summaryrefslogtreecommitdiffstats
path: root/src/H5SMcache.c
blob: 78b50338f130eaa6523b50fb70f7f95f3e2a3ef9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
 * of the source code distribution tree; Copyright.html can be found at the  *
 * root level of an installed copy of the electronic HDF5 document set and   *
 * is linked from the top-level documents page.  It can also be found at     *
 * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html.  If you do not have     *
 * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/****************/
/* Module Setup */
/****************/

#define H5SM_PACKAGE		/*suppress error about including H5SMpkg	  */
#define H5F_PACKAGE		/*suppress error about including H5Fpkg 	  */

/***********/
/* Headers */
/***********/
/* JAMES: these need to go first or else FILE isn't defined in H5Fpkg.h */
/* JAMES: which of these are really needed?  H5Fpkg.h, even? */
#include "H5private.h"		/* Generic Functions			*/
#include "H5Aprivate.h"		/* Attributes				*/
#include "H5ACprivate.h"	/* Metadata cache			*/
#include "H5Dprivate.h"		/* Datasets				*/
#include "H5Eprivate.h"		/* Error handling		  	*/

#include "H5Fpkg.h"		/* File access                          */
#include "H5FLprivate.h"	/* Free Lists                           */
#include "H5FOprivate.h"        /* File objects                         */
#include "H5HLprivate.h"	/* Local heaps				*/
#include "H5MFprivate.h"        /* File memory management		*/
#include "H5MMprivate.h"	/* Memory management			*/
#include "H5Vprivate.h"		/* Vectors and arrays 			*/
#include "H5SMpkg.h"            /* Shared object header messages        */
#include "H5FDprivate.h"	/* File drivers				*/

/****************/
/* Local Macros */
/****************/
#define H5F_TABLEBUF_SIZE  H5SM_TABLE_SIZEOF_MAGIC + 20 + (H5SM_MAX_NINDEXES * 26)
/* JAMES: should this change according to address size? */
#define H5F_LISTBUF_SIZE  H5SM_LIST_SIZEOF_MAGIC + H5SM_MAX_LIST_ELEMS * 16

#define H5SM_LIST_VERSION	0	/* Verion of Shared Object Header Message List Indexes */

/******************/
/* Local Typedefs */
/******************/

/********************/
/* Local Prototypes */
/********************/
static herr_t H5SM_flush_table(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5SM_master_table_t *table);
static H5SM_master_table_t *H5SM_load_table(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *udata1, void *table);
static herr_t H5SM_clear_table(H5F_t *f, H5SM_master_table_t *table, hbool_t destroy);
static herr_t H5SM_dest_table(H5F_t *f, H5SM_master_table_t* table);
static herr_t H5SM_table_size(const H5F_t *f, const H5SM_master_table_t *table, size_t *size_ptr);

static herr_t H5SM_flush_list(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5SM_list_t *list);
static H5SM_list_t *H5SM_load_list(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *udata1, void *udata2);
static herr_t H5SM_clear_list(H5F_t *f, H5SM_list_t *list, hbool_t destroy);
static herr_t H5SM_dest_list(H5F_t *f, H5SM_list_t* list);
static herr_t H5SM_list_size(const H5F_t *f, const H5SM_list_t UNUSED *list, size_t *size_ptr);

/*********************/
/* Package Variables */
/*********************/
/* H5SM inherits cache-like properties from H5AC */
const H5AC_class_t H5AC_SOHM_TABLE[1] = {{
    H5AC_SOHM_TABLE_ID,
      (H5AC_load_func_t) H5SM_load_table,
      (H5AC_flush_func_t) H5SM_flush_table,
      (H5AC_dest_func_t) H5SM_dest_table,
      (H5AC_clear_func_t)H5SM_clear_table,
      (H5AC_size_func_t) H5SM_table_size,
}};

const H5AC_class_t H5AC_SOHM_LIST[1] = {{
      H5AC_SOHM_LIST_ID,
      (H5AC_load_func_t) H5SM_load_list,
      (H5AC_flush_func_t) H5SM_flush_list,
      (H5AC_dest_func_t) H5SM_dest_list,
      (H5AC_clear_func_t)H5SM_clear_list,
      (H5AC_size_func_t) H5SM_list_size,
}};

/*****************************/
/* Library Private Variables */
/*****************************/

/*******************/
/* Local Variables */
/*******************/

/*-------------------------------------------------------------------------
 * Function:	H5SM_flush_table
 *
 * Purpose:	Flushes (and destroys) the table of Shared Object Header
 *              Message indexes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_flush_table(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5SM_master_table_t *table)
{
    herr_t          ret_value=SUCCEED;

    FUNC_ENTER_NOAPI(H5SM_flush_table, FAIL)

    /* check arguments */
    HDassert(f);
    HDassert(H5F_addr_defined(addr));
    HDassert(table);

    if (table->cache_info.is_dirty) {
        uint8_t buf[H5F_TABLEBUF_SIZE];  /* Temporary buffer */   /* JAMES This is big. Do I need to use H5FL_BLK_MALLOC instead? */
        uint8_t  *p;                 /* Pointer into raw data buffer */
        size_t	 size;               /* Header size on disk */
        uint32_t computed_chksum;    /* Computed metadata checksum value */
        int      x;                  /* Counter variable */

        /* Encode the master table and all of the index headers as one big blob */
        size = H5SM_TABLE_SIZE(f) + (H5SM_INDEX_HEADER_SIZE(f) * table->num_indexes);

        /* Encode the master table */
        p = buf;

        /* Encode magic number */
        HDmemcpy(p, H5SM_TABLE_MAGIC, (size_t)H5SM_TABLE_SIZEOF_MAGIC);
        p += H5SM_TABLE_SIZEOF_MAGIC;

        *p++ = table->version; /* Version */

        /* Encode each index header */
        for(x=0; x<table->num_indexes; ++x) {
            *p++ = table->indexes[x].index_type;      /* Is message index a list or a B-tree? */

            UINT16ENCODE(p, table->indexes[x].mesg_types);    /* Type of messages in the index */
            UINT32ENCODE(p, table->indexes[x].min_mesg_size); /* Minimum size of message to share */
            UINT16ENCODE(p, table->indexes[x].list_to_btree);  /* List cutoff; fewer than this number and index becomes a list */
            UINT16ENCODE(p, table->indexes[x].btree_to_list);  /* B-tree cutoff; more than this number and index becomes a B-tree */
            UINT16ENCODE(p, table->indexes[x].num_messages);   /* Number of messages shared */
            H5F_addr_encode(f, &p, table->indexes[x].index_addr); /* Address of the actual index */
            H5F_addr_encode(f, &p, table->indexes[x].heap_addr); /* Address of the index's heap */
        }

        /* Compute checksum on buffer */
        computed_chksum = H5_checksum_metadata(buf, (size - H5SM_SIZEOF_CHECKSUM), 0);
        UINT32ENCODE(p, computed_chksum);

        /* Write the table to disk */
        HDassert((size_t)(p - buf) == size);
	if(H5F_block_write(f, H5FD_MEM_SOHM_TABLE, addr, size, dxpl_id, buf) < 0)
	    HGOTO_ERROR(H5E_SOHM, H5E_CANTFLUSH, FAIL, "unable to save sohm table to disk")

	table->cache_info.is_dirty = FALSE;
    }

    if(destroy)
        if(H5SM_dest_table(f, table) < 0)
	    HGOTO_ERROR(H5E_SOHM, H5E_CANTFREE, FAIL, "unable to destroy sohm table")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5SM_flush_table */



/*-------------------------------------------------------------------------
 * Function:	H5SM_load_table
 *
 * Purpose:	Loads the master table of Shared Object Header Message
 *              indexes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static H5SM_master_table_t *
H5SM_load_table(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *udata1, void UNUSED *udata2)
{
    H5SM_master_table_t *table = NULL;
    size_t        table_size;          /* Size of SOHM master table on disk */
    uint8_t       *buf=NULL;           /* Reading buffer */
    const uint8_t *p;                  /* Pointer into input buffer */
    uint32_t      stored_chksum;       /* Stored metadata checksum value */
    uint32_t      computed_chksum;     /* Computed metadata checksum value */
    uint8_t       x;                   /* Counter variable for index headers */
    H5SM_master_table_t *ret_value;

    FUNC_ENTER_NOAPI(H5SM_load_table, NULL)

    /* Allocate space for the master table in memory */
    if(NULL == (table = H5MM_calloc(sizeof(H5SM_master_table_t))))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    /* Read number of indexes and version from file superblock */
    table->num_indexes = f->shared->sohm_nindexes;
    table->version = f->shared->sohm_vers;

    HDassert(addr == f->shared->sohm_addr);
    HDassert(addr != HADDR_UNDEF);
    HDassert(table->num_indexes > 0);

    /* Compute the size of the SOHM table header on disk.  This is the "table" itself
     * plus each index within the table
     */
    table_size = H5SM_TABLE_SIZE(f) + (table->num_indexes * H5SM_INDEX_HEADER_SIZE(f));

    /* Allocate temporary buffer */
    if(NULL == (buf = HDmalloc(table_size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    /* Read header from disk */
    if(H5F_block_read(f, H5FD_MEM_SOHM_TABLE, addr, table_size, dxpl_id, buf) < 0)
	HGOTO_ERROR(H5E_SOHM, H5E_READERROR, NULL, "can't read SOHM table")

    p = buf;

    /* Check magic number */
    if(HDmemcmp(p, H5SM_TABLE_MAGIC, (size_t)H5SM_TABLE_SIZEOF_MAGIC))
	HGOTO_ERROR(H5E_SOHM, H5E_CANTLOAD, NULL, "bad SOHM table signature");
    p += H5SM_TABLE_SIZEOF_MAGIC;

    /* Version number */
    if (table->version != *p++)
        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "wrong SOHM table version number")

    /* Don't count the checksum in the table size yet, since it comes after
     * all of the index headers
     */
    HDassert((size_t)(p - buf) == H5SM_TABLE_SIZE(f) - H5SM_SIZEOF_CHECKSUM);

    /* Allocate space for the index headers in memory*/
    if(NULL == (table->indexes = H5FL_ARR_MALLOC(H5SM_index_header_t, (size_t)table->num_indexes)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for SOHM indexes")

    /* Read in the index headers */
    for(x=0; x<table->num_indexes; ++x) {
        table->indexes[x].index_type= *p++;  /* type of the index (list or B-tree) */

        UINT16DECODE(p, table->indexes[x].mesg_types);
        UINT32DECODE(p, table->indexes[x].min_mesg_size);
        UINT16DECODE(p, table->indexes[x].list_to_btree);
        UINT16DECODE(p, table->indexes[x].btree_to_list);
        UINT16DECODE(p, table->indexes[x].num_messages);
        H5F_addr_decode(f, &p, &(table->indexes[x].index_addr));
        H5F_addr_decode(f, &p, &(table->indexes[x].heap_addr));
    }

    /* Read in checksum */
    UINT32DECODE(p, stored_chksum);

    /* Sanity check */
    HDassert((size_t)(p - buf) == table_size);

    /* Compute checksum on entire header */
    computed_chksum = H5_checksum_metadata(buf, (table_size - H5SM_SIZEOF_CHECKSUM), 0);

    /* Verify checksum */
    if(stored_chksum != computed_chksum)
        HGOTO_ERROR(H5E_SOHM, H5E_BADVALUE, NULL, "incorrect metadata checksum for shared message table");

    ret_value = table;

done:
    /* Free buffer if it was allocated */
    if(buf)
        HDfree(buf);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5SM_load_table */ 



/*-------------------------------------------------------------------------
 * Function:	H5SM_clear_table
 *
 * Purpose:	Mark this table as no longer being dirty.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_clear_table(H5F_t *f, H5SM_master_table_t *table, hbool_t destroy)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT(H5SM_clear_table)

    /*
     * Check arguments.
     */
    HDassert(table);

    /* Reset the dirty flag.  */
    table->cache_info.is_dirty = FALSE;

    if(destroy)
        if(H5SM_dest_table(f, table) < 0)
	    HGOTO_ERROR(H5E_SOHM, H5E_CANTFREE, FAIL, "unable to delete SOHM master table")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5SM_clear_table */



/*-------------------------------------------------------------------------
 * Function:	H5SM_dest_table
 *
 * Purpose:	Frees memory used by the SOHM table.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_dest_table(H5F_t UNUSED *f, H5SM_master_table_t* table)
{
    FUNC_ENTER_NOAPI_NOFUNC(H5SM_dest_table)

    HDassert(table);
    HDassert(table->indexes);

    H5FL_ARR_FREE(H5SM_index_header_t, table->indexes);

    H5MM_free(table);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5SM_dest_table */


/*-------------------------------------------------------------------------
 * Function:	H5SM_table_size
 *
 * Purpose:	Returns the size of the table encoded on disk.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_table_size(const H5F_t *f, const H5SM_master_table_t *table, size_t *size_ptr)
{
    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_table_size)

    /* check arguments */
    HDassert(f);
    HDassert(table);
    HDassert(size_ptr);

    /* Set size value */
    *size_ptr = H5SM_TABLE_SIZE(f) + (table->num_indexes * H5SM_INDEX_HEADER_SIZE(f));

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5SM_table_size */



/*-------------------------------------------------------------------------
 * Function:	H5SM_flush_list
 *
 * Purpose:	Flush this list index.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_flush_list(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5SM_list_t *list)
{
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5SM_flush_list, FAIL)

    /* check arguments */
    HDassert(f);
    HDassert(H5F_addr_defined(addr));
    HDassert(list);
    HDassert(list->header);

    if (list->cache_info.is_dirty) {
        uint8_t buf[H5F_LISTBUF_SIZE];  /* Temporary buffer */   /* JAMES Do I need to use H5FL_BLK_MALLOC instead? */
        uint8_t *p;                 /* Pointer into raw data buffer */
        size_t	size;               /* Header size on disk */
        uint32_t computed_chksum;   /* Computed metadata checksum value */
        hsize_t x;

        /* JAMES: consider only writing as many messages as necessary, and then adding a
         * blank "end of list" message or something?
         */
        size = H5SM_LIST_SIZE(f, list->header->num_messages);

        /* Encode the list */
        p = buf;

        /* Encode magic number */
        HDmemcpy(p, H5SM_LIST_MAGIC, (size_t)H5SM_LIST_SIZEOF_MAGIC);
        p += H5SM_LIST_SIZEOF_MAGIC;

        /* Encode version */
        *p++ = H5SM_LIST_VERSION;

        /* Write messages from the messages array to disk */
        /* JAMES: we have to search the whole array.  not the best way to do it; could go until we've written
         * num_messages */
        for(x=0; x<list->header->list_to_btree; x++) {
            if(list->messages[x].fheap_id != 0 && list->messages[x].hash != H5O_HASH_UNDEF) {
              /* JAMES: use H5SM_message_encode here */
              UINT32ENCODE(p, list->messages[x].hash);  /* Read the hash value for this message */
              UINT32ENCODE(p, list->messages[x].ref_count);  /* Read the reference count for this message */
              UINT64ENCODE(p, list->messages[x].fheap_id); /* Get the heap ID for the message */
            }
        }

        /* Compute checksum on buffer */
        computed_chksum = H5_checksum_metadata(buf, (size - H5SM_SIZEOF_CHECKSUM), 0);
        UINT32ENCODE(p, computed_chksum);

        /* Write the list to disk */
        HDassert((size_t)(p - buf) == size);
	if(H5F_block_write(f, H5FD_MEM_SOHM_INDEX, addr, size, dxpl_id, buf) < 0)
	    HGOTO_ERROR(H5E_SOHM, H5E_CANTFLUSH, FAIL, "unable to save sohm table to disk")

        list->cache_info.is_dirty = FALSE;
    }

    if(destroy)
        if(H5SM_dest_list(f, list) < 0)
	    HGOTO_ERROR(H5E_SOHM, H5E_CANTFREE, FAIL, "unable to destroy list")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5SM_flush_list */



/*-------------------------------------------------------------------------
 * Function:	H5SM_load_list
 *
 * Purpose:	Loads a list of SOHM messages.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static H5SM_list_t *
H5SM_load_list(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *udata1, void *udata2)
{
    H5SM_list_t *list;              /* The SOHM list being read in */
    H5SM_index_header_t *header = (H5SM_index_header_t *) udata2;     /* Index header for this list */
    size_t size;                    /* Size of SOHM list on disk */
    uint8_t *buf = NULL;            /* Reading buffer */
    uint8_t *p;                     /* Pointer into input buffer */
    uint32_t stored_chksum;         /* Stored metadata checksum value */
    uint32_t computed_chksum;       /* Computed metadata checksum value */
    hsize_t x;                      /* Counter variable for messages in list */
    H5SM_list_t *ret_value=NULL;

    FUNC_ENTER_NOAPI(H5SM_load_list, NULL)

    HDassert(header);

    /* Allocate space for the SOHM list data structure and initialize list JAMES don't need to initialize all of list */
    if(NULL == (list = H5FL_MALLOC(H5SM_list_t)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
    HDmemset(&list->cache_info, 0, sizeof(H5AC_info_t));

    /* Allocate list in memory as an array*/
    if((list->messages = H5FL_ARR_MALLOC(H5SM_sohm_t, header->list_to_btree)) == NULL)
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "file allocation failed for SOHM list")

    list->header = header;

    /* Compute the size of the SOHM list on disk */
    size = H5SM_LIST_SIZE(f, header->num_messages);

    /* Allocate temporary buffer */
    /* JAMES: is BLK_MALLOC somehow better for this? */
    if(NULL == (buf = HDmalloc(size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    /* Read list from disk */
    if(H5F_block_read(f, H5FD_MEM_SOHM_INDEX, addr, size, dxpl_id, buf) < 0)
	HGOTO_ERROR(H5E_SOHM, H5E_READERROR, NULL, "can't read SOHM list")
    p = buf;

    /* Check magic number */
    if(HDmemcmp(p, H5SM_LIST_MAGIC, (size_t)H5SM_LIST_SIZEOF_MAGIC))
	HGOTO_ERROR(H5E_SOHM, H5E_CANTLOAD, NULL, "bad SOHM list signature");
    p += H5SM_LIST_SIZEOF_MAGIC;

    /* Check version JAMES: should be in master table, not list */
    if (H5SM_LIST_VERSION != *p++)
        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "wrong shared message list version number")

    /* Read messages into the list array */
    for(x=0; x<header->num_messages; x++)
    {
        UINT32DECODE(p, list->messages[x].hash);  /* Read the hash value for this message */
        UINT32DECODE(p, list->messages[x].ref_count);  /* Read the reference count for this message */
        UINT64DECODE(p, list->messages[x].fheap_id); /* Get the heap ID for the message */
    }

    /* Read in checksum */
    UINT32DECODE(p, stored_chksum);

    /* Sanity check */
    HDassert((size_t)(p - buf) == size);


    /* Compute checksum on entire header */
    computed_chksum = H5_checksum_metadata(buf, (size - H5SM_SIZEOF_CHECKSUM), 0);

    /* Verify checksum */
    if(stored_chksum != computed_chksum)
        HGOTO_ERROR(H5E_SOHM, H5E_BADVALUE, NULL, "incorrect metadata checksum for shared message list");


    /* Initialize the rest of the array */
    for(x=header->num_messages; x<header->list_to_btree; x++)
    {
        list->messages[x].fheap_id = 0; /* JAMES: would making this one operation make it faster? */
        list->messages[x].ref_count = 0;
        list->messages[x].hash = H5O_HASH_UNDEF;
    }

    ret_value = list;
done:
    if(buf)
        HDfree(buf);

    if(ret_value == NULL) {
        if(list) {
            if(list->messages) {
                H5FL_ARR_FREE(H5SM_sohm_t, list->messages);
            }
            H5FL_FREE(H5SM_list_t, list);
        }
    }
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5SM_load_list */


/*-------------------------------------------------------------------------
 * Function:	H5SM_clear_list
 *
 * Purpose:	Marks a list as not dirty.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_clear_list(H5F_t *f, H5SM_list_t *list, hbool_t destroy)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT(H5SM_clear_list)

    /*
     * Check arguments.
     */
    HDassert(list);

    /* Reset the dirty flag.  */
    list->cache_info.is_dirty = FALSE;

    if(destroy)
        if(H5SM_dest_list(f, list) < 0)
	    HGOTO_ERROR(H5E_SOHM, H5E_CANTFREE, FAIL, "unable to destroy SOHM list")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end of H5SM_clear_list */


/*-------------------------------------------------------------------------
 * Function:	H5SM_dest_list
 *
 * Purpose:	Frees all memory used by the list.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_dest_list(H5F_t UNUSED *f, H5SM_list_t* list)
{
    FUNC_ENTER_NOAPI_NOFUNC(H5SM_dest_list)

    HDassert(list);
    HDassert(list->messages);

    H5FL_ARR_FREE(H5SM_sohm_t, list->messages);

    H5FL_FREE(H5SM_list_t, list);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5SM_dest_list */


/* JAMES: should this number be constant, or should it increase and decrease as
 * messages are added and removed? */
/*-------------------------------------------------------------------------
 * Function:	H5SM_list_size
 *
 * Purpose:	Gets the size of a list on disk.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	James Laird
 *		November 6, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5SM_list_size(const H5F_t UNUSED *f, const H5SM_list_t *list, size_t *size_ptr)
{
    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_list_size)

    /* check arguments */
    HDassert(f);
    HDassert(list);
    HDassert(list->header);
    HDassert(size_ptr);

    /* Set size value */
    *size_ptr = H5SM_LIST_SIZE(f, list->header->list_to_btree); /* JAMES: might want to have variable-sized lists */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5SM_list_size */