2 * cache-memcache.c: memcached caching for Subversion
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13 * http://www.apache.org/licenses/LICENSE-2.0
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19 * specific language governing permissions and limitations
21 * ====================================================================
26 #include "svn_pools.h"
27 #include "svn_base64.h"
30 #include "svn_private_config.h"
31 #include "private/svn_cache.h"
32 #include "private/svn_dep_compat.h"
36 #ifdef SVN_HAVE_MEMCACHE
38 #include <apr_memcache.h>
40 /* A note on thread safety:
42 The apr_memcache_t object does its own mutex handling, and nothing
43 else in memcache_t is ever modified, so this implementation should
47 /* The (internal) cache object. */
48 typedef struct memcache_t {
49 /* The memcached server set we're using. */
50 apr_memcache_t *memcache;
52 /* A prefix used to differentiate our data from any other data in
53 * the memcached (URI-encoded). */
56 /* The size of the key: either a fixed number of bytes or
57 * APR_HASH_KEY_STRING. */
61 /* Used to marshal values in and out of the cache. */
62 svn_cache__serialize_func_t serialize_func;
63 svn_cache__deserialize_func_t deserialize_func;
66 /* The wrapper around apr_memcache_t. */
67 struct svn_memcache_t {
72 /* The memcached protocol says the maximum key length is 250. Let's
73 just say 249, to be safe. */
74 #define MAX_MEMCACHED_KEY_LEN 249
75 #define MEMCACHED_KEY_UNHASHED_LEN (MAX_MEMCACHED_KEY_LEN - \
76 2 * APR_MD5_DIGESTSIZE)
79 /* Set *MC_KEY to a memcache key for the given key KEY for CACHE, allocated
82 build_key(const char **mc_key,
87 const char *encoded_suffix;
89 apr_size_t long_key_len;
91 if (cache->klen == APR_HASH_KEY_STRING)
92 encoded_suffix = svn_path_uri_encode(raw_key, pool);
95 const svn_string_t *raw = svn_string_ncreate(raw_key, cache->klen, pool);
96 const svn_string_t *encoded = svn_base64_encode_string2(raw, FALSE,
98 encoded_suffix = encoded->data;
101 long_key = apr_pstrcat(pool, "SVN:", cache->prefix, ":", encoded_suffix,
103 long_key_len = strlen(long_key);
105 /* We don't want to have a key that's too big. If it was going to
106 be too big, we MD5 the entire string, then replace the last bit
107 with the checksum. Note that APR_MD5_DIGESTSIZE is for the pure
108 binary digest; we have to double that when we convert to hex.
110 Every key we use will either be at most
111 MEMCACHED_KEY_UNHASHED_LEN bytes long, or be exactly
112 MAX_MEMCACHED_KEY_LEN bytes long. */
113 if (long_key_len > MEMCACHED_KEY_UNHASHED_LEN)
115 svn_checksum_t *checksum;
116 SVN_ERR(svn_checksum(&checksum, svn_checksum_md5, long_key, long_key_len,
119 long_key = apr_pstrcat(pool,
120 apr_pstrmemdup(pool, long_key,
121 MEMCACHED_KEY_UNHASHED_LEN),
122 svn_checksum_to_cstring_display(checksum, pool),
130 /* Core functionality of our getter functions: fetch DATA from the memcached
131 * given by CACHE_VOID and identified by KEY. Indicate success in FOUND and
132 * use a tempoary sub-pool of POOL for allocations.
135 memcache_internal_get(char **data,
137 svn_boolean_t *found,
142 memcache_t *cache = cache_void;
143 apr_status_t apr_err;
153 subpool = svn_pool_create(pool);
154 SVN_ERR(build_key(&mc_key, cache, key, subpool));
156 apr_err = apr_memcache_getp(cache->memcache,
161 NULL /* ignore flags */);
162 if (apr_err == APR_NOTFOUND)
165 svn_pool_destroy(subpool);
168 else if (apr_err != APR_SUCCESS || !*data)
169 return svn_error_wrap_apr(apr_err,
170 _("Unknown memcached error while reading"));
174 svn_pool_destroy(subpool);
180 memcache_get(void **value_p,
181 svn_boolean_t *found,
184 apr_pool_t *result_pool)
186 memcache_t *cache = cache_void;
189 SVN_ERR(memcache_internal_get(&data,
196 /* If we found it, de-serialize it. */
199 if (cache->deserialize_func)
201 SVN_ERR((cache->deserialize_func)(value_p, data, data_len,
206 svn_stringbuf_t *value = svn_stringbuf_create_empty(result_pool);
208 value->blocksize = data_len;
209 value->len = data_len - 1; /* account for trailing NUL */
217 /* Implement vtable.has_key in terms of the getter.
220 memcache_has_key(svn_boolean_t *found,
223 apr_pool_t *scratch_pool)
227 SVN_ERR(memcache_internal_get(&data,
237 /* Core functionality of our setter functions: store LENGH bytes of DATA
238 * to be identified by KEY in the memcached given by CACHE_VOID. Use POOL
239 * for temporary allocations.
242 memcache_internal_set(void *cache_void,
246 apr_pool_t *scratch_pool)
248 memcache_t *cache = cache_void;
250 apr_status_t apr_err;
252 SVN_ERR(build_key(&mc_key, cache, key, scratch_pool));
253 apr_err = apr_memcache_set(cache->memcache, mc_key, (char *)data, len, 0, 0);
255 /* ### Maybe write failures should be ignored (but logged)? */
256 if (apr_err != APR_SUCCESS)
257 return svn_error_wrap_apr(apr_err,
258 _("Unknown memcached error while writing"));
265 memcache_set(void *cache_void,
268 apr_pool_t *scratch_pool)
270 memcache_t *cache = cache_void;
271 apr_pool_t *subpool = svn_pool_create(scratch_pool);
279 if (cache->serialize_func)
281 SVN_ERR((cache->serialize_func)(&data, &data_len, value, subpool));
285 svn_stringbuf_t *value_str = value;
286 data = value_str->data;
287 data_len = value_str->len + 1; /* copy trailing NUL */
290 err = memcache_internal_set(cache_void, key, data, data_len, subpool);
292 svn_pool_destroy(subpool);
297 memcache_get_partial(void **value_p,
298 svn_boolean_t *found,
301 svn_cache__partial_getter_func_t func,
303 apr_pool_t *result_pool)
305 svn_error_t *err = SVN_NO_ERROR;
309 SVN_ERR(memcache_internal_get(&data,
316 /* If we found it, de-serialize it. */
318 ? func(value_p, data, size, baton, result_pool)
324 memcache_set_partial(void *cache_void,
326 svn_cache__partial_setter_func_t func,
328 apr_pool_t *scratch_pool)
330 svn_error_t *err = SVN_NO_ERROR;
334 svn_boolean_t found = FALSE;
336 apr_pool_t *subpool = svn_pool_create(scratch_pool);
337 SVN_ERR(memcache_internal_get((char **)&data,
344 /* If we found it, modify it and write it back to cache */
347 SVN_ERR(func(&data, &size, baton, subpool));
348 err = memcache_internal_set(cache_void, key, data, size, subpool);
351 svn_pool_destroy(subpool);
357 memcache_iter(svn_boolean_t *completed,
359 svn_iter_apr_hash_cb_t user_cb,
361 apr_pool_t *scratch_pool)
363 return svn_error_create(SVN_ERR_UNSUPPORTED_FEATURE, NULL,
364 _("Can't iterate a memcached cache"));
368 memcache_is_cachable(void *unused, apr_size_t size)
372 /* The memcached cutoff seems to be a bit (header length?) under a megabyte.
373 * We round down a little to be safe.
375 return size < 1000000;
379 memcache_get_info(void *cache_void,
380 svn_cache__info_t *info,
382 apr_pool_t *result_pool)
384 memcache_t *cache = cache_void;
386 info->id = apr_pstrdup(result_pool, cache->prefix);
388 /* we don't have any memory allocation info */
393 static svn_cache__vtable_t memcache_vtable = {
398 memcache_is_cachable,
399 memcache_get_partial,
400 memcache_set_partial,
405 svn_cache__create_memcache(svn_cache__t **cache_p,
406 svn_memcache_t *memcache,
407 svn_cache__serialize_func_t serialize_func,
408 svn_cache__deserialize_func_t deserialize_func,
413 svn_cache__t *wrapper = apr_pcalloc(pool, sizeof(*wrapper));
414 memcache_t *cache = apr_pcalloc(pool, sizeof(*cache));
416 cache->serialize_func = serialize_func;
417 cache->deserialize_func = deserialize_func;
419 cache->prefix = svn_path_uri_encode(prefix, pool);
420 cache->memcache = memcache->c;
422 wrapper->vtable = &memcache_vtable;
423 wrapper->cache_internal = cache;
424 wrapper->error_handler = 0;
425 wrapper->error_baton = 0;
426 wrapper->pretend_empty = !!getenv("SVN_X_DOES_NOT_MARK_THE_SPOT");
433 /*** Creating apr_memcache_t from svn_config_t. ***/
435 /* Baton for add_memcache_server. */
437 apr_memcache_t *memcache;
438 apr_pool_t *memcache_pool;
442 /* Implements svn_config_enumerator2_t. */
444 add_memcache_server(const char *name,
449 struct ams_baton *b = baton;
452 apr_status_t apr_err;
453 apr_memcache_server_t *server;
455 apr_err = apr_parse_addr_port(&host, &scope, &port,
457 if (apr_err != APR_SUCCESS)
459 b->err = svn_error_wrap_apr(apr_err,
460 _("Error parsing memcache server '%s'"),
467 b->err = svn_error_createf(SVN_ERR_BAD_SERVER_SPECIFICATION, NULL,
468 _("Scope not allowed in memcache server "
475 b->err = svn_error_createf(SVN_ERR_BAD_SERVER_SPECIFICATION, NULL,
476 _("Must specify host and port for memcache "
482 /* Note: the four numbers here are only relevant when an
483 apr_memcache_t is being shared by multiple threads. */
484 apr_err = apr_memcache_server_create(b->memcache_pool,
487 0, /* min connections */
488 5, /* soft max connections */
489 10, /* hard max connections */
490 /* time to live (in microseconds) */
491 apr_time_from_sec(50),
493 if (apr_err != APR_SUCCESS)
495 b->err = svn_error_wrap_apr(apr_err,
496 _("Unknown error creating memcache server"));
500 apr_err = apr_memcache_add_server(b->memcache, server);
501 if (apr_err != APR_SUCCESS)
503 b->err = svn_error_wrap_apr(apr_err,
504 _("Unknown error adding server to memcache"));
511 #else /* ! SVN_HAVE_MEMCACHE */
513 /* Stubs for no apr memcache library. */
515 struct svn_memcache_t {
516 void *unused; /* Let's not have a size-zero struct. */
520 svn_cache__create_memcache(svn_cache__t **cache_p,
521 svn_memcache_t *memcache,
522 svn_cache__serialize_func_t serialize_func,
523 svn_cache__deserialize_func_t deserialize_func,
528 return svn_error_create(SVN_ERR_NO_APR_MEMCACHE, NULL, NULL);
531 #endif /* SVN_HAVE_MEMCACHE */
533 /* Implements svn_config_enumerator2_t. Just used for the
534 entry-counting return value of svn_config_enumerate2. */
536 nop_enumerator(const char *name,
545 svn_cache__make_memcache_from_config(svn_memcache_t **memcache_p,
546 svn_config_t *config,
547 apr_pool_t *result_pool,
548 apr_pool_t *scratch_pool)
551 svn_config_enumerate2(config,
552 SVN_CACHE_CONFIG_CATEGORY_MEMCACHED_SERVERS,
553 nop_enumerator, NULL, scratch_pool);
555 if (server_count == 0)
561 if (server_count > APR_INT16_MAX)
562 return svn_error_create(SVN_ERR_TOO_MANY_MEMCACHED_SERVERS, NULL, NULL);
564 #ifdef SVN_HAVE_MEMCACHE
567 svn_memcache_t *memcache = apr_pcalloc(result_pool, sizeof(*memcache));
568 apr_status_t apr_err = apr_memcache_create(result_pool,
569 (apr_uint16_t)server_count,
572 if (apr_err != APR_SUCCESS)
573 return svn_error_wrap_apr(apr_err,
574 _("Unknown error creating apr_memcache_t"));
576 b.memcache = memcache->c;
577 b.memcache_pool = result_pool;
578 b.err = SVN_NO_ERROR;
579 svn_config_enumerate2(config,
580 SVN_CACHE_CONFIG_CATEGORY_MEMCACHED_SERVERS,
581 add_memcache_server, &b,
587 *memcache_p = memcache;
591 #else /* ! SVN_HAVE_MEMCACHE */
593 return svn_error_create(SVN_ERR_NO_APR_MEMCACHE, NULL, NULL);
595 #endif /* SVN_HAVE_MEMCACHE */