vfsreadahead.cpp@ 76553

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1	/* $Id: vfsreadahead.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */
2	/** @file
3	* IPRT - Virtual File System, Read-Ahead Thread.
4	*/
5
6	/*
7	* Copyright (C) 2010-2019 Oracle Corporation
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
27
28	/*********************************************************************************************************************************
29	* Header Files *
30	*********************************************************************************************************************************/
31	#define LOG_GROUP RTLOGGROUP_VFS
32	#include "internal/iprt.h"
33	#include <iprt/vfs.h>
34
35	#include <iprt/asm.h>
36	#include <iprt/assert.h>
37	#include <iprt/err.h>
38	#include <iprt/file.h>
39	#include <iprt/list.h>
40	#include <iprt/log.h>
41	#include <iprt/poll.h>
42	#include <iprt/string.h>
43	#include <iprt/vfslowlevel.h>
44
45
46
47	/*********************************************************************************************************************************
48	* Header Files *
49	*********************************************************************************************************************************/
50	#include "internal/iprt.h"
51	#include <iprt/vfs.h>
52
53	#include <iprt/critsect.h>
54	#include <iprt/err.h>
55	#include <iprt/mem.h>
56	#include <iprt/thread.h>
57
58
59	/*********************************************************************************************************************************
60	* Structures and Typedefs *
61	*********************************************************************************************************************************/
62	/**
63	* Buffer descriptor.
64	*/
65	typedef struct RTVFSREADAHEADBUFDESC
66	{
67	/** List entry. */
68	RTLISTNODE ListEntry;
69	/** The offset of this extent within the file. */
70	uint64_t off;
71	/** The amount of the buffer that has been filled.
72	* (Buffer size is RTVFSREADAHEAD::cbBuffer.) */
73	uint32_t cbFilled;
74	/** */
75	uint32_t volatile fReserved;
76	/** Pointer to the buffer. */
77	uint8_t *pbBuffer;
78	} RTVFSREADAHEADBUFDESC;
79	/** Pointer to a memory file extent. */
80	typedef RTVFSREADAHEADBUFDESC *PRTVFSREADAHEADBUFDESC;
81
82	/**
83	* Read ahead file or I/O stream.
84	*/
85	typedef struct RTVFSREADAHEAD
86	{
87	/** The I/O critical section (protects offActual).
88	* The thread doing I/O or seeking always need to own this. */
89	RTCRITSECT IoCritSect;
90
91	/** The critical section protecting the buffer lists and offConsumer.
92	*
93	* This can be taken while holding IoCritSect as that eliminates a race
94	* condition between the read ahead thread inserting into ConsumerList and
95	* a consumer thread deciding to do a direct read. */
96	RTCRITSECT BufferCritSect;
97	/** List of buffers available for consumption.
98	* The producer thread (hThread) puts buffers into this list once it's done
99	* reading into them. The consumer moves them to the FreeList once the
100	* current position has passed beyond each buffer. */
101	RTLISTANCHOR ConsumerList;
102	/** List of buffers available for the producer. */
103	RTLISTANCHOR FreeList;
104
105	/** The current file position from the consumer point of view. */
106	uint64_t offConsumer;
107
108	/** The end-of-file(/stream) offset. This is initially UINT64_MAX and later
109	* set when reading past EOF. */
110	uint64_t offEof;
111
112	/** The read ahead thread. */
113	RTTHREAD hThread;
114	/** Set when we want the thread to terminate. */
115	bool volatile fTerminateThread;
116	/** Creation flags. */
117	uint32_t fFlags;
118
119	/** The I/O stream we read from. */
120	RTVFSIOSTREAM hIos;
121	/** The file face of hIos, if we're fronting for an actual file. */
122	RTVFSFILE hFile;
123	/** The buffer size. */
124	uint32_t cbBuffer;
125	/** The number of buffers. */
126	uint32_t cBuffers;
127	/** Single big buffer allocation, cBuffers * cbBuffer in size. */
128	uint8_t *pbAllBuffers;
129	/** Array of buffer descriptors (cBuffers in size). */
130	RTVFSREADAHEADBUFDESC aBufDescs[1];
131	} RTVFSREADAHEAD;
132	/** Pointer to a memory file. */
133	typedef RTVFSREADAHEAD *PRTVFSREADAHEAD;
134
135
136
137	/**
138	* @interface_method_impl{RTVFSOBJOPS,pfnClose}
139	*/
140	static DECLCALLBACK(int) rtVfsReadAhead_Close(void *pvThis)
141	{
142	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
143	int rc;
144
145	/*
146	* Stop the read-ahead thread.
147	*/
148	if (pThis->hThread != NIL_RTTHREAD)
149	{
150	ASMAtomicWriteBool(&pThis->fTerminateThread, true);
151	rc = RTThreadUserSignal(pThis->hThread);
152	AssertRC(rc);
153	rc = RTThreadWait(pThis->hThread, RT_INDEFINITE_WAIT, NULL);
154	AssertRCReturn(rc, rc);
155	pThis->hThread = NIL_RTTHREAD;
156	}
157
158	/*
159	* Release the upstream objects.
160	*/
161	RTCritSectEnter(&pThis->IoCritSect);
162
163	RTVfsIoStrmRelease(pThis->hIos);
164	pThis->hIos = NIL_RTVFSIOSTREAM;
165	RTVfsFileRelease(pThis->hFile);
166	pThis->hFile = NIL_RTVFSFILE;
167
168	RTCritSectLeave(&pThis->IoCritSect);
169
170	/*
171	* Free the buffers.
172	*/
173	RTCritSectEnter(&pThis->BufferCritSect);
174	if (pThis->pbAllBuffers)
175	{
176	RTMemPageFree(pThis->pbAllBuffers, pThis->cBuffers * pThis->cbBuffer);
177	pThis->pbAllBuffers = NULL;
178	}
179	RTCritSectLeave(&pThis->BufferCritSect);
180
181	/*
182	* Destroy the critical sections.
183	*/
184	RTCritSectDelete(&pThis->BufferCritSect);
185	RTCritSectDelete(&pThis->IoCritSect);
186
187	return VINF_SUCCESS;
188	}
189
190
191	/**
192	* @interface_method_impl{RTVFSOBJOPS,pfnQueryInfo}
193	*/
194	static DECLCALLBACK(int) rtVfsReadAhead_QueryInfo(void *pvThis, PRTFSOBJINFO pObjInfo, RTFSOBJATTRADD enmAddAttr)
195	{
196	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
197	return RTVfsIoStrmQueryInfo(pThis->hIos, pObjInfo, enmAddAttr);
198	}
199
200
201	/**
202	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnRead}
203	*/
204	static DECLCALLBACK(int) rtVfsReadAhead_Read(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbRead)
205	{
206	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
207
208	Assert(pSgBuf->cSegs == 1); /* Caller deals with multiple SGs. */
209
210	/*
211	* We loop here to repeat the buffer search after entering the I/O critical
212	* section, just in case a buffer got inserted while we were waiting for it.
213	*/
214	int rc = VINF_SUCCESS;
215	uint8_t pbDst = (uint8_t )pSgBuf->paSegs[0].pvSeg;
216	size_t cbDst = pSgBuf->paSegs[0].cbSeg;
217	size_t cbTotalRead = 0;
218	bool fPokeReader = false;
219	bool fOwnsIoCritSect = false;
220	RTCritSectEnter(&pThis->BufferCritSect);
221	for (;;)
222	{
223	/*
224	* Try satisfy the read from the buffers.
225	*/
226	uint64_t offCur = pThis->offConsumer;
227	if (off != -1)
228	{
229	offCur = (uint64_t)off;
230	if (pThis->offConsumer != offCur)
231	fPokeReader = true; /* If the current position changed, poke it in case it stopped at EOF. */
232	pThis->offConsumer = offCur;
233	}
234
235	PRTVFSREADAHEADBUFDESC pBufDesc, pNextBufDesc;
236	RTListForEachSafe(&pThis->ConsumerList, pBufDesc, pNextBufDesc, RTVFSREADAHEADBUFDESC, ListEntry)
237	{
238	/* The buffers are sorted and reads must start in a buffer if
239	anything should be taken from the buffer (at least for now). */
240	if (offCur < pBufDesc->off)
241	break;
242
243	/* Anything we can read from this buffer? */
244	uint64_t offCurBuf = offCur - pBufDesc->off;
245	if (offCurBuf < pBufDesc->cbFilled)
246	{
247	size_t const cbFromCurBuf = RT_MIN(pBufDesc->cbFilled - offCurBuf, cbDst);
248	memcpy(pbDst, pBufDesc->pbBuffer + offCurBuf, cbFromCurBuf);
249	pbDst += cbFromCurBuf;
250	cbDst -= cbFromCurBuf;
251	cbTotalRead += cbFromCurBuf;
252	offCur += cbFromCurBuf;
253	}
254
255	/* Discard buffers we've read past. */
256	if (pBufDesc->off + pBufDesc->cbFilled <= offCur)
257	{
258	RTListNodeRemove(&pBufDesc->ListEntry);
259	RTListAppend(&pThis->FreeList, &pBufDesc->ListEntry);
260	fPokeReader = true; /* Poke it as there are now more buffers available. */
261	}
262
263	/* Stop if we're done. */
264	if (!cbDst)
265	break;
266	}
267
268	pThis->offConsumer = offCur;
269	if (off != -1)
270	off = offCur;
271
272	if (!cbDst)
273	break;
274
275	/*
276	* Check if we've reached the end of the file/stream.
277	*/
278	if (offCur >= pThis->offEof)
279	{
280	rc = pcbRead ? VINF_EOF : VERR_EOF;
281	Log(("rtVfsReadAhead_Read: ret %Rrc; offCur=%#llx offEof=%#llx\n", rc, offCur, pThis->offEof));
282	break;
283	}
284
285
286	/*
287	* First time around we don't own the I/O critsect and need to take it
288	* and repeat the above buffer reading code.
289	*/
290	if (!fOwnsIoCritSect)
291	{
292	RTCritSectLeave(&pThis->BufferCritSect);
293	RTCritSectEnter(&pThis->IoCritSect);
294	RTCritSectEnter(&pThis->BufferCritSect);
295	fOwnsIoCritSect = true;
296	continue;
297	}
298
299
300	/*
301	* Do a direct read of the remaining data.
302	*/
303	if (off == -1)
304	{
305	RTFOFF offActual = RTVfsIoStrmTell(pThis->hIos);
306	if (offActual >= 0 && (uint64_t)offActual != offCur)
307	off = offCur;
308	}
309	RTSGSEG TmpSeg = { pbDst, cbDst };
310	RTSGBUF TmpSgBuf;
311	RTSgBufInit(&TmpSgBuf, &TmpSeg, 1);
312	size_t cbThisRead = cbDst;
313	rc = RTVfsIoStrmSgRead(pThis->hIos, off, &TmpSgBuf, fBlocking, pcbRead ? &cbThisRead : NULL);
314	if (RT_SUCCESS(rc))
315	{
316	cbTotalRead += cbThisRead;
317	offCur += cbThisRead;
318	pThis->offConsumer = offCur;
319	if (rc != VINF_EOF)
320	fPokeReader = true;
321	else
322	{
323	pThis->offEof = offCur;
324	Log(("rtVfsReadAhead_Read: EOF %llu (%#llx)\n", pThis->offEof, pThis->offEof));
325	}
326	}
327	/* else if (rc == VERR_EOF): hard to say where exactly the current position
328	is here as cannot have had a non-NULL pcbRead. Set offEof later. */
329	break;
330	}
331	RTCritSectLeave(&pThis->BufferCritSect);
332	if (fOwnsIoCritSect)
333	RTCritSectLeave(&pThis->IoCritSect);
334	if (fPokeReader && rc != VINF_EOF && rc != VERR_EOF)
335	RTThreadUserSignal(pThis->hThread);
336
337	if (pcbRead)
338	*pcbRead = cbTotalRead;
339	Assert(cbTotalRead <= pSgBuf->paSegs[0].cbSeg);
340
341	return rc;
342	}
343
344
345	/**
346	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnWrite}
347	*/
348	static DECLCALLBACK(int) rtVfsReadAhead_Write(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbWritten)
349	{
350	RT_NOREF_PV(pvThis); RT_NOREF_PV(off); RT_NOREF_PV(pSgBuf); RT_NOREF_PV(fBlocking); RT_NOREF_PV(pcbWritten);
351	AssertFailed();
352	return VERR_ACCESS_DENIED;
353	}
354
355
356	/**
357	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnFlush}
358	*/
359	static DECLCALLBACK(int) rtVfsReadAhead_Flush(void *pvThis)
360	{
361	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
362	return RTVfsIoStrmFlush(pThis->hIos);
363	}
364
365
366	/**
367	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnPollOne}
368	*/
369	static DECLCALLBACK(int) rtVfsReadAhead_PollOne(void *pvThis, uint32_t fEvents, RTMSINTERVAL cMillies, bool fIntr,
370	uint32_t *pfRetEvents)
371	{
372	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
373	if (pThis->hThread != NIL_RTTHREAD)
374	{
375	/** @todo poll one with read-ahead thread. */
376	return VERR_NOT_IMPLEMENTED;
377	}
378	return RTVfsIoStrmPoll(pThis->hIos, fEvents, cMillies, fIntr, pfRetEvents);
379	}
380
381
382	/**
383	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnTell}
384	*/
385	static DECLCALLBACK(int) rtVfsReadAhead_Tell(void *pvThis, PRTFOFF poffActual)
386	{
387	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
388
389	RTCritSectEnter(&pThis->BufferCritSect);
390	*poffActual = pThis->offConsumer;
391	RTCritSectLeave(&pThis->BufferCritSect);
392
393	return VINF_SUCCESS;
394	}
395
396
397	/**
398	* @interface_method_impl{RTVFSOBJSETOPS,pfnMode}
399	*/
400	static DECLCALLBACK(int) rtVfsReadAhead_SetMode(void *pvThis, RTFMODE fMode, RTFMODE fMask)
401	{
402	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
403	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
404
405	RTCritSectEnter(&pThis->IoCritSect);
406	RT_NOREF_PV(fMode); RT_NOREF_PV(fMask); /// @todo int rc = RTVfsFileSetMode(pThis->hFile, fMode, fMask);
407	int rc = VERR_NOT_SUPPORTED;
408	RTCritSectLeave(&pThis->IoCritSect);
409
410	return rc;
411	}
412
413
414	/**
415	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetTimes}
416	*/
417	static DECLCALLBACK(int) rtVfsReadAhead_SetTimes(void *pvThis, PCRTTIMESPEC pAccessTime, PCRTTIMESPEC pModificationTime,
418	PCRTTIMESPEC pChangeTime, PCRTTIMESPEC pBirthTime)
419	{
420	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
421	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
422
423	RTCritSectEnter(&pThis->IoCritSect);
424	RT_NOREF_PV(pAccessTime); RT_NOREF_PV(pModificationTime); RT_NOREF_PV(pChangeTime); RT_NOREF_PV(pBirthTime);
425	/// @todo int rc = RTVfsFileSetTimes(pThis->hFile, pAccessTime, pModificationTime, pChangeTime, pBirthTime);
426	int rc = VERR_NOT_SUPPORTED;
427	RTCritSectLeave(&pThis->IoCritSect);
428
429	return rc;
430	}
431
432
433	/**
434	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetOwner}
435	*/
436	static DECLCALLBACK(int) rtVfsReadAhead_SetOwner(void *pvThis, RTUID uid, RTGID gid)
437	{
438	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
439	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
440
441	RTCritSectEnter(&pThis->IoCritSect);
442	RT_NOREF_PV(uid); RT_NOREF_PV(gid);
443	/// @todo int rc = RTVfsFileSetOwner(pThis->hFile, uid, gid);
444	int rc = VERR_NOT_SUPPORTED;
445	RTCritSectLeave(&pThis->IoCritSect);
446
447	return rc;
448	}
449
450
451	/**
452	* @interface_method_impl{RTVFSFILEOPS,pfnSeek}
453	*/
454	static DECLCALLBACK(int) rtVfsReadAhead_Seek(void *pvThis, RTFOFF offSeek, unsigned uMethod, PRTFOFF poffActual)
455	{
456	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
457	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
458
459	RTCritSectEnter(&pThis->IoCritSect); /* protects against concurrent I/O using the offset. */
460	RTCritSectEnter(&pThis->BufferCritSect); /* protects offConsumer */
461
462	uint64_t offActual = UINT64_MAX;
463	int rc = RTVfsFileSeek(pThis->hFile, offSeek, uMethod, &offActual);
464	if (RT_SUCCESS(rc))
465	{
466	pThis->offConsumer = offActual;
467	if (poffActual)
468	*poffActual = offActual;
469	}
470
471	RTCritSectLeave(&pThis->BufferCritSect);
472	RTCritSectLeave(&pThis->IoCritSect);
473
474	return rc;
475	}
476
477
478	/**
479	* @interface_method_impl{RTVFSFILEOPS,pfnQuerySize}
480	*/
481	static DECLCALLBACK(int) rtVfsReadAhead_QuerySize(void pvThis, uint64_t pcbFile)
482	{
483	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
484	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
485
486	RTCritSectEnter(&pThis->IoCritSect); /* paranoia */
487	int rc = RTVfsFileGetSize(pThis->hFile, pcbFile);
488	RTCritSectLeave(&pThis->IoCritSect);
489
490	return rc;
491	}
492
493
494	/**
495	* @interface_method_impl{RTVFSFILEOPS,pfnSetSize}
496	*/
497	static DECLCALLBACK(int) rtVfsReadAhead_SetSize(void *pvThis, uint64_t cbFile, uint32_t fFlags)
498	{
499	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
500	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
501
502	RTCritSectEnter(&pThis->IoCritSect); /* paranoia */
503	int rc = RTVfsFileSetSize(pThis->hFile, cbFile, fFlags);
504	RTCritSectLeave(&pThis->IoCritSect);
505
506	return rc;
507	}
508
509
510	/**
511	* @interface_method_impl{RTVFSFILEOPS,pfnQueryMaxSize}
512	*/
513	static DECLCALLBACK(int) rtVfsReadAhead_QueryMaxSize(void pvThis, uint64_t pcbMax)
514	{
515	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvThis;
516	AssertReturn(pThis->hFile != NIL_RTVFSFILE, VERR_NOT_SUPPORTED);
517
518	RTCritSectEnter(&pThis->IoCritSect); /* paranoia */
519	int rc = RTVfsFileQueryMaxSize(pThis->hFile, pcbMax);
520	RTCritSectLeave(&pThis->IoCritSect);
521
522	return rc;
523	}
524
525
526	/**
527	* Read ahead I/O stream operations.
528	*/
529	DECL_HIDDEN_CONST(const RTVFSIOSTREAMOPS) g_VfsReadAheadIosOps =
530	{ /* Stream */
531	{ /* Obj */
532	RTVFSOBJOPS_VERSION,
533	RTVFSOBJTYPE_IO_STREAM,
534	"Read ahead I/O stream",
535	rtVfsReadAhead_Close,
536	rtVfsReadAhead_QueryInfo,
537	RTVFSOBJOPS_VERSION
538	},
539	RTVFSIOSTREAMOPS_VERSION,
540	RTVFSIOSTREAMOPS_FEAT_NO_SG,
541	rtVfsReadAhead_Read,
542	rtVfsReadAhead_Write,
543	rtVfsReadAhead_Flush,
544	rtVfsReadAhead_PollOne,
545	rtVfsReadAhead_Tell,
546	NULL /Skip/,
547	NULL /ZeroFill/,
548	RTVFSIOSTREAMOPS_VERSION,
549	};
550
551
552	/**
553	* Read ahead file operations.
554	*/
555	DECL_HIDDEN_CONST(const RTVFSFILEOPS) g_VfsReadAheadFileOps =
556	{
557	{ /* Stream */
558	{ /* Obj */
559	RTVFSOBJOPS_VERSION,
560	RTVFSOBJTYPE_FILE,
561	"Read ahead file",
562	rtVfsReadAhead_Close,
563	rtVfsReadAhead_QueryInfo,
564	RTVFSOBJOPS_VERSION
565	},
566	RTVFSIOSTREAMOPS_VERSION,
567	RTVFSIOSTREAMOPS_FEAT_NO_SG,
568	rtVfsReadAhead_Read,
569	rtVfsReadAhead_Write,
570	rtVfsReadAhead_Flush,
571	rtVfsReadAhead_PollOne,
572	rtVfsReadAhead_Tell,
573	NULL /Skip/,
574	NULL /ZeroFill/,
575	RTVFSIOSTREAMOPS_VERSION,
576	},
577	RTVFSFILEOPS_VERSION,
578	/RTVFSIOFILEOPS_FEAT_NO_AT_OFFSET/ 0,
579	{ /* ObjSet */
580	RTVFSOBJSETOPS_VERSION,
581	RT_UOFFSETOF(RTVFSFILEOPS, ObjSet) - RT_UOFFSETOF(RTVFSFILEOPS, Stream.Obj),
582	rtVfsReadAhead_SetMode,
583	rtVfsReadAhead_SetTimes,
584	rtVfsReadAhead_SetOwner,
585	RTVFSOBJSETOPS_VERSION
586	},
587	rtVfsReadAhead_Seek,
588	rtVfsReadAhead_QuerySize,
589	rtVfsReadAhead_SetSize,
590	rtVfsReadAhead_QueryMaxSize,
591	RTVFSFILEOPS_VERSION
592	};
593
594
595	/**
596	* @callback_method_impl{PFNRTTHREAD, Read ahead thread procedure}
597	*/
598	static DECLCALLBACK(int) rtVfsReadAheadThreadProc(RTTHREAD hThreadSelf, void *pvUser)
599	{
600	PRTVFSREADAHEAD pThis = (PRTVFSREADAHEAD)pvUser;
601	Assert(pThis);
602
603	while (!pThis->fTerminateThread)
604	{
605	int rc;
606
607	/*
608	* Is there a buffer handy for reading ahead.
609	*/
610	PRTVFSREADAHEADBUFDESC pBufDesc = NULL;
611	RTCritSectEnter(&pThis->BufferCritSect);
612	if (!pThis->fTerminateThread)
613	pBufDesc = RTListRemoveFirst(&pThis->FreeList, RTVFSREADAHEADBUFDESC, ListEntry);
614	RTCritSectLeave(&pThis->BufferCritSect);
615
616	if (pBufDesc)
617	{
618	/*
619	* Got a buffer, take the I/O lock and read into it.
620	*/
621	rc = VERR_CALLBACK_RETURN;
622	RTCritSectEnter(&pThis->IoCritSect);
623	if (!pThis->fTerminateThread)
624	{
625
626	pBufDesc->off = RTVfsIoStrmTell(pThis->hIos);
627	size_t cbRead = 0;
628	rc = RTVfsIoStrmRead(pThis->hIos, pBufDesc->pbBuffer, pThis->cbBuffer, true /fBlocking/, &cbRead);
629	if (RT_SUCCESS(rc))
630	{
631	if (rc == VINF_EOF)
632	{
633	pThis->offEof = pBufDesc->off + cbRead;
634	Log(("rtVfsReadAheadThreadProc: EOF %llu (%#llx)\n", pThis->offEof, pThis->offEof));
635	}
636	pBufDesc->cbFilled = (uint32_t)cbRead;
637
638	/*
639	* Put back the buffer. The consumer list is sorted by offset, but
640	* we should usually end up appending the buffer.
641	*/
642	RTCritSectEnter(&pThis->BufferCritSect);
643	PRTVFSREADAHEADBUFDESC pAfter = RTListGetLast(&pThis->ConsumerList, RTVFSREADAHEADBUFDESC, ListEntry);
644	if (!pAfter \|\| pAfter->off <= pBufDesc->off)
645	RTListAppend(&pThis->ConsumerList, &pBufDesc->ListEntry);
646	else
647	{
648	do
649	pAfter = RTListGetPrev(&pThis->ConsumerList, pAfter, RTVFSREADAHEADBUFDESC, ListEntry);
650	while (pAfter && pAfter->off > pBufDesc->off);
651	if (!pAfter)
652	RTListPrepend(&pThis->ConsumerList, &pBufDesc->ListEntry);
653	else
654	{
655	Assert(pAfter->off <= pBufDesc->off);
656	RTListNodeInsertAfter(&pAfter->ListEntry, &pBufDesc->ListEntry);
657	}
658	}
659	RTCritSectLeave(&pThis->BufferCritSect);
660	pBufDesc = NULL;
661
662	#ifdef RT_STRICT
663	/* Verify the list ordering. */
664	unsigned cAsserted = 0;
665	uint64_t offAssert = 0;
666	PRTVFSREADAHEADBUFDESC pAssertCur;
667	RTListForEach(&pThis->ConsumerList, pAssertCur, RTVFSREADAHEADBUFDESC, ListEntry)
668	{
669	Assert(offAssert <= pAssertCur->off);
670	offAssert = pAssertCur->off;
671	Assert(cAsserted < pThis->cBuffers);
672	cAsserted++;
673	}
674	#endif
675	}
676	else
677	Assert(rc != VERR_EOF);
678	}
679	RTCritSectLeave(&pThis->IoCritSect);
680
681	/*
682	* If we succeeded and we didn't yet reach the end of the stream,
683	* loop without delay to start processing the next buffer.
684	*/
685	if (RT_LIKELY(!pBufDesc && rc != VINF_EOF))
686	continue;
687
688	/* Put any unused buffer back in the free list (termination/failure, not EOF). */
689	if (pBufDesc)
690	{
691	RTCritSectEnter(&pThis->BufferCritSect);
692	RTListPrepend(&pThis->FreeList, &pBufDesc->ListEntry);
693	RTCritSectLeave(&pThis->BufferCritSect);
694	}
695	if (pThis->fTerminateThread)
696	break;
697	}
698
699	/*
700	* Wait for more to do.
701	*/
702	rc = RTThreadUserWait(hThreadSelf, RT_MS_1MIN);
703	if (RT_SUCCESS(rc))
704	rc = RTThreadUserReset(hThreadSelf);
705	}
706
707	return VINF_SUCCESS;
708	}
709
710
711	static int rtVfsCreateReadAheadInstance(RTVFSIOSTREAM hVfsIosSrc, RTVFSFILE hVfsFileSrc, uint32_t fFlags,
712	uint32_t cBuffers, uint32_t cbBuffer, PRTVFSIOSTREAM phVfsIos, PRTVFSFILE phVfsFile)
713	{
714	/*
715	* Validate input a little.
716	*/
717	int rc = VINF_SUCCESS;
718	AssertStmt(cBuffers < _4K, rc = VERR_OUT_OF_RANGE);
719	if (cBuffers == 0)
720	cBuffers = 4;
721	AssertStmt(cbBuffer <= _4M, rc = VERR_OUT_OF_RANGE);
722	if (cbBuffer == 0)
723	cbBuffer = _256K / cBuffers;
724	AssertStmt(cbBuffer * cBuffers < (ARCH_BITS < 64 ? _64M : _256M), rc = VERR_OUT_OF_RANGE);
725	AssertStmt(!fFlags, rc = VERR_INVALID_FLAGS);
726
727	if (RT_SUCCESS(rc))
728	{
729	/*
730	* Create a file or I/O stream instance.
731	*/
732	RTVFSFILE hVfsFileReadAhead = NIL_RTVFSFILE;
733	RTVFSIOSTREAM hVfsIosReadAhead = NIL_RTVFSIOSTREAM;
734	PRTVFSREADAHEAD pThis;
735	size_t cbThis = RT_UOFFSETOF_DYN(RTVFSREADAHEAD, aBufDescs[cBuffers]);
736	if (hVfsFileSrc != NIL_RTVFSFILE)
737	rc = RTVfsNewFile(&g_VfsReadAheadFileOps, cbThis, RTFILE_O_READ, NIL_RTVFS, NIL_RTVFSLOCK,
738	&hVfsFileReadAhead, (void **)&pThis);
739	else
740	rc = RTVfsNewIoStream(&g_VfsReadAheadIosOps, cbThis, RTFILE_O_READ, NIL_RTVFS, NIL_RTVFSLOCK,
741	&hVfsIosReadAhead, (void **)&pThis);
742	if (RT_SUCCESS(rc))
743	{
744	RTListInit(&pThis->ConsumerList);
745	RTListInit(&pThis->FreeList);
746	pThis->hThread = NIL_RTTHREAD;
747	pThis->fTerminateThread = false;
748	pThis->fFlags = fFlags;
749	pThis->hFile = hVfsFileSrc;
750	pThis->hIos = hVfsIosSrc;
751	pThis->cBuffers = cBuffers;
752	pThis->cbBuffer = cbBuffer;
753	pThis->offEof = UINT64_MAX;
754	pThis->offConsumer = RTVfsIoStrmTell(hVfsIosSrc);
755	if ((RTFOFF)pThis->offConsumer >= 0)
756	{
757	rc = RTCritSectInit(&pThis->IoCritSect);
758	if (RT_SUCCESS(rc))
759	rc = RTCritSectInit(&pThis->BufferCritSect);
760	if (RT_SUCCESS(rc))
761	{
762	pThis->pbAllBuffers = (uint8_t )RTMemPageAlloc(pThis->cbBuffer pThis->cBuffers);
763	if (pThis->pbAllBuffers)
764	{
765	for (uint32_t i = 0; i < cBuffers; i++)
766	{
767	pThis->aBufDescs[i].cbFilled = 0;
768	pThis->aBufDescs[i].off = UINT64_MAX / 2;
769	pThis->aBufDescs[i].pbBuffer = &pThis->pbAllBuffers[cbBuffer * i];
770	RTListAppend(&pThis->FreeList, &pThis->aBufDescs[i].ListEntry);
771	}
772
773	/*
774	* Create thread.
775	*/
776	rc = RTThreadCreate(&pThis->hThread, rtVfsReadAheadThreadProc, pThis, 0, RTTHREADTYPE_DEFAULT,
777	RTTHREADFLAGS_WAITABLE, "vfsreadahead");
778	if (RT_SUCCESS(rc))
779	{
780	/*
781	* We're good.
782	*/
783	if (phVfsFile)
784	*phVfsFile = hVfsFileReadAhead;
785	else if (hVfsFileReadAhead == NIL_RTVFSFILE)
786	*phVfsIos = hVfsIosReadAhead;
787	else
788	{
789	*phVfsIos = RTVfsFileToIoStream(hVfsFileReadAhead);
790	RTVfsFileRelease(hVfsFileReadAhead);
791	AssertReturn(*phVfsIos != NIL_RTVFSIOSTREAM, VERR_INTERNAL_ERROR_5);
792	}
793	return VINF_SUCCESS;
794	}
795	}
796	}
797	}
798	else
799	rc = (int)pThis->offConsumer;
800	}
801	}
802
803	RTVfsFileRelease(hVfsFileSrc);
804	RTVfsIoStrmRelease(hVfsIosSrc);
805	return rc;
806	}
807
808
809	RTDECL(int) RTVfsCreateReadAheadForIoStream(RTVFSIOSTREAM hVfsIos, uint32_t fFlags, uint32_t cBuffers, uint32_t cbBuffer,
810	PRTVFSIOSTREAM phVfsIos)
811	{
812	AssertPtrReturn(phVfsIos, VERR_INVALID_POINTER);
813	*phVfsIos = NIL_RTVFSIOSTREAM;
814
815	/*
816	* Retain the input stream, trying to obtain a file handle too so we can
817	* fully mirror it.
818	*/
819	uint32_t cRefs = RTVfsIoStrmRetain(hVfsIos);
820	AssertReturn(cRefs != UINT32_MAX, VERR_INVALID_HANDLE);
821	RTVFSFILE hVfsFile = RTVfsIoStrmToFile(hVfsIos);
822
823	/*
824	* Do the job. (This always consumes the above retained references.)
825	*/
826	return rtVfsCreateReadAheadInstance(hVfsIos, hVfsFile, fFlags, cBuffers, cbBuffer, phVfsIos, NULL);
827	}
828
829
830	RTDECL(int) RTVfsCreateReadAheadForFile(RTVFSFILE hVfsFile, uint32_t fFlags, uint32_t cBuffers, uint32_t cbBuffer,
831	PRTVFSFILE phVfsFile)
832	{
833	AssertPtrReturn(phVfsFile, VERR_INVALID_POINTER);
834	*phVfsFile = NIL_RTVFSFILE;
835
836	/*
837	* Retain the input file and cast it o an I/O stream.
838	*/
839	RTVFSIOSTREAM hVfsIos = RTVfsFileToIoStream(hVfsFile);
840	AssertReturn(hVfsIos != NIL_RTVFSIOSTREAM, VERR_INVALID_HANDLE);
841	uint32_t cRefs = RTVfsFileRetain(hVfsFile);
842	AssertReturnStmt(cRefs != UINT32_MAX, RTVfsIoStrmRelease(hVfsIos), VERR_INVALID_HANDLE);
843
844	/*
845	* Do the job. (This always consumes the above retained references.)
846	*/
847	return rtVfsCreateReadAheadInstance(hVfsIos, hVfsFile, fFlags, cBuffers, cbBuffer, NULL, phVfsFile);
848	}
849
850
851	/**
852	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnValidate}
853	*/
854	static DECLCALLBACK(int) rtVfsChainReadAhead_Validate(PCRTVFSCHAINELEMENTREG pProviderReg, PRTVFSCHAINSPEC pSpec,
855	PRTVFSCHAINELEMSPEC pElement, uint32_t *poffError, PRTERRINFO pErrInfo)
856	{
857	RT_NOREF(pProviderReg, poffError, pErrInfo);
858
859	/*
860	* Basics.
861	*/
862	if ( pElement->enmType != RTVFSOBJTYPE_FILE
863	&& pElement->enmType != RTVFSOBJTYPE_IO_STREAM)
864	return VERR_VFS_CHAIN_ONLY_FILE_OR_IOS;
865	if (pElement->enmTypeIn == RTVFSOBJTYPE_INVALID)
866	return VERR_VFS_CHAIN_CANNOT_BE_FIRST_ELEMENT;
867	if ( pElement->enmTypeIn != RTVFSOBJTYPE_FILE
868	&& pElement->enmTypeIn != RTVFSOBJTYPE_IO_STREAM)
869	return VERR_VFS_CHAIN_TAKES_FILE_OR_IOS;
870	if (pSpec->fOpenFile & RTFILE_O_WRITE)
871	return VERR_VFS_CHAIN_READ_ONLY_IOS;
872	if (pElement->cArgs > 2)
873	return VERR_VFS_CHAIN_AT_MOST_TWO_ARGS;
874
875	/*
876	* Parse the two optional arguments.
877	*/
878	uint32_t cBuffers = 0;
879	if (pElement->cArgs > 0)
880	{
881	const char *psz = pElement->paArgs[0].psz;
882	if (*psz)
883	{
884	int rc = RTStrToUInt32Full(psz, 0, &cBuffers);
885	if (RT_FAILURE(rc))
886	{
887	*poffError = pElement->paArgs[0].offSpec;
888	return VERR_VFS_CHAIN_INVALID_ARGUMENT;
889	}
890	}
891	}
892
893	uint32_t cbBuffer = 0;
894	if (pElement->cArgs > 1)
895	{
896	const char *psz = pElement->paArgs[1].psz;
897	if (*psz)
898	{
899	int rc = RTStrToUInt32Full(psz, 0, &cbBuffer);
900	if (RT_FAILURE(rc))
901	{
902	*poffError = pElement->paArgs[1].offSpec;
903	return VERR_VFS_CHAIN_INVALID_ARGUMENT;
904	}
905	}
906	}
907
908	/*
909	* Save the parsed arguments in the spec since their both optional.
910	*/
911	pElement->uProvider = RT_MAKE_U64(cBuffers, cbBuffer);
912
913	return VINF_SUCCESS;
914	}
915
916
917	/**
918	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnInstantiate}
919	*/
920	static DECLCALLBACK(int) rtVfsChainReadAhead_Instantiate(PCRTVFSCHAINELEMENTREG pProviderReg, PCRTVFSCHAINSPEC pSpec,
921	PCRTVFSCHAINELEMSPEC pElement, RTVFSOBJ hPrevVfsObj,
922	PRTVFSOBJ phVfsObj, uint32_t *poffError, PRTERRINFO pErrInfo)
923	{
924	RT_NOREF(pProviderReg, pSpec, pElement, poffError, pErrInfo);
925	AssertReturn(hPrevVfsObj != NIL_RTVFSOBJ, VERR_VFS_CHAIN_IPE);
926
927	/* Try for a file if we can. */
928	int rc;
929	RTVFSFILE hVfsFileIn = RTVfsObjToFile(hPrevVfsObj);
930	if (hVfsFileIn != NIL_RTVFSFILE)
931	{
932	RTVFSFILE hVfsFile = NIL_RTVFSFILE;
933	rc = RTVfsCreateReadAheadForFile(hVfsFileIn, 0 /fFlags/, RT_LO_U32(pElement->uProvider),
934	RT_HI_U32(pElement->uProvider), &hVfsFile);
935	RTVfsFileRelease(hVfsFileIn);
936	if (RT_SUCCESS(rc))
937	{
938	*phVfsObj = RTVfsObjFromFile(hVfsFile);
939	RTVfsFileRelease(hVfsFile);
940	if (*phVfsObj != NIL_RTVFSOBJ)
941	return VINF_SUCCESS;
942	rc = VERR_VFS_CHAIN_CAST_FAILED;
943	}
944	}
945	else if (pElement->enmType == RTVFSOBJTYPE_IO_STREAM)
946	{
947	RTVFSIOSTREAM hVfsIosIn = RTVfsObjToIoStream(hPrevVfsObj);
948	if (hVfsIosIn != NIL_RTVFSIOSTREAM)
949	{
950	RTVFSIOSTREAM hVfsIos = NIL_RTVFSIOSTREAM;
951	rc = RTVfsCreateReadAheadForIoStream(hVfsIosIn, 0 /fFlags/, RT_LO_U32(pElement->uProvider),
952	RT_HI_U32(pElement->uProvider), &hVfsIos);
953	RTVfsIoStrmRelease(hVfsIosIn);
954	if (RT_SUCCESS(rc))
955	{
956	*phVfsObj = RTVfsObjFromIoStream(hVfsIos);
957	RTVfsIoStrmRelease(hVfsIos);
958	if (*phVfsObj != NIL_RTVFSOBJ)
959	return VINF_SUCCESS;
960	rc = VERR_VFS_CHAIN_CAST_FAILED;
961	}
962	}
963	else
964	rc = VERR_VFS_CHAIN_CAST_FAILED;
965	}
966	else
967	rc = VERR_VFS_CHAIN_CAST_FAILED;
968	return rc;
969	}
970
971
972	/**
973	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnCanReuseElement}
974	*/
975	static DECLCALLBACK(bool) rtVfsChainReadAhead_CanReuseElement(PCRTVFSCHAINELEMENTREG pProviderReg,
976	PCRTVFSCHAINSPEC pSpec, PCRTVFSCHAINELEMSPEC pElement,
977	PCRTVFSCHAINSPEC pReuseSpec, PCRTVFSCHAINELEMSPEC pReuseElement)
978	{
979	RT_NOREF(pProviderReg, pSpec, pElement, pReuseSpec, pReuseElement);
980	return false;
981	}
982
983
984	/** VFS chain element 'pull'. */
985	static RTVFSCHAINELEMENTREG g_rtVfsChainReadAheadReg =
986	{
987	/* uVersion = */ RTVFSCHAINELEMENTREG_VERSION,
988	/* fReserved = */ 0,
989	/* pszName = */ "pull",
990	/* ListEntry = */ { NULL, NULL },
991	/* pszHelp = */ "Takes an I/O stream or file and provides read-ahead caching.\n"
992	"Optional first argument specifies how many buffers to use, 0 indicating the default.\n"
993	"Optional second argument specifies the buffer size, 0 indicating the default.",
994	/* pfnValidate = */ rtVfsChainReadAhead_Validate,
995	/* pfnInstantiate = */ rtVfsChainReadAhead_Instantiate,
996	/* pfnCanReuseElement = */ rtVfsChainReadAhead_CanReuseElement,
997	/* uEndMarker = */ RTVFSCHAINELEMENTREG_VERSION
998	};
999
1000	RTVFSCHAIN_AUTO_REGISTER_ELEMENT_PROVIDER(&g_rtVfsChainReadAheadReg, rtVfsChainReadAheadReg);
1001

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source: vbox/trunk/src/VBox/Runtime/common/vfs/vfsreadahead.cpp@ 76553

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