aboutsummaryrefslogtreecommitdiffstats
path: root/buckets/allocator.c
blob: 108167e016caf1ba13909e063e88daa26a852201 (plain) (blame)
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
/* Copyright 2002-2004 Justin Erenkrantz and Greg Stein
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdlib.h>

#include <apr_pools.h>

#include "serf.h"
#include "serf_bucket_util.h"


typedef struct node_header_t {
    apr_size_t size;
    union {
        struct node_header_t *next;      /* if size == 0 (freed/inactive) */
        /* no data                          if size == STANDARD_NODE_SIZE */
        apr_memnode_t *memnode;          /* if size > STANDARD_NODE_SIZE */
    } u;
} node_header_t;

/* The size of a node_header_t, properly aligned. Note that (normally)
 * this macro will round the size to a multiple of 8 bytes. Keep this in
 * mind when altering the node_header_t structure. Also, keep in mind that
 * node_header_t is an overhead for every allocation performed through
 * the serf_bucket_mem_alloc() function.
 */
#define SIZEOF_NODE_HEADER_T  APR_ALIGN_DEFAULT(sizeof(node_header_t))


/* STANDARD_NODE_SIZE is manually set to an allocation size that will
 * capture most allocators performed via this API. It must be "large
 * enough" to avoid lots of spillage to allocating directly from the
 * apr_allocator associated with the bucket allocator. The apr_allocator
 * has a minimum size of 8k, which can be expensive if you missed the
 * STANDARD_NODE_SIZE by just a few bytes.
 */
/* ### we should define some rules or ways to determine how to derive
 * ### a "good" value for this. probably log some stats on allocs, then
 * ### analyze them for size "misses". then find the balance point between
 * ### wasted space due to min-size allocator, and wasted-space due to
 * ### size-spill to the 8k minimum.
 */
#define STANDARD_NODE_SIZE 128

/* When allocating a block of memory from the allocator, we should go for
 * an 8k block, minus the overhead that the allocator needs.
 */
#define ALLOC_AMT (8192 - APR_MEMNODE_T_SIZE)

/* Define DEBUG_DOUBLE_FREE if you're interested in debugging double-free
 * calls to serf_bucket_mem_free().
 */
#define DEBUG_DOUBLE_FREE


typedef struct {
    const serf_bucket_t *bucket;
    apr_status_t last;
} read_status_t;

#define TRACK_BUCKET_COUNT 100  /* track N buckets' status */

typedef struct {
    int next_index;    /* info[] is a ring. next bucket goes at this idx. */
    int num_used;

    read_status_t info[TRACK_BUCKET_COUNT];
} track_state_t;


struct serf_bucket_alloc_t {
    apr_pool_t *pool;
    apr_allocator_t *allocator;
    int own_allocator;

    serf_unfreed_func_t unfreed;
    void *unfreed_baton;

    apr_uint32_t num_alloc;

    node_header_t *freelist;    /* free STANDARD_NODE_SIZE blocks */
    apr_memnode_t *blocks;      /* blocks we allocated for subdividing */

    track_state_t *track;
};

/* ==================================================================== */


static apr_status_t allocator_cleanup(void *data)
{
    serf_bucket_alloc_t *allocator = data;

    /* If we allocated anything, give it back. */
    if (allocator->blocks) {
        apr_allocator_free(allocator->allocator, allocator->blocks);
    }

    /* If we allocated our own allocator (?!), destroy it here. */
    if (allocator->own_allocator) {
        apr_allocator_destroy(allocator->allocator);
    }

    return APR_SUCCESS;
}

serf_bucket_alloc_t *serf_bucket_allocator_create(
    apr_pool_t *pool,
    serf_unfreed_func_t unfreed,
    void *unfreed_baton)
{
    serf_bucket_alloc_t *allocator = apr_pcalloc(pool, sizeof(*allocator));

    allocator->pool = pool;
    allocator->allocator = apr_pool_allocator_get(pool);
    if (allocator->allocator == NULL) {
        /* This most likely means pools are running in debug mode, create our
         * own allocator to deal with memory ourselves */
        apr_allocator_create(&allocator->allocator);
        allocator->own_allocator = 1;
    }
    allocator->unfreed = unfreed;
    allocator->unfreed_baton = unfreed_baton;

#ifdef SERF_DEBUG_BUCKET_USE
    {
        track_state_t *track;

        track = allocator->track = apr_palloc(pool, sizeof(*allocator->track));
        track->next_index = 0;
        track->num_used = 0;
    }
#endif

    /* NOTE: On a fork/exec, the child won't bother cleaning up memory.
             This is just fine... the memory will go away at exec.

       NOTE: If the child will NOT perform an exec, then the parent or
             the child will need to decide who to clean up any
             outstanding connection/buckets (as appropriate).  */
    apr_pool_cleanup_register(pool, allocator,
                              allocator_cleanup, apr_pool_cleanup_null);

    return allocator;
}

apr_pool_t *serf_bucket_allocator_get_pool(
    const serf_bucket_alloc_t *allocator)
{
    return allocator->pool;
}


void *serf_bucket_mem_alloc(
    serf_bucket_alloc_t *allocator,
    apr_size_t size)
{
    node_header_t *node;

    ++allocator->num_alloc;

    size += SIZEOF_NODE_HEADER_T;
    if (size <= STANDARD_NODE_SIZE) {
        if (allocator->freelist) {
            /* just pull a node off our freelist */
            node = allocator->freelist;
            allocator->freelist = node->u.next;
#ifdef DEBUG_DOUBLE_FREE
            /* When we free an item, we set its size to zero. Thus, when
             * we return it to the caller, we must ensure the size is set
             * properly.
             */
            node->size = STANDARD_NODE_SIZE;
#endif
        }
        else {
            apr_memnode_t *active = allocator->blocks;

            if (active == NULL
                || active->first_avail + STANDARD_NODE_SIZE >= active->endp) {
                apr_memnode_t *head = allocator->blocks;

                /* ran out of room. grab another block. */
                active = apr_allocator_alloc(allocator->allocator, ALLOC_AMT);

                /* System couldn't provide us with memory. */
                if (active == NULL)
                    return NULL;

                /* link the block into our tracking list */
                allocator->blocks = active;
                active->next = head;
            }

            node = (node_header_t *)active->first_avail;
            node->size = STANDARD_NODE_SIZE;
            active->first_avail += STANDARD_NODE_SIZE;
        }
    }
    else {
        apr_memnode_t *memnode = apr_allocator_alloc(allocator->allocator,
                                                     size);

        if (memnode == NULL)
            return NULL;

        node = (node_header_t *)memnode->first_avail;
        node->u.memnode = memnode;
        node->size = size;
    }

    return ((char *)node) + SIZEOF_NODE_HEADER_T;
}


void *serf_bucket_mem_calloc(
    serf_bucket_alloc_t *allocator,
    apr_size_t size)
{
    void *mem;
    mem = serf_bucket_mem_alloc(allocator, size);
    if (mem == NULL)
        return NULL;
    memset(mem, 0, size);
    return mem;
}


void serf_bucket_mem_free(
    serf_bucket_alloc_t *allocator,
    void *block)
{
    node_header_t *node;

    --allocator->num_alloc;

    node = (node_header_t *)((char *)block - SIZEOF_NODE_HEADER_T);

    if (node->size == STANDARD_NODE_SIZE) {
        /* put the node onto our free list */
        node->u.next = allocator->freelist;
        allocator->freelist = node;

#ifdef DEBUG_DOUBLE_FREE
        /* note that this thing was freed. */
        node->size = 0;
    }
    else if (node->size == 0) {
        /* damn thing was freed already. */
        abort();
#endif
    }
    else {
#ifdef DEBUG_DOUBLE_FREE
        /* note that this thing was freed. */
        node->size = 0;
#endif

        /* now free it */
        apr_allocator_free(allocator->allocator, node->u.memnode);
    }
}


/* ==================================================================== */


#ifdef SERF_DEBUG_BUCKET_USE

static read_status_t *find_read_status(
    track_state_t *track,
    const serf_bucket_t *bucket,
    int create_rs)
{
    read_status_t *rs;

    if (track->num_used) {
        int count = track->num_used;
        int idx = track->next_index;

        /* Search backwards. In all likelihood, the bucket which just got
         * read was read very recently.
         */
        while (count-- > 0) {
            if (!idx--) {
                /* assert: track->num_used == TRACK_BUCKET_COUNT */
                idx = track->num_used - 1;
            }
            if ((rs = &track->info[idx])->bucket == bucket) {
                return rs;
            }
        }
    }

    /* Only create a new read_status_t when asked. */
    if (!create_rs)
        return NULL;

    if (track->num_used < TRACK_BUCKET_COUNT) {
        /* We're still filling up the ring. */
        ++track->num_used;
    }

    rs = &track->info[track->next_index];
    rs->bucket = bucket;
    rs->last = APR_SUCCESS;     /* ### the right initial value? */

    if (++track->next_index == TRACK_BUCKET_COUNT)
        track->next_index = 0;

    return rs;
}

#endif /* SERF_DEBUG_BUCKET_USE */


apr_status_t serf_debug__record_read(
    const serf_bucket_t *bucket,
    apr_status_t status)
{
#ifndef SERF_DEBUG_BUCKET_USE
    return status;
#else

    track_state_t *track = bucket->allocator->track;
    read_status_t *rs = find_read_status(track, bucket, 1);

    /* Validate that the previous status value allowed for another read. */
    if (APR_STATUS_IS_EAGAIN(rs->last) /* ### or APR_EOF? */) {
        /* Somebody read when they weren't supposed to. Bail. */
        abort();
    }

    /* Save the current status for later. */
    rs->last = status;

    return status;
#endif
}


void serf_debug__entered_loop(serf_bucket_alloc_t *allocator)
{
#ifdef SERF_DEBUG_BUCKET_USE

    track_state_t *track = allocator->track;
    read_status_t *rs = &track->info[0];

    for ( ; track->num_used; --track->num_used, ++rs ) {
        if (rs->last == APR_SUCCESS) {
            /* Somebody should have read this bucket again. */
            abort();
        }

        /* ### other status values? */
    }

    /* num_used was reset. also need to reset the next index. */
    track->next_index = 0;

#endif
}


void serf_debug__closed_conn(serf_bucket_alloc_t *allocator)
{
#ifdef SERF_DEBUG_BUCKET_USE

    /* Just reset the number used so that we don't examine the info[] */
    allocator->track->num_used = 0;
    allocator->track->next_index = 0;

#endif
}


void serf_debug__bucket_destroy(const serf_bucket_t *bucket)
{
#ifdef SERF_DEBUG_BUCKET_USE

    track_state_t *track = bucket->allocator->track;
    read_status_t *rs = find_read_status(track, bucket, 0);

    if (rs != NULL && rs->last != APR_EOF) {
        /* The bucket was destroyed before it was read to completion. */

        /* Special exception for socket buckets. If a connection remains
         * open, they are not read to completion.
         */
        if (SERF_BUCKET_IS_SOCKET(bucket))
            return;

        /* Ditto for SSL Decrypt buckets. */
        if (SERF_BUCKET_IS_SSL_DECRYPT(bucket))
            return;

        /* Ditto for SSL Encrypt buckets. */
        if (SERF_BUCKET_IS_SSL_ENCRYPT(bucket))
            return;

        /* Ditto for barrier buckets. */
        if (SERF_BUCKET_IS_BARRIER(bucket))
            return;


        abort();
    }

#endif
}


void serf_debug__bucket_alloc_check(
    serf_bucket_alloc_t *allocator)
{
#ifdef SERF_DEBUG_BUCKET_USE
    if (allocator->num_alloc != 0) {
        abort();
    }
#endif
}