summaryrefslogtreecommitdiff
path: root/content/hlcache.c
blob: dd520c8c63bab50fa36d7c8c5403c459110fb4f2 (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
/*
 * Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \file
 * High-level resource cache (implementation)
 */

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include "content/content.h"
#include "content/hlcache.h"
#include "utils/http.h"
#include "utils/log.h"
#include "utils/messages.h"
#include "utils/url.h"
#include "utils/ring.h"

typedef struct hlcache_entry hlcache_entry;
typedef struct hlcache_retrieval_ctx hlcache_retrieval_ctx;

/** High-level cache retrieval context */
struct hlcache_retrieval_ctx {
	struct hlcache_retrieval_ctx *r_prev; /**< Previous retrieval context in the ring */
	struct hlcache_retrieval_ctx *r_next; /**< Next retrieval context in the ring */
	
	llcache_handle *llcache;	/**< Low-level cache handle */

	hlcache_handle *handle;		/**< High-level handle for object */

	uint32_t flags;			/**< Retrieval flags */

	const content_type *accepted_types;	/**< Accepted types, or NULL */

	hlcache_child_context child;	/**< Child context */	
};

/** High-level cache handle */
struct hlcache_handle {
	hlcache_entry *entry;		/**< Pointer to cache entry */

	hlcache_handle_callback cb;	/**< Client callback */
	void *pw;			/**< Client data */
};

/** Entry in high-level cache */
struct hlcache_entry {
	struct content *content;	/**< Pointer to associated content */

	hlcache_entry *next;		/**< Next sibling */
	hlcache_entry *prev;		/**< Previous sibling */
};

/** List of cached content objects */
static hlcache_entry *hlcache_content_list;

/** Ring of retrieval contexts */
static hlcache_retrieval_ctx *hlcache_retrieval_ctx_ring;

static void hlcache_clean(void);
static nserror hlcache_llcache_callback(llcache_handle *handle,
		const llcache_event *event, void *pw);
static bool hlcache_type_is_acceptable(llcache_handle *llcache, 
		const content_type *accepted_types, 
		content_type *computed_type);
static nserror hlcache_find_content(hlcache_retrieval_ctx *ctx);
static void hlcache_content_callback(struct content *c,
		content_msg msg, union content_msg_data data, void *pw);

/******************************************************************************
 * Public API								      *
 ******************************************************************************/

/* See hlcache.h for documentation */
nserror hlcache_poll(void)
{
	llcache_poll();

	/* Give the cache a clean */
	hlcache_clean();

	return NSERROR_OK;
}

/* See hlcache.h for documentation */
nserror hlcache_handle_retrieve(const char *url, uint32_t flags,
		const char *referer, llcache_post_data *post,
		hlcache_handle_callback cb, void *pw,
		hlcache_child_context *child, 
		const content_type *accepted_types, hlcache_handle **result)
{
	hlcache_retrieval_ctx *ctx;
	nserror error;

	assert(cb != NULL);

	ctx = calloc(1, sizeof(hlcache_retrieval_ctx));
	if (ctx == NULL)
		return NSERROR_NOMEM;

	ctx->handle = calloc(1, sizeof(hlcache_handle));
	if (ctx->handle == NULL) {
		free(ctx);
		return NSERROR_NOMEM;
	}

	if (child != NULL) {
		if (child->charset != NULL) {
			ctx->child.charset = strdup(child->charset);
			if (ctx->child.charset == NULL) {
				free(ctx->handle);
				free(ctx);
				return NSERROR_NOMEM;
			}
		}
		ctx->child.quirks = child->quirks;
	}

	ctx->flags = flags;
	ctx->accepted_types = accepted_types;

	ctx->handle->cb = cb;
	ctx->handle->pw = pw;

	error = llcache_handle_retrieve(url, flags, referer, post, 
			hlcache_llcache_callback, ctx, 
			&ctx->llcache);
	if (error != NSERROR_OK) {
		free((char *) ctx->child.charset);
		free(ctx->handle);
		free(ctx);
		return error;
	}
	
	RING_INSERT(hlcache_retrieval_ctx_ring, ctx);
	
	*result = ctx->handle;

	return NSERROR_OK;
}

/* See hlcache.h for documentation */
nserror hlcache_handle_release(hlcache_handle *handle)
{
	if (handle->entry != NULL) {
		content_remove_user(handle->entry->content, 
				hlcache_content_callback, handle);
	} else {
		RING_ITERATE_START(struct hlcache_retrieval_ctx,
				   hlcache_retrieval_ctx_ring,
				   ictx) {
			if (ictx->handle == handle) {
				/* This is the nascent context for us, 
				 * so abort the fetch */
				llcache_handle_abort(ictx->llcache);
				llcache_handle_release(ictx->llcache);
				/* Remove us from the ring */
				RING_REMOVE(hlcache_retrieval_ctx_ring, ictx);
				/* Throw us away */
				free((char *) ictx->child.charset);
				free(ictx);
				/* And stop */
				RING_ITERATE_STOP(hlcache_retrieval_ctx_ring, 
						ictx);
			}
		} RING_ITERATE_END(hlcache_retrieval_ctx_ring, ictx);
	}

	handle->cb = NULL;
	handle->pw = NULL;

	/** \todo Provide hlcache_poll() to perform cache maintenance */

	return NSERROR_OK;
}

/* See hlcache.h for documentation */
struct content *hlcache_handle_get_content(const hlcache_handle *handle)
{
	assert(handle != NULL);

	if (handle->entry != NULL)
		return handle->entry->content;

	return NULL;
}

/* See hlcache.h for documentation */
nserror hlcache_handle_abort(hlcache_handle *handle)
{
	struct hlcache_entry *entry = handle->entry;
	struct content *c;
	
	if (entry == NULL) {
		/* This handle is not yet associated with a cache entry.
		 * The implication is that the fetch for the handle has
		 * not progressed to the point where the entry can be
		 * created. */
		
		RING_ITERATE_START(struct hlcache_retrieval_ctx,
				   hlcache_retrieval_ctx_ring,
				   ictx) {
			if (ictx->handle == handle) {
				/* This is the nascent context for us, 
				 * so abort the fetch */
				llcache_handle_abort(ictx->llcache);
				llcache_handle_release(ictx->llcache);
				/* Remove us from the ring */
				RING_REMOVE(hlcache_retrieval_ctx_ring, ictx);
				/* Throw us away */
				free((char *) ictx->child.charset);
				free(ictx);
				/* And stop */
				RING_ITERATE_STOP(hlcache_retrieval_ctx_ring, 
						ictx);
			}
		} RING_ITERATE_END(hlcache_retrieval_ctx_ring, ictx);
		
		return NSERROR_OK;
	}

	c = entry->content;
	
	if (content_count_users(c) > 1) {
		/* We are not the only user of 'c' so clone it. */
		struct content *clone = content_clone(c);
		
		if (clone == NULL)
			return NSERROR_NOMEM;
		
		entry = calloc(sizeof(struct hlcache_entry), 1);
		
		if (entry == NULL) {
			content_destroy(clone);
			return NSERROR_NOMEM;
		}
		
		if (content_add_user(clone, 
				hlcache_content_callback, handle) == false) {
			content_destroy(clone);
			free(entry);
			return NSERROR_NOMEM;
		}
		
		content_remove_user(c, hlcache_content_callback, handle);
		
		entry->content = clone;
		handle->entry = entry;
		entry->prev = NULL;
		entry->next = hlcache_content_list;
		if (hlcache_content_list != NULL)
			hlcache_content_list->prev = entry;
		hlcache_content_list = entry;
		
		c = clone;
	}
	
	return content_abort(c);
}

/******************************************************************************
 * High-level cache internals						      *
 ******************************************************************************/

/**
 * Attempt to clean the cache
 */
void hlcache_clean(void)
{
	hlcache_entry *entry, *next;

	for (entry = hlcache_content_list; entry != NULL; entry = next) {
		next = entry->next;

		if (entry->content == NULL)
			continue;

		if (content_count_users(entry->content) != 0)
			continue;

		/** \todo This is over-zealous: all unused contents will be 
		 * immediately destroyed. Ideally, we want to purge all 
		 * unused contents that are using stale source data, and 
		 * enough fresh contents such that the cache fits in the 
		 * configured cache size limit.
		 */

		/* Remove entry from cache */
		if (entry->prev == NULL)
			hlcache_content_list = entry->next;
		else
			entry->prev->next = entry->next;

		if (entry->next != NULL)
			entry->next->prev = entry->prev;

		/* Destroy content */
		content_destroy(entry->content);

		/* Destroy entry */
		free(entry);
	}
}

/**
 * Handler for low-level cache events
 *
 * \param handle  Handle for which event is issued
 * \param event	  Event data
 * \param pw	  Pointer to client-specific data
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror hlcache_llcache_callback(llcache_handle *handle,
		const llcache_event *event, void *pw)
{
	hlcache_retrieval_ctx *ctx = pw;
	nserror error;

	assert(ctx->llcache == handle);

	switch (event->type) {
	case LLCACHE_EVENT_HAD_HEADERS:
	{
		content_type type = CONTENT_UNKNOWN;
		
		/* Unlink the context to prevent recursion */
		RING_REMOVE(hlcache_retrieval_ctx_ring, ctx);
		
		if (hlcache_type_is_acceptable(handle, 
				ctx->accepted_types, &type)) {
			error = hlcache_find_content(ctx);
			if (error != NSERROR_OK) {
				free((char *) ctx->child.charset);
				free(ctx);
				return error;
			}
		} else if (type == CONTENT_OTHER && 
				ctx->flags & HLCACHE_RETRIEVE_MAY_DOWNLOAD) {
			/* Unknown type, and we can download, so convert */
			llcache_handle_force_stream(handle);

			if (ctx->handle->cb != NULL) {
				hlcache_event hlevent;

				hlevent.type = CONTENT_MSG_DOWNLOAD;
				hlevent.data.download = handle;

				ctx->handle->cb(ctx->handle, &hlevent,
						ctx->handle->pw);
			}
		} else {
			/* Unacceptable type: abort fetch and report error */
			llcache_handle_abort(handle);
			llcache_handle_release(handle);

			if (ctx->handle->cb != NULL) {
				hlcache_event hlevent;

				hlevent.type = CONTENT_MSG_ERROR;
				hlevent.data.error = messages_get("BadType");

				ctx->handle->cb(ctx->handle, &hlevent, 
						ctx->handle->pw);
			}
		}

		/* No longer require retrieval context */
		free((char *) ctx->child.charset);
		free(ctx);
	}
		break;
	case LLCACHE_EVENT_HAD_DATA:
		/* fall through */
	case LLCACHE_EVENT_DONE:
		/* should never happen: the handler must be changed */
		break;
	case LLCACHE_EVENT_ERROR:
		if (ctx->handle->cb != NULL) {
			hlcache_event hlevent;

			hlevent.type = CONTENT_MSG_ERROR;
			hlevent.data.error = event->data.msg;

			ctx->handle->cb(ctx->handle, &hlevent, ctx->handle->pw);
		}	
		break;
	case LLCACHE_EVENT_PROGRESS:
		break;
	}

	return NSERROR_OK;
}

/**
 * Determine if the type of a low-level cache object is acceptable
 *
 * \param llcache	  Low-level cache object to consider
 * \param accepted_types  Array of acceptable types, or NULL for any
 * \param computed_type	  Pointer to location to receive computed type of object
 * \return True if the type is acceptable, false otherwise
 */
bool hlcache_type_is_acceptable(llcache_handle *llcache, 
		const content_type *accepted_types, content_type *computed_type)
{
	const char *content_type_header;
	char *mime_type;
	http_parameter *params;
	content_type type;
	nserror error;
	bool acceptable;

	content_type_header = 
			llcache_handle_get_header(llcache, "Content-Type");
	if (content_type_header == NULL)
		content_type_header = "text/plain";

	error = http_parse_content_type(content_type_header, &mime_type, 
			&params);
	if (error != NSERROR_OK)
		return false;

	type = content_lookup(mime_type);

	free(mime_type);
	http_parameter_list_destroy(params);

	if (accepted_types == NULL) {
		acceptable = type != CONTENT_OTHER;
	} else {
		while (*accepted_types != CONTENT_UNKNOWN) {
			if (*accepted_types == type)
				break;

			accepted_types++;
		}

		acceptable = *accepted_types == type;
	}

	*computed_type = type;

	return acceptable;
}

/**
 * Find a content for the high-level cache handle
 *
 * \param ctx	High-level cache retrieval context
 * \return NSERROR_OK on success, appropriate error otherwise
 *
 * \pre handle::state == HLCACHE_HANDLE_NEW
 * \pre Headers must have been received for associated low-level handle
 * \post Low-level handle is either released, or associated with new content
 * \post High-level handle is registered with content
 */
nserror hlcache_find_content(hlcache_retrieval_ctx *ctx)
{
	hlcache_entry *entry;
	hlcache_event event;

	/* Search list of cached contents for a suitable one */
	for (entry = hlcache_content_list; entry != NULL; entry = entry->next) {
		hlcache_handle entry_handle = { entry, NULL, NULL };
		const llcache_handle *entry_llcache;

		if (entry->content == NULL)
			continue;

		/* Ignore contents in the error state */
		if (content_get_status(&entry_handle) == CONTENT_STATUS_ERROR)
			continue;

		/* Ensure that content is shareable */
		if (content_is_shareable(entry->content) == false)
			continue;

		/* Ensure that quirks mode is acceptable */
		if (content_matches_quirks(entry->content, 
				ctx->child.quirks) == false)
			continue;

		/* Ensure that content uses same low-level object as 
		 * low-level handle */
		entry_llcache = content_get_llcache_handle(entry->content);

		if (llcache_handle_references_same_object(entry_llcache, 
				ctx->llcache))
			break;
	}

	if (entry == NULL) {
		/* No existing entry, so need to create one */
		entry = malloc(sizeof(hlcache_entry));
		if (entry == NULL)
			return NSERROR_NOMEM;

		/* Create content using llhandle */
		entry->content = content_create(ctx->llcache, 
				ctx->child.charset, ctx->child.quirks);
		if (entry->content == NULL) {
			free(entry);
			return NSERROR_NOMEM;
		}

		/* Insert into cache */
		entry->prev = NULL;
		entry->next = hlcache_content_list;
		if (hlcache_content_list != NULL)
			hlcache_content_list->prev = entry;
		hlcache_content_list = entry;
	} else {
		/* Found a suitable content: no longer need low-level handle */
		llcache_handle_release(ctx->llcache);	
	}

	/* Associate handle with content */
	if (content_add_user(entry->content, 
			hlcache_content_callback, ctx->handle) == false)
		return NSERROR_NOMEM;

	/* Associate cache entry with handle */
	ctx->handle->entry = entry;

	/* Catch handle up with state of content */
	if (ctx->handle->cb != NULL) {
		content_status status = content_get_status(ctx->handle);

		if (status == CONTENT_STATUS_LOADING) {
			event.type = CONTENT_MSG_LOADING;
			ctx->handle->cb(ctx->handle, &event, ctx->handle->pw);
		} else if (status == CONTENT_STATUS_READY) {
			event.type = CONTENT_MSG_LOADING;
			ctx->handle->cb(ctx->handle, &event, ctx->handle->pw);

			if (ctx->handle->cb != NULL) {
				event.type = CONTENT_MSG_READY;
				ctx->handle->cb(ctx->handle, &event, 
						ctx->handle->pw);
			}
		} else if (status == CONTENT_STATUS_DONE) {
			event.type = CONTENT_MSG_LOADING;
			ctx->handle->cb(ctx->handle, &event, ctx->handle->pw);

			if (ctx->handle->cb != NULL) {
				event.type = CONTENT_MSG_READY;
				ctx->handle->cb(ctx->handle, &event, 
						ctx->handle->pw);
			}

			if (ctx->handle->cb != NULL) {
				event.type = CONTENT_MSG_DONE;
				ctx->handle->cb(ctx->handle, &event, 
						ctx->handle->pw);
			}
		}
	}

	return NSERROR_OK;
}

/**
 * Veneer between content callback API and hlcache callback API
 *
 * \param c	Content to emit message for
 * \param msg	Message to emit
 * \param data	Data for message
 * \param pw	Pointer to private data (hlcache_handle)
 */
void hlcache_content_callback(struct content *c, content_msg msg, 
		union content_msg_data data, void *pw)
{
	hlcache_handle *handle = pw;
	hlcache_event event;
	nserror error = NSERROR_OK;

	event.type = msg;
	event.data = data;

	if (handle->cb != NULL)
		error = handle->cb(handle, &event, handle->pw);

	if (error != NSERROR_OK)
		LOG(("Error in callback: %d", error));
}