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ec_protect.c
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ec_protect.c
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/*
* s3backer - FUSE-based single file backing store via Amazon S3
*
* Copyright 2008-2023 Archie L. Cobbs <[email protected]>
*
* This program 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; either version 2
* of the License, or (at your option) any later version.
*
* This program 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations including
* the two.
*
* You must obey the GNU General Public License in all respects for all
* of the code used other than OpenSSL. If you modify file(s) with this
* exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do
* so, delete this exception statement from your version. If you delete
* this exception statement from all source files in the program, then
* also delete it here.
*/
#include "s3backer.h"
#include "ec_protect.h"
#include "hash.h"
#include "util.h"
/*
* Written block information caching.
*
* The purpose of this is to minimize problems from the weak guarantees provided
* by S3's "eventual consistency". We do this by:
*
* (a) Enforcing a minimum delay between the completion of one PUT/DELETE
* of a block and the initiation of the next PUT/DELETE of the same block.
* This is to allow the PUT/DELETE to be propagated across the S3 network.
* (b) Caching the ETag (which is usually just the MD5 checksum) of every block
* written for some minimum time and verifying that data returned from subsequent
* GETs matches, allowing us to verify we are not reading back stale data.
*
* The theory here is that if you choose a value of X seconds large enough, and you
* assume all S3 reads will be up-to-date X seconds after they've been written, then
* using X seconds with (a) and (b) above guarantees consistent reads. However, this
* guarantee is only as good as that assumption about maximum convergence time X.
*
* These are the relevant configuration parameters:
*
* min_write_delay
* Minimum time delay after a PUT/DELETE completes before the next PUT/DELETE
* can be initiated (for the same block).
* cache_time
* How long after writing a block we'll remember its ETag. This must be
* at least as long as min_write_delay. This value determines the limit of
* our ability to detect out-of-date reads. Zero means infinity.
* cache_size
* Maximum number of blocks we'll track at one time. When the table is full
* and no WRITTEN blocks have exipred yet, additional writes will block.
* Note if cache_time is zero (infinity), then this must be big enough to
* contain ALL of the blocks, otherwise you will eventually deadlock.
*
* Blocks we are currently tracking can be in the following states:
*
* State Meaning Hash table List Other invariants
* ----- ------- ---------- ---- ----------------
*
* CLEAN initial state No No
* WRITING currently being written Yes No timestamp == 0, u.data valid
* WRITTEN written and ETag cached Yes Yes timestamp != 0, u.etag valid
*
* The steady state for a block is CLEAN. WRITING means the block is currently
* being sent; concurrent attempts to write will simply sleep until the first one
* finishes. WRITTEN is where you go after successfully writing a block. The WRITTEN
* state will timeout (and the entry revert to CLEAN) after cache_time.
*
* If another attempt to write a block in the WRITTEN state occurs occurs before
* min_write_delay has elapsed, the second attempt will sleep until it has.
*
* In the WRITING state, we have the data still so any reads are local. In the WRITTEN
* state we don't have the data but we do know its ETag, so therefore we can verify what
* comes back from the read; if it doesn't verify, we retry as we would with any other error.
*
* There is a special case that occurs when we get an error while WRITING: in this case,
* we don't know whether the block was successfully written or not, so we transition to
* WRITTEN but with an all zeros ETag indicating "don't know".
*
* If we hit the 'cache_size' limit, we sleep a little while and then try again.
*
* We keep track of blocks in 'struct block_info' structures. These structures
* are themselves tracked in both (a) a linked list and (b) a hash table.
*
* The hash table contains all structures, and is keyed by block number. This
* is simply so we can quickly find the structure associated with a specific block.
*
* The linked list contains WRITTEN blocks, and is sorted in increasing order by timestamp,
* so the entries that will expire first are at the front of the list.
*/
struct block_info {
s3b_block_t block_num; // block number - MUST BE FIRST
uint64_t timestamp; // time PUT/DELETE completed (if WRITTEN)
TAILQ_ENTRY(block_info) link; // list entry link
union {
const void *data; // block's actual content (if WRITING)
u_char etag[MD5_DIGEST_LENGTH];// block's ETag (if WRITTEN)
} u;
};
// Internal state
struct ec_protect_private {
struct ec_protect_conf *config;
struct s3backer_store *inner;
struct ec_protect_stats stats;
struct s3b_hash *hashtable;
u_int num_sleepers; // count of sleeping threads
TAILQ_HEAD(, block_info) list;
block_list_func_t *survey_callback;// non-zero survey is running and this is the callback
void *survey_arg; // non-zero survey is running and this is the arg
pthread_mutex_t mutex;
pthread_cond_t space_cond; // signaled when cache space available
pthread_cond_t sleepers_cond; // signaled when no more threads are sleeping
pthread_cond_t never_cond; // never signaled; used for sleeping only
};
// s3backer_store functions
static int ec_protect_create_threads(struct s3backer_store *s3b);
static int ec_protect_meta_data(struct s3backer_store *s3b, off_t *file_sizep, u_int *block_sizep);
static int ec_protect_set_mount_token(struct s3backer_store *s3b, int32_t *old_valuep, int32_t new_value);
static int ec_protect_read_block(struct s3backer_store *s3b, s3b_block_t block_num, void *dest,
u_char *actual_etag, const u_char *expect_etag, int strict);
static int ec_protect_write_block(struct s3backer_store *s3b, s3b_block_t block_num, const void *src, u_char *etag,
check_cancel_t *check_cancel, void *check_cancel_arg);
static int ec_protect_flush_blocks(struct s3backer_store *s3b, const s3b_block_t *block_nums, u_int num_blocks, long timeout);
static int ec_protect_shutdown(struct s3backer_store *s3b);
static void ec_protect_destroy(struct s3backer_store *s3b);
// Misc
static uint64_t ec_protect_sleep_until(struct ec_protect_private *priv, pthread_cond_t *cond, uint64_t wake_time_millis);
static void ec_protect_scrub_expired_writtens(struct ec_protect_private *priv, uint64_t current_time);
static uint64_t ec_protect_get_time(void);
static int ec_protect_survey_non_zero(struct s3backer_store *s3b, block_list_func_t *callback, void *arg);
static s3b_hash_visit_t ec_protect_append_block_list;
static s3b_hash_visit_t ec_protect_free_one;
// Invariants checking
#ifndef NDEBUG
static s3b_hash_visit_t ec_protect_check_one;
static void ec_protect_check_invariants(struct ec_protect_private *priv);
#define EC_PROTECT_CHECK_INVARIANTS(priv) ec_protect_check_invariants(priv)
#else
#define EC_PROTECT_CHECK_INVARIANTS(priv) do { } while (0)
#endif
// Special all-zeros MD5 value signifying a zeroed block
static const u_char zero_etag[MD5_DIGEST_LENGTH];
// Special all-ones MD5 value signifying a just-written block whose content is unknown
static u_char unknown_etag[MD5_DIGEST_LENGTH];
/*
* Constructor
*
* On error, returns NULL and sets `errno'.
*/
struct s3backer_store *
ec_protect_create(struct ec_protect_conf *config, struct s3backer_store *inner)
{
struct s3backer_store *s3b;
struct ec_protect_private *priv;
int r;
// Initialize structures
if ((s3b = calloc(1, sizeof(*s3b))) == NULL) {
r = errno;
(*config->log)(LOG_ERR, "calloc(): %s", strerror(r));
goto fail0;
}
s3b->create_threads = ec_protect_create_threads;
s3b->meta_data = ec_protect_meta_data;
s3b->set_mount_token = ec_protect_set_mount_token;
s3b->read_block = ec_protect_read_block;
s3b->write_block = ec_protect_write_block;
s3b->bulk_zero = generic_bulk_zero;
s3b->flush_blocks = ec_protect_flush_blocks;
s3b->survey_non_zero = ec_protect_survey_non_zero;
s3b->shutdown = ec_protect_shutdown;
s3b->destroy = ec_protect_destroy;
if ((priv = calloc(1, sizeof(*priv))) == NULL) {
r = errno;
(*config->log)(LOG_ERR, "calloc(): %s", strerror(r));
goto fail1;
}
priv->config = config;
priv->inner = inner;
if ((r = pthread_mutex_init(&priv->mutex, NULL)) != 0)
goto fail2;
if ((r = pthread_cond_init(&priv->space_cond, NULL)) != 0)
goto fail3;
if ((r = pthread_cond_init(&priv->sleepers_cond, NULL)) != 0)
goto fail4;
if ((r = pthread_cond_init(&priv->never_cond, NULL)) != 0)
goto fail5;
TAILQ_INIT(&priv->list);
if ((r = s3b_hash_create(&priv->hashtable, config->cache_size)) != 0)
goto fail6;
s3b->data = priv;
memset(unknown_etag, 0xff, sizeof(unknown_etag));
// Done
EC_PROTECT_CHECK_INVARIANTS(priv);
return s3b;
fail6:
pthread_cond_destroy(&priv->never_cond);
fail5:
pthread_cond_destroy(&priv->sleepers_cond);
fail4:
pthread_cond_destroy(&priv->space_cond);
fail3:
pthread_mutex_destroy(&priv->mutex);
fail2:
free(priv);
fail1:
free(s3b);
fail0:
(*config->log)(LOG_ERR, "ec_protect creation failed: %s", strerror(r));
errno = r;
return NULL;
}
static int
ec_protect_create_threads(struct s3backer_store *s3b)
{
struct ec_protect_private *const priv = s3b->data;
return (*priv->inner->create_threads)(priv->inner);
}
static int
ec_protect_meta_data(struct s3backer_store *s3b, off_t *file_sizep, u_int *block_sizep)
{
struct ec_protect_private *const priv = s3b->data;
return (*priv->inner->meta_data)(priv->inner, file_sizep, block_sizep);
}
static int
ec_protect_set_mount_token(struct s3backer_store *s3b, int32_t *old_valuep, int32_t new_value)
{
struct ec_protect_private *const priv = s3b->data;
return (*priv->inner->set_mount_token)(priv->inner, old_valuep, new_value);
}
static int
ec_protect_flush_blocks(struct s3backer_store *s3b, const s3b_block_t *block_nums, u_int num_blocks, long timeout)
{
struct ec_protect_private *const priv = s3b->data;
return (*priv->inner->flush_blocks)(priv->inner, block_nums, num_blocks, timeout);
}
static int
ec_protect_shutdown(struct s3backer_store *const s3b)
{
struct ec_protect_private *const priv = s3b->data;
// Grab lock and sanity check
pthread_mutex_lock(&priv->mutex);
EC_PROTECT_CHECK_INVARIANTS(priv);
// Wait for all sleeping writers to finish
while (priv->num_sleepers > 0)
pthread_cond_wait(&priv->sleepers_cond, &priv->mutex);
// Release lock
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
// Propagate to lower layer
return (*priv->inner->shutdown)(priv->inner);
}
static void
ec_protect_destroy(struct s3backer_store *const s3b)
{
struct ec_protect_private *const priv = s3b->data;
// Grab lock and sanity check
pthread_mutex_lock(&priv->mutex);
EC_PROTECT_CHECK_INVARIANTS(priv);
assert(priv->num_sleepers == 0);
// Destroy inner store
(*priv->inner->destroy)(priv->inner);
// Free structures
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
pthread_mutex_destroy(&priv->mutex);
pthread_cond_destroy(&priv->space_cond);
pthread_cond_destroy(&priv->sleepers_cond);
pthread_cond_destroy(&priv->never_cond);
s3b_hash_foreach(priv->hashtable, ec_protect_free_one, NULL);
s3b_hash_destroy(priv->hashtable);
free(priv);
free(s3b);
}
void
ec_protect_get_stats(struct s3backer_store *s3b, struct ec_protect_stats *stats)
{
struct ec_protect_private *const priv = s3b->data;
pthread_mutex_lock(&priv->mutex);
memcpy(stats, &priv->stats, sizeof(*stats));
stats->current_cache_size = s3b_hash_size(priv->hashtable);
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
}
void
ec_protect_clear_stats(struct s3backer_store *s3b)
{
struct ec_protect_private *const priv = s3b->data;
pthread_mutex_lock(&priv->mutex);
memset(&priv->stats, 0, sizeof(priv->stats));
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
}
static int
ec_protect_survey_non_zero(struct s3backer_store *s3b, block_list_func_t *callback, void *arg)
{
struct ec_protect_private *const priv = s3b->data;
struct block_list list;
int r;
// Lock mutex
pthread_mutex_lock(&priv->mutex);
assert(priv->survey_callback == NULL);
// Record survey in progress
priv->survey_callback = callback;
priv->survey_arg = arg;
// Inventory all blocks currently in the cache; we don't bother trying to discern the zero blocks
block_list_init(&list);
if ((r = s3b_hash_foreach(priv->hashtable, ec_protect_append_block_list, &list)) != 0)
goto done;
// Unlock mutex
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
// Report all blocks inventoried above
(*callback)(arg, list.blocks, list.num_blocks);
block_list_free(&list);
// Invoke lower layer
r = (*priv->inner->survey_non_zero)(priv->inner, callback, arg);
// Lock mutex
pthread_mutex_lock(&priv->mutex);
// Finish up
assert(priv->survey_callback != NULL);
priv->survey_callback = NULL;
priv->survey_arg = NULL;
done:
// Done
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
return r;
}
static int
ec_protect_append_block_list(void *arg, void *value)
{
struct block_info *const entry = value;
struct block_list *const list = arg;
return block_list_append(list, entry->block_num);
}
static int
ec_protect_read_block(struct s3backer_store *const s3b, s3b_block_t block_num, void *dest,
u_char *actual_etag, const u_char *expect_etag, int strict)
{
struct ec_protect_private *const priv = s3b->data;
struct ec_protect_conf *const config = priv->config;
u_char etag[MD5_DIGEST_LENGTH];
struct block_info *binfo;
// Sanity check
if (config->block_size == 0)
return EINVAL;
// Grab lock and sanity check
pthread_mutex_lock(&priv->mutex);
EC_PROTECT_CHECK_INVARIANTS(priv);
again:
// Scrub the list of WRITTENs
ec_protect_scrub_expired_writtens(priv, ec_protect_get_time());
// Find info for this block
if ((binfo = s3b_hash_get(priv->hashtable, block_num)) != NULL) {
// In WRITING state: we have the data already!
if (binfo->timestamp == 0) {
if (binfo->u.data == NULL)
memset(dest, 0, config->block_size);
else
memcpy(dest, binfo->u.data, config->block_size);
if (actual_etag != NULL)
memset(actual_etag, 0, MD5_DIGEST_LENGTH); // we don't know it yet!
priv->stats.cache_data_hits++;
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
return 0;
}
// In WRITTEN state: special case: unknown ETag. Wait for settle time, then try again
if (memcmp(binfo->u.etag, unknown_etag, MD5_DIGEST_LENGTH) == 0) {
// Have we waited long enough already? If so, reset block and try again
if (ec_protect_get_time() >= binfo->timestamp + config->min_write_delay) {
TAILQ_REMOVE(&priv->list, binfo, link);
s3b_hash_remove(priv->hashtable, binfo->block_num);
free(binfo);
goto again;
}
// Sleep to allow previous failed write to resolve, and then try again
ec_protect_sleep_until(priv, NULL, binfo->timestamp + config->min_write_delay);
goto again;
}
// In WRITTEN state: special case: zero block
if (memcmp(binfo->u.etag, zero_etag, MD5_DIGEST_LENGTH) == 0) {
if (expect_etag != NULL && strict && memcmp(expect_etag, zero_etag, MD5_DIGEST_LENGTH) != 0)
(*config->log)(LOG_ERR, "ec_protect_read_block(): impossible expected ETag?");
memset(dest, 0, config->block_size);
if (actual_etag != NULL)
memset(actual_etag, 0, MD5_DIGEST_LENGTH);
priv->stats.cache_data_hits++;
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
return 0;
}
// In WRITTEN state: we know the expected ETag
memcpy(etag, binfo->u.etag, MD5_DIGEST_LENGTH);
if (expect_etag != NULL && strict && memcmp(etag, expect_etag, MD5_DIGEST_LENGTH) != 0)
(*config->log)(LOG_ERR, "ec_protect_read_block(): impossible expected ETag?");
expect_etag = etag;
strict = 1;
}
// Release lock
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
// Read block normally
return (*priv->inner->read_block)(priv->inner, block_num, dest, actual_etag, expect_etag, strict);
}
static int
ec_protect_write_block(struct s3backer_store *const s3b, s3b_block_t block_num, const void *src, u_char *caller_etag,
check_cancel_t *check_cancel, void *check_cancel_arg)
{
struct ec_protect_private *const priv = s3b->data;
struct ec_protect_conf *const config = priv->config;
u_char etag[MD5_DIGEST_LENGTH];
struct block_info *binfo;
uint64_t current_time;
uint64_t delay;
int r;
// Sanity check
if (config->block_size == 0)
return EINVAL;
// Grab lock
pthread_mutex_lock(&priv->mutex);
// Conservatively disqualify any non-zero block as being zero in any ongoing non-zero survey
if (src != NULL && priv->survey_callback != NULL)
(*priv->survey_callback)(priv->survey_arg, &block_num, 1);
again:
// Sanity check
EC_PROTECT_CHECK_INVARIANTS(priv);
// Scrub the list of WRITTENs
current_time = ec_protect_get_time();
ec_protect_scrub_expired_writtens(priv, current_time);
// Find info for this block
binfo = s3b_hash_get(priv->hashtable, block_num);
// CLEAN case: add new entry in state WRITING and write the block
if (binfo == NULL) {
// If we have reached max cache capacity, wait until there's more room
if (s3b_hash_size(priv->hashtable) >= config->cache_size) {
// Report deadlock situation
if (config->cache_time == 0)
(*config->log)(LOG_ERR, "md5 cache is full, but timeout is infinite: you have write deadlock!");
// Sleep until space becomes available
if ((binfo = TAILQ_FIRST(&priv->list)) != NULL && config->cache_time > 0)
delay = ec_protect_sleep_until(priv, &priv->space_cond, binfo->timestamp + config->cache_time);
else
delay = ec_protect_sleep_until(priv, &priv->space_cond, 0); // sleep indefinitely...
priv->stats.cache_full_delay += delay;
goto again;
}
// Create new entry in WRITING state
if ((binfo = calloc(1, sizeof(*binfo))) == NULL) {
r = errno;
(*config->log)(LOG_ERR, "can't alloc new MD5 cache entry: %s", strerror(r));
priv->stats.out_of_memory_errors++;
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
return r;
}
binfo->block_num = block_num;
binfo->u.data = src;
s3b_hash_put_new(priv->hashtable, binfo);
writeit:
// Write the block
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
r = (*priv->inner->write_block)(priv->inner, block_num, src, etag, check_cancel, check_cancel_arg);
pthread_mutex_lock(&priv->mutex);
EC_PROTECT_CHECK_INVARIANTS(priv);
/*
* Wake up at least one thread that might be sleeping indefinitely (see above). This handles an obscure
* case where the cache is full and every entry is in the WRITING state. The next thread that attempts
* to write could be stuck waiting indefinitely unless we wake it up here.
*/
pthread_cond_signal(&priv->space_cond);
/*
* Move to state WRITTEN.
*
* If there was an error, we can't assume we know whether the write succeeded or not,
* so mark the block as WRITTEN but with a special ETag value meaning "unknown".
* We have to wait for min_write_delay before trying to read the block again.
*/
binfo->timestamp = ec_protect_get_time();
memcpy(binfo->u.etag, r == 0 ? etag : unknown_etag, MD5_DIGEST_LENGTH);
TAILQ_INSERT_TAIL(&priv->list, binfo, link);
CHECK_RETURN(pthread_mutex_unlock(&priv->mutex));
// Copy expected ETag for caller
if (r == 0 && caller_etag != NULL)
memcpy(caller_etag, etag, MD5_DIGEST_LENGTH);
return r;
}
/*
* WRITING case: wait until current write completes (hmm, why is kernel doing overlapping writes?).
* Since we know after current write completes we'll have to wait another 'min_write_time' milliseconds
* anyway, we conservatively just wait exactly that long now. There may be an extra wakeup or two,
* but that's OK.
*/
if (binfo->timestamp == 0) {
delay = ec_protect_sleep_until(priv, NULL, current_time + config->min_write_delay);
priv->stats.repeated_write_delay += delay;
goto again;
}
/*
* WRITTEN case: wait until at least 'min_write_time' milliseconds has passed since previous write.
*/
if (current_time < binfo->timestamp + config->min_write_delay) {
delay = ec_protect_sleep_until(priv, NULL, binfo->timestamp + config->min_write_delay);
priv->stats.repeated_write_delay += delay;
goto again;
}
/*
* WRITTEN case: 'min_write_time' milliseconds have indeed passed, so go back to WRITING.
*/
binfo->timestamp = 0;
binfo->u.data = src;
TAILQ_REMOVE(&priv->list, binfo, link);
goto writeit;
}
/*
* Return current time in milliseconds.
*/
static uint64_t
ec_protect_get_time(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return (uint64_t)tv.tv_sec * 1000 + (uint64_t)tv.tv_usec / 1000;
}
/*
* Remove expired WRITTEN entries from the list.
* This assumes the mutex is held.
*/
static void
ec_protect_scrub_expired_writtens(struct ec_protect_private *priv, uint64_t current_time)
{
struct ec_protect_conf *const config = priv->config;
struct block_info *binfo;
int num_removed = 0;
if (config->cache_time > 0) {
while ((binfo = TAILQ_FIRST(&priv->list)) != NULL && current_time >= binfo->timestamp + config->cache_time) {
TAILQ_REMOVE(&priv->list, binfo, link);
s3b_hash_remove(priv->hashtable, binfo->block_num);
free(binfo);
num_removed++;
}
}
switch (num_removed) {
case 0:
break;
case 1:
pthread_cond_signal(&priv->space_cond);
break;
default:
pthread_cond_broadcast(&priv->space_cond);
break;
}
}
/*
* Sleep until specified time (if non-zero) or condition (if non-NULL).
* Note: in rare cases there can be spurious early wakeups.
* Returns number of milliseconds slept.
*
* This assumes the mutex is locked.
*/
static uint64_t
ec_protect_sleep_until(struct ec_protect_private *priv, pthread_cond_t *cond, uint64_t wake_time_millis)
{
uint64_t time_before;
uint64_t time_after;
assert(cond != NULL || wake_time_millis != 0);
if (cond == NULL)
cond = &priv->never_cond;
time_before = ec_protect_get_time();
priv->num_sleepers++;
if (wake_time_millis != 0) {
struct timespec wake_time;
wake_time.tv_sec = wake_time_millis / 1000;
wake_time.tv_nsec = (wake_time_millis % 1000) * 1000000;
if (pthread_cond_timedwait(cond, &priv->mutex, &wake_time) == ETIMEDOUT)
time_after = wake_time_millis;
else
time_after = ec_protect_get_time();
} else {
pthread_cond_wait(cond, &priv->mutex);
time_after = ec_protect_get_time();
}
assert(priv->num_sleepers > 0);
if (--priv->num_sleepers == 0)
pthread_cond_broadcast(&priv->sleepers_cond);
return time_after - time_before;
}
static int
ec_protect_free_one(void *arg, void *value)
{
free(value);
return 0;
}
#ifndef NDEBUG
// Accounting structure
struct check_info {
u_int num_in_list;
u_int written;
u_int writing;
};
static int
ec_protect_check_one(void *arg, void *value)
{
struct block_info *const binfo = value;
struct check_info *const info = arg;
if (binfo->timestamp == 0)
info->writing++;
else
info->written++;
return 0;
}
static void
ec_protect_check_invariants(struct ec_protect_private *priv)
{
struct block_info *binfo;
struct check_info info;
memset(&info, 0, sizeof(info));
for (binfo = TAILQ_FIRST(&priv->list); binfo != NULL; binfo = TAILQ_NEXT(binfo, link)) {
assert(binfo->timestamp != 0);
assert(s3b_hash_get(priv->hashtable, binfo->block_num) == binfo);
info.num_in_list++;
}
s3b_hash_foreach(priv->hashtable, ec_protect_check_one, &info);
assert(info.written == info.num_in_list);
assert(info.written + info.writing == s3b_hash_size(priv->hashtable));
}
#endif