_t u32Magic;
137	/** The handle table flags specified to RTHandleTableCreateEx. */
138	uint32_t fFlags;
139	/** The base handle value (i.e. the first handle). */
140	uint32_t uBase;
141	/** The current number of handles.
142	* This indirectly gives the size of the first level lookup table. */
143	uint32_t cCur;
144	/** The spinlock handle (NIL if RTHANDLETABLE_FLAGS_LOCKED wasn't used). */
145	RTSPINLOCK hSpinlock;
146	/** The level one lookup table. */
147	void **papvLevel1;
148	/** The retainer callback. Can be NULL. */
149	PFNRTHANDLETABLERETAIN pfnRetain;
150	/** The user argument to the retainer. */
151	void *pvRetainUser;
152	/** The max number of handles. */
153	uint32_t cMax;
154	/** The number of handles currently allocated. (for optimizing destruction) */
155	uint32_t cCurAllocated;
156	/** The current number of 1st level entries. */
157	uint32_t cLevel1;
158	/** Head of the list of free handle entires (index). */
159	uint32_t iFreeHead;
160	/** Tail of the list of free handle entires (index). */
161	uint32_t iFreeTail;
162	} RTHANDLETABLEINT;
163	/** Pointer to an handle table structure. */
164	typedef RTHANDLETABLEINT *PRTHANDLETABLEINT;
165
166
167
168	/**
169	* Looks up a simple handle.
170	*
171	* @returns Pointer to the handle table entry on success, NULL on failure.
172	* @param pThis The handle table structure.
173	* @param h The handle to look up.
174	*/
175	DECLINLINE(PRTHTENTRY) rtHandleTableLookupSimple(PRTHANDLETABLEINT pThis, uint32_t h)
176	{
177	uint32_t i = h - pThis->uBase;
178	if (i < pThis->cCur)
179	{
180	PRTHTENTRY paTable = (PRTHTENTRY)pThis->papvLevel1[i / RTHT_LEVEL2_ENTRIES];
181	if (paTable)
182	return &paTable[i % RTHT_LEVEL2_ENTRIES];
183	}
184
185	return NULL;
186	}
187
188
189	/**
190	* Looks up a context handle.
191	*
192	* @returns Pointer to the handle table entry on success, NULL on failure.
193	* @param pThis The handle table structure.
194	* @param h The handle to look up.
195	*/
196	DECLINLINE(PRTHTENTRYCTX) rtHandleTableLookupWithCtx(PRTHANDLETABLEINT pThis, uint32_t h)
197	{
198	uint32_t i = h - pThis->uBase;
199	if (i < pThis->cCur)
200	{
201	PRTHTENTRYCTX paTable = (PRTHTENTRYCTX)pThis->papvLevel1[i / RTHT_LEVEL2_ENTRIES];
202	if (paTable)
203	return &paTable[i % RTHT_LEVEL2_ENTRIES];
204	}
205
206	return NULL;
207	}
208
209
210	DECLINLINE(void) rtHandleTableLock(PRTHANDLETABLEINT pThis, PRTSPINLOCKTMP pTmp)
211	{
212	if (pThis->hSpinlock != NIL_RTSPINLOCK)
213	RTSpinlockRelease(pThis->hSpinlock, pTmp);
214	}
215
216
217	DECLINLINE(void) rtHandleTableUnlock(PRTHANDLETABLEINT pThis, PRTSPINLOCKTMP pTmp)
218	{
219	if (pThis->hSpinlock != NIL_RTSPINLOCK)
220	RTSpinlockAcquire(pThis->hSpinlock, pTmp);
221	}
222
223
224	RTDECL(int) RTHandleTableCreateEx(PRTHANDLETABLE phHandleTable, uint32_t fFlags, uint32_t uBase, uint32_t cMax,
225	PFNRTHANDLETABLERETAIN pfnRetain, void *pvUser)
226	{
227	return VERR_NOT_IMPLEMENTED;
228	}
229
230
231	RTDECL(int) RTHandleTableCreate(PRTHANDLETABLE phHandleTable)
232	{
233	return RTHandleTableCreateEx(phHandleTable, RTHANDLETABLE_FLAGS_LOCKED, 1, 65534, NULL, NULL);
234	}
235
236
237	RTDECL(int) RTHandleTableDestroy(RTHANDLETABLE hHandleTable, PFNRTHANDLETABLEDELETE pfnDelete, void *pvUser)
238	{
239	return -1;
240	}
241
242
243	/**
244	* Allocates a handle from the handle table.
245	*
246	* @returns IPRT status code, almost any.
247	* @retval VINF_SUCCESS on success.
248	* @retval VERR_NO_MEMORY if we failed to extend the handle table.
249	* @retval VERR_NO_MORE_HANDLES if we're out of handles.
250	*
251	* @param hHandleTable The handle to the handle table.
252	* @param pvObj The object to associate with the new handle.
253	* @param ph Where to return the handle on success.
254	*
255	* @remarks Do not call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation.
256	*/
257	RTDECL(int) RTHandleTableAlloc(RTHANDLETABLE hHandleTable, void pvObj, uint32_t ph);
258
259	/**
260	* Looks up a handle.
261	*
262	* @returns The object pointer on success. NULL on failure.
263	*
264	* @param hHandleTable The handle to the handle table.
265	* @param h The handle to lookup.
266	*
267	* @remarks Do not call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation.
268	*/
269	RTDECL(void *) RTHandleTableLookup(RTHANDLETABLE hHandleTable, uint32_t h);
270
271	/**
272	* Looks up and frees a handle.
273	*
274	* @returns The object pointer on success. NULL on failure.
275	*
276	* @param hHandleTable The handle to the handle table.
277	* @param h The handle to lookup.
278	*
279	* @remarks Do not call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation.
280	*/
281	RTDECL(void *) RTHandleTableFree(RTHANDLETABLE hHandleTable, uint32_t h);
282
283
284	RTDECL(int) RTHandleTableAllocWithCtx(RTHANDLETABLE hHandleTable, void pvObj, void pvCtx, uint32_t *ph)
285	{
286	/* validate the input */
287	PRTHANDLETABLEINT pThis = (PRTHANDLETABLEINT)hHandleTable;
288	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
289	AssertReturn(pThis->u32Magic == RTHANDLETABLE_MAGIC, VERR_INVALID_HANDLE);
290	AssertReturn(pThis->fFlags & RTHANDLETABLE_FLAGS_CONTEXT, VERR_INVALID_FUNCTION);
291	AssertReturn(RTHT_IS_FREE(pvObj), VERR_INVALID_PARAMETER);
292	AssertPtrReturn(ph, VERR_INVALID_POINTER);
293	*ph = pThis->uBase - 1;
294
295	/*
296	* Allocation loop.
297	*/
298	RTSPINLOCKTMP Tmp = RTSPINLOCKTMP_INITIALIZER;
299	rtHandleTableLock(pThis, &Tmp);
300
301	int rc;
302	do
303	{
304	/*
305	* Try grab a free entry from the head of the free list.
306	*/
307	uint32_t i = pThis->iFreeHead;
308	if (i != NIL_RTHT_INDEX)
309	{
310	PRTHTENTRYFREE pFree = (PRTHTENTRYFREE)rtHandleTableLookupWithCtx(pThis, i + pThis->uBase);
311	Assert(pFree);
312	if (i == pThis->iFreeTail)
313	pThis->iFreeTail = pThis->iFreeHead = NIL_RTHT_INDEX;
314	else
315	pThis->iFreeHead = RTHT_GET_FREE_IDX(pFree);
316	pThis->cCurAllocated++;
317	Assert(pThis->cCurAllocated <= pThis->cCur);
318
319	/*
320	* Setup the entry and return.
321	*/
322	PRTHTENTRYCTX pEntry = (PRTHTENTRYCTX)pFree;
323	pEntry->pvObj = pvObj;
324	pEntry->pvCtx = pvCtx;
325	*ph = i + pThis->uBase;
326	rc = VINF_SUCCESS;
327	}
328	/*
329	* Must expand the handle table, unless it's full.
330	*/
331	else if (pThis->cCur >= pThis->cMax)
332	{
333	rc = VERR_NO_MORE_HANDLES;
334	Assert(pThis->cCur == pThis->cCurAllocated);
335	}
336	else
337	{
338	/*
339	* Do we have to expand the 1st level table too?
340	*/
341	uint32_t const iLevel1 = pThis->cCur / RTHT_LEVEL2_ENTRIES;
342	uint32_t cLevel1 = iLevel1 + 1 >= pThis->cLevel1
343	? pThis->cLevel1 + PAGE_SIZE / sizeof(void *)
344	: 0;
345	if (cLevel1 > pThis->cMax / RTHT_LEVEL2_ENTRIES)
346	cLevel1 = pThis->cMax / RTHT_LEVEL2_ENTRIES;
347
348	/* leave the lock (never do fancy stuff from behind a spinlock). */
349	rtHandleTableUnlock(pThis, &Tmp);
350
351	/*
352	* Do the allocation(s).
353	*/
354	rc = VERR_TRY_AGAIN;
355	void **papvLevel1 = NULL;
356	if (cLevel1)
357	{
358	papvLevel1 = (void *)RTMemAlloc(sizeof(void ) * cLevel1);
359	if (!papvLevel1)
360	return VERR_NO_MEMORY;
361	}
362
363	PRTHTENTRYCTX paTable = (PRTHTENTRYCTX)RTMemAlloc(sizeof(paTable) RTHT_LEVEL2_ENTRIES);
364	if (!paTable)
365	{
366	RTMemFree(papvLevel1);
367	return VERR_NO_MEMORY;
368	}
369
370	/* re-enter the lock. */
371	rtHandleTableLock(pThis, &Tmp);
372
373	/*
374	* Insert the new bits, but be a bit careful as someone might have
375	* raced us expanding the table.
376	*/
377
378	if (cLevel1)
379	{
380	if (cLevel1 > pThis->cLevel1)
381	{
382	/* Replace the 1st level table. */
383	memcpy(papvLevel1, pThis->papvLevel1, sizeof(void ) pThis->cLevel1);
384	memset(&papvLevel1[pThis->cLevel1], 0, sizeof(void ) (cLevel1 - pThis->cLevel1));
385	void **papvTmp = pThis->papvLevel1;
386	pThis->papvLevel1 = papvLevel1;
387	papvLevel1 = papvTmp;
388	}
389
390	/* free the obsolete one (outside the lock of course) */
391	rtHandleTableLock(pThis, &Tmp);
392	RTMemFree(papvLevel1);
393	rtHandleTableUnlock(pThis, &Tmp);
394	}
395
396	/* insert the table we allocated */
397	if (pThis->cCur < pThis->cMax)
398	{
399	uint32_t iLevel1New = pThis->cCur / RTHT_LEVEL2_ENTRIES;
400	pThis->papvLevel1[iLevel1New] = paTable;
401
402	/* link all entries into a free list. */
403	Assert(!(pThis->cCur % RTHT_LEVEL2_ENTRIES));
404	for (uint32_t i = 0; i < RTHT_LEVEL2_ENTRIES - 1; i++)
405	{
406	RTHT_SET_FREE_IDX((PRTHTENTRYFREE)&paTable[i], i + 1);
407	paTable[i].pvCtx = (void *)~(uintptr_t)7;
408	}
409	RTHT_SET_FREE_IDX((PRTHTENTRYFREE)&paTable[RTHT_LEVEL2_ENTRIES - 1], NIL_RTHT_INDEX);
410	paTable[RTHT_LEVEL2_ENTRIES - 1].pvCtx = (void *)~(uintptr_t)7;
411
412	/* join the free list with the other. */
413	if (pThis->iFreeTail == NIL_RTHT_INDEX)
414	pThis->iFreeHead = pThis->cCur;
415	else
416	{
417	PRTHTENTRYFREE pPrev = (PRTHTENTRYFREE)rtHandleTableLookupWithCtx(pThis, pThis->iFreeTail);
418	Assert(pPrev);
419	RTHT_SET_FREE_IDX(pPrev, pThis->cCur);
420	}
421	pThis->iFreeTail = pThis->cCur + RTHT_LEVEL2_ENTRIES - 1;
422
423	pThis->cCur += RTHT_LEVEL2_ENTRIES;
424	}
425	else
426	{
427	/* free the table (raced someone, and we lost). */
428	rtHandleTableLock(pThis, &Tmp);
429	RTMemFree(paTable);
430	rtHandleTableUnlock(pThis, &Tmp);
431	}
432
433	rc = VERR_TRY_AGAIN;
434	}
435	} while (rc == VERR_TRY_AGAIN);
436
437	rtHandleTableUnlock(pThis, &Tmp);
438
439	return rc;
440	}
441
442
443	RTDECL(void ) RTHandleTableLookupWithCtx(RTHANDLETABLE hHandleTable, uint32_t h, void pvCtx)
444	{
445	/* validate the input */
446	PRTHANDLETABLEINT pThis = (PRTHANDLETABLEINT)hHandleTable;
447	AssertPtrReturn(pThis, NULL);
448	AssertReturn(pThis->u32Magic == RTHANDLETABLE_MAGIC, NULL);
449	AssertReturn(pThis->fFlags & RTHANDLETABLE_FLAGS_CONTEXT, NULL);
450
451	void *pvObj = NULL;
452
453	/* acquire the lock */
454	RTSPINLOCKTMP Tmp = RTSPINLOCKTMP_INITIALIZER;
455	rtHandleTableLock(pThis, &Tmp);
456
457	/*
458	* Perform the lookup and retaining.
459	*/
460	PRTHTENTRYCTX pEntry = rtHandleTableLookupWithCtx(pThis, h);
461	if (pEntry && pEntry->pvCtx == pvCtx)
462	{
463	pvObj = pEntry->pvObj;
464	if (!RTHT_IS_FREE(pvObj))
465	{
466	if (pThis->pfnRetain)
467	{
468	int rc = pThis->pfnRetain(hHandleTable, pEntry->pvObj, pvCtx, pThis->pvRetainUser);
469	if (RT_FAILURE(rc))
470	pvObj = NULL;
471	}
472	}
473	else
474	pvObj = NULL;
475	}
476
477	/* release the lock */
478	rtHandleTableUnlock(pThis, &Tmp);
479	return pvObj;
480	}
481
482
483	RTDECL(void ) RTHandleTableFreeWithCtx(RTHANDLETABLE hHandleTable, uint32_t h, void pvCtx)
484	{
485	/* validate the input */
486	PRTHANDLETABLEINT pThis = (PRTHANDLETABLEINT)hHandleTable;
487	AssertPtrReturn(pThis, NULL);
488	AssertReturn(pThis->u32Magic == RTHANDLETABLE_MAGIC, NULL);
489	AssertReturn(pThis->fFlags & RTHANDLETABLE_FLAGS_CONTEXT, NULL);
490
491	void *pvObj = NULL;
492
493	/* acquire the lock */
494	RTSPINLOCKTMP Tmp = RTSPINLOCKTMP_INITIALIZER;
495	rtHandleTableLock(pThis, &Tmp);
496
497	/*
498	* Perform the lookup and retaining.
499	*/
500	PRTHTENTRYCTX pEntry = rtHandleTableLookupWithCtx(pThis, h);
501	if (pEntry && pEntry->pvCtx == pvCtx)
502	{
503	pvObj = pEntry->pvObj;
504	if (!RTHT_IS_FREE(pvObj))
505	{
506	if (pThis->pfnRetain)
507	{
508	int rc = pThis->pfnRetain(hHandleTable, pEntry->pvObj, pvCtx, pThis->pvRetainUser);
509	if (RT_FAILURE(rc))
510	pvObj = NULL;
511	}
512
513	/*
514	* Link it into the free list.
515	*/
516	if (pvObj)
517	{
518	pEntry->pvCtx = (void *)~(uintptr_t)7;
519
520	PRTHTENTRYFREE pFree = (PRTHTENTRYFREE)pEntry;
521	RTHT_SET_FREE_IDX(pFree, NIL_RTHT_INDEX);
522
523	uint32_t const i = h - pThis->uBase;
524	if (pThis->iFreeTail == NIL_RTHT_INDEX)
525	pThis->iFreeHead = pThis->iFreeTail = i;
526	else
527	{
528	PRTHTENTRYFREE pPrev = (PRTHTENTRYFREE)rtHandleTableLookupWithCtx(pThis, pThis->iFreeTail + pThis->uBase);
529	Assert(pPrev);
530	RTHT_SET_FREE_IDX(pPrev, i);
531	pThis->iFreeTail = i;
532	}
533
534	Assert(pThis->cCurAllocated > 0);
535	pThis->cCurAllocated--;
536	}
537	}
538	else
539	pvObj = NULL;
540	}
541
542	/* release the lock */
543	rtHandleTableUnlock(pThis, &Tmp);
544	return pvObj;
545	}
546

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