diff options
Diffstat (limited to 'libglusterfs/src/throttle-tbf.c')
| -rw-r--r-- | libglusterfs/src/throttle-tbf.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/libglusterfs/src/throttle-tbf.c b/libglusterfs/src/throttle-tbf.c new file mode 100644 index 00000000000..16630a243c2 --- /dev/null +++ b/libglusterfs/src/throttle-tbf.c @@ -0,0 +1,291 @@ +/* + Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com> + This file is part of GlusterFS. + + This file is licensed to you under your choice of the GNU Lesser + General Public License, version 3 or any later version (LGPLv3 or + later), or the GNU General Public License, version 2 (GPLv2), in all + cases as published by the Free Software Foundation. +*/ + +/** + * + * Basic token bucket implementation for rate limiting. As of now interfaces + * to throttle disk read request, directory entry scan and hash calculation + * are available. To throttle a particular request (operation), the call needs + * to be wrapped in-between throttling APIs, for e.g. + * + * TBF_THROTTLE_BEGIN (...); <-- induces "delays" if required + * { + * call (...); + * } + * TBF_THROTTLE_END (...); <-- not used atm, maybe needed later + * + */ + +#include "mem-pool.h" +#include "throttle-tbf.h" + +typedef struct tbf_throttle { + char done; + + pthread_mutex_t mutex; + pthread_cond_t cond; + + unsigned long tokens; + + struct list_head list; +} tbf_throttle_t; + +static tbf_throttle_t * +tbf_init_throttle (unsigned long tokens_required) +{ + tbf_throttle_t *throttle = NULL; + + throttle = GF_CALLOC (1, sizeof (*throttle), + gf_common_mt_tbf_throttle_t); + if (!throttle) + return NULL; + + throttle->done = 0; + throttle->tokens = tokens_required; + INIT_LIST_HEAD (&throttle->list); + + (void) pthread_mutex_init (&throttle->mutex, NULL); + (void) pthread_cond_init (&throttle->cond, NULL); + + return throttle; +} + +void +_tbf_dispatch_queued (tbf_bucket_t *bucket) +{ + gf_boolean_t xcont = _gf_false; + tbf_throttle_t *tmp = NULL; + tbf_throttle_t *throttle = NULL; + + list_for_each_entry_safe (throttle, tmp, &bucket->queued, list) { + + pthread_mutex_lock (&throttle->mutex); + { + if (bucket->tokens < throttle->tokens) { + xcont = _gf_true; + goto unblock; + } + + /* this request can now be serviced */ + throttle->done = 1; + list_del_init (&throttle->list); + + bucket->tokens -= throttle->tokens; + pthread_cond_signal (&throttle->cond); + } + unblock: + pthread_mutex_unlock (&throttle->mutex); + if (xcont) + break; + } +} + +void *tbf_tokengenerator (void *arg) +{ + unsigned long tokenrate = 0; + unsigned long maxtokens = 0; + unsigned long token_gen_interval = 0; + tbf_bucket_t *bucket = arg; + + tokenrate = bucket->tokenrate; + maxtokens = bucket->maxtokens; + token_gen_interval = bucket->token_gen_interval; + + while (1) { + usleep (token_gen_interval); + + LOCK (&bucket->lock); + { + bucket->tokens += tokenrate; + if (bucket->tokens > maxtokens) + bucket->tokens = maxtokens; + + if (!list_empty (&bucket->queued)) + _tbf_dispatch_queued (bucket); + } + UNLOCK (&bucket->lock); + } + + return NULL; +} + +/** + * There is lazy synchronization between this routine (when invoked + * under tbf_mod() context) and tbf_throttle(). *bucket is + * updated _after_ all the required variables are initialized. + */ +static int32_t +tbf_init_bucket (tbf_t *tbf, tbf_opspec_t *spec) +{ + int ret = 0; + tbf_bucket_t *curr = NULL; + tbf_bucket_t **bucket = NULL; + + GF_ASSERT (spec->op >= TBF_OP_MIN); + GF_ASSERT (spec->op <= TBF_OP_MAX); + + /* no rate? no throttling. */ + if (!spec->rate) + return 0; + + bucket = tbf->bucket + spec->op; + + curr = GF_CALLOC (1, sizeof (*curr), gf_common_mt_tbf_bucket_t); + if (!curr) + goto error_return; + + LOCK_INIT (&curr->lock); + INIT_LIST_HEAD (&curr->queued); + + curr->tokens = 0; + curr->tokenrate = spec->rate; + curr->maxtokens = spec->maxlimit; + curr->token_gen_interval = spec->token_gen_interval; + + ret = gf_thread_create (&curr->tokener, + NULL, tbf_tokengenerator, curr); + if (ret != 0) + goto freemem; + + *bucket = curr; + return 0; + + freemem: + LOCK_DESTROY (&curr->lock); + GF_FREE (curr); + error_return: + return -1; +} + +#define TBF_ALLOC_SIZE \ + (sizeof (tbf_t) + (TBF_OP_MAX * sizeof (tbf_bucket_t))) + +tbf_t * +tbf_init (tbf_opspec_t *tbfspec, unsigned int count) +{ + int32_t i = 0; + int32_t ret = 0; + tbf_t *tbf = NULL; + tbf_opspec_t *opspec = NULL; + + tbf = GF_CALLOC (1, TBF_ALLOC_SIZE, gf_common_mt_tbf_t); + if (!tbf) + goto error_return; + + tbf->bucket = (tbf_bucket_t **) ((char *)tbf + sizeof (*tbf)); + for (i = 0; i < TBF_OP_MAX; i++) { + *(tbf->bucket + i) = NULL; + } + + for (i = 0; i < count; i++) { + opspec = tbfspec + i; + + ret = tbf_init_bucket (tbf, opspec); + if (ret) + break; + } + + if (ret) + goto error_return; + + return tbf; + + error_return: + return NULL; +} + +static void +tbf_mod_bucket (tbf_bucket_t *bucket, tbf_opspec_t *spec) +{ + LOCK (&bucket->lock); + { + bucket->tokens = 0; + bucket->tokenrate = spec->rate; + bucket->maxtokens = spec->maxlimit; + } + UNLOCK (&bucket->lock); + + /* next token tick would unqueue pending operations */ +} + +int +tbf_mod (tbf_t *tbf, tbf_opspec_t *tbfspec) +{ + int ret = 0; + tbf_bucket_t *bucket = NULL; + tbf_ops_t op = TBF_OP_MIN; + + if (!tbf || !tbfspec) + return -1; + + op = tbfspec->op; + + GF_ASSERT (op >= TBF_OP_MIN); + GF_ASSERT (op <= TBF_OP_MAX); + + bucket = *(tbf->bucket + op); + if (bucket) { + tbf_mod_bucket (bucket, tbfspec); + } else { + ret = tbf_init_bucket (tbf, tbfspec); + } + + return ret; +} + +void +tbf_throttle (tbf_t *tbf, tbf_ops_t op, unsigned long tokens_requested) +{ + char waitq = 0; + tbf_bucket_t *bucket = NULL; + tbf_throttle_t *throttle = NULL; + + GF_ASSERT (op >= TBF_OP_MIN); + GF_ASSERT (op <= TBF_OP_MAX); + + bucket = *(tbf->bucket + op); + if (!bucket) + return; + + LOCK (&bucket->lock); + { + /** + * if there are enough tokens in the bucket there is no need + * to throttle the request: therefore, consume the required + * number of tokens and continue. + */ + if (tokens_requested <= bucket->tokens) { + bucket->tokens -= tokens_requested; + } else { + throttle = tbf_init_throttle (tokens_requested); + if (!throttle) /* let it slip through for now.. */ + goto unblock; + + waitq = 1; + pthread_mutex_lock (&throttle->mutex); + list_add_tail (&throttle->list, &bucket->queued); + } + } + unblock: + UNLOCK (&bucket->lock); + + if (waitq) { + while (!throttle->done) { + pthread_cond_wait (&throttle->cond, &throttle->mutex); + } + + pthread_mutex_unlock (&throttle->mutex); + + pthread_mutex_destroy (&throttle->mutex); + pthread_cond_destroy (&throttle->cond); + + GF_FREE (throttle); + } +} |