diff options
Diffstat (limited to 'database/engine/pagecache.c')
| -rw-r--r-- | database/engine/pagecache.c | 792 |
1 files changed, 792 insertions, 0 deletions
diff --git a/database/engine/pagecache.c b/database/engine/pagecache.c new file mode 100644 index 00000000..c90947a6 --- /dev/null +++ b/database/engine/pagecache.c @@ -0,0 +1,792 @@ +// SPDX-License-Identifier: GPL-3.0-or-later +#define NETDATA_RRD_INTERNALS + +#include "rrdengine.h" + +/* Forward declerations */ +static int pg_cache_try_evict_one_page_unsafe(struct rrdengine_instance *ctx); + +/* always inserts into tail */ +static inline void pg_cache_replaceQ_insert_unsafe(struct rrdengine_instance *ctx, + struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + if (likely(NULL != pg_cache->replaceQ.tail)) { + descr->prev = pg_cache->replaceQ.tail; + pg_cache->replaceQ.tail->next = descr; + } + if (unlikely(NULL == pg_cache->replaceQ.head)) { + pg_cache->replaceQ.head = descr; + } + pg_cache->replaceQ.tail = descr; +} + +static inline void pg_cache_replaceQ_delete_unsafe(struct rrdengine_instance *ctx, + struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + struct rrdeng_page_cache_descr *prev, *next; + + prev = descr->prev; + next = descr->next; + + if (likely(NULL != prev)) { + prev->next = next; + } + if (likely(NULL != next)) { + next->prev = prev; + } + if (unlikely(descr == pg_cache->replaceQ.head)) { + pg_cache->replaceQ.head = next; + } + if (unlikely(descr == pg_cache->replaceQ.tail)) { + pg_cache->replaceQ.tail = prev; + } + descr->prev = descr->next = NULL; +} + +void pg_cache_replaceQ_insert(struct rrdengine_instance *ctx, + struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + uv_rwlock_wrlock(&pg_cache->replaceQ.lock); + pg_cache_replaceQ_insert_unsafe(ctx, descr); + uv_rwlock_wrunlock(&pg_cache->replaceQ.lock); +} + +void pg_cache_replaceQ_delete(struct rrdengine_instance *ctx, + struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + uv_rwlock_wrlock(&pg_cache->replaceQ.lock); + pg_cache_replaceQ_delete_unsafe(ctx, descr); + uv_rwlock_wrunlock(&pg_cache->replaceQ.lock); +} +void pg_cache_replaceQ_set_hot(struct rrdengine_instance *ctx, + struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + uv_rwlock_wrlock(&pg_cache->replaceQ.lock); + pg_cache_replaceQ_delete_unsafe(ctx, descr); + pg_cache_replaceQ_insert_unsafe(ctx, descr); + uv_rwlock_wrunlock(&pg_cache->replaceQ.lock); +} + +struct rrdeng_page_cache_descr *pg_cache_create_descr(void) +{ + struct rrdeng_page_cache_descr *descr; + + descr = mallocz(sizeof(*descr)); + descr->page = NULL; + descr->page_length = 0; + descr->start_time = INVALID_TIME; + descr->end_time = INVALID_TIME; + descr->id = NULL; + descr->extent = NULL; + descr->flags = 0; + descr->prev = descr->next = descr->private = NULL; + descr->refcnt = 0; + descr->waiters = 0; + descr->handle = NULL; + assert(0 == uv_cond_init(&descr->cond)); + assert(0 == uv_mutex_init(&descr->mutex)); + + return descr; +} + +void pg_cache_destroy_descr(struct rrdeng_page_cache_descr *descr) +{ + uv_cond_destroy(&descr->cond); + uv_mutex_destroy(&descr->mutex); + free(descr); +} + +/* The caller must hold page descriptor lock. */ +void pg_cache_wake_up_waiters_unsafe(struct rrdeng_page_cache_descr *descr) +{ + if (descr->waiters) + uv_cond_broadcast(&descr->cond); +} + +/* + * The caller must hold page descriptor lock. + * The lock will be released and re-acquired. The descriptor is not guaranteed + * to exist after this function returns. + */ +void pg_cache_wait_event_unsafe(struct rrdeng_page_cache_descr *descr) +{ + ++descr->waiters; + uv_cond_wait(&descr->cond, &descr->mutex); + --descr->waiters; +} + +/* + * Returns page flags. + * The lock will be released and re-acquired. The descriptor is not guaranteed + * to exist after this function returns. + */ +unsigned long pg_cache_wait_event(struct rrdeng_page_cache_descr *descr) +{ + unsigned long flags; + + uv_mutex_lock(&descr->mutex); + pg_cache_wait_event_unsafe(descr); + flags = descr->flags; + uv_mutex_unlock(&descr->mutex); + + return flags; +} + +/* + * The caller must hold page descriptor lock. + * Gets a reference to the page descriptor. + * Returns 1 on success and 0 on failure. + */ +int pg_cache_try_get_unsafe(struct rrdeng_page_cache_descr *descr, int exclusive_access) +{ + if ((descr->flags & (RRD_PAGE_LOCKED | RRD_PAGE_READ_PENDING)) || + (exclusive_access && descr->refcnt)) { + return 0; + } + if (exclusive_access) + descr->flags |= RRD_PAGE_LOCKED; + ++descr->refcnt; + + return 1; +} + +/* + * The caller must hold page descriptor lock. + * Same return values as pg_cache_try_get_unsafe() without doing anything. + */ +int pg_cache_can_get_unsafe(struct rrdeng_page_cache_descr *descr, int exclusive_access) +{ + if ((descr->flags & (RRD_PAGE_LOCKED | RRD_PAGE_READ_PENDING)) || + (exclusive_access && descr->refcnt)) { + return 0; + } + + return 1; +} + +/* + * The caller must hold the page descriptor lock. + * This function may block doing cleanup. + */ +void pg_cache_put_unsafe(struct rrdeng_page_cache_descr *descr) +{ + descr->flags &= ~RRD_PAGE_LOCKED; + if (0 == --descr->refcnt) { + pg_cache_wake_up_waiters_unsafe(descr); + } + /* TODO: perform cleanup */ +} + +/* + * This function may block doing cleanup. + */ +void pg_cache_put(struct rrdeng_page_cache_descr *descr) +{ + uv_mutex_lock(&descr->mutex); + pg_cache_put_unsafe(descr); + uv_mutex_unlock(&descr->mutex); +} + +/* The caller must hold the page cache lock */ +static void pg_cache_release_pages_unsafe(struct rrdengine_instance *ctx, unsigned number) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + pg_cache->populated_pages -= number; +} + +static void pg_cache_release_pages(struct rrdengine_instance *ctx, unsigned number) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + pg_cache_release_pages_unsafe(ctx, number); + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); +} +/* + * This function will block until it reserves #number populated pages. + * It will trigger evictions or dirty page flushing if the ctx->max_cache_pages limit is hit. + */ +static void pg_cache_reserve_pages(struct rrdengine_instance *ctx, unsigned number) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + assert(number < ctx->max_cache_pages); + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + if (pg_cache->populated_pages + number >= ctx->max_cache_pages + 1) + debug(D_RRDENGINE, "=================================\nPage cache full. Reserving %u pages.\n=================================", + number); + while (pg_cache->populated_pages + number >= ctx->max_cache_pages + 1) { + if (!pg_cache_try_evict_one_page_unsafe(ctx)) { + /* failed to evict */ + struct completion compl; + struct rrdeng_cmd cmd; + + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); + + init_completion(&compl); + cmd.opcode = RRDENG_FLUSH_PAGES; + cmd.completion = &compl; + rrdeng_enq_cmd(&ctx->worker_config, &cmd); + /* wait for some pages to be flushed */ + debug(D_RRDENGINE, "%s: waiting for pages to be written to disk before evicting.", __func__); + wait_for_completion(&compl); + destroy_completion(&compl); + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + } + } + pg_cache->populated_pages += number; + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); +} + +/* + * This function will attempt to reserve #number populated pages. + * It may trigger evictions if the ctx->cache_pages_low_watermark limit is hit. + * Returns 0 on failure and 1 on success. + */ +static int pg_cache_try_reserve_pages(struct rrdengine_instance *ctx, unsigned number) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + unsigned count = 0; + int ret = 0; + + assert(number < ctx->max_cache_pages); + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + if (pg_cache->populated_pages + number >= ctx->cache_pages_low_watermark + 1) { + debug(D_RRDENGINE, + "=================================\nPage cache full. Trying to reserve %u pages.\n=================================", + number); + do { + if (!pg_cache_try_evict_one_page_unsafe(ctx)) + break; + ++count; + } while (pg_cache->populated_pages + number >= ctx->cache_pages_low_watermark + 1); + debug(D_RRDENGINE, "Evicted %u pages.", count); + } + + if (pg_cache->populated_pages + number < ctx->max_cache_pages + 1) { + pg_cache->populated_pages += number; + ret = 1; /* success */ + } + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); + + return ret; +} + +/* The caller must hold the page cache and the page descriptor locks in that order */ +static void pg_cache_evict_unsafe(struct rrdengine_instance *ctx, struct rrdeng_page_cache_descr *descr) +{ + free(descr->page); + descr->page = NULL; + descr->flags &= ~RRD_PAGE_POPULATED; + pg_cache_release_pages_unsafe(ctx, 1); + ++ctx->stats.pg_cache_evictions; +} + +/* + * The caller must hold the page cache lock. + * Lock order: page cache -> replaceQ -> descriptor + * This function iterates all pages and tries to evict one. + * If it fails it sets in_flight_descr to the oldest descriptor that has write-back in progress, + * or it sets it to NULL if no write-back is in progress. + * + * Returns 1 on success and 0 on failure. + */ +static int pg_cache_try_evict_one_page_unsafe(struct rrdengine_instance *ctx) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + unsigned long old_flags; + struct rrdeng_page_cache_descr *descr; + + uv_rwlock_wrlock(&pg_cache->replaceQ.lock); + for (descr = pg_cache->replaceQ.head ; NULL != descr ; descr = descr->next) { + uv_mutex_lock(&descr->mutex); + old_flags = descr->flags; + if ((old_flags & RRD_PAGE_POPULATED) && !(old_flags & RRD_PAGE_DIRTY) && pg_cache_try_get_unsafe(descr, 1)) { + /* must evict */ + pg_cache_evict_unsafe(ctx, descr); + pg_cache_put_unsafe(descr); + uv_mutex_unlock(&descr->mutex); + pg_cache_replaceQ_delete_unsafe(ctx, descr); + uv_rwlock_wrunlock(&pg_cache->replaceQ.lock); + + return 1; + } + uv_mutex_unlock(&descr->mutex); + }; + uv_rwlock_wrunlock(&pg_cache->replaceQ.lock); + + /* failed to evict */ + return 0; +} + +/* + * TODO: last waiter frees descriptor ? + */ +void pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + Pvoid_t *PValue; + struct pg_cache_page_index *page_index; + int ret; + + uv_rwlock_rdlock(&pg_cache->metrics_index.lock); + PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, descr->id, sizeof(uuid_t)); + assert(NULL != PValue); + page_index = *PValue; + uv_rwlock_rdunlock(&pg_cache->metrics_index.lock); + + uv_rwlock_wrlock(&page_index->lock); + ret = JudyLDel(&page_index->JudyL_array, (Word_t)(descr->start_time / USEC_PER_SEC), PJE0); + uv_rwlock_wrunlock(&page_index->lock); + if (unlikely(0 == ret)) { + error("Page under deletion was not in index."); + if (unlikely(debug_flags & D_RRDENGINE)) + print_page_cache_descr(descr); + goto destroy; + } + assert(1 == ret); + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + ++ctx->stats.pg_cache_deletions; + --pg_cache->page_descriptors; + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); + + uv_mutex_lock(&descr->mutex); + while (!pg_cache_try_get_unsafe(descr, 1)) { + debug(D_RRDENGINE, "%s: Waiting for locked page:", __func__); + if(unlikely(debug_flags & D_RRDENGINE)) + print_page_cache_descr(descr); + pg_cache_wait_event_unsafe(descr); + } + /* even a locked page could be dirty */ + while (unlikely(descr->flags & RRD_PAGE_DIRTY)) { + debug(D_RRDENGINE, "%s: Found dirty page, waiting for it to be flushed:", __func__); + if (unlikely(debug_flags & D_RRDENGINE)) + print_page_cache_descr(descr); + pg_cache_wait_event_unsafe(descr); + } + uv_mutex_unlock(&descr->mutex); + + if (descr->flags & RRD_PAGE_POPULATED) { + /* only after locking can it be safely deleted from LRU */ + pg_cache_replaceQ_delete(ctx, descr); + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + pg_cache_evict_unsafe(ctx, descr); + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); + } + pg_cache_put(descr); +destroy: + pg_cache_destroy_descr(descr); + pg_cache_update_metric_times(page_index); +} + +static inline int is_page_in_time_range(struct rrdeng_page_cache_descr *descr, usec_t start_time, usec_t end_time) +{ + usec_t pg_start, pg_end; + + pg_start = descr->start_time; + pg_end = descr->end_time; + + return (pg_start < start_time && pg_end >= start_time) || + (pg_start >= start_time && pg_start <= end_time); +} + +static inline int is_point_in_time_in_page(struct rrdeng_page_cache_descr *descr, usec_t point_in_time) +{ + return (point_in_time >= descr->start_time && point_in_time <= descr->end_time); +} + +/* Update metric oldest and latest timestamps efficiently when adding new values */ +void pg_cache_add_new_metric_time(struct pg_cache_page_index *page_index, struct rrdeng_page_cache_descr *descr) +{ + usec_t oldest_time = page_index->oldest_time; + usec_t latest_time = page_index->latest_time; + + if (unlikely(oldest_time == INVALID_TIME || descr->start_time < oldest_time)) { + page_index->oldest_time = descr->start_time; + } + if (likely(descr->end_time > latest_time || latest_time == INVALID_TIME)) { + page_index->latest_time = descr->end_time; + } +} + +/* Update metric oldest and latest timestamps when removing old values */ +void pg_cache_update_metric_times(struct pg_cache_page_index *page_index) +{ + Pvoid_t *firstPValue, *lastPValue; + Word_t firstIndex, lastIndex; + struct rrdeng_page_cache_descr *descr; + usec_t oldest_time = INVALID_TIME; + usec_t latest_time = INVALID_TIME; + + uv_rwlock_rdlock(&page_index->lock); + /* Find first page in range */ + firstIndex = (Word_t)0; + firstPValue = JudyLFirst(page_index->JudyL_array, &firstIndex, PJE0); + if (likely(NULL != firstPValue)) { + descr = *firstPValue; + oldest_time = descr->start_time; + } + lastIndex = (Word_t)-1; + lastPValue = JudyLLast(page_index->JudyL_array, &lastIndex, PJE0); + if (likely(NULL != lastPValue)) { + descr = *lastPValue; + latest_time = descr->end_time; + } + uv_rwlock_rdunlock(&page_index->lock); + + if (unlikely(NULL == firstPValue)) { + assert(NULL == lastPValue); + page_index->oldest_time = page_index->latest_time = INVALID_TIME; + return; + } + page_index->oldest_time = oldest_time; + page_index->latest_time = latest_time; +} + +/* If index is NULL lookup by UUID (descr->id) */ +void pg_cache_insert(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, + struct rrdeng_page_cache_descr *descr) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + Pvoid_t *PValue; + struct pg_cache_page_index *page_index; + + if (descr->flags & RRD_PAGE_POPULATED) { + pg_cache_reserve_pages(ctx, 1); + if (!(descr->flags & RRD_PAGE_DIRTY)) + pg_cache_replaceQ_insert(ctx, descr); + } + + if (unlikely(NULL == index)) { + uv_rwlock_rdlock(&pg_cache->metrics_index.lock); + PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, descr->id, sizeof(uuid_t)); + assert(NULL != PValue); + page_index = *PValue; + uv_rwlock_rdunlock(&pg_cache->metrics_index.lock); + } else { + page_index = index; + } + + uv_rwlock_wrlock(&page_index->lock); + PValue = JudyLIns(&page_index->JudyL_array, (Word_t)(descr->start_time / USEC_PER_SEC), PJE0); + *PValue = descr; + pg_cache_add_new_metric_time(page_index, descr); + uv_rwlock_wrunlock(&page_index->lock); + + uv_rwlock_wrlock(&pg_cache->pg_cache_rwlock); + ++ctx->stats.pg_cache_insertions; + ++pg_cache->page_descriptors; + uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock); +} + +/* + * Searches for a page and triggers disk I/O if necessary and possible. + * Does not get a reference. + * Returns page index pointer for given metric UUID. + */ +struct pg_cache_page_index * + pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time, usec_t end_time) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + struct rrdeng_page_cache_descr *descr = NULL, *preload_array[PAGE_CACHE_MAX_PRELOAD_PAGES]; + int i, j, k, count, found; + unsigned long flags; + Pvoid_t *PValue; + struct pg_cache_page_index *page_index; + Word_t Index; + uint8_t failed_to_reserve; + + uv_rwlock_rdlock(&pg_cache->metrics_index.lock); + PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, id, sizeof(uuid_t)); + if (likely(NULL != PValue)) { + page_index = *PValue; + } + uv_rwlock_rdunlock(&pg_cache->metrics_index.lock); + if (NULL == PValue) { + debug(D_RRDENGINE, "%s: No page was found to attempt preload.", __func__); + return NULL; + } + + uv_rwlock_rdlock(&page_index->lock); + /* Find first page in range */ + found = 0; + Index = (Word_t)(start_time / USEC_PER_SEC); + PValue = JudyLLast(page_index->JudyL_array, &Index, PJE0); + if (likely(NULL != PValue)) { + descr = *PValue; + if (is_page_in_time_range(descr, start_time, end_time)) { + found = 1; + } + } + if (!found) { + Index = (Word_t)(start_time / USEC_PER_SEC); + PValue = JudyLFirst(page_index->JudyL_array, &Index, PJE0); + if (likely(NULL != PValue)) { + descr = *PValue; + if (is_page_in_time_range(descr, start_time, end_time)) { + found = 1; + } + } + } + if (!found) { + uv_rwlock_rdunlock(&page_index->lock); + debug(D_RRDENGINE, "%s: No page was found to attempt preload.", __func__); + return page_index; + } + + for (count = 0 ; + descr != NULL && is_page_in_time_range(descr, start_time, end_time); + PValue = JudyLNext(page_index->JudyL_array, &Index, PJE0), + descr = unlikely(NULL == PValue) ? NULL : *PValue) { + /* Iterate all pages in range */ + + if (unlikely(0 == descr->page_length)) + continue; + uv_mutex_lock(&descr->mutex); + flags = descr->flags; + if (pg_cache_can_get_unsafe(descr, 0)) { + if (flags & RRD_PAGE_POPULATED) { + /* success */ + uv_mutex_unlock(&descr->mutex); + debug(D_RRDENGINE, "%s: Page was found in memory.", __func__); + continue; + } + } + if (!(flags & RRD_PAGE_POPULATED) && pg_cache_try_get_unsafe(descr, 1)) { + preload_array[count++] = descr; + if (PAGE_CACHE_MAX_PRELOAD_PAGES == count) { + uv_mutex_unlock(&descr->mutex); + break; + } + } + uv_mutex_unlock(&descr->mutex); + + }; + uv_rwlock_rdunlock(&page_index->lock); + + failed_to_reserve = 0; + for (i = 0 ; i < count && !failed_to_reserve ; ++i) { + struct rrdeng_cmd cmd; + struct rrdeng_page_cache_descr *next; + + descr = preload_array[i]; + if (NULL == descr) { + continue; + } + if (!pg_cache_try_reserve_pages(ctx, 1)) { + failed_to_reserve = 1; + break; + } + cmd.opcode = RRDENG_READ_EXTENT; + cmd.read_extent.page_cache_descr[0] = descr; + /* don't use this page again */ + preload_array[i] = NULL; + for (j = 0, k = 1 ; j < count ; ++j) { + next = preload_array[j]; + if (NULL == next) { + continue; + } + if (descr->extent == next->extent) { + /* same extent, consolidate */ + if (!pg_cache_try_reserve_pages(ctx, 1)) { + failed_to_reserve = 1; + break; + } + cmd.read_extent.page_cache_descr[k++] = next; + /* don't use this page again */ + preload_array[j] = NULL; + } + } + cmd.read_extent.page_count = k; + rrdeng_enq_cmd(&ctx->worker_config, &cmd); + } + if (failed_to_reserve) { + debug(D_RRDENGINE, "%s: Failed to reserve enough memory, canceling I/O.", __func__); + for (i = 0 ; i < count ; ++i) { + descr = preload_array[i]; + if (NULL == descr) { + continue; + } + pg_cache_put(descr); + } + } + if (!count) { + /* no such page */ + debug(D_RRDENGINE, "%s: No page was eligible to attempt preload.", __func__); + } + return page_index; +} + +/* + * Searches for a page and gets a reference. + * When point_in_time is INVALID_TIME get any page. + * If index is NULL lookup by UUID (id). + */ +struct rrdeng_page_cache_descr * + pg_cache_lookup(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id, + usec_t point_in_time) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + struct rrdeng_page_cache_descr *descr = NULL; + unsigned long flags; + Pvoid_t *PValue; + struct pg_cache_page_index *page_index; + Word_t Index; + uint8_t page_not_in_cache; + + if (unlikely(NULL == index)) { + uv_rwlock_rdlock(&pg_cache->metrics_index.lock); + PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, id, sizeof(uuid_t)); + if (likely(NULL != PValue)) { + page_index = *PValue; + } + uv_rwlock_rdunlock(&pg_cache->metrics_index.lock); + if (NULL == PValue) { + return NULL; + } + } else { + page_index = index; + } + pg_cache_reserve_pages(ctx, 1); + + page_not_in_cache = 0; + uv_rwlock_rdlock(&page_index->lock); + while (1) { + Index = (Word_t)(point_in_time / USEC_PER_SEC); + PValue = JudyLLast(page_index->JudyL_array, &Index, PJE0); + if (likely(NULL != PValue)) { + descr = *PValue; + } + if (NULL == PValue || + 0 == descr->page_length || + (INVALID_TIME != point_in_time && + !is_point_in_time_in_page(descr, point_in_time))) { + /* non-empty page not found */ + uv_rwlock_rdunlock(&page_index->lock); + + pg_cache_release_pages(ctx, 1); + return NULL; + } + uv_mutex_lock(&descr->mutex); + flags = descr->flags; + if ((flags & RRD_PAGE_POPULATED) && pg_cache_try_get_unsafe(descr, 0)) { + /* success */ + uv_mutex_unlock(&descr->mutex); + debug(D_RRDENGINE, "%s: Page was found in memory.", __func__); + break; + } + if (!(flags & RRD_PAGE_POPULATED) && pg_cache_try_get_unsafe(descr, 1)) { + struct rrdeng_cmd cmd; + + uv_rwlock_rdunlock(&page_index->lock); + + cmd.opcode = RRDENG_READ_PAGE; + cmd.read_page.page_cache_descr = descr; + rrdeng_enq_cmd(&ctx->worker_config, &cmd); + + debug(D_RRDENGINE, "%s: Waiting for page to be asynchronously read from disk:", __func__); + if(unlikely(debug_flags & D_RRDENGINE)) + print_page_cache_descr(descr); + while (!(descr->flags & RRD_PAGE_POPULATED)) { + pg_cache_wait_event_unsafe(descr); + } + /* success */ + /* Downgrade exclusive reference to allow other readers */ + descr->flags &= ~RRD_PAGE_LOCKED; + pg_cache_wake_up_waiters_unsafe(descr); + uv_mutex_unlock(&descr->mutex); + rrd_stat_atomic_add(&ctx->stats.pg_cache_misses, 1); + return descr; + } + uv_rwlock_rdunlock(&page_index->lock); + debug(D_RRDENGINE, "%s: Waiting for page to be unlocked:", __func__); + if(unlikely(debug_flags & D_RRDENGINE)) + print_page_cache_descr(descr); + if (!(flags & RRD_PAGE_POPULATED)) + page_not_in_cache = 1; + pg_cache_wait_event_unsafe(descr); + uv_mutex_unlock(&descr->mutex); + + /* reset scan to find again */ + uv_rwlock_rdlock(&page_index->lock); + } + uv_rwlock_rdunlock(&page_index->lock); + + if (!(flags & RRD_PAGE_DIRTY)) + pg_cache_replaceQ_set_hot(ctx, descr); + pg_cache_release_pages(ctx, 1); + if (page_not_in_cache) + rrd_stat_atomic_add(&ctx->stats.pg_cache_misses, 1); + else + rrd_stat_atomic_add(&ctx->stats.pg_cache_hits, 1); + return descr; +} + +struct pg_cache_page_index *create_page_index(uuid_t *id) +{ + struct pg_cache_page_index *page_index; + + page_index = mallocz(sizeof(*page_index)); + page_index->JudyL_array = (Pvoid_t) NULL; + uuid_copy(page_index->id, *id); + assert(0 == uv_rwlock_init(&page_index->lock)); + page_index->oldest_time = INVALID_TIME; + page_index->latest_time = INVALID_TIME; + + return page_index; +} + +static void init_metrics_index(struct rrdengine_instance *ctx) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + pg_cache->metrics_index.JudyHS_array = (Pvoid_t) NULL; + assert(0 == uv_rwlock_init(&pg_cache->metrics_index.lock)); +} + +static void init_replaceQ(struct rrdengine_instance *ctx) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + pg_cache->replaceQ.head = NULL; + pg_cache->replaceQ.tail = NULL; + assert(0 == uv_rwlock_init(&pg_cache->replaceQ.lock)); +} + +static void init_commited_page_index(struct rrdengine_instance *ctx) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + pg_cache->commited_page_index.JudyL_array = (Pvoid_t) NULL; + assert(0 == uv_rwlock_init(&pg_cache->commited_page_index.lock)); + pg_cache->commited_page_index.latest_corr_id = 0; + pg_cache->commited_page_index.nr_commited_pages = 0; +} + +void init_page_cache(struct rrdengine_instance *ctx) +{ + struct page_cache *pg_cache = &ctx->pg_cache; + + pg_cache->page_descriptors = 0; + pg_cache->populated_pages = 0; + assert(0 == uv_rwlock_init(&pg_cache->pg_cache_rwlock)); + + init_metrics_index(ctx); + init_replaceQ(ctx); + init_commited_page_index(ctx); +}
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